key: cord-0998413-lfce2xb4
authors: Koltai, Tomas; Fliegel, Larry
title: Role of Silymarin in Cancer Treatment: Facts, Hypotheses, and Questions
date: 2022-01-12
journal: J Evid Based Integr Med
DOI: 10.1177/2515690x211068826
sha: 053e95266c30eb386f416ea0dc6241e69abc9931
doc_id: 998413
cord_uid: lfce2xb4

The flavonoid silymarin extracted from the seeds of Sylibum marianum is a mixture of 6 flavolignan isomers. The 3 more important isomers are silybin (or silibinin), silydianin, and silychristin. Silybin is functionally the most active of these compounds. This group of flavonoids has been extensively studied and they have been used as hepato-protective substances for the mushroom Amanita phalloides intoxication and mainly chronic liver diseases such as alcoholic cirrhosis and nonalcoholic fatty liver. Hepatitis C progression is not, or slightly, modified by silymarin. Recently, it has also been proposed for SARS COVID-19 infection therapy. The biochemical and molecular mechanisms of action of these substances in cancer are subjects of ongoing research. Paradoxically, many of its identified actions such as antioxidant, promoter of ribosomal synthesis, and mitochondrial membrane stabilization, may seem protumoral at first sight, however, silymarin compounds have clear anticancer effects. Some of them are: decreasing migration through multiple targeting, decreasing hypoxia inducible factor-1α expression, inducing apoptosis in some malignant cells, and inhibiting promitotic signaling among others. Interestingly, the antitumoral activity of silymarin compounds is limited to malignant cells while the nonmalignant cells seem not to be affected. Furthermore, there is a long history of silymarin use in human diseases without toxicity after prolonged administration. The ample distribution and easy accessibility to milk thistle—the source of silymarin compounds, its over the counter availability, the fact that it is a weed, some controversial issues regarding bioavailability, and being a nutraceutical rather than a drug, has somehow led medical professionals to view its anticancer effects with skepticism. This is a fundamental reason why it never achieved bedside status in cancer treatment. However, in spite of all the antitumoral effects, silymarin actually has dual effects and in some cases such as pancreatic cancer it can promote stemness. This review deals with recent investigations to elucidate the molecular actions of this flavonoid in cancer, and to consider the possibility of repurposing it. Particular attention is dedicated to silymarin's dual role in cancer and to some controversies of its real effectiveness.

Research on plants and their possible curative properties is not new. It has been occurring since ancient times. In the last 200 years this search has become more scientifically oriented and led to discoveries such as curare, strychnine, atropine, salicylate, digitalis, and more recently taxanes, artemisinin, vitamins, and many others. These naturally originated molecules "have cellular targets similar to those of new drugs developed by pharmaceutical companies." 1 Many of these natural products were so strikingly important for human health that they swiftly entered clinical practice. Sometimes, they were favorably modified by the pharmaceutical industry and then derivatives with enhanced benefits were born. While taxane compounds are one of the best examples of a success story in oncology, other compounds, not so blatantly effective as taxanes are on the waiting list. There is also a group of natural products that were, and are, used for known diseases other than cancer. In some cases, their antitumoral effects were slowly recognized and they were repurposed. Silymarin is one of this type of products, with some recognized antitumor effects however, repurposing has not yet occurred. Seeds of Silybum marianum, 2 popularly known as milk thistle, have been used since ancient times to treat diverse ailments, and more recently liver damage due to toxins, particularly Amanita phaloides poisoning (but including many others such as carbon tetrachloride, 3 metals, allylalcohol) and alcohol-induced damage, including hepatitis, cirrhosis, and jaundice. 4-6 (From a technical point, what are commonly called seeds are actually fruits, but we shall call them seeds following other publication precedents). The last 15 years have witnessed a growing interest in silymarin and the plant it comes from: Silybum marianum (L.) Gaertn (also known as Carduus marianus and wild artichoke).

Although Silymarin is probably the most thoroughly studied nutraceutical, it is looked upon with skepticism by the medical profession for multiple reasons, such as:

1. ample distribution and easy accessibility to milk thistle; 2. over the counter availability; 3. the fact that it is a weed; 4. some controversial issues regarding bioavailability, and pharmacological actions; 5. its status as a nutraceutical rather than a drug according to FDA; 6. its vulgarization through many nonscientific Internet pages dedicated to silymarin compounds; 7. the enormous number of manufacturers, many of them scarcely known ( Figure 1 ); 8. the direct consequence of this "popularization" is that it is available over the counter at the herbalist shop or through the Internet, rather than with a prescription in the pharmacy; 7 9. the lack of striking effects on the disease; 10 . the fact that it is not usually considered in university-level pharmacology courses.

Definition. Silymarin is the standardized extract obtained from the dried seeds of Silybum marianum (milk thistle) containing approximately 70% to 80% of the silymarin complex and an approximately 20% to 30% chemically undefined fraction, comprising mostly other polyphenolic compounds. The main component is silybin (silibinin). Silymarin and silybin are not synonyms. However, many older reports indistinctly use one or the other term, leading to some confusion. Silymarin extract and its components may frequently differ in their effects due to differences in solubility and bioavailability.

History. Silymarin has been used in Europe since the fourth century BCE by Theophrastus of Eresus, and reappears in the year 65 of current era in Pedanius Dioscorides' De Materia Medica. Here he proposed milk thistle for the treatment of serpent venom bite and called it silybon. 8 It does not seem to be part of Traditional Chinese Medicine. 9 It was also used in Ancient Egypt, 10 however, we do not know exactly for what purpose. 11 During the Renaissance some of the therapeutic effects were discovered and published by herbalists and physicians such as Pietro Andrea Mattioli (1544) and Hieronymus Bock (1539), among others. In the seventeenth century, an English botanist, Nicholas Culpeper, suggested that milk thistle was useful for liver diseases.

Location and Habitat. This invasive annual plant was originally found in the Mediterranean basin, but now it is present in all the continents. It requires dry, warm soil and it is very competitive eliminating other plants. 12 Chemistry. The standardized extract obtained from the seeds of Sylibum marianum is known as silymarin which contains between 70% and 80% of silymarin flavolignans. Sylibum marianum is a mixture of 8 flavolignan structurally related isomers: silybin (or silibinin), isosilibinin, silydianin, silychristin, isosilychristin, and taxifolin. 13, 14 The main component of silymarin is Silibinin which is a compound consisting of equal amounts of silybin A and silybin B (CAS 22888-70-6).

Average composition of silymarin.

Silybin 60% to 70% Silychristin 20% Silydianin 10% Isosilybin 5% Taxifolin 1% Small amounts of the flavonoids: quercetin, kaempferol, apigenin, naringin, eriodyctiol.

In 1959, Möschlin isolated silybin, 15 and then in 1968 silymarin chemistry was described in detail by Wagner et al, 16, 17 and Pelter and Hansel. 18 Today, more than 50 years have elapsed since the initial hepatic antitoxic and protective function of the compound was discovered and now, its antitumor activity is under scrutiny (Figures 2 to 4) . Silymarin, the active principal component of milk thistle, was originally thought to be one substance, until it was discovered that it is actually composed of a group of different flavolignans (Box 1).

Silybin is stable in acidic conditions but unstable under alkaline conditions. Alkaline media disrupt flavolignan's skeleton. This is important because the extracellular matrix of tumors has a low pH (approximate pH = 6.8), while intracellular tumor pH is alkaline (approximate pH = 7.5), but only slightly more alkaline than normal cell intracellular pH (approximately = 7.2). 19 Normal cells, on the other hand, have an alkaline extracellular milieu (approximate pH = 7.35). We presume, without evidence to sustain the presumption, that silybin can reach the malignant cell's acidic extracellular space without degradation. This singular feature, the acidic extracellular pH of tumors, 20 may explain why silybin effects differ in normal versus malignant cells. Silymarin may be able to better access the malignant cell compared with normal cells. This theory needs experimental confirmation.

Production. Silymarin extract is obtained by compressing the seeds which leads to a loss of lipids. Then, the active principal component is extracted with acetone, methanol, ethanol, or ethyl acetate. After a second lipid and impurities extraction, what is left is a mixture of flavolignans called silymarin. 21 Silybin is obtained from silymarin through methanolic extraction.

Biological activity. In 1975, Desplaces et al 27 showed that silymarin had a protective effect on hepatocytes against phalloidin, the toxin of Amanita phalloides, when it was administered before the poison. When it was given immediately after phalloidin, it still protected hepatocytes but when given 30 min later, this protective action was negligible. Phalloidin produces acute hemorrhagic necrosis of hepatocytes. When silymarin was administered before the poison there were no morphologic (electron microscopic level) or biochemical signs of hepatic lesions. 28 Silymarin was adopted as an "hepato-protector" by lay persons and the medical profession based on sometimes controversial evidence.

Hepato-protection. For example in:

1. Chronic hepatitis B and C: silymarin was able to lower transaminases but there was no change in viral load. 29 However, Fried et al did not find benefits in chronic hepatitis C virus infected patients with high doses of silymarin, and did not find effective lowering of transaminases. 30 In spite of the evidence favoring its benefits in chronic liver disease, "the overall efficacy of silymarin remains unclear" Figure 1 . A glimpse of the multiple brands and presentations of silymarin compounds in the US and European markets with the resultant "vulgarization." There are many "silymarins" developed in well accredited pharmaceutical laboratories, but there are also many produced by scarcely known sources. Most can be acquired through the Internet.

according to Tighe et al. 39 However, there are many, and some potentially beneficial, known biochemical effects of silymarin and silybin. For example, free radical scavenging and antioxidative properties of silybin are well known and have been thoroughly investigated. 40 It is considered 10-fold more antioxidant than vitamin E. In 1977, Machicao and Sonnenbichler 41 showed that silybin increased RNA synthesis in rat liver cells and mainly increased the production of ribosomal RNA and polymerase A. Shriever et al 42 found that silymarin inhibited fatty acid synthesis in rat liver: fatty-acid-synthase and ATP-citrate-lyase, 2 of the main lipogenic enzymes, were diminished by about 50%. Fiebrich and Koch 43,44 described silymarin as a blocker of prostaglandin production in vitro through inhibition of both prostaglandin synthetase and lipoxygenase. This reduction of lipoxygenation was confirmed on liver ribosomes and mitochondria as well and probably explains silymarin's hepatoprotective actions. 45 A few years later Sonnenbichler et al 46 presented the first evidence that silymarin acted in a different way in noncancerous hepatic tissue and malignant cells: in the first case it stimulated DNA synthesis, in the second it did not. Silymarin is also a potent blocker of cyclic AMP breakdown (in vitro) by a Figure 2 . Milk thistle and the chemical structure of silybin (C25 H22 O10), with its proprietary numbering. Of note, is the similarity between silybin and steroid hormones. The lower panel shows silibinin's structural formula where 3 different chemical groups can be identified: a taxifolin and a coniferyl alcohol united by an oxirane ring. According to Biedermann et al, 22 "the 20-OH group was established to be the most active radical scavenging moiety and also the most important group responsible for the lipoperoxidation inhibitory activity." Positions 2-3 also play a role in antioxidant activity because these positions can be oxidized to produce 2-3 dehydrosilybin (see Figure 3 ). Silybin has 5 hydroxyl groups in positions 3, 5, 7, 20, and 23 which are the targets to produce silybin derivatives. Positions 7 and 20 are usual sites of glucuronidation of silybin during its conjugation in human metabolism. phosphodiesterase preparation, 47 an inhibitor of histamine release from human basophil leukocytes, 48 dose-dependent downregulator of in vitro lymphocyte blastogenesis 49 and alters the mitochondrial electron transport chain through mitochondrial calcium release, 50 in addition to its antioxidant properties. 51 Immunostimulatory effects of silymarin were also described in experimental models, but not in the context of cancer treatment. 52, 53 Silymarin and Other Diseases (Table 1) Silymarin has been investigated and proposed for the treatment of many different diseases, from Alzheimer dementia 54 to SARS 2 Covid-19, including diabetes, 55 diabetic complications, 56-58 hyperlipidemia, and hypercholesterolemia, 50-61 among others. However, in the last 15 years, the main focus has been cancer.

The first observation of silymarin's possible benefits in cancer is the 1991 publication by Mehta and Moon. 118 They showed that silymarin could act as a preventive (antipromoter) of cancer in mouse mammary glands treated with DMBA (dimethylbenzanthracene) and TPA (tetradecanoylphorbol acetate). The treatment protocol they employed made it possible to differentiate whether the chemoprevention worked at the initiation stage of carcinogenesis (DMBA phase) or during promotion (TPA phase).

A 1991 review on the advances in pharmacological studies of silymarin by Rui, 119 did not mention anticancer activities. But in 1994, Agarwal et al 120 performed a study on skin treated with TPA confirming the protective effect of this flavonoid against tumor promotion. Silymarin protected against induction of ornithine decarboxylase by TPA. Ornithine decarboxylase inhibition protects against tumor promotion. A protective effect of silymarin was also found in colon and small intestine adenocarcinoma cells induced by 1,2-dimethylhydrazine. 121 Silymarin and its components also inhibit beta-glucuronidase. 122 Valenzuela and Garrido 123 proposed 3 levels for silymarin's action in experimental animals:

(a) as an antioxidant, by scavenging prooxidant free radicals and by increasing the intracellular concentration of the tripeptide glutathione; (b) through a regulatory action of cell membrane permeability and increase in its stability against xenobiotic injury; (c) through nuclear expression, by increasing ribosomal RNA synthesis, by stimulating DNA polymerase I, and by exerting a steroid-like regulatory effect on DNA transcription.

Silymarin also inhibits rat liver cytosolic glutathione S-transferase, 124 although this function does not clearly hint towards anticancer activity. On the other hand, silymarin scavenges reactive oxygen species as noted above, and inhibits 24 Isosilybin B seems to be the most powerful anticancer fraction. 25 Silymarin and Silibinin are different concepts, however some older publications use both terms interchangeably. Silibinin is the more active form of the silymarin extract. Only silymarin extracts are available in pharmacies while researchers usually use silibinin for their experiments. Standard silymarin extracts usually contain 33.5% silybin, 13% silychristin, 8.35% isosilybin, 3.5% silydianin 26 (see Figure 5 ).

arachidonic acid metabolism in human cells, 125 has antiinflammatory effects similar to those of indomethacin, 126 protects skin against carcinogenic agents 127, 128 and ultraviolet radiation. [129] [130] [131] These publications strongly suggest a cancer-preventive activity and silymarin is slowly emerging as an anticancer drug. For example, Scambia et al 132 tested the antiproliferative activity of silymarin on human ovarian and breast cancer cell lines and found a growth-inhibiting effect on both. Silymarin also showed synergism with the commonly used anticancer compounds doxorubicin and cisplatin. In DU145, prostate carcinoma cells, silymarin showed inhibition of Erb1 (eukaryotic ribosome biogenesis protein 1) signaling and G1 arrest. 133 In MDA-MB 486 breast cancer cells, G1 arrest was found due to increased p21 and decreased CDKs activity. 134 In advanced human prostate carcinoma cells, silymarin decreased ligand binding to Erb1 135 and NF-kB expression was strongly inhibited by silymarin in hepatoma cells, 136 as well as in histiocytic lymphoma, HeLa and Jurkat cells. 137 According to Zi and Agarwal, low doses of silymarin inhibited ERK1 and ERK2 Map kinases in a skin cancer cell line (human epidermoid carcinoma A431) and at higher doses activated MAPK/JNK1. This means that at lower doses the effect was antiproliferative and at higher doses proapoptotic. 138 Treating prostate carcinoma cells with silymarin the levels of PSA were significantly decreased and cell growth was inhibited through decreased CDK activity and induction of Cip1/p21 and Kip1/p27. 139 Silymarin has also been shown to have a variety of other protective effects in various cell types, such as anti-COX2 and anti-IL-1α activity, 140 antiangiogenic effects through inhibition of VEGF secretion, upregulation of Insulin like Growth Factor Binding Protein 3 (IGFBP3), 141 and inhibition of androgen receptors. 142 In leukemia HL-60 cells, silymarin inhibited proliferation and induced differentiation into monocytes in a dosedependent manner. 143 Another important effect of silymarin in cancer is the downregulation of the STAT3 pathway which was seen in many cell models. STAT3 is active in many types of cancer and is associated with poor prognosis and resistance to treatments. [144] [145] [146] Telomerase activity is another important factor in promoting carcinogenesis and evading senescense, thus inducing cancer cell immortality; silymarin has the ability to decrease telomerase activity in prostate cancer cells. 147 

The apoptotic mechanism silymarin employs on cancer cells is generally p53 dependent, and follows the usual steps: increased proapoptotic proteins; decreased antiapoptotic proteins; mitochondrial cytochrome C release-caspase activation. 148 Caspase inhibitors terminate silymarin apoptotic activity. Malignant p53 negative cells show only minimal apoptosis when treated with silymarin. Therefore, one conclusion is that silymarin may be useful in tumors with conserved p53.

Enhanced cell migration is an important part of cancer progression. The antimigratory effects of silymarin in cancer cells are the result of mechanisms that 149 :

1. inhibit histone deacetylase activity; 149 2. increase histone acetyltransferase activity; 149 3. reduce expression of the transcription factor ZEB1; 149 4. increase expression of E-cadherin; 149 Multiple sclerosis 68, 69 Diabetic cognitive impairment 70 Learning and memory deficits (in mice) 71 Diabetes Diabetic complications [72] [73] [74] [75] [76] Hypercholesterolemia [77] [78] [79] [80] [81] Renal diseases Cyclosporine nephrotoxicity 82 Diabetic nephropathy 83, 84 Ischemia/reperfusion Damage prevention in general 85 In heart muscle 86 In the central nervous system 87, 88 In the kidney 89, 90 In intestine and bowel 91 In the stomach 92 In the lungs 93 In the liver 94 Anti-Mayaro virus 105 Anti-Chikungunya virus 106 Anti-Zika virus 107 Infections: bacterial Escherichia coli 108 Amiodarone Improved effects on atrial flutter 5. increase expression of miR-203; 149 6. reduce activation of sodium hydrogen isoform 1 exchanger (NHE1); 150 7. target β catenin and reduce the levels of MMP2 and MMP9; 151 8. reduce activation of prostaglandin E2; 152 9. suppress vimentin expression; 153 10. inhibit Wnt signaling; 154 11. modulate β1 integrin signaling. 155 

Angiogenesis is important in cancer growth because solid tumors need a blood supply to grow. Silymarin inhibits angiogenesis. There are various postulated mechanisms:

1. Decreased migration of endothelial cells. 156 2. Flt1 (VEGFR1) upregulation. 157 

EMT is involved in tumor progression and metastatic expansion. In a transcriptome study of nonsmall cell lung cancer (NSCLC) cells, Kaipa et al 159 found that silibinin had no effect on EMT. However, the opposite was found in other malignant tissues [160] [161] [162] where it showed inhibitory effects.

High expression of the tissue inactivator of metalloproteases I, or TIMP1, in cancer is a marker of poor prognosis 163,164 54 because it is involved in tumor progression, metastasis, and shorter overall patient survival. TIMP1 also promotes accumulation of tumor-associated fibroblasts. 165 Therefore, it may be considered a target in cancer treatment. Silymarin has the capacity to decrease TIMP1 expression [166] [167] [168] in mice.

LPAR1 and 3 (lisophosphatidic receptors 1 and 3) are related to cancer invasiveness. [169] [170] [171] [172] Silymarin has the ability to downregulate LPAR1. 173 

Silibinin reduces the expression of TGF β2 in different tumors such as triple negative breast, 174 prostate, and colorectal cancers. 175 TGF β2 downregulation impedes the TGF β2/ Smad pathway reducing cellular motility and MMP2 and MMP9 (metalloproteases) reducing invasion. In the liver, TGF β2 downregulation results in an antifibrotic effect, preventing hepatic fibrosis induced by inflammatory liver diseases. 166 

When cells are exposed to hypoxia, HIF-1α accumulates in the nucleus activating transcription of many genes and this plays an important role in tumor progression. Silymarin was found to decrease HIF-1α expression in rainbow trout brain 177 and in rat lung under hypoxic conditions. 93 In prostate cancer cells silibinin inhibited HIF-1α translation. 178 Silymarin and CD44 and EGFR CD44, the transmembrane receptor for hyaluronan, is increased in breast cancer and many other tumors, due to EGF (epidermal growth factor) stimulation. Silibinin decreased CD44 expression and the activation of EGFR (epidermal growth factor receptor) by EGF. 179 In prostate cancer, silibinin decreased/ inhibited CD44 expression as well. 180 CD44 binding with hyaluronan triggers important protumoral signaling from its intracellular segment, inducing cancer cell survival, angiogenesis, migration, and invasion. The CD44 antigen (synonym HCAM) is a glycoprotein acting as an adhesion molecule 181 on the cell surface. Cell adhesion molecules play an important role in cell migration. In fact, CD44 has been shown to be strongly correlated with invasion 182,183 and metastasis. [184] [185] [186] Silymarin Modulation of TNFα (Tumor Necrosis Factor Alpha)

Tyagi et al 187 showed that silibinin pretreatment of lung cancer cells inhibited TNFα induced "phosphorylation of STAT3, STAT1, and Erk1/2, NF-κB-DNA binding, and expression of COX2, iNOS, matrix metalloproteinases (MMP)2, and MMP9, which was mediated through impairment of STAT3 and STAT1 nuclear localization."

The Wnt/β-catenin pathway is critical in cell proliferation, migration, and differentiation. It is a powerful regulator of embryonic development and tumorigenesis. Lu et al 188 showed that silibinin inhibited the Wnt/β-catenin pathway in both prostate and breast cancer cells.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is part of the TNF superfamily. It is known to selectively induce apoptosis in cancer cells without having significant toxicity toward normal cells. Kauntz et al 189, 190 found silibinin potentiated TRAIL-induced apoptosis in human colon adenocarcinoma cells. Furthermore, this potentiation was also found in TRAIL-resistant cells. Silibinin upregulated Death Receptors 4 and 5, thus increasing the number of receptors for TRAIL binding. Silibinin had the ability to induce not only the extrinsic apoptotic pathway, but also the intrinsic pathway. TRAIL sensitization by silymarin was also found in glioblastoma cells 191 and in hepatocarcinoma. 192 

Secreted phospholipase A2 participates in inflammation and carcinogenesis. Silibinin downregulates secreted phospholipase A2 in cancer cells. 193 Silymarin and Platelet-Derived Growth Factor (PDGF) PDGF and its receptor are required for fibroblast proliferation and differentiation. It was found that silibinin had the ability to downregulate PDFG in fibroblasts, thus decreasing proliferation. 194 

Interleukin 8 has been identified as a protumoral cytokine [195] [196] [197] [198] and there is evidence showing that inhibition of IL-8 reduces tumorigenesis. 199 Flavonoids, in general, reduce levels of IL-8. Curcumin, 200 apigenin, 201 and silybin showed the ability to decrease IL-8 levels. 150, 202, 203 Silymarin Inhibits the Signal Transducer and Activator of Transcription 3 (STAT3) Pathway STAT3 exists in the cytosol of cells and is a focal point of multiple oncogenic pathways. Silymarin inhibited STAT3 phosphorylation and decreased the expression of intranuclear sterol regulatory element binding protein 1 (SREBP1), decreasing lipid synthesis. The final consequences of these inhibitions were growth arrest and apoptosis. 204 

Si et al, 205 experimenting with 2 human breast cancer cell lines, MCF7 and MDA-MB-231, found that silibinin produced morphological and functional changes in mitochondria: decreased mitochondrial mass, condensed crests, reduced membrane potential and ATP content, and decreased mitochondrial biogenesis.

MMP2 and MMP9 play an important role in extracellular matrix remodeling and their levels correlate with progression of neuroblastoma tumors. 206 Yousefi et al 207 found that silibinin decreased MMP2, MMP9, and urokinase plasminogen activator receptor level (uPAR) in neuroblastoma cells. uPAR is also a marker of cell invasion.

COX-2 expression in cancer can stimulate angiogenesis and is associated with tumor growth, invasion, and metastasis. 208 Silymarin decreased the expression of COX2 in a model of chemically induced hepatocarcinoma in rats. 209 Silibinin and Programmed Death-Ligand 1 (PD-L1)

The programmed cell death protein and its ligand (PD-L1) complex play a key role in tumor progression being involved in growth regulation disturbance. This results in a defect in programmed cell death, apoptosis. 210 Silibinin inhibits PD-L1 by impeding STAT5 binding in NSCLC. 211 This hints at the possible usefulness of silymarin as a complement to immune checkpoint inhibitors. A similar effect was found in nasopharyngeal carcinoma. 212 In renal carcinoma cells, silibinin decreased PD-L1 in murine renal cancer cells in vitro and in vivo. 213 

The Notch signaling pathway is highly conserved, regulating development and is involved in angiogenesis and metastasis. 214 Silybin inhibited Notch signaling in hepatocellular carcinoma cells showing antitumoral effects. 215 However, dibenzazepine is much more powerful in this respect. 216 Notch was also downregulated by silibinin in breast cancer cells impeding notch-1/ ERK/Akt signaling 217 and inducing apoptosis.

SIRT1 can deacetylate histones and other substrates and may act in a dual manner: as tumor suppressor or tumor promoter. 218, 219 Silymarin has the ability to increase hepatic SIRT1 expression. 220 Silymarin can also increase SIRT1 expression in other tissues, such as hippocampus, 221 articular chondrocytes, 222 and heart muscle. 223 Silymarin seems to act differently in tumors: in lung cancer cells SIRT downregulated SIRT1 and exerted multiple antitumor effects such as reduced adhesion and migration and increased apoptosis. When SIRT1 was independently downregulated with siRNA the silymarin's antitumoral effects were increased. 224 

The angiogenic cytokine vascular endothelial growth factor (VEGF) and its receptor (VEGFR) play critical roles in vasculogenesis and angiogenesis. Jiang et al 225 found that adding silymarin to prostate and breast cancer cells swiftly reduced the secretion of VEGF to the medium in a dose-dependent manner. Silymarin also prevented VEGF expression in myocardial cells exposed to doxorubicin toxicity 226 as well as other manifestations of cardiotoxicity. A similar decrease in VEGF and VEGFR levels was found with silymarin in preeclamptic placenta, however the effect was very modest. 227 There is evidence showing that silymarin reduces VEGF expression at the transcription level. 228 Silymarin and Myc C-Myc is a multifunctional master regulator transcription factor; it is activated by oncogenic pathways, drives many functions for rapid cell division, and inhibits antiproliferative pathways. 229 There is direct and indirect evidence that silymarin interacts with c-Myc, 230 in some cases increasing its expression in liver cells as a response to hepatic chemical injuries 231 or decreasing it in malignancies. 232 Rajamanickam et al 233, 234 found that silymarin could prevent spontaneous tumorigenesis in an APC min/+ mouse model (prone to develop intestinal tumors) by decreasing β-catenin, cyclin D1, c-Myc, phospho-glycogen synthase kinase-3β expression, phospho-Akt, and cyclooxygenase-2 in polyps. This report confirms silymarin's multitargeting effects in tumors and its different behavior in nonmalignant cells.

Carbonic anhydrases (CAs) play an important role in cancer progression, particularly those associated with the cell membrane (membrane CAs), namely isoforms CA9 (CAIX) and CA12 (CAXII). These CAs intervene in acidifying the extracellular substance and, working in tandem with sodium bicarbonate cotransporters, increase the intracellular pH. Downregulating or inhibiting membrane CAs has become a valid target for cancer therapy. Silymarin has the ability to inhibit CA isoforms CA I and CA II. 235, 236 However, we could not find any publications specifically addressing silymarin's role as a possible inhibitor of membrane CAs.

This is a controversial relationship. On one side, silymarin showed ability to reduce oxygen consumption in mitochondria NAD-dependent substrates, while on the other hand stimulating respiration in mitochondria oxidizing succinate. 50 Silymarin increases mitochondrial release of Ca ++ and lowers mitochondrial membrane potential in cancer cells 237 and increases the transmembrane potential in toxic aggressions. 238 Regarding mitochondria we may presume that silymarin has contextdependent effects.

Many of the features discussed above hint towards silymarin's antimetastatic potential. In a TRAMP (Transgenic Adenocarcinoma of the Mouse Prostate) model of prostate carcinoma, when mice were fed with silibinin invasion and metastasis were reduced. 239 The antimetastatic effect was due to less invasion, less EMT, less collagen I-cancer cell adhesion, and less expression of CD44. 240 In a randomized clinical study with patients harboring solid tumors, silymarin was added to standard chemotherapy. Although silymarin failed to improve the results, there was a a slight-not significant-trend towards reduced metastasis. 241 We think that this study had some flaws which included a small sample size (15 patients with silymarin and 15 with placebo), tumors being present in different organs, and very low dosage (420 mg/day). In spite of these flaws, the trend towards a decrease in metastasis is still interesting and further study with a larger sample population was suggested by the authors.

Silymarin coadministered with chemotherapeutic drugs has the ability to reduce toxicity in normal organs 242,243 :

• It protects against liver and kidney toxicities induced by methotrexate in children and adults treated for leukemia. 244, 245 • Silibinin decreased cisplatin's nephrotoxicity without affecting its antitumoral effectiveness. 246, 247 • There is also evidence that it protects the heart from doxorubicin toxicity, however, it is less potent than quercetin in this effect. 248 • Silymarin reduced docetaxel central and peripheral neurotoxicity. 249 • Silymarin was able to decrease diarrhea produced by irinotecan treatment. 250 • Silymarin reduced hepatotoxicity in patients with nonmetastatic breast cancer receiving doxorubicin /cyclophosphamidepaclitaxel. 251 Silymarin and Resistance to Treatment

Rho et al 252 found that adding silymarin to epidermal growth factor receptor tyrosine kinase inhibitors could overcome Table 3 . Prostate.

Year, Ref. Findings resistance produced by the T790M mutation in NSCLC xenografts. The mechanism of action seems to be impeding EGFR dimerization. It was found that bladder cancer cell lines resistant to cisplatin could be resensitized with silymarin. 253 A similar result was obtained with ovarian cancer cells resistant to paclitaxel. 254 The mechanism involved in resensitization to chemotherapeutic drugs is not fully known, however possible factors are: inhibition of NF-kB nuclear migration, 136 inhibition of survivin protein levels, downregulation of Pgp (MDR 1), [255] [256] [257] [258] and multidrug resistance-associated protein 1 (MRP 1). 258, 259 Silychristin (a component of silymarin) and silychristin derivatives have shown the particular ability to inhibit Pgp activity in a concentration-dependent manner 260 (see Tables 2 to 12 ).

Silymarin's Cancer Chemopreventive Actions Table 5 summarizes the findings by Vinh et al that show that silymarin was able to significantly decrease the incidence of bladder neoplasms in male rats receiving the carcinogenic substance N-butyl-.N-(4-hydroxybutyl) nitrosamine. Interestingly, these results were achieved by oral administration of silymarin and were found in those animals that received silymarin not only at the initiation of carcinogenesis, but also in those of the postcarcinogenic period (for more examples on chemoprevention, see Tables 2 to 12) .

Silymarin is a selective estrogen β receptor (ER-β) agonist. 261 However, it also has some estrogenic effects through ER-α. 262 Silymarin has strong binding affinity to ER-β and a mild affinity for ER-α. 263 Silymarin's estrogenic actions should be seriously considered as a problem in female hormone-dependent tumors. Furthermore, silymarin's estrogenic effects are confirmed by the observation that it produces benefits in menopausal women with hot flashes. 116 Contrario sensu, it may be advantageous in benign prostate hyperplasia 264, 265 and prostate cancer. However, in an experiment carried out in albino rats, silymarin increased testosterone and LH. 266 It also increased spermatogenesis in rats. 267 In spite of these 2 findings, the evidence for silymarin benefits in prostate cancer is abundant (see Table 3 ). Our conclusion is that the possible benefits found in prostate cancer are independent of silymarin's hormonal effects.

Endocytosis is an important mechanism of cell intercommunication which acquires major relevance in cancer. This process is initiated by the invagination of the plasma membrane. The protein clathrin provides A coat to this invagination ( Figure 5 ). The clathrin coated vesicle has the ability to select for the adequate cellular receptor. 268 There is also endocytosis without clathrin coating. Silibinin reversed chemotherapeutic resistance in bladder cancer cells in a NF-kB signal-dependent and independent manner. 2017 315 Silibinin is an antiproliferative compound whose mechanism of action depended on p53 status (WT or mutated). 2002 316 X In an induced bladder carcinogenesis mouse model, silymarin reduced the incidence of bladder lesions and cell proliferation.

Silymarin acted as a preventive compound. 2017 317 The anticancer mechanism of silibinin in bladder cancer was through downregulation of the actin cytoskeleton, the PI3K/Akt pathway and KRAS. 2011 318 X Oral silibinin prevented carcinogenesis, decreased proliferation, and increased apoptosis in vivo in a mouse model. Intravesical silibinin had a similar effect. 2013 319 X Silibinin decreased bladder cancer metastasis and prolonged animal survival through downregulation of the GSK3β/β catenin pathway and Zeb1 expression. Silibinin also suppressed EMT and stemness. 307 Silibinin meglumine impeded the epithelial-mesenchymal transition in EGFR mutant NSCLC cells. 2010 308 Silibinin decreased NSCLC cell growth through cell cycle arrest and decreased cell cycle modulators. 2011 309 Silymarin produced apoptosis in a highly metastatic lung cancer cell line through the mitochondrial caspase pathway. 2003 310 Silibinin inhibited growth and apoptosis in NSCLC and SCLC line cells in a dose-dependent manner. 2012 311 HDAC inhibitors in combination with silibinin showed enhanced antitumor activity in NSCLC cells. There was also increased transcription of p21 through higher acetylation of its promoter. The augmented p21 was responsible for proteasomal destruction of cyclin B1. 2013 312 EGFR-mutated lung cancer cells, resistant to erlotinib and overexpressing ALDH, were resensitized by silibinin. 2009 313 X Treating a xenograft lung cancer mouse model with silibinin resulted in a decreased tumor size through decreased angiogenesis.

HIF-1α was also decreased by silibinin. 2016 314 Through downregulation of STAT3, silibinin reinstated sensitivity to crizotinib therapy in ALK rearranged lung cancer.

Silymarin has the ability to inhibit clathrin-dependent trafficking at least in the case of certain viruses such as Hepatitis C virus, reovirus, influenza virus, 269, 270 and Hepatitis B virus. 271 The mechanism behind this inhibition is through interference with the clathrin endocytic pathway. Actually, silymarin interferes with all the clathrin-dependent endocytic processes. Taxifolin, a close relative of silybin, was also found to inhibit receptor-mediated endocytosis of β-hexosaminidase in normal fibroblast culture. There were similar findings with other flavonoids. 272 Although there is no experimental evidence in this sense, we may presume that silymarin decreases endocytic trafficking in cancer cells too. Additionally, clathrin has protumoral effects beyond endocytosis: it switches TGF-β into a procancer role. 273 Figure 6 shows a simplified overview of the clathrindependent endocytosis.

When targeting renal carcinoma cells with silymarin, migration and invasion were significantly decreased by inhibition of the EGFR/MMP-9 pathway: silymarin blocked phosphorylation of EGFR and ERK1/ERK2 and reduced expression of MMP-9. 275 This was confirmed by Liang et al 276 

Silymarin has not been extensively tested in pancreatic ductal adenocarcinoma (PDAC) (see Table 6 ). However, it does have an important antifibrotic effect. One of the major problems in PDAC is the intense stromal reaction with abundant production of stromal collagen fibers. 278 These impede delivery of the chemotherapeutic drug to the tumor mass and create interstitial hypertension through the strongly hydrophilic hyluronan. Therefore, silymarin's antifibrotic effects may provide an interesting complement to standard treatment. 279 Desmoplastic tumors are the consequence of the intense activity of cancer-associated fibroblasts (CAFs) producing 326 Silibinin synergized with conventional chemotherapeutic drugs in anticancer effects on breast cancer cells. 2009 327 Silibinin decreased MMP9 and VEGF expression induced by TPA through downregulation of the Raf/Mek/Erk pathway. 2013 328 Silymarin showed synergy with doxorubicin in producing MCF7 cell apoptosis 2014 329 Silymarin showed much higher proapoptotic gene induction in a lung cancer cell line than in a breast cancer cell line. 2014 330 X Silibinin inhibited the accumulation of myeloid derived suppressor cells (MDSC) in murine breast cancer and increased overall survival. Silibinin decreased tumor volume. 2015 331 Silibinin induced autophagic death in breast cancer cells. Silibinin treatment decreased ATP levels and altered mitochondrial electric potential with increased ROS accumulation. 2015 332 Silibinin induced apoptosis in breast cancer cells. (Comment: the concentrations used were too high and are not achievable in human use). 2015 333 ERα inhibition was a key factor in silibinin-induced autophagy and apoptosis. Using ERα inhibitors with silibinin, both apoptosis and autophagia were further increased. 2016 334 Silibinin decreased BCL2 proteins in breast cancer cells and normal breast cells and ununiformly increased PTEN in different cancer cell lines. 2017 335 Silibinin sensitized breast cancer cells to doxorubicin treatment. (Comment: The concentrations used were excessively high and difficult to achieve in the clinical setting). 2017 336 Silymarin-loaded iron nanoparticles produced cell cycle arrest in triple negative breast cancer cells. 2017 337 Silymarin's anticancer effects were due to inhibition of Akt and MAPK pathway. 320 Silibinin induced cell cycle arrest and apoptosis in certain pancreatic cancer cell lines. 2015 321 The combination of an HDAC inhibitor and silibinin had additive effects on growth inhibition and apoptosis of pancreatic cancer cells. 2015 322 X In an orthotopic model of pancreatic cancer, silibinin reduced glycolytic activity of cancer cells, proliferation, and cachexia. 2013 323 X Dose-dependent cell growth inhibition was produced by silibinin concentrations between 25 and 100 μM. In xenograft in nude mice, tumor weight was significantly decreased by dietary silibinin. 2018 324 SW1990 pancreatic cancer cells showed G1 arrest with decreased cyclins and CDKs and apoptosis with silibinin.

collagen fibers. PDAC and the liver have specialized CAFs known as stellate cells considered the producers of the desmoplastic reaction. Silymarin has been found to inhibit/decrease the desmoplastic reaction through 2 mechanisms:

(a) it inhibits TGF β2 that induces the desmoplastic phenotype of naïve fibroblasts; 280 (b) it increases E-cadherin expression 281,282 decreasing the invasive nature of the desmoplastic reaction.

Silymarin decreased fibrosis not only in 2 models of induced liver fibrosis 37,283 but also in lung fibrosis induced by cigarette smoke. 284 In this last case, this occurred by downregulation of the TGF-β1/Smad 2/3 pathway signaling. Although we could not find any publication showing that silymarin could reduce the desmoplastic reaction in pancreatic cancer, we may assume that it has the potential to do so, because the mechanisms behind this are similar to those found in liver and lung cancers. Long et al suggested this possibility, however they did not incorporate any evidence in their review. 279 Tables 2 to 12: Evidence of silymarin's anticancer effects. In vivo experiments are marked with an X in column 1.

In spite of the long list of publications mentioned in Tables 2 to 12, 5 cautionary notes should be added:

1. In a mouse model of induced mammary carcinogenesis, the administration of silymarin, slightly increased mammary tumor incidence. 369 This may be due to silymarin's estrogenic effects, 115, 261, 370 however, the issue remains controversial because silymarin increases ERβ and decreases ERα expression. 264 2. In a model of mouse hepatic carcinogenesis (with diethylnitrosamine), silymarin showed no effects at all. 371 3. In a mouse model of alcohol-dependent hepatocarcinoma, silibinin increased tumor progression if chronic alcohol intake continued. 372 Table 2 to 12 were performed at very high concentrations that are difficult or impossible to achieve in vivo. On the other hand, in vivo experiments (marked with an X in Tables 2 to 12) were mainly conducted with oral administration of silymarin or silibinin, so those results should have a more significant impact on future clinical research. 5. Most of the published literature on silymarin and cancer does not mention the p53 status of the cells and this information is of capital importance (silymarin shows apoptotic effects on p53 positive cells but not on mutated p53).

Flavolignans (silymarin is a mixture of flavolignans) generally have poor bioavailability. This is the consequence of: 349 Silibinin decreased cell proliferation and migration of human hepatocellular cancer cells by inhibiting the Erk 1/2 cascade. 2009 350 Silymarin decreased growth of hepatocellular carcinoma (HCC) cells and induced apoptosis. 2009 351 X In a xenograft mouse model of HCC, silibinin reduced growth and proliferation through reduction of Akt/Erk signaling and increased histone acetylation. 2015 352 Silibinin increased growth inhibition of hepatocarcinoma cells by either sorafenib or gefitinib. 2020 353 Silymarin showed antimetastatic and proapoptotic effects on HepG2 cells through the Slit-2/Robo-1 pathway. 341 Silymarin induced proteasomal degradation of cyclin D1 and inhibited growth of colon cancer cells. 2016 342 Treatment with silymarin increased the efficacy of ionizing radiation on colon cancer cells causing increased cell death. 2017 343 Silibinin inhibited proliferation and increased apoptosis in colon cancer cells. 2017 344 X The combination of regorafenib and silybin had synergistic antiproliferative and proapoptotic effect. This combination was tested in 22 patients with metastatic colon cancer. No control group was available. 2020 345 Sylimarin, associated with other nutraceuticals, reduced intestinal polyp growth in an animal model.

1. their strongly hydrophobic nature that does permit dilution to more than 50 μg/mL in water. Some organic solvents have a much better performance for this purpose. For example, ethanol shows a solubility of 225 mg/mL; 373 2. the fact that they are quickly metabolized; 3. the fact they are poorly absorbed in the intestine.

The pharmacokinetic considerations we shall make refer to the standardized form of silymarin with known amounts of silybin.

Absorption. silymarin is not soluble in water and oral administration shows poor absorption in the alimentary tract (approximately 1% in rats, 374 however, other authors mention a higher absorption around 30%). In spite of this low absorption, according to Janiak et al, a plasma level of 500 mg/L (500 μg/mL) is achievable 90 min after oral administration of 200 mg/kg of silymarin in mice. 375 Excretion. Silymarin is mainly excreted in the bile and halflife is 6 h.

Toxicity. Toxicity is almost absent 376 Absorption studies in animals. Administration of silybin to animals also showed divergent results. In dogs, 380 the silybinphosphatidylcholine complex (SPC) showed increased concentrations when compared with silymarin extract, however, the results showed a low level in general: SPC: 1.310 ± 880 ng/ ml; silymarin: 383 ± 472 ng/ml. While Morazzoni et al 381 found higher peak levels of silybin in the form of silipide when administered to rats: "After oral silipide, silybin reached peak plasma levels within 2 h, with a C max of 9.0 ± 3.0 μg/ml for unconjugated drug and 93.4 ± 16.7 μg/ml for total (free + unconjugated drug)."

Pharmacodynamic conclusions: The above studies show that the achievable concentration in humans (with a low dose) is far lower than what was found in rodents (with a high dose). The important issue is that most of the experiments found in the literature at cellular level used a concentration around 100 μg/mL. Even in the study by Morazzoni et al, 381 the level of 100 μg/mL was not achieved and in any case it is a peak level that cannot be sustained. Therefore, is the experimental level of 100 μg/mL achievable at the bedside?

We think that there is no evidence that it can be. Oral administration of silymarin in humans achieves nanogram, but not microgram levels. Furthermore, we should not extrapolate Morazzoni's findings in rats to humans as their pharmacokinetics may differ. Silymarin inhibited proliferation and induces differentiation into monocytes. It showed synergy with vitamin D3. 2010 357 Acute myeloid leukemia

Silibinin induced differentiation of acute myeloid leukemia cells ex vivo (only in cases in which there were no chromosome aberrations). 2016 358 Lymphoma Silibinin induced apoptosis in Alk-positive anaplastic large cell lymphoma by suppressing the phosphorylation of NPM/ALK. 2020 359 Lymphoma Epstein-Barr positive lymphoma cell proliferation was inhibited and apoptosis induced through NF-kB inhibition by silymarin. 2016 360 Multiple myeloma Silybin suppressed myeloma cell proliferation and induced apoptosis by inhibiting the PI3K/Akt/mTOR pathway.

Therefore, the evidence based on these high concentration experiments should be viewed with caution. On the other hand, experiments with xenograft models are more reliable (Tables 2 to 12, xenograft results are marked with an X).

Tissue concentration. For cancer treatment purposes the important data to know are the concentrations achievable in tissues. Zhao and Agarwal 382 After an oral intake, silipide (the lipophilic SPC), achieved a maximum concentration of silybin in bile within 4 h and then declined with a mean time of approximately 10 h. 383 Silibinin complexed with the amino-sugar meglumine is water soluble and can reach a tissue concentration high enough to show clear antigrowth effects in NSCLC xenografts. 307 The distribution in different tissues also varies widely according to the type of tissue considered. It is higher in the liver and dimishes in lungs, pancreas, and prostate. 382 A relatively high concentration is achievable in colorectal muscosa (20-141 nmol/g of tissue). 384 The tissue levels obtainable compare unfavorably with those used in cell studies. To achieve apoptosis in cell studies, a concentration of more than 20 μM was necessary, 385 and this concentration does not seem easy to achieve by oral intake of standard preparations. It was also necessary to use a concentration of 100 μg/mL to induce apoptosis in Ramos cells (B lymphocytes). 386 Kamrani et al 387 used concentrations between 50 and 100 μg/mL to induce apoptosis in colon cancer cells. Therefore, while only a nanomolar concentration can be attained in tissues, micromolar concentrations were needed to induce apoptosis in these studies (the molecular weight of silybin is 482, 100 μg/ml = 207 μM).

In spite of this difficulty, Sing and Agarwal 298 found an important decrease in tumor volume in xenografted mice with human prostate carcinoma cells when the mice were orally fed with silymarin.

There are also different requirements for effects on cell migration versus proliferation. For endothelial cells, it was necessary to use a concentration of 48.1 μg/mL of silymarin to achieve a 20% reduction in proliferation and 16.1 μg/mL to achieve the same reduction in proliferation of LoVo colon cancer cells 156 to achieve a reduction of migration of 50%, it is necessary a concentration of 1.15 μg/mL on endothelial cells (with silibinin instead of silymarin 0.66 μg/mL were enough to achieve the same). 156 Our conclusion is that, from a bioavailability standpoint, it is much easier to achieve migration inhibition, than proliferative reduction.

In Europe one of the most used brands of silymarin is Legalon® L (silybin 3,23-O-bis-hemisuccinate) that comes in capsules of 150 mg. It also comes in vials containing 350 mg of silibinin for intravenous use. In the United States, silymarin is considered a nutritional supplement. 388 The intake of 5 of these capsules in 6 human volunteers, showed no adverse events. The concentration in plasma correlated with the dose and only 10% of it was unconjugated silymarin. A half life of 6 h was estimated. 389 In experimental conditions, many researchers dilute silybin in DMSO, a polar solvent in which silymarin is highly soluble. Unfortunately, this is not possible at the bedside.

Silymarin's low solubility, rapid metabolism, and quick excretion, led researchers and pharmaceutical industry to develop methods that could solve these very important drawbacks. Therefore, many compounds have been formulated mainly using nanotechnology. These compounds include nanosuspensions, solid dispersions, complexes with cyclodextrins and phospholipids, microemulsions, nanoemulsions, liposomes, polymer nanocarriers, solid-lipid nanoparticles and nanostructured 362 Glioma Silibinin induced apoptosis in glioma cells through downregulation of PI3K pathway and decreased FoxM1 transcription factor expression. 2018 363 X

In vivo, silymarin reduced tumor growth and volume; in vitro it produced apoptosis through induction of the DR5 (death receptor 5)-caspase 8-truncated Bid pathway. 2017 364 Salivary glands Silymarin increased proapoptotic Bim protein in mucoepidermoid carcinoma cells, inducing apoptosis. 2012 365 Cervical Silymarin induced apoptosis in cervical cancer cells through increase of PTEN, inhibition of Akt phosphorylation, and decreased expression of MMP9. 2007 366 Osteosarcoma Silibinin decreased human osteosarcoma cell invasion through Erk inhibition of a FAK/ERK/uPA/MMP2 pathway. 2017 367 Rabdoid tumor Silibinin inhibited rabdoid tumor cell migration and invasion through inhibition of the PI3K/Akt pathway. 2019 368 Human gastric cancer cells

Silymarin downregulated the MAP kinase pathway inhibiting growth and inducing apoptosis.

lipid carriers, and polymer-based nanocarriers. 390 We shall discuss only a few of them.

► Combination with succinate: is available on the market under the trade mark Legalon® (bis hemisuccinate silybin). ► Combination with phosphatidylcholine: this was the first system developed for a better bioavailability: it consists of the combination of 2 molecules of phosphatidylcholine with one of sylibin. It has been registered under the name Siliphos®, but is also known as Idb1016, silipide, or phytosome. [391] [392] [393] [394] This method increased bioavailability 10-fold. 395 ► Silybin-cyclodextrin complex: adding cyclodextrin considerably enhances silymarin's water solubility. 

A phase I study of silymarin in prostate cancer patients showed that 13 g daily per os divided into 3 doses was well tolerated. The most frequent adverse event was asymptomatic liver toxicity. 403 Side effects, although rare, were mainly related to the gastrointestinal tract, such as diarrhea, bloating, and nausea. 404 Abenavoli et al 405 found that daily doses beyond 1500 mg had laxative effects and increased bile flow. The usual dose of 400 or 800 mg a day is probably insufficient to achieve anticancer effects. It may be necessary to administer 800 mg 4 times a day because the half-life is short. However, the dose of silymarin for cancer treatment remains controversial. In one study, a high dose of silybinin was administered to patients prior to prostatectomy (13 g daily). They achieved high plasma concentrations, but nevertheless, low levels of silibinin were found in prostate tissue. 406 In an attempt to circumvent some of these problems one group used a silymarinphosphatidylcholine compound administered orally as a daily dose of 2.8 g for 4 weeks prior to surgery. They achieved high levels in human breast cancer tissue. 407 This high bioavailability in this breast cancer study is an encouraging signal for a phase II clinical trial. It should also be noted that silymarin constituents have different anticancer abilities, 22 therefore a formulation of the strongest combination would represent a fundamental step in order to incorporate this flavonoid into standard treatments.

Problem 1: Bioavailability. The evidence gathered in Tables 2 to 12 clearly shows that silymarin should have a place in cancer treatment. The main problem is its bioavailability. Many of the in vitro investigations have used concentrations that are very difficult to achieve at the bedside. The combination of silymarin with phosphatidylcholine (silipide) has a better bioavailability, however this combination is not available for clinical use. Problem 2: Dual nature of silymarin's effects. Silymarin has protumoral and antitumoral effects. For example, in pancreatic cancer it promotes growth arrest and apoptosis (see Table 6 ) and decreases CD44 signaling. However, Lee et al 408 found that in addition to the antitumoral actions, silymarin also upregulated cancer stemness-related genes, namely TWIST1, Snail, and c-Jun. At the same time, it decreased p53 wild type and increased Ki-67 (a marker of proliferation). This is a powerful call for caution. On the other hand, in bladder cancer, silymarin seems to decrease stemness through inhibition of the β-cathenin/ZEB1 signaling (Wu 178) . In pancreatic tumors (PANC1), it was also found that silymarin targeted stem cells decreasing proliferation and increasing apoptosis, 409 and had similar effects in breast cancer cells. 410, 411 These controversies on silymarin prostemness or antistemness effects may be due to context or tumor dependency. The question remains unsolved.

Problem 3: DNA intercalation. In 2020, Pawar and Jaldappagari 412 reported that flavolignans had the ability to intercalate into the DNA double helix with moderate binding affinity. Other authors have vehemently contradicted this finding. 413 However, if this silymarin effect on DNA is confirmed, it may have unthought consequences which are favorable (modulating gene activities against cancer) or undesirable (genotoxicity and or mutations). The issue is important enough to encourage further basic research in this area. 

The United States Clinical Trials web-page lists the following trials for silymarin in cancer: Schröder et al 414 conducted a randomized double-blind, cross-over placebo-controlled trial (with 2 periods of 10 weeks with a wash out period in the middle) with 49 patients that showed rising PSA levels after radical prostatectomy (34) or radiotherapy (15) . They received a supplement containing soy, different isoflavones, silymarin, vitamins, minerals, and antioxidants. While receiving the treatment the doubling time for PSA was 1150 days compared with 445 days with the placebo. The fact that the supplement contained many other components besides the silymarin makes it impossible to draw conclusions about this compound. But it is evident that the supplement modified the biochemical evolution of the disease, delaying PSA progression.

Four clinical case reports are available, which though they cannot in themselves constitute a proof for the efficacy of silymarin, are nonetheless interesting and suggest a need for further studies. Hsu et al 415 describe the case of a 66-year-old Taiwanese patient with a regression of an 11 cm diameter hepatocellular carcinoma. The patient was receiving 450 mg of silymarin daily, and no other medication. Even if we cannot consider this regression as a consequence of silymarin treatment, the fact that spontaneous regression of hepatomas is quite infrequent, makes us think of some intervention of silymarin in this unusual event. Moroni and Zanlorenzi 416 published another case of complete regression of an advanced unresectable hepatocellular carcinoma treated with sorafenib and silymarin. Additionally, Bosch-Barrera et al 417 presented 2 cases of brain metastases from lung cancer in which the treatment with silymarin decreased edema and the size of metastases, without improvement of the primary tumor.

The concept of a tumor as a consequence of the mutation of one gene, and with one driver signaling or metabolic pathway, is flawed in most cases with the exception of cases such as chronic myeloid leukemia. Usually many genes and pathways are involved. The approach of attacking only one of the many hallmarks of cancer is also flawed. 418 Recent evidence suggests that multiple genes are usually involved along with many signaling pathways, all interconnected, and interdependent and generating an extraordinary ability of tumor cells to survive and resist internal and external threats. 419 This is one of the reasons why treatments made up of many different drugs are implemented in most treatment protocols.

Silymarin and its derivatives, through its multipronged attacks, allow one drug to reach many targets at the same time. Of course, we cannot expect silymarin to "cure" cancer all by itself, and it cannot replace any conventional chemotherapeutic treatment, but it is rather a privileged companion to therapeutic schemes in which it may develop useful complementary activity. This activity entails 3 concepts:

(a) cancer prevention; (b) synergy with some treatment protocols; (c) decrease of collateral damage induced by chemotherapeutic drugs.

Silymarin's clinically achievable concentration in serum and at the tumor site, with the possible exception of the liver, seems insufficient for inducing apoptosis. However, xenograft model experiments showed that even with this low bioavailability drawback, silymarin could stop tumor growth. 288, 351, 356 The first studies on silymarin activity in cancer were performed in hepatic cells showing some characteristics that cannot be really considered antitumoral such as increased ribosomal synthesis and RNA polymerase I activation. This did not happen in hepatoma cells or in other malignant cells (Figure 8 ).

Antiproliferative activity was found against almost all types of tumors, whether solid or nonsolid (Tables 2 to 12 ). These findings were confirmed not only at cellular level but also in vivo.

Silymarin has many other antitumor effects that can complement mainstream treatment protocols, such as:

• reduction of cell motility and invasion through TGF-β2 inhibition; • inhibition of HIF-1α translation;

• decreased TIMP1 expression, thus decreasing metalloproteases activation; • inhibition of the EGFR-MMP9 pathway;

• decreasing the accumulation of MDSCs in the tumor; • inhibition of ERK and AKT signaling;

• protection against off-target toxicity of chemotherapeutic drugs; • synergistic or added effects with some chemotherapeutics; • reduction of extracellular fibronectin production.

To this short list we must add that there is evidence sustaining clear benefits in clinical cases such as hepatocarcinoma and clear cell renal carcinoma.

However, silymarin also has some effects that work against classical chemotherapy. For example, its ability as an antioxidant reduces ROS production. Many of the drugs currently used against cancer are precisely based on the creation of an oxidative stress with increased ROS that induces apoptosis of malignant cells.

Therefore, we must ask: why is silymarin a useful complement to chemotherapy?

Evidence indicates that there may be 2 possible answers: 1. silymarin has context-dependent effects: its behavior is different in normal and malignant cells as can be seen in BOX 2. 2. Its anticancer effects overwhelm those that seem favorable for cancer cell survival.

Box 2. built on references. [420] [421] [422] [423] The dual effects of silymarin can be clearly seen in an experiment by Su et al. 424 Here nasopharyngeal carcinoma cells were exposed to low concentrations of silymarin and this showed protumoral effects: "Silymarin increased the expressions of superoxide dismutase 1, catalase, and glutathione peroxidase. Consequently, the cell apoptosis was reduced markedly. An increase of Bcl-2 expression and a decrease of activated caspase-3…." Additionally, there is the problem of increased stemness induced by silymarin in pancreatic adenocarcinoma cells.

In spite of these isolated discouraging report, 424 the overwhelming sum of experimental evidence shows that silymarin has clear anticancer effect, and at the same time protects normal cells from the collateral damage of chemotherapy. There is reasonable doubt that the concentration that can be reached in vivo is enough to induce apoptosis. However, xenografted tumors were reduced in size suggesting that somehow silymarin induces tumor apoptosis. In a small cohort prospective study there were no benefits found when silymarin was added to standard chemotherapy. On the other hand, a slight tendency to lower metastatic behavior was seen in the cohort receiving silymarin. 425 As already mentioned, silymarin is not a stand-alone compound against cancer and it should be used alongside other medications. On this point, it is important to note that silymarin is an inhibitor of the Cytochrome P450 system, particularly silychristin. Therefore, caution should be exercised in this respect. 426 Silybin could be used as a scaffold or structure that can be modified improving its antitumoral effects. For example, Manivannan et al 427 have synthesized silybin analogues with increased anticancer capacity. One of these compounds named "15k," was very potent and selective for ovarian cancer cells, where it bound to tubulin with high affinity. Subsequent experiments found that 15k induced growth arrest and apoptosis of ovarian cancer cells at a much lower concentration than silymarin. Furthermore, it showed no toxicity in animals. 428 Finally, it is important to note that many of silymarin's multipronged antitumoral actions are equally, or sometimes even better conveyed by other flavonoids such as genistein and epigallocatechin gallate. 429, 430 What Remains to be Done?

In the first place, some of silymarin's protumoral effects demand further research with the objective of ascertaining if they need to be counteracted. Then, the precise silymarin concentrations required for the different antitumoral effects need to be established. And finally, the tumor concentration achievable with the different pharmaceutical preparations has to be determined. Once these 3 pieces of information are combined silymarin will be ready for serious clinical trials as a complement to classical chemotherapeutic schedules.

Silymarin compounds have considerable antitumoral effects. Well-planned clinical trials should be necessary to finally asses its bedside indications. Its dual, antitumoral and protumoral, effects merit further research.

Silymarin should be used at very high doses because low concentrations may induce protumoral effects. There is no toxicity even with very high doses. Silymarin's low absorption and bioavailability make it preferable to use modified pharmaceutical forms, such as nanoparticles or conjugated with compounds that increase its water solubility. These combinations already exist even if they have not been marketed as yet. The abundant existing evidence shows that silymarin has a definite place in cancer treatment. It has the ability to interfere with the expression of proteins related to cell cycle regulation, apoptosis, angiogenesis, and multidrug resistance. These characteristics define an anticancer drug. On the other hand, its strong antioxidant activity makes it a useful drug in cancer prevention.

Silymarin's lack of toxicity, even at very high doses, and the lack of effects on normal cells are important reasons for its further development.

Is there any other drug, that with no toxicity at all that can: Probably no other drug can achieve all these results without adverse events or high toxicity. We cannot expect that such a nontoxic pharmaceutical work as a stand-alone drug against cancer. But it can be an important factor in a multidrug anticancer schedule. Having mentioned this, the reports of increased stemness problem remain an unsolved issue which needs further investigation.

The inability to patent the compound is no doubt a drawback for the pharmaceutical industry and will restrict investment in these types of compounds. In its bioavailable formulations, silymarin deserves to be tested on clinical grounds, not as a standalone pharmaceutical, but as part of a treatment schedule.

Finally, the low concentrations that can be achieved with silymarin extracts at the bedside (in the order of ng/mL) hints to a serious bias in much of the past and present research at the cellular level where the average concentration range used was between 50 and 100 μg/mL. As a precondition for repurposing silymarin, newer pharmaceutical formulations should be screened in order to establish whether they can reach the necessary therapeutic concentrations. Silymarin inhibits the development of diet-induced

Silibinin had inhibitory effects on survival, motility and adhesion of highly metastatic prostate cancer cells

Isosylibin B was the most potent fraction of silymarin against proliferation in different prostate cancer cell lines (LNCaP, DU145, and PC3)

Silymarin inhibited the androgen receptor (AR) by reducing its localization in the nucleus without modifying AR expression or binding ability. This action was probably related to silymarin's downregulation of FKBP51

Silymarin inhibited DU 145 cell proliferation through two mechanisms: activation of the SLIT 2 protein and inhibition of CXCR4

Silibinin inhibited growth by G1 cell cycle arrest in hormone-refractory human prostate carcinoma cells without apoptosis. It decreased CDKs and PSA and increased p21 and p27

Silymarin and silibinin produced G1 and G2-M cell cycle arrest with a decrease in CDKs and Cdc2 kinase activity, and an increase in CDK inhibitors

Silibinin treatment caused growth inhibition, apoptosis, and decreased viability in different prostate cancer cell lines

Isosylibin B caused growth arrest and apoptosis in human prostate cancer cell lines

Silibinin inhibited mitogenic signaling in prostate cancer cells

Silibinin had a synergistic effect on Mitoxantrone inhibition of cell growth arrest and apoptosis of prostate cancer cells

X Dietary supplementation of silymarin in rats decreased the incidence of induced rat prostate carcinoma

Silibinin reversed epithelial mesenchymal transition, induced upregulation of cytokeratin-18, and downregulation of vimentin, MMP2, NF-kB nuclear translocation, and transcription factors ZEB1 and SLUG

Isosylibin A induced apoptosis in prostate cancer cells through phosphoAkt, NF-kB, and AR downregulation

X In nude mice with xenografted prostate carcinomas, silibinin feeding increased apoptosis and reduced growth and angiogenesis

X In nude mice xenografted with human prostate carcinoma cells silibinin feeding decreased tumor growth by 35% to 58%. 2002 305 In human androgen-dependent prostate cancer silibinin inhibited Rb phosphorylation and increased Rb-E2F

Table 2. Melanoma. Year, Ref. Findings 2006 285 Silymarin proposed for chemoprevention of melanoma

Silymarin increased proapoptotic effects of anti-Fas agonistic antibody CH11 in melanoma cells. 2013 287 Silymarin for prevention for melanoma invasion

Silymarin decreased the growth of melanoma xenografts and locked MEK1/2-ERK1/2-RSK signaling that led to a reduction of NF-kB activator protein1 and STAT3, which resulted in cell cycle arrest and inhibited tumor growth in vitro and in vivo 2015 289 X Silymarin targeted cell cycle regulators, angiogenesis, and induced apoptosis in vitro and in vivo

Silymarin and derivatives: from biosynthesis to health benefits

Milk thistle (Silybum marianum) seed germination

Mechanism for the protective effects of silymarin against carbon tetrachlorideinduced lipid peroxidation and hepatotoxicity in mice

Silybin and silymarin-new effects and applications

The use of silymarin in the treatment of liver diseases

Hepatoprotective effect of silymarin

Milk thistle (Silybum marianum) for the therapy of liver disease

Bioavailability of silymarin flavonolignans: drug formulations and biotransformation

Hepatoprotective and antiviral functions of silymarin components in hepatitis C virus infection

Silymarin/silybin and chronic liver disease: a marriage of many years

The history of silymarin. Contribution to the history of liver therapy

Effect of sowing date and rate on the yield and flavonolignan content of the fruits of milk thistle (Silybum marianum L. Gaertn.) grown on light soil in a moderate climate

Studies on constituents of Silybum marianum (L.) gaertn. I. New flavonolignans named 2,3-dehydrosilymarin and 2,3-dehydrosilychristin. AGRIS (FAO of the UN)

Complete isolation and characterization of silybins and isosilybins from milk thistle (Silybum marianum)

Chemical evaluation of a silymarin-containing flavonoid concentrate from Silybum marianum (L.)

On the chemistry of silymarin (silybin), the active principle of the fruits from Silybum marianum (L.) Gaertn. (Carduus marianus L.)

The structure of silybin (silybum substance E6), the first flavonolignan

The role of sodium hydrogen exchanger 1 in dysregulation of proton dynamics and reprogramming of cancer metabolism as a sequela

Dysregulated pH: a perfect storm for cancer progression

Silymarin: what is in the name…? An appeal for a change of editorial policy

Chemistry of silybin

Oxidised derivatives of silybin and their antiradical and antioxidant activity

Milk thistle nomenclature: why it matters in cancer research and pharmacokinetic studies

Identifying the differential effects of silymarin constituents on cell growth and cell cycle regulatory molecules in human prostate cancer cells

Determination of active component in silymarin by RP-LC and LC/MS

The effects of silymarin on experimental phalloidine poisoning

Prevention by silybin of phalloidin-induced acute hepatoxicity

Silymarin treatment of viral hepatitis: a systematic review

Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon therapy: a randomized controlled trial

hypercholesterolemia in rats

New therapeutic potentials of milk thistle

Effects of silymarin and silybin on lipoprotein cholesterol levels and oxidizability of low density lipoproteins in rats

Silymarin and neurodegenerative diseases: therapeutic potential and basic molecular mechanisms

Neuroprotective potential of silymarin against CNS disorders: insight into the pathways and molecular mechanisms of action

Silymarin protects dopaminergic neurons against lipopolysaccharide-induced neurotoxicity by inhibiting microglia activation

Silymarin attenuated the amyloid β plaque burden and improved behavioral abnormalities in an Alzheimer's disease mouse model

Silymarin effect on amyloid-β plaque accumulation and gene expression of APP in an Alzheimer's disease rat model

Structure-activity relationship for ( + )-taxifolin isolated from silymarin as an inhibitor of amyloid β aggregation

Silymarin restores regulatory T cells (tregs) function in multiple sclerosis (MS) patients in vitro

Immunoregulatory effects of silymarin on proliferation and activation of Th1 cells isolated from newly diagnosed and IFN-β 1b-treated MS patients

The effect of silymarin supplementation on cognitive impairment induced by diabetes in rats

Silibinin rescues learning and memory deficits by attenuating microglia activation and preventing neuroinflammatory reactions in SAMP8 mice

Prevention of alloxan-induced diabetes mellitus in the rat by silymarin

Silymarin protects pancreatic β-cells against cytokine-mediated toxicity: implication of c-Jun NH2-terminal kinase and janus kinase/signal transducer and activator of transcription pathways

The efficacy of Silybum marianum (L.) gaertn.(silymarin) in the treatment of type II diabetes: a randomized, double-blind, placebo-controlled, clinical trial

Silymarin as an adjunct to glibenclamide therapy improves long-term and postprandial glycemic control and body mass index in type 2 diabetes

Silymarin in type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

Effect of silymarin and its polyphenolic fraction on cholesterol absorption in rats

Effects of polyphenolic fraction of silymarin on lipoprotein profile in rats fed cholesterol-rich diets

Silymarin as a potential hypocholesterolaemic drug

Effect of silibinin on biliary lipid composition experimental and clinical study

Short term treatment of type II hyperlipoproteinaemia with silymarin

The effect of silibinin on experimental cyclosporine nephrotoxicity. Renal Fail

Effect of silymarin on kidneys of rats suffering from alloxan-induced diabetes mellitus

Effect of addition of silymarin to renin-angiotensin system inhibitors on proteinuria in type 2 diabetic patients with overt nephropathy: a randomized, double-blind, placebo-controlled trial

The protective effects of silymarin on ischemia-reperfusion injuries: a mechanistic review

Cardioprotective activity of silymarin in ischemia-reperfusion-induced myocardial infarction in albino rats

Preventive effect of silymarin in cerebral ischemia-reperfusion-induced brain injury in rats possibly through impairing NF-κB and STAT-1 activation

Preventive effect of silymarin-loaded chitosan nanoparticles against global cerebral ischemia/reperfusion injury in rats

Silymarin attenuates the renal ischemia/reperfusion injury-induced morphological changes in the rat kidney

Antioxidant and protective effects of silymarin on ischemia and reperfusion injury in the kidney tissues of rats

The effect of silymarin on mesenteric ischemia-reperfusion injury

Gastroprotection induced by silymarin, the hepatoprotective principle of Silybum marianum in ischemia-reperfusion mucosal injury: role of neutrophils

Modulatory effect of silymarin on pulmonary vascular dysfunction through HIF-1α-iNOS following rat lung ischemia-reperfusion injury

Silymarin preconditioning protected insulin resistant rats from liver ischemia-reperfusion injury: role of endogenous H2S

Protection against post-ischemic mitochondrial injury in rat liver by silymarin or TUDC

Intraperitoneal administration of silymarin protects end organs from multivisceral ischemia/reperfusion injury in a rat model

Attenuation of UVA-induced damage to human keratinocytes by silymarin

Silymarin protects epidermal keratinocytes from ultraviolet radiation-induced apoptosis and DNA damage by nucleotide excision repair mechanism

Skin protective activity of silymarin and its flavonolignans

The treatment of melasma by silymarin cream

Combined effects of silymarin and methylsulfonylmethane in the management of rosacea: clinical and instrumental evaluation

Silymarin inhibits UV radiation-induced immunosuppression through augmentation of interleukin-12 in mice

Phyto-pharmacological perspective of silymarin: a potential prophylactic or therapeutic agent for COVID-19, based on its promising immunomodulatory, anti-coagulant and anti-viral property

Lead finding from selected flavonoids with antiviral (SARS-CoV-2) potentials against COVID-19: an in-silico evaluation

Antiviral activity of silymarin against mayaro virus and protective effect in virus-induced oxidative stress

Antiviral activity of silymarin against chikungunya virus

Antiviral effect of silymarin against Zika virus in vitro

In vitro antimicrobial and modulatory activity of the natural products silymarin and silibinin

Combined amiodarone and silymarin treatment, but not amiodarone alone, prevents sustained atrial flutter in dogs

Silymarin and vitamin E reduce amiodarone-induced lysosomal phospholipidosis in rats

A randomized, double blinded, placebo-controlled clinical trial of silymarin in ulcerative colitis

Improving silymarin oral bioavailability using silica-installed redox nanoparticle to suppress inflammatory bowel disease

Poly) phenols in inflammatory bowel disease and irritable bowel syndrome: a review

Investigating the effectiveness of silymarin in treatment of migraine patients referred to medical centers affiliated to arak university of medical sciences

Silymarin BIO-C®, an extract from Silybum marianum fruits, induces hyperprolactinemia in intact female rats

Evaluation of the effect of Silybum marianum extract on menopausal symptoms: a randomized, double-blind placebocontrolled trial

Anti-inflammatory effect of silymarin on ovarian immunohistochemical localization of TNF-α associated with systemic inflammation in polycystic ovarian syndrome

Characterization of effective chemopreventive agents in mammary gland in vitro using an initiationpromotion protocol

Advances in pharmacological studies of silymarin

Inhibitory effect of silymarin, an antihepatotoxic flavonoid, on 12-O-tetradecanoylphorbol-13-acetate-induced epidermal ornithine decarboxylase activity and mRNA in SENCAR mice

Action of dietary trypsin, pressed coffee oil, silymarin and iron salt on 1,2-dimethylhydrazine tumorigenesis by gavage

Silymarin and its components are inhibitors of betaglucuronidase

Biochemical bases of the pharmacological action of the flavonoid silymarin and of its structural isomer silibinin

Inhibition of rat liver cytosolic glutathione S transferase by silybin

Scavenging of reactive oxygen species and inhibition of arachidonic acid metabolism by silibinin in human cells

Effect of silymarin on different acute inflammatory models and leukocyte migration

Novel cancer chemopreventive effects of a flavonoid antioxidant silymarin: inhibition of mRNA expression of an endogenous tumor promoter TNF alpha

Skin cancer chemopreventive effects of a flavonoid antioxidant silymarin are mediated via impairment of receptor tyrosine kinase signaling and perturbation in cell cycle progression

Protective effects of silymarin against photocarcinogenesis in a mouse skin model

Antioxidants modulate acute solar ultraviolet radiation-induced NF-kappa-B activation in a human keratinocyte cell line. Free Radical Biology and Medicine

A flavonoid antioxidant, silymarin, affords exceptionally high protection against tumor promotion in the SENCAR mouse skin tumorigenesis model

Antiproliferative effect of silybin on gynaecological malignancies: synergism with cisplatin and doxorubicin

A flavonoid antioxidant, silymarin, inhibits activation of erbB1 signaling and induces cyclin-dependent kinase inhibitors, G1 arrest, and anticarcinogenic effects in human prostate carcinoma DU145 cells

Anticarcinogenic effect of a flavonoid antioxidant, silymarin, in human breast cancer cells MDA-MB 468: induction of G1 arrest through an increase in Cip1/p21 concomitant with a decrease in kinase activity of cyclin-dependent kinases and associated cyclins

Inhibitory effect of silibinin on ligand binding to erbB1 and associated mitogenic signaling, growth, and DNA synthesis in advanced human prostate carcinoma cells

Selective inhibition of NF-kB activation by the flavonoid hepatoprotector silymarin in HepG2. Evidence for different activating pathways

Silymarin suppresses TNF-induced activation of NF-kappa B, c-Jun N-terminal kinase, and apoptosis

Modulation of mitogen-activated protein kinase activation and cell cycle regulators by the potent skin cancer preventive agent silymarin

Anticancer potential of silymarin: from bench to bed side

Significant inhibition by the flavonoid antioxidant silymarin against 12-O-tetradecanoylphorbol 13-acetate-caused modulation of antioxidant and inflammatory enzymes, and cyclooxygenase 2 and interleukin-1alpha expression in SENCAR mouse epidermis: implications in the prevention of stage I tumor promotion

Silibinin up-regulates insulin-like growth factor-binding protein 3 expression and inhibits proliferation of androgen-independent prostate cancer cells

Silymarin inhibits function of the androgen receptor by reducing nuclear localization of the receptor in the human prostate cancer cell line LNCaP

Induction of human promyelocytic leukemia HL-60 cell differentiation into monocytes by silibinin: involvement of protein kinase C

Silibinin is a direct inhibitor of STAT3

Targeting STAT3 with silibinin to improve cancer therapeutics

Combined treatment with sorafenib and silibinin synergistically targets both HCC cells and cancer stem cells by enhanced inhibition of the phosphorylation of STAT3/ERK/AKT

Inhibition of telomerase activity and secretion of prostate specific antigen by silibinin in prostate cancer cells

Silymarin induces apoptosis primarily through a p53-dependent pathway involving Bcl-2/ Bax, cytochrome c release, and caspase activation

Therapeutic intervention of silymarin on the migration of non-small cell lung cancer cells is associated with the axis of multiple molecular targets including class

ZEB1 expression, and restoration of miR-203 and E-cadherin expression

Silybin, a component of sylimarin, exerts anti-inflammatory and anti-fibrogenic effects on human hepatic stellate cells

Silymarin targets β-catenin signaling in blocking migration/invasion of human melanoma cells

Silymarin suppresses the PGE2-induced cell migration through inhibition of EP2 activation; G protein-dependent PKA-CREB and G proteinindependent Src-STAT3 signal pathways

Silibinin inhibits prostate cancer invasion, motility and migration by suppressing vimentin and MMP-2 expression

Inhibition of wnt signaling by silymarin in human colorectal cancer cells

Inhibition of silibinin on migration and adhesion capacity of human highly metastatic breast cancer cell line, MDA-MB-231, by evaluation of β1-integrin and downstream molecules, Cdc42, Raf-1 and D4GDI

Anti-angiogenic effect of silymarin on colon cancer LoVo cell line

Silibinin inhibits angiogenesis via Flt-1, but not KDR, receptor up-regulation

Transcriptome profiling reveals silibinin dose-dependent response network in non-small lung cancer cells

Cold atmospheric plasma and silymarin nanoemulsion synergistically inhibits human melanoma tumorigenesis via targeting HGF/c-MET downstream pathway

Silymarin attenuates invasion and migration through the regulation of epithelial-mesenchymal transition in Huh7 cells

Taxifolin inhibits breast cancer cells proliferation, migration and invasion by promoting mesenchymal to epithelial transition via β-catenin signaling

High levels of tissue inhibitor of metalloproteinase-1 predict poor outcome in patients with breast cancer

Serum matrix metalloproteinases-2,-9 and tissue inhibitors of metalloproteinases-1,-2 in lung cancer--TIMP-1 as a prognostic marker

TIMP-1 Promotes accumulation of cancer associated fibroblasts and cancer progression

Antifibrotic effect of silymarin in rat secondary biliary fibrosis is mediated by downregulation of procollagen α1 (I) and TIMP-1

Hepatoprotection of silymarin against thioacetamide-induced chronic liver fibrosis

Hepatoprotective and antifibrotic effect of a new silybin-phosphatidylcholinevitamin E complex in rats

LPA Receptor heterodimerizes with CD97 to amplify LPA-initiated RHO-dependent signaling and invasion in prostate cancer cells

Opposite roles of LPA 1 and LPA 3 on cell motile and invasive activities of pancreatic cancer cells

Massively parallel sequencing reveals an accumulation of de novo mutations and an activating mutation of LPAR1 in a patient with metastatic neuroblastoma

The LPA1/ZEB1/ miR-21-activation pathway regulates metastasis in basal breast cancer

Silymarin and caffeine combination ameliorates experimentallyinduced hepatic fibrosis through down-regulation of LPAR1 expression

Silibinin inhibits triple negative breast cancer cell motility by suppressing TGF-β2 expression

Silibinin inhibits TGF-β-induced MMP-2 and MMP-9 through smad signaling pathway in colorectal cancer HT-29 cells

Anti-inflammatory/anti-fibrotic effects of the hepatoprotective silymarin and the schistosomicide praziquantel against schistosoma mansoni-induced liver fibrosis

Silymarin regulates HIF-1α and iNOS expression in the brain and gills of hypoxic-reoxygenated rainbow trout oncorhynchus mykiss

Silibinin inhibits expression of HIF-1α through suppression of protein translation in prostate cancer cells

Silibinin suppresses EGFR ligand-induced CD44 expression through inhibition of EGFR activity in breast cancer cells

Silibinin suppresses CD44 expression in prostate cancer cells

miRNA-34a inhibits cell adhesion by targeting CD44 in human renal epithelial cells: implications for renal stone disease

CD44 Mediates human glioma cell adhesion and invasion in vitro

Non-small cell lung cancer cyclooxygenase-2-dependent invasion is mediated by CD44

CD44 And its partners in metastasis

The non-coding 3 ′ UTR of CD44 induces metastasis by regulating extracellular matrix functions

CD44 Facilitates metastasis by promoting co-clustering of breast cancer cells and cancer associated fibroblasts

Silibinin modulates TNF-α and IFN-γ mediated signaling to regulate COX2 and iNOS expression in tumorigenic mouse lung epithelial LM2 cells

Silibinin inhibits Wnt/β-catenin signaling by suppressing Wnt co-receptor LRP6 expression in human prostate and breast cancer cells

The flavonolignan silibinin potentiates TRAIL-induced apoptosis in human colon adenocarcinoma and in derived TRAIL-resistant metastatic cells

Silibinin triggers apoptotic signaling pathways and autophagic survival response in human colon adenocarcinoma cells and their derived metastatic cells

Silibinin sensitizes human glioma cells to TRAIL-mediated apoptosis via DR5 up-regulation and down-regulation of c-FLIP and survivin

Silibinin inhibits tumor growth in a murine orthotopic hepatocarcinoma model and activates the TRAIL apoptotic signaling pathway

Silibinin down-regulates expression of secreted phospholipase A2 enzymes in cancer cells

Silibinin inhibits platelet-derived growth factor-driven cell proliferation via downregulation of N-glycosylation in human Tenon's Fibroblasts in a proteasome-dependent manner

Interleukin 8 expression regulates tumorigenicity and metastases in androgen-independent prostate cancer

Induction of interleukin-8 preserves the angiogenic response in HIF-1α-deficient colon cancer cells

Concentration of interleukin-6 (IL-6), interleukin-8 (IL-8) and interleukin-10 (IL-10) in blood serum of breast cancer patients

Interleukin 8 expression regulates tumorigenicity and metastasis in human bladder cancer

Inhibition of interleukin-8 reduces tumorigenesis of human non-small cell lung cancer in SCID mice

Curcumin induces glutathione biosynthesis and inhibits NF-κB activation and interleukin-8 release in alveolar epithelial cells: mechanism of free radical scavenging activity

Flavonoids inhibit cytokine-induced endothelial cell adhesion protein gene expression

Anti-inflammatory activity of silymarin in patients with knee osteoarthritis

Silybin inhibits interleukin-1β-induced production of pro-inflammatory mediators in canine hepatocyte cultures

Silibinin inhibits endometrial carcinoma via blocking pathways of STAT3 activation and SREBP1-mediated lipid accumulation

Silibinin-induced apoptosis of breast cancer cells involves mitochondrial impairment

Matrix metalloproteinases and tissue inhibitors of metalloproteinases structure, function, and biochemistry

Therapeutic efficacy of silibinin on human neuroblastoma cells: akt and NF-κB expressions may play an important role in silibinin-induced response

Tumor cyclooxygenase-2 levels correlate with tumor invasiveness in human hepatocellular carcinoma

Silymarin downregulates COX-2 expression and attenuates hyperlipidemia during NDEA-induced rat hepatocellular carcinoma

Apoptosis and carcinogenesis

Silibinin regulates tumor progression and tumorsphere formation by suppressing PD-L1 expression in Non-small cell lung cancer (NSCLC) cells

Silibinin downregulates PD-L1 expression in nasopharyngeal carcinoma by interfering with tumor cell glycolytic metabolism

Evaluation of anti-cancer potency of silibinin on murine renal carcinoma RenCa cells in an animal model with an intact immune system. Anti-Cancer Drugs

The notch signaling pathway as a mediator of tumor survival

Silybin-mediated inhibition of notch signaling exerts antitumor activity in human hepatocellular carcinoma cells

Dibenzazepine combats acute liver injury in rats via amendments of notch signaling and activation of autophagy

Silibinin induces cell death through reactive oxygen species-dependent downregulation of notch-1/ERK/Akt signaling in human breast cancer cells

The roles of SIRT1 in cancer

Multifaceted modulation of SIRT1 in cancer and inflammation

Silymarin ameliorates the disordered glucose metabolism of mice with diet-induced obesity by activating the hepatic SIRT1 pathway

Chronic silymarin, quercetin and naringenin treatments increase monoamines synthesis and hippocampal Sirt1 levels improving cognition in aged rats

Silymarin modulates catabolic cytokine expression through Sirt1 and SOX9 in human articular chondrocytes

Silibinin protects against isoproterenol-induced rat cardiac myocyte injury through mitochondrial pathway after up-regulation of SIRT1

Inhibition of SIRT1 signaling sensitizes the antitumor activity of silybin against human lung adenocarcinoma cells in vitro and in vivo

Anti-angiogenic potential of a cancer chemopreventive flavonoid antioxidant, silymarin: inhibition of key attributes of vascular endothelial cells and angiogenic cytokine secretion by cancer epithelial cells

Silymarin decreases the expression of VEGF-A, iNOS and caspase-3 and preserves the ultrastructure of cardiac cells in doxorubicin induced cardiotoxicity in rats: a possible protective role

The effect of silymarin on VEGF, VEGFR-1 and IL-1α levels in placental cultures of severe preeclamptic women

Silymarin inhibits invasion and migration of hepatoma cell line MHCC97

c-Myc and cancer metabolism

Milk thistle

Physiological responses to a natural antioxidant flavonoid mixture, silymarin, in BALB/c mice: i. Induction of transforming growth factor beta1 and c-myc in liver with marginal effects on other genes

Silymarin and hepatocellular carcinoma: a systematic, comprehensive, and critical review. Anti-Cancer Drugs

Silibinin suppresses spontaneous tumorigenesis in APC min/ + mouse model by modulating beta-catenin pathway

Chemoprevention of intestinal tumorigenesis in APCmin/ + mice by silibinin

In vitro inhibition of human carbonic anhydrase I and II isozymes with natural phenolic compounds

Analysis of saponins and phenolic compounds as inhibitors of α-carbonic anhydrase isoenzymes

Silymarin and its role in chronic diseases. Drug discovery from mother nature

Silymarin protects against renal injury through normalization of lipid metabolism and mitochondrial biogenesis in high fat-fed mice

Silibinin inhibits established prostate tumor growth, progression, invasion, and metastasis and suppresses tumor angiogenesis and epithelial-mesenchymal transition in transgenic adenocarcinoma of the mouse prostate model mice

Antimetastatic efficacy of silibinin: molecular mechanisms and therapeutic potential against cancer

The effects of concomitant use of silymarin and chemotherapy on solid tumors: a pilot randomized controlled trial

Milk thistle (Silybum Marianum) as an antidote or a protective agent against natural or chemical toxicities: a review

Toward the definition of the mechanism of action of silymarin: activities related to cellular protection from toxic damage induced by chemotherapy

Protective role of silymarin on hepatic and renal toxicity induced by MTX based chemotherapy in children with acute lymphoblastic leukemia

Silymarine during maintenance therapy of acute promyelocytic leukemia

Silibinin protects against cisplatin-induced nephrotoxicity without compromising cisplatin or ifosfamide anti-tumour activity

Cisplatin nephrotoxicity and protection by silibinin

Influence of silymarin and its flavonolignans on doxorubicin-iron induced lipid peroxidation in rat heart microsomes and mitochondria in comparison with quercetin

Silymarin alleviates docetaxel-induced central and peripheral neurotoxicity by reducing oxidative stress, inflammation and apoptosis in rats

Pilot study of silymarin as supplementation to reduce toxicities in metastatic colorectal cancer patients treated with first-line FOLFIRI Plus bevacizumab

Oral silymarin formulation efficacy in management of AC-T protocol induced hepatotoxicity in breast cancer patients: a randomized, triple blind

Combined treatment with silibinin and epidermal growth factor receptor tyrosine kinase inhibitors overcomes drug resistance caused by T790 M mutation

Silibinin suppresses bladder cancer cell malignancy and chemoresistance in an NF-κB signaldependent and signal-independent manner

Silibinin restores paclitaxel sensitivity to paclitaxel-resistant human ovarian carcinoma cells

Effects of the flavonoids biochanin A, morin, phloretin, and silymarin on P-glycoprotein-mediated transport

The flavanolignan silybin and its hemisynthetic derivatives, a novel series of potential modulators of P-glycoprotein

New derivatives of silybin and 2, 3-dehydrosilybin and their cytotoxic and P-glycoprotein modulatory activity

Modulation of multidrug resistance protein 1 (MRP1/ABCC1) transport and ATPase activities by interaction with dietary flavonoids

Effect of flavonoids on MRP1-mediated transport in Panc-1 cells

Antioxidant, antiinflammatory, and multidrug resistance modulation activity of silychristin derivatives

Silymarin is a selective estrogen receptor β (ERβ) agonist and has estrogenic effects in the metaphysis of the femur but no or antiestrogenic effects in the uterus of ovariectomized

Effects of silymarin flavonolignans and synthetic silybin derivatives on estrogen and aryl hydrocarbon receptor activation

Evidences for antiosteoporotic and selective estrogen receptor modulator activity of silymarin compared with ethinylestradiol in ovariectomized rats

Abdel-Naim AB. Role of the phytoestrogenic, pro-apoptotic and antioxidative properties of silymarin in inhibiting experimental benign prostatic hyperplasia in rats

Use of selenium-silymarin mix reduces lower urinary tract symptoms and prostate specific antigen in men

Hormonal profile and histopathological study on the influence of silymarin on both female and male albino rats

The effect of silymarin on spermatogenesis process in rats

Endocytosis and cancer

Silibinin inhibits hepatitis C virus entry into hepatocytes by hindering clathrin-dependent trafficking

Silymarin for hepatitis C virus infection

Inhibitory effect of silibinin on hepatitis B virus entry

Effects of flavonoids on enzyme secretion and endocytosis in normal and mucolipidosis II fibroblasts

Clathrin switches transforming growth factor-β role to pro-tumorigenic in liver cancer

Inhibition of clathrin by pitstop 2 activates the spindle assembly checkpoint and induces cell death in dividing HeLa cancer cells

Silibinin inhibits cell growth and induces apoptosis by caspase activation, down regulating survivin and blocking EGFR-ERK activation in renal cell carcinoma

Inhibitory effect of silibinin on EGFR signal-induced renal cell carcinoma progression via suppression of the EGFR/MMP-9 signaling pathway

Silibinin inhibits the invasion and migration of renal carcinoma 786-O cells in vitro, inhibits the growth of xenografts in vivo and enhances chemosensitivity to 5-fluorouracil and paclitaxel

Targeting the stromal pro-tumoral hyaluronan-CD44 pathway in pancreatic cancer

Overcoming drug resistance in pancreatic cancer

Silibinin prevents prostate cancer cell-mediated differentiation of naïve fibroblasts into cancer-associated fibroblast phenotype by targeting TGF β2

A novel silybin derivative, multi-targets metastatic ovarian cancer cells and is safe in zebrafish toxicity studies

Restoring E-cadherin expression by natural compounds for anticancer therapies in genital and urinary cancers

Silymarin retards the progression of alcohol-induced hepatic fibrosis in baboons

Silibinin inhibits the fibrotic responses induced by cigarette smoke via suppression of TGF-β1/smad 2/3 signaling

Targeting events in melanoma carcinogenesis for the prevention of melanoma

Silymarin enhanced cytotoxic effect of anti-Fas agonistic antibody CH11 on A375-S2 cells

Emerging phytochemicals for prevention of melanoma invasion

Direct targeting of MEK1/2 and RSK2 by silybin induces cell-cycle arrest and inhibits melanoma cell growth

Silymarin inhibits melanoma cell growth both in vitro and in vivo by targeting cell cycle regulators, angiogenic biomarkers and induction of apoptosis

Modulation of WNT/β-catenin pathway in melanoma by biologically active components derived from plants

Evaluation of silibinin on the viability, migration and adhesion of the human prostate adenocarcinoma (PC-3) cell line

Milk thistle and prostate cancer: differential effects of pure flavonolignans from Silybum marianum on antiproliferative end points in human prostate carcinoma cells

Silymarin inhibited DU145 cells by activating SLIT2 protein and suppressing expression of CXCR4

Silibinin decreases prostate-specific antigen with cell growth inhibition via G1 arrest, leading to differentiation of prostate carcinoma cells: implications for prostate cancer intervention

Silymarin and silibinin cause G1 and G2-M cell cycle arrest via distinct circuitries in human prostate cancer PC3 cells: a comparison of flavanone silibinin with flavanolignan mixture silymarin

Antiproliferative and apoptotic effects of silibinin in rat prostate cancer cells

Isosilybin B and isosilybin A inhibit growth, induce G1 arrest and cause apoptosis in human prostate cancer LNCaP and 22Rv1 cells

A cancer chemopreventive agent silibinin, targets mitogenic and survival signaling in prostate cancer

Silibinin synergizes with mitoxantrone to inhibit cell growth and induce apoptosis in human prostate cancer cells

Dietary supplementation with silymarin inhibits 3, 2 ′ -dimethyl-4-aminobiphenyl-induced prostate carcinogenesis in male F344 rats

Silibinin reverses epithelial-tomesenchymal transition in metastatic prostate cancer cells by targeting transcription factors

Isosilybin A induces apoptosis in human prostate cancer cells via targeting Akt, NF-κB, and androgen receptor signaling

Suppression of advanced human prostate tumor growth in athymic mice by silibinin feeding is associated with reduced cell proliferation, increased apoptosis, and inhibition of angiogenesis

Dietary feeding of silibinin inhibits advance human prostate carcinoma growth in athymic nude mice and increases plasma insulin-like growth factor-binding protein-3 levels

Inhibition of retinoblastoma protein (Rb) phosphorylation at serine sites and an increase in Rb-E2F complex formation by silibinin in androgen-dependent human prostate carcinoma LNCaP cells: role in prostate cancer prevention

Silibinin inhibits the invasion of human lung cancer cells via decreased productions of urokinase-plasminogen activator and matrix metalloproteinase-2

Silibinin meglumine, a water-soluble form of milk thistle silymarin, is an orally active anti-cancer agent that impedes the epithelialto-mesenchymal transition (EMT) in EGFR-mutant non-smallcell lung carcinoma cells

Silibinin inhibits human nonsmall cell lung cancer cell growth through cell-cycle arrest by modulating expression and function of key cell-cycle regulators

Molecular mechanism of silymarin-induced apoptosis in a highly metastatic lung cancer cell line anip973

Silibinin induces growth inhibition and apoptotic cell death in human lung carcinoma cells

Epigenetic modifications and p21-cyclin B1 nexus in anticancer effect of histone deacetylase inhibitors in combination with silibinin on non-small cell lung cancer cells

Stem celllike ALDHbright cellular states in EGFR-mutant non-small cell lung cancer: a novel mechanism of acquired resistance to erlotinib targetable with the natural polyphenol silibinin

Growth inhibition and regression of lung tumors by silibinin: modulation of angiogenesis by macrophage-associated cytokines and nuclear factor-κB and signal transducers and activators of transcription 3

STAT3-targeted Treatment with silibinin overcomes the acquired resistance to crizotinib in ALK-rearranged lung cancer

Cytotoxic and toxicogenomic effects of silibinin in bladder cancer cells with different TP53 status

Chemopreventive effects of a flavonoid antioxidant silymarin on N-butyl-N-(4-hydroxybutyl) nitrosamine-induced urinary bladder carcinogenesis in male ICR mice

Silibinin suppresses bladder cancer through down-regulation of actin cytoskeleton and PI3K/Akt signaling pathways

Chemopreventive and chemotherapeutic effects of intravesical silibinin against bladder cancer by acting on mitochondria

Silibinin inhibits β-catenin/ZEB1 signaling and suppresses bladder cancer metastasis via dualblocking epithelial-mesenchymal transition and stemness

Silibinin causes apoptosis and cell cycle arrest in some human pancreatic cancer cells

Combination of HDAC inhibitor TSA and silibinin induces cell cycle arrest and apoptosis by targeting survivin and cyclinB1/Cdk1 in pancreatic cancer cells

Silibinin-mediated metabolic reprogramming attenuates pancreatic cancer-induced cachexia and tumor growth

In vitro and in vivo anticancer efficacy of silibinin against human pancreatic cancer BxPC-3 and PANC-1 cells

Silibinin induces G1 arrest, apoptosis and JNK/SAPK upregulation in SW1990 human pancreatic cancer cells

Combined effects of multiple flavonoids on breast cancer resistance protein (ABCG2)-mediated transport

Synergistic anticancer effects of silibinin with conventional cytotoxic agents doxorubicin, cisplatin and carboplatin against human breast carcinoma MCF-7 and MDA-MB468 cells

Silibinin prevents TPA-induced MMP-9 expression and VEGF secretion by inactivation of the Raf/MEK/ERK pathway in MCF-7 human breast cancer cells

The role of milk thistle extract in breast carcinoma cell line (MCF-7) apoptosis with doxorubicin

Anti-cancer activity of silymarin on MCF-7 and NCIH-23 cell lines

Silibinin inhibits accumulation of myeloid-derived suppressor cells and tumor growth of murine breast cancer

Silibinin, a natural flavonoid, induces autophagy via ROS-dependent mitochondrial dysfunction and loss of ATP involving BNIP3 in human MCF7 breast cancer cells

Silibilin-induces apoptosis in breast cancer cells by modulating p53, p21, Bak and Bcl-XL pathways

ERα down-regulation plays a key role in silibinin-induced autophagy and apoptosis in human breast cancer MCF-7 cells

Comparative evaluation of silibinin effects on cell cycling and apoptosis in human breast cancer MCF-7 and T47D cell lines

Silibinin sensitizes chemoresistant breast cancer cells to chemotherapy

78P In vivo activation of mitochondrial pathway and cell cycle arrest through silymarin loaded iron nanoparticles as proficient nanocomplex system for triple negative breast cancer therapy

Anticancer effect of silymarin on breast cancer cells through inhibition of Akt and MAPK pathway expression

Silymarin inhibits proliferation of human breast cancer cells via regulation of the MAPK signaling pathway and induction of apoptosis

Silymarin, a naturally occurring polyphenolic antioxidant flavonoid, inhibits azoxymethane-induced colon carcinogenesis in male F344 rats

Effect of silibinin in human colorectal cancer cells: targeting the activation of NF-κB signaling

Silymarin induces cyclin D1 proteasomal degradation via its phosphorylation of threonine-286 in human colorectal cancer cells

Studies on radiation sensitization efficacy by silymarin in colon carcinoma cells

The effects of silibinin on colorectal cancer cell line

Regorafenib in combination with silybin as a novel potential strategy for the treatment of metastatic colorectal cancer

Silymarin, boswellic acid and curcumin enriched dietetic formulation reduces the growth of inherited intestinal polyps in an animal model

Silibinin efficacy against human hepatocellular carcinoma

Suppression of N-nitrosodiethylamine induced hepatocarcinogenesis by silymarin in rats

Silymarin attenuated mast cell recruitment thereby decreased the expressions of matrix metalloproteinases-2 and 9 in rat liver carcinogenesis

Effects of silibinin on cell growth and invasive properties of a human hepatocellular carcinoma cell line, HepG-2, through inhibition of extracellular signal-regulated kinase 1/2 phosphorylation

Silymarin inhibited proliferation and induced apoptosis in hepatic cancer cells

Effects and mechanisms of silibinin on human hepatocellular carcinoma xenografts in nude mice

Combined treatment with silibinin and either sorafenib or gefitinib enhances their growth-inhibiting effects in hepatocellular carcinoma cells

Silymarin suppresses HepG2 hepatocarcinoma cell progression through downregulation of slit-2/robo-1 pathway

Silymarin induces cell cycle arrest and apoptosis in ovarian cancer cells

Antitumour activity of the silybin-phosphatidylcholine complex, IdB 1016, against human ovarian cancer

Silibinin inhibits tumor growth through downregulation of extracellular signal-regulated kinase and Akt in vitro and in vivo in human ovarian cancer cells

Silibinin can induce differentiation as well as enhance vitamin D3-induced differentiation of human AML cells ex vivo and regulates the levels of differentiation-related transcription factors

Silibinin suppresses NPM-ALK, potently induces apoptosis and enhances chemosensitivity in ALK-positive anaplastic large cell lymphoma

Silymarin inhibits proliferation and induces apoptosis in epstein-barr virus-positive lymphoma cells by suppressing nuclear factor-kappa B pathway

Silybin suppresses cell proliferation and induces apoptosis of multiple myeloma cells via the PI3K/Akt/ mTOR signaling pathway

Increase of phosphatase and tensin homolog by silymarin to inhibit human pharynx squamous cancer

Silibinin-induced glioma cell apoptosis by PI3K-mediated but Akt-independent downregulation of FoxM1 expression

In vitro and in vivo anti-cancer activity of silymarin on oral cancer

Silymarin and its active component silibinin act as novel therapeutic alternatives for salivary gland cancer by targeting the ERK1/2-Bim signaling cascade

Silymarin inhibits cervical cancer cell through an increase of phosphatase and tensin homolog

Silibinin suppresses human osteosarcoma MG-63 cell invasion by inhibiting the ERK-dependent c-Jun/AP-1 induction of MMP-2

Silibinin inhibits migration and invasion of the rhabdoid tumor G401 cell line via inactivation of the PI3K/Akt signaling pathway

Silymarin induces inhibition of growth and apoptosis through modulation of the MAPK signaling pathway in AGS human gastric cancer cells

Enhancement of mammary carcinogenesis in two rodent models by silymarin dietary supplements

Estrogenic effects of silymarin in ovariectomized rats

Null anticarcinogenic effect of silymarin on diethylnitrosamine-induced hepatocarcinogenesis in rats

Silibinin (milk thistle) potentiates ethanol-dependent hepatocellular carcinoma progression in male mice

Reassessing bioavailability of silymarin

Analysis of silibinin in rat plasma and bile for hepatobiliary excretion and oral bioavailability application

Die wirkung von silymarin auf gehalt und function einiger durch einwirkung von tetrachlorkohlenstoff bzw. Halothan beeinflussten mikrosomalen leberenzyme

Pharmacology of silymarin

Pharmacokinetic studies with silymarin in human serum and bile

Inhibitory effects of silibinin on cytochrome P-450 enzymes in human liver microsomes

Plasma concentrations of free and conjugated silybin after oral intake of a silybin-phosphatidylcholine complex (silipide) in healthy volunteers

Bioavailability of a silybinphosphatidylcholine complex in dogs

Comparative pharmacokinetics of silipide and silymarin in rats

Tissue distribution of silibinin, the major active constituent of silymarin, in mice and its association with enhancement of phase II enzymes: implications in cancer chemoprevention

Pharmacokinetics of silybin in bile following administration of silipide and silymarin in cholecystectomy patients

Pilot study of oral silibinin, a putative chemopreventive agent, in colorectal cancer patients: silibinin levels in plasma, colorectum, and liver and their pharmacodynamic consequences

Silibinin strongly synergizes human prostate carcinoma DU145 cells to doxorubicin-induced growth inhibition, G2-M arrest, and apoptosis

Silymarin inhibits tolllike receptor 8 gene expression and apoptosis in ramos cancer cell line

Evauation effects of silymarin on cytotoxicity and apoptosis on SW480 colon cancer cell line

Hepatoprotective herbal drug, silymarin from experimental pharmacology to clinical medicine

Study on doselinearity of the pharmacokinetics of silibinin diastereomers using a new stereospecific assay

Formulation strategies for enhancing the bioavailability of silymarin: the state of the art

A review of the bioavailability and clinical efficacy of milk thistle phytosome: a silybin-phosphatidylcholine complex (siliphos)

Scavenging effect of silipide, a new silybin-phospholipid complex, on ethanol-derived free radicals

Systematic review of pharmacokinetics and potential pharmacokinetic interactions of flavonolignans from silymarin

Phytosome as a novel biomedicine: a microencapsulated drug delivery system

Comparative bioavailability of silipide, a new !avanolignan complex, in rats

Micronization of silybin by the emulsion solvent diffusion method

Enhanced bioavailability of silymarin by selfmicroemulsifying drug delivery system

Formulation design and in vitro evaluation of silymarin loaded self micro emulsifying drug delivery systems

Preparation and pharmacological evaluation of silibinin liposomes

A supersaturating delivery system of silibinin exhibiting high payload achieved by amorphous nano-complexation with chitosan

Formulation strategies for enhancing the bioavailability of silymarin: the state of the art

Formulation of nanomicelles to improve the solubility and the oral absorption of silymarin

A phase I and pharmacokinetic study of silybin-phytosome in prostate cancer patients

Milk thistle for the treatment of liver disease: a systematic review and meta-analysis

Milk thistle in liver diseases: past, present, future

A study of high-dose oral silybin-phytosome followed by prostatectomy in patients with localized prostate cancer

A presurgical study of oral silybin-phosphatidylcholine in patients with early breast cancer

Dual Effects of Silibinin on Human Pancreatic Cancer Cells

PANC-1 cancer stem-like cell death with silybin encapsulated in polymersomes and deregulation of stemness-related miRNAs and their potential targets

Silibinin affects tumor cell growth because of reduction of stemness properties and induction of apoptosis in 2D and 3D models of MDA-MB-468. Anti-cancer Drugs

Evaluation of inhibitory effect of silibinin on growth and stemness property of MCF-7 cell line derived mammospheres

Intercalation of a flavonoid, silibinin into DNA base pairs: experimental and theoretical approach

Flavonolignans from silymarin do not intercalate into DNA: rebuttal of data published in the paper

Randomized, doubleblind, placebo-controlled crossover study in men with prostate cancer and rising PSA: effectiveness of a dietary supplement

Spontaneous regression of advanced hepatocellular carcinoma: a case report

Complete regression following sorafenib in unresectable, locally advanced hepatocellular carcinoma

Response of brain metastasis from lung cancer patients to an oral nutraceutical product containing silibinin

Hallmarks of cancer: the next generation

Graph-theoretical model of global human interactome reveals enhanced long-range communicability in cancer networks

Inhibition of T-cell inflammatory cytokines, hepatocyte NF-κB signaling, and HCV infection by standardized silymarin

Silymarin causes caspases activation and apoptosis in K562 leukemia cells through inactivation of Akt pathway

Silybin and silymarin-new effects and applications

An updated systematic review with meta-analysis for the clinical evidence of silymarin

Dual effects of silymarin on nasopharyngeal carcinoma cells (NPC-TW01)

The effects of concomitant use of silymarin and chemotherapy on solid tumors: a pilot randomized controlled trial

Interaction of silymarin components and their sulfate metabolites with human serum albumin and cytochrome P450 (2C9, 2C19, 2D6, and 3A4) enzymes

Design and discovery of silybin analogues as antiproliferative compounds using a ring disjunctive-based

A novel silybin derivative, multi-targets metastatic ovarian cancer cells and is safe in zebrafish toxicity studies

Detrimental effect of cancer preventive phytochemicals silymarin, genistein and epigallocatechin 3-gallate on epigenetic events in human prostate carcinoma DU145 cells

Silymarin (milk thistle extract) as a therapeutic agent in gastrointestinal cancer

Ms. Julia Hanna Weiss cooperated in the revision and correction of the article.

Both authors equally contributed in the writing of the article.

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The authors received no financial support for the research, authorship, and/or publication of this article.