key: cord-267345-pmtecdko
authors: Hao, Da Cheng; Gu, Xiao-Jie; Xiao, Pei Gen
title: Phytochemical and biological research of Polygoneae medicinal resources
date: 2015-07-03
journal: Medicinal Plants
DOI: 10.1016/b978-0-08-100085-4.00012-8
sha: 
doc_id: 267345
cord_uid: pmtecdko

This chapter synthesizes current knowledge on phytochemistry, bioactivity, molecular phylogeny, and omics of Polygoneae medicinal resources. Many species in the seven genera of Polygoneae are traditional and popular medicinal herbs. Anthraquinones and stilbenes are characteristic medicinal compounds of Polygoneae, while other useful constituents, such as alkaloids, glycosides, flavonoids, volatile oils, tannins, resins, coumarins, and lignans, have also been isolated from Polygoneae species. Among versatile bioactivities of Polygoneae compounds, their effects on the cardiovascular and nervous systems and their anti-inflammatory, antimicrobial, antiparasitic, insecticidal, anticancer, and antioxidant activities are highlighted. Interspecific hybridization and the following polyploidization play a major role in Polygoneae diversification. Nuclear ITS and chloroplast DNA sequences are retrieved to resolve the interspecific relationship and reassign some taxa to the appropriate genus. Omics study of Polygoneae is at the budding stage, which will revolutionize the sustainable utilization of Polygoneae medicinal resources.

No. R 85.66% of the total organic ester compounds. 1-Phenyl-1-pentanone and acetophenone were 16.30% and 4.33% of the total volatiles, respectively. The liverwort (Porella vernicosa) complex produces a very hot tasting polygodial, a drimane-type sesquiterpene dialdehyde. The same compound has been isolated from two ferns, Thelypteris hispidula and Blechnum fluviatile, as well as from the higher plants Polygonum hydropiper and P. hydropiper f. purpurascens (Polygonaceae); Cinnamosma, Caspicodendron, Canella, and Warburgia species (Canellaceae); and Pseudowintera colorata, Tasmannia lanceolata, Drimys, and Zygogynum species (Winteraceae) (Asakawa et al., 2012) . In addition, the liverworts and higher plants that elaborate polygodial and its related pungent drimane dials contain a small amount of a-tocopherol, g-tocopherol, or d-tocotrienol. The drimane-type sesquiterpenoids and tocopherols might be useful chemotaxonomic markers in some lower and higher plants, including Polygonaceae.

2-Furanmethanol, 2 (5H)-furanone, 2-hydroxy-2-cyclopenten-1-one, 2, 4-dihydroxy-2,5-dimethyl-3(2H)-furan-3-one, 2H-pyran-2,6 (3H)-dione, 2-hydroxy-gammabutyrolactone, 2,5-dimethyl-4-hydroxy-3 (2H)-furanone, 2,5-furandicarboxaldehyde, 2,3-dihydro-3,5-dihydroxy-6-methyl 4H-pyran-4-one, (S)-(+)-2 0 , 3 0 -dideoxyribonolactone, 5-(hydroxymethyl)-furancarboxaldehyde, 3-deoxy-D-mannoic lactone, etc. were found in the callus of P. minus (Vikram et al., 2014) . Tantry 

Resveratrol (3,5,4 0 -trihydroxy-trans-stilbene) is a natural polyphenolic compound that exists in P. cuspidatum, grapes, peanuts, and berries, as well as their manufactured products. Resveratrol is a pharmacologically active compound that interacts with multiple targets in a variety of cardiovascular disease models to exert protective effects or induce a reduction in cardiovascular risk parameters . Endothelial hyperpermeability induced by hyperglycemia is the initial step in the development of atherosclerosis, one of the most serious cardiovascular complications in diabetes. Resveratrol ameliorates high-glucose-induced hyperpermeability mediated by caveolae via VEGF/KDR pathway (Tian et al., 2013) . Polydatin, a resveratrol glucoside extracted from P. cuspidatum, attenuates cardiac hypertrophy through modulation of cardiac Ca 2+ handling and calcineurin-NFAT signaling pathway (Ding et al., 2014) . 2,3,4 0 ,5-Tetrahydroxystilbene-2-O-b-D-glucoside (TSG), extracted from the root of P. multiflorum (He Shou Wu), had inhibitory effects on angiotensin II-induced proliferation of vascular smooth muscle cells (Xu et al., 2014a) . Its antiproliferative effect might be associated with the downregulation of intracellular reactive oxygen species (ROS), followed by the suppression of the Src-MEK1/2-ERK1/2 signaling pathway, hence blocking cell cycle progression. TSG could prevent cardiac remodeling induced by pressure overload in rats (Xu et al., 2014b) , which may be related to a decreasing angiotensin II level, an antioxidant effect, suppression of transforming growth factor-b1 expression, and inhibition of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase activation. Proteomic analysis was used to investigate the molecular events occurring in the atherosclerotic rats after TSG treatment (Yao et al., 2013) . TSG treatment suppresses atherosclerosis by altering the expression of different proteins. Calreticulin, vimentin, HSP 70, lipocortin 1, and Apo A-I are key proteins that may be novel molecular targets responsible for atherogenesis suppression induced by TSG treatment.

Dysregulated tonic tension and calcium sensitization in blood vessels have frequently been observed in many cardiovascular diseases. Emodin of P. multiflorum inhibits tonic tension through suppressing PKCd-mediated inhibition of myosin phosphatase in rat isolated thoracic aorta (Lim et al., 2014) .

P. viviparum (PV) is a perennial herb and widely distributed in high-elevation mountain regions, such as the Tibetan Plateau. In Tibetan traditional medicine, PV is usually used to boost the blood circulation to dissipate blood stasis. PV induces vasorelaxation in the rat thoracic aorta via activation of nitric oxide (NO) synthase in endothelial cells (Chang et al., 2014) .

2,3,4 0 ,5-Tetrahydroxystilbene-2-O-b-D-glucoside (TSG) of P. multiflorum could raise the content of CYP (cytochrome p450) 7A and then promote the lipolysis of cholesterol (Wang et al., 2014a) . TSG also showed the best LDL-reducing effect. Emodin could inhibit HMG-CoA reductase and DGAT1, which were key enzymes in the synthesis of TC and TG. Physcion increased the content of HTGL and then could boost the lipolysis of triglyceride. Physcion showed the best VLDL-reducing effect. The lipid regulation activity might be due to an overall synergy of TSG, emodin, and physcion. TSG attenuates human platelet aggregation, secretion, and spreading in vitro (Xiang et al., 2014) .

Antiatherosclerotic effects of P. aviculare L. ethanol extract in ApoE knockout mice fed a Western diet are mediated via the MAPK pathway (Haeng Park et al., 2014) .

Extracts of P. persicaria inhibit G protein-activated inwardly rectifying K + channels (Lajter et al., 2013a) . The electrophysiologically active agents, not the new flavonoids from the chloroform extract, are among the minor compounds of HPLC eluates.

Resveratroloside and catechin-(4a ! 8)-catechin, the newly found constituents in the invasive variety, have similar NO inhibition potency as that of piceid (the major constituent of P. cuspidatum) (Fan et al., 2013b) , but the newly found major constituent, that is, piceatannol glucoside, showed no apparent effect. The total content of resveratrol measured in the root extracts of the Swiss sample was about 2.5 times less than that of the Chinese one. When the invasive variety of P. cuspidatum is used in traditional medicine, the chemical difference should be kept in mind.

P. tinctorium, a traditional medicine used in China and Korea, improves 2, 4-dinitrofluorobenzene-induced atopic dermatitis-like lesional skin (Han et al., 2014) . P. tinctorium inhibited IL-32 and TSLP production through the attenuation of caspase-1 activation in an animal model of allergic rhinitis (Jeong et al., 2014) .

Flavonol glucuronides at physiologically achievable concentrations within the range of 0.5-10 mM significantly inhibited the production of ROS as well as elastase release in human neutrophils model and should be considered as responsible for the anti-inflammatory activity of the P. aviculare (Granica et al., 2013) .

P. chinense aqueous leaf extract has gastroprotective activity on ethanol-induced hemorrhagic mucosal lesions in rats (Ismail et al., 2012) . P. viviparum inhibits the lipopolysaccharide-induced inflammatory response in RAW264.7 macrophages through heme oxygenase-1 induction and activation of the Nrf2 pathway (Cheng et al., 2013) .

Guizhou Miao medicine P. capitatum has antibacterial activity and can be used in bladder infection (Hu et al., 2014) . Methanolic crude extract of aerial parts of P. maritimum showed a high antibacterial activity against gram-positive bacterial strains: Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus with a highest MIC of 120 mg/ml (El-Haci et al., 2013) . P. orientale extracts had protective effect against Clavibacter michiganense subsp. sepedonicum, the causal agent of bacterial ring rot of potato (Cai et al., 2013) .

Ethanol extracts of P. cuspidatum, resveratrol, (+)-catechin, and emodin 8-O-b-Dglucopyranoside inhibit HIV-1-induced syncytium formation ). An ethyl acetate subfraction separated from P. cuspidatum root and its major component, emodin, inhibited Epstein-Barr virus lytic cycle (Yiu et al., 2014) . In vitro and in vivo studies suggested the inhibitory effects of emodin isolated from P. cuspidatum on Coxsackievirus B₄ . Resveratrol, (E)-3, 5, 12-trihydroxystilbene-3-O-beta-D-glucopyranoside-2 0 -(3 00 , 4 00 , 5 00 -trihydroxybenzoate), and catechin-3-Ogallate, isolated from P. cuspidatum, had inhibitory effect against neuraminidase (NA) activity , with IC50 values of 129.8, 44.8, and 21.3 mmol/ l, respectively. (E)-3, 5, 12-trihydroxystilbene-3-O-beta-D-glucopyranoside-2 0 -(3 00 , 4 00 , 5 00 -trihydroxybenzoate) and catechin-3-O-gallate had significant inhibitory effect against H1N influenza virus (EC50 ¼ 5.9, 0.9 mmol/l, respectively), with very low cytotoxicity to the host cells; their therapeutic selective index (SI) in MDCK cells ranged from 56 to 269. Emodin blocks the SARS coronavirus spike protein and angiotensin-converting enzyme 2 interaction (Ho et al., 2007) .

P. chinense had antidiarrheal activity (Xiao et al., 2013) . Ellagic acid and corilagin are two components contributing to this effect. Cinnamoylphenethyl amides from P. hyrcanicum possess antitrypanosomal activity (Moradi-Afrapoli et al., 2012b) .

The essential oil of P. hydropiper exhibited LC50 values of 194.63 and 199.65 and confertifolin exhibited LC50 values of 2.02 and 3.16 against the second and fourth instar larvae of Aedes albopictus (dengue vector mosquito), respectively (Maheswaran and Ignacimuthu, 2014) . The ovicidal activity of 100% on 0-6 h old eggs, repellent activity of 320.6 min, oviposition deterrent activity of 98.51%, and adulticidal activity of 100% at 10 ppm concentration of confertifolin were recorded.

Trans-piceid (T-Pc) is abundant in P. cuspidatum and in grapes and grape products such as wine. Piceid presents antiproliferative effects in intestinal epithelial Caco-2 cells, which is unrelated to resveratrol release (Storniolo et al., 2014) . 2-Methoxystypandrone of P. cuspidatum inhibits signal transducer and activator of transcription 3 and nuclear factor-kB signaling by inhibiting Janus kinase 2 and IkB kinase (Kuang et al., 2014) . Resveratrol inhibits invasion and metastasis of colorectal cancer cells via MALAT1-mediated Wnt/b-catenin signal pathway (Ji et al., 2013) . Constitutively activated STAT3 plays a pivotal role in oncogenesis and metastasis in many human cancers, and STAT3 has been validated as a novel anticancer drug target. 2-Methoxystypandrone of P. cuspidatum demonstrated a potent inhibitory effect on STAT3 activation and significantly inhibited cell proliferation of human breast cancer cells (Liu et al., 2012b) , especially those with constitutively activated STAT3 (IC50 2.7-3.1 mM). The SAR analysis of quinone analogs suggested that the phenolic and carbonyl groups are the key structures contributing to their inhibitory activities against the STAT3 signaling.

Aqueous and organic extracts of 27 selected species from five genera (Fallopia, Oxyria, Persicaria, Polygonum, and Rumex) of the family Polygonaceae occurring in the Carpathian Basin were screened in vitro for antiproliferative activity against HeLa (cervix epithelial adenocarcinoma), A431 (skin epidermoid carcinoma), and MCF7 (breast epithelial adenocarcinoma) cells (Lajter et al., 2013b) , using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. A total of 196 n-hexane, chloroform, 50% methanol, and water extracts of different plant parts were investigated. Extracts of P. hydropiper, Rumex acetosa, R. alpinus, R. aquaticus, R. scutatus, and R. thyrsiflorus at 10 or 30 mg/ml demonstrated substantial cell growth inhibitory activity (at least 50% inhibition of cell proliferation) against one or more cell lines. R. acetosa and R. thyrsiflorus proved to be the most active and are considered worthy of activity-guided phytochemical investigations.

3,5-Dihydroxybenzyl alcohol of Reynoutria japonica (P. cuspidatum) showed more potent inhibitory activity against topoisomerase I (IC50 4 mM) than camptothecin (Hwangbo et al., 2012) , the positive control (IC50 18 mM). 3,5-Dihydroxybenzyl alcohol, citreorosein, cis-resveratrol, trans-resveratrol, and trans-resveratrol-5-O-b-D-glucopyranoside showed stronger inhibitory activities toward DNA topoisomerase II (IC50 0.54, 14, 15, 0.77, and 3 mM, respectively) than the positive control, etoposide (IC50 44 mM). Emodin and citreorosein displayed weak cytotoxicities against human lung cancer (A549), ovarian cancer (SK-OV-3), human liver hepatoblastoma (HepG2), and colon adenocarcinoma (HT-29) cell lines.

Flavonoid glucuronides of P. amphibium had antileukemic activity (Smolarz et al., 2008) . A potential antitumor ellagitannin of P. capitatum, davidiin, inhibited hepatocellular tumor growth by targeting EZH2 (Wang et al., 2014b) . The n-butanol extract of P. bellardii has the highest cytotoxicity in HeLa, MCF-7, and HepG-2 cells, with IC50 values of 15.26, 50.66, and 30.09 mg/ml, respectively (Abd El-Kader et al., 2013b). Myricetin-3-O-(5 00 -acetyl-a-arabinofuranoside) exhibited a marked cytotoxicity in HeLa (IC50 75.04 mg/ml) and HepG-2 (41.03 mg/ml) cells.

(À)-Loliolide of P. aviculare exerted inhibitory activity against cellular senescence in human dermal fibroblasts (Yang et al., 2014a) . Quercetin-3-O-b-D-glucuronide isolated from P. aviculare inhibits cellular senescence in human primary cells (Yang et al., 2014b) .

Apoptosis induction by P. minus is related to antioxidant capacity, alterations in expression of apoptotic-related genes, and S-phase cell cycle arrest in HepG2 cell line (Mohd Ghazali et al., 2014) . Resveratrol-4-O-D-(2 0 -galloyl)-glucopyranoside isolated from P. cuspidatum exhibits anti-hepatocellular carcinoma viability by inducing apoptosis via the JNK and ERK pathway . Polydatin inhibits growth of lung cancer cells by inducing apoptosis and causing cell cycle arrest .

8-Methyltryptanthrin of P. tinctorium induced differentiation of P19CL6 embryonal carcinoma cells into spontaneously beating cardiomyocyte-like cells (Seya et al., 2014) .

Polydatin from P. cuspidatum exhibited protective effects against carbon tetrachlorideinduced liver injury in mice . P. cuspidatum contained many more contributing antioxidants other than resveratrol (Kurita et al., 2014) .

Tetrahydroxystilbene glucoside of P. multiflorum exhibited protective effect against hydrogen peroxide-induced dysfunction and oxidative stress in osteoblastic MC3T3-E1 cells . Compared with P. multiflorum polysaccharide PMP-1, PMP-2 exhibited a much stronger antioxidant capacity against free radicals, lipid oxidation, and protein glycation (Lv et al., 2014) . The IC₅₀ values of PMP-2 were 0.47, 0.6, and 0.93 mg/ml for superoxide anion scavenging, hydroxyl radical scavenging, and hydroxyl peroxide scavenging, respectively. The inhibitory ability of PMP-2 on lipid oxidation marked in the rat liver, followed by the heart and kidney. PMP-2 also showed satisfactory suppression of AGEs formation.

The EtOAc fraction of P. aviculare displayed the highest content of flavonoids (sum, 208.9 mg/g) with the strongest peroxynitrite scavenging activity (IC50, 2.68 mg/ml) (Nugroho et al., 2014) . The activities of the eight compounds (myricitrin, isoquercitrin, avicularin, quercitrin, myricetin, desmanthin-1, quercetin, and kaempferol) were comparable to that of the positive control (l-penicillamine; IC50: 1.03 mg/ml). The folkloric medicinal uses of P. aviculare are mainly attributed to flavonoids, such as particularly highly contained myricetin, myricitrin, and desmanthin-1.

Xanthone and lignan glycosides from the aerial parts of P. bellardii showed significant antioxidant potential by DPPH(Á) scavenging activity test (Abd El-Kader et al., 2013a). 5, 6-Dihydropyranobenzopyrone, amplexicine, catechin, rutin, quercetin-3-O-b-D-galactopyranoside, chlorogenic acid, galloyl glucose, caffeic acid, gallic acid, and scopoletin, isolated from P. amplexicaule, exhibited considerable antioxidant activity in a DPPH radical scavenging assay (Tantry et al., 2012) .

Resveratrol reverses the effects of chronic unpredictable mild stress on behavior, serum corticosterone levels, and BDNF expression in rats . Resveratrol attenuates oxidative damage and ameliorates cognitive impairment in the brain of senescence-accelerated mice (Liu et al., 2012a) .

P. minus possesses antioxidant and anticholinesterase activity and demonstrated enhanced cognition in vivo . The data suggest neuroprotective properties of the extract. Hexane extracts of P. multiflorum improve tissue and functional outcome following focal cerebral ischemia in mice . Tetrahydroxystilbene glucoside of P. multiflorum attenuates neuroinflammation through the inhibition of microglia activation (Zhang et al., 2013a) . 8-Hydroxycalamenene of Reynoutria elliptica (P. ellipticum) attenuated the cell death of transformed RGC-5 cells (Jo et al., 2013) .

Neurons rely on the release and subsequent cleavage of GSH to cysteinylglycine (Cys-Gly) by astrocytes in order to maintain optimal intracellular GSH levels. In neurodegenerative diseases characterized by oxidative stress, neurons need an optimal GSH supply to defend themselves against free radicals released from activated microglia and astroglia. The rate of GSH synthesis is controlled largely by the activity of g-glutamyl cysteine ligase. Expression of g-glutamyl cysteine ligase and of the Xc-system, which facilitates cystine uptake, is regulated by the redox-sensitive transcription factor, nuclear factor erythroid-2-related factor 2 (Nrf2). Resveratrol and P. multiflorum were all identified as potent Nrf2 activators and "GSH and Cys-Gly boosters" (Steele et al., 2013) .

The antidepressant-like effects of resveratrol in the FST (forced swim test) and TST (tail suspension test) are mediated, at least in part, by modulating hypothalamic-pituitary-adrenal axis, BDNF expression, and ERK phosphorylation in the brain region of mice .

The antimelanogenic activity of 2,3,5,4 0 -tetrahydroxystilbene-2-O-b-D-glucopyranoside, isolated from P. multiflorum, is likely mediated through a noncompetitive inhibition on tyrosinase, downregulation of the expression of melanogenic proteins, and reduction of tyrosinase/TRP-1 complex formation (Cheung et al., 2014) .

Supplementation for 12 weeks with P. minus and the proprietary Eurycoma longifolia extract, Physta, was well tolerated and more effective than placebo in enhancing sexual performance in healthy volunteers (Udani et al., 2014) . P. cuspidatum inhibits pancreatic lipase activity and adipogenesis via attenuation of lipid accumulation , thus having antiobesity effect.

Constituents from the root of P. multiflorum have promotion effect on hair growth (Sun et al., 2013) .

The semialcoholic extract of P. senegalensis possesses a-glucosidase inhibitory activity and antioxidant potency (Bothon et al., 2013) . Proanthocyanidins, isolated from stems of P. multiflorum, strongly inhibit a-amylase with an acarbose equivalence (AE) value of 1954.7 mmol AE/g and inhibit a-glucosidase with an AE value of 211.1 mmol AE/g (Wang et al., 2013b) . They have potential as functional ingredients in reducing postprandial hyperglycemia. Phenolic constituents from aerial parts of P. hyrcanicum had in vitro a-glucosidase inhibitory activity (Moradi-Afrapoli et al., 2012a).

Adverse reactions induced by P. multiflorum are common, with patients developing drug-induced liver injury (DILI) and even liver failure . Although the mechanism is unknown, many studies have suggested that an idiosyncratic reaction occurs, which is related to genetic polymorphisms of CYP1A2. The influence of stilbene glucoside on the pharmacokinetics of emodin may be attributed to the inhibition of UGT1A8 mRNA expression (Ma et al., 2013) . P. cuspidatum markedly increased the systemic exposure and brain concentration of carbamazepine (CBZ) and CBZE through inhibiting the activities of CYP 3A and MRP 2 (Chi et al., 2012) .

Molecular markers can help elucidate how neutral evolutionary forces and introduction history contribute to genetic variation in invaders. Genetic diversity, population structure, and colonization patterns in the invasive P. cespitosum, a highly selfing, tetraploid Asian annual introduced to North America, were examined using nine diploidized polymorphic microsatellite markers (SSR; Matesanz et al., 2014) . Low heterozygosity was found in all 16 populations, consistent with the selfing mating system of P. cespitosum. Despite the high selfing levels, substantial genetic variation within and among P. cespitosum populations was revealed, based on the percentage of polymorphic loci, allelic richness, and expected heterozygosity. Inferences from individual assignment tests and pairwise FST values indicated high among-population differentiation, which indicates that the effects of gene flow are limited relative to those of genetic drift, probably due to the high selfing rates and the limited seed dispersal ability of P. cespitosum. Population structure appears to be the result of the random movement of propagules across the introduced range, possibly associated with human dispersal. The high population differentiation, genetic diversity, and fine-scale genetic structure (populations founded by individuals from different genetic sources) in the introduced range suggest that multiple introductions to this region may have occurred. High genetic diversity may further contribute to the invasive success of P. cespitosum in its introduced range.

Among 50 RAPD primers, only C29 primer had two specific bands, which could distinguish P. capitatum from P. nepalense (Zhou et al., 2013) . Four pairs of specific primers were designed based on the two sequences of RAPD marker bands, and only one pair primer (Z1-2) was successfully converted into SCAR marker, which could be used as an effective SCAR mark to identify Z300 DNA for P. capitatum.

AFLP was used to identify the knotgrass (P. aviculare) population at the crime site as the most likely origin of the botanical evidence (Koopman et al., 2012) . The genetic diversity of 48 representational populations of P. capitatum including 240 individuals was investigated by ISSR marker (Zhou et al., 2010) . SRAP (sequence-related amplified polymorphism) was used to detect the polymorphisms of Radix Polygoni Multiflori in Chongqing (Cheng et al., 2013) . SRAP might be superior to RAPD in genetic diversity studies.

Analysis of nuclear internal transcribed spacer (nrITS) sequences reveals polymorphism among five P. barbata populations belonging to five geographic locations in India (Choudhary et al., 2011) . UPGMA analysis based on the ITS datasets shows that the sampled populations are grouped according to their geographic locations and are supposed to evolve under reproductive isolation, which most likely are due to the long-distance distribution and population fragmentation.

DNA bar codes are used to discriminate the Polygonaceae in China Pharmacopoeia and their adulterants (Song et al., 2009) . The amplification efficiency of six candidate DNA bar codes (rbcL, trnH-psbA, ndhJ, rpoB, rpoC1, and accD) was 100%, while the efficiency of YCF5 and nrITS was 56% and 44%, respectively. The interspecific divergence was highest for the trnH-psbA (20.05%), followed by the nrITS (14.01%) across all species pairs, while intraspecific variation both within populations and between populations was absent. The trnH-psbA can not only distinguish 10 species of Polygonaceae in China Pharmacopoeia but also recognize eight other species of Polygonaceae including their adulterants.

P. multiflorum (Fallopia multiflora) is often confused and substituted with the roots of Fallopia multiflora var. ciliinervis, Pteroxygonum giraldii, Cynanchum auriculatum, and Stephania cepharantha. The nrITS regions of six Fallopia species were sequenced and analyzed (Zheng et al., 2009) . The diagnostic primers PMITS28 and PMITS545, which amplified an expected 517 bp ITS fragment from F. multiflora, were designed. No amplified product was observed when other species was used. Based on 18S rRNA gene sequence analysis, P. multiflorum could be easily distinguished from adulterants and other herbs with similar medicinal components (Yan et al., 2008) . All P. multiflorum samples were divided into four clades based on matK sequence. Permutations of matK were related to the geographic distributions of the samples. These markers can be used to authenticate the botanical origin of P. multiflorum. The best bar code of P. multiflorum is psbA-trnH, with significant interpopulation variability (Sun et al., 2013) . The combination of loci gave better performance for distinguishing populations than a single locus. It could be good to use matK + rbcL + psbA-trnH + ITS2 or psbA-trnH alone for P. multiflorum in geoherbalism identification.

cDNA-amplified fragment length polymorphism (cDNA-AFLP) transcript profiling was applied to generate the expression profiles of P. minus in response to salicylic acid (SA) and methyl jasmonate (MeJA) elicitations (Ee et al., 2013) . Two sets of genes were induced by SA and MeJA, respectively. Stress-related genes were proved to lead to the expression of genes involved in secondary metabolite biosynthetic pathways. A total of 98 transcript-derived fragments (TDFs) were upregulated, including 46 from SA-treated and 52 from MeJA-treated samples. The cDNA-AFLP transcripts generated using 64 different Mse1/Taq1 primer combinations showed that treatments with SA and MeJA induced genes mostly involved in scavenging ROS, including zeaxanthin epoxidase, cytosolic ascorbate peroxidase 1, and peroxidase. Of these stress-related genes, 15% of other annotated TDFs are involved mainly in secondary metabolic processes, and two genes encoding (+)-delta cadinene synthase and cinnamoyl-CoA reductase were highlighted.

The leaf of an aromatic plant P. minus is widely used as a food additive and in the perfume industry. The leaf also accumulates secondary metabolites such as flavonoid. A standard cDNA library of P. minus leaves was constructed, and two normalized fulllength enriched cDNA libraries were constructed from stem and root in order to create a gene resource for the biosynthesis of secondary metabolites, especially flavonoid biosynthesis (Roslan et al., 2012) . Large-scale sequencing of P. minus cDNA libraries identified 4196 expressed sequence tags (ESTs). From the three cDNA libraries, 11 ESTs encoding seven genes were mapped to the flavonoid biosynthetic pathway. Three flavonoid biosynthetic pathway-related ESTs, namely, chalcone synthase, CHS (JG745304); flavonol synthase, FLS (JG705819; Figure 12 .2); and leucoanthocyanidin dioxygenase, LDOX (JG745247), were selected for further examination by quantitative RT-PCR (qRT-PCR) in different P. minus organs. Expression was detected in leaf, stem, and root. Based on transcriptome data, gene expression studies can be initiated to better understand the underlying physiological processes.

Various active components have been extracted from the root of P. cuspidatum. However, the genetic basis for their activity is little known. 25,600,002 short reads (2.3 Gb) of P. cuspidatum root transcriptome were obtained via Illumina HiSeq 2000 sequencing (Hao et al., 2012) . A total of 86,418 unigenes were assembled de novo and annotated. 12, 18, 60, and 54 unigenes were, respectively, mapped to the mevalonic acid (MVA), methyl-D-erythritol 4-phosphate (MEP), shikimate ( Figure 12. 3), and resveratrol biosynthesis pathways, suggesting that they are (Hao et al., 2012) , which is responsible for biosynthesis of anthraquinone and stilbene. involved in the biosynthesis of pharmaceutically important anthraquinone and resveratrol. Eighteen potential UDP-glycosyltransferase unigenes were identified as the candidates most likely to be involved in the biosynthesis of glycosides of secondary metabolites. Identification of relevant genes could be important in eventually increasing the yields of the medicinally useful constituents of the P. cuspidatum root. From the previously published transcriptome data of 19 nonmodel plant taxa, 1127 shared orthologs were identified and characterized. This information will be very useful for future functional, phylogenetic, and evolutionary studies of these plants.

The buckwheat family Polygonaceae is a diverse group of plants and is a good model for investigating biogeography, breeding systems, coevolution with symbionts such as ants and fungi, functional trait evolution, hybridization, invasiveness, morphological plasticity, pollen morphology, and wood anatomy. Age estimates for Polygonaceae were obtained by calibrating a Bayesian phylogenetic analysis (Schuster et al., 2013) , using a relaxed molecular clock with fossil data. Eighty-one species of Polygonaceae were analyzed with MrBayes to infer species relationships. One nuclear (nrITS) and three chloroplast (cp) markers (the trnL-F spacer region and matK and ndhF genes) were used. Seven calibration points including fossil pollen and a leaf fossil of Muehlenbeckia (a Southern Hemisphere group) were used to infer node ages. Results of the Beast analyses indicate an age of 110.9/118.7 million years (My) with an uncertainty interval of 90.7-125.0 My for the stem age of Polygonaceae. This age is older than previously thought (approximately 65.5-70.6 My). The estimated divergence time for Muehlenbeckia is 41.0/41.6 (39.6-47.8) My and its crown clade is 20.5/22.3 (14.2-33.5) My. Because the breakup of Gondwana occurred from 95 to 30 My ago, diversification of Muehlenbeckia is best explained by oceanic longdistance and maybe stepping-stone dispersal rather than vicariance. Interspecific hybridization and the following polyploidization play a major role in plant diversification, but quantifying the contribution of this mechanism to diversification within taxonomically complex clades remains difficult. Incongruence among gene trees can provide critical insights, especially when combined with data on chromosome numbers, morphology, and geography. Molecular phylogenetic studies using three cpDNA regions and nrITS sequences were performed to explore the hybrid speciation in Persicaria (Polygonum, Polygonaceae; Figure 12 .4) (Kim and Donoghue, 2008) , with an emphasis on sampling within section Eupersicaria. There are major conflicts between the combined cpDNA tree and the nrITS tree; a variety of incongruence tests rejected stochastic error as the cause of incongruence in most cases. Both the tree incongruence results and information on chromosome numbers suggest that the origin of 10 polyploid species involved interspecific hybridization. The recognition of several previously named species that have been treated as belonging within other species was supported. Repeated allotetraploidy (as distinct from radiation at the tetraploid level) might be the key mechanism governing the diversification of this taxonomically challenging group.

Multiple instances of allopolyploid speciation were also shown in Persicaria using a low-copy nuclear gene region (LEAFY second intron) (Kim et al., 2008b) , which belong to Polygonum in Flora of China. Fifteen species seem to be allopolyploids, which is higher than the number found in previous comparisons of cp DNA (Tamura et al., 2013) . B, matK + rbcL + trnL-F tree inferred from neighbor joining method. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the maximum composite likelihood method and are in the units of the number of base substitutions per site. The analysis involved 46 nucleotide sequences. All ambiguous positions were removed for each sequence pair. There were a total of 4645 positions in the final dataset.

phylogenies (Kim and Donoghue, 2008) . This underestimation of the extent of allopolyploidy is due in at least three cases to homogenization of nrITS toward the maternal lineage. The diploid species, P. lapathifolia, has been involved in at least six cases of allopolyploid speciation. Of the diploids, this species is the most widespread geographically and ecologically and also bears more numerous and conspicuous flowers, illustrating ecological factors that may influence hybridization frequency. With a few exceptions, the allopolyploid species also are widespread, plastic, ecological generalists. Hybridization events fostered by human introductions may be fueling the production of new species that have the potential to become aggressive weeds. ITS sequences from 44 Indian Polygonum taxa were examined to investigate relationships among various sections proposed previously (Choudhary et al., 2012) . The maximum parsimony trees obtained from ITS sequences suggested eight major groups of the Indian Polygonum spp. The relationships among different sections were largely congruent with those inferred from morphological characters as described by Hooker. The treatment of the Persicaria suggested by Haraldson on the basis of anatomical characters proved to be nearly in line with that based on ITS data. A high resolution of phylogeny of the Himalayan Polygonum (e.g., P. microcephalum, P. assamicum, P. recumbens, and P. effusum) was provided and merger of the section Amblygonon in the section Persicaria was supported. Molecular differences were detected among Persicaria barbata collected from different geographic locations of India, although these were not differentiated at the morphological level.

To examine the phylogenetic relationships of Koenigia (Polygonaceae), 43 samples representing all species of Koenigia and closely related taxa (Aconogonon, Bistorta, and Persicaria) were sequenced for nr ITS and four cp regions (trnL-F, atpB-rbcL, rbcL, and rpl32-trnL(UAG); Fan et al., 2013a,b) . Trib. Polygoneae and trib. Rumiceae are recovered on both cp and ITS trees (Figure 12.4) , while trib. Atraphaxideae is not. The placement of P. bistorta is uncertain due to conflict between cp and ITS trees (Figure 12.4) . It was proposed that the genus Koenigia be circumscribed to include five species, that is, perennials (K. forrestii and K. nummularifolia) and annuals (K. islandica, K. pilosa, and K. nepalensis). However, on both cp and ITS trees, K. nepalensis (P. nepalense) is more closely related to P. capitatum and P. chinense (Figure 12.4) , instead of Koenigia. K. islandica and K. fertilis (P. fertile, Figure 12 .4a), both of which are from the Himalayan region, can be merged into a single species. P. delicatulum (K. delicatula), P. campanulatum, and P. lichiangense occupy an isolated position at the base of the Polygonaceae (Figure 12.4a) , which might be reassigned to a new genus.

The tetraploid P. minor (P. minus), which is sister to the P. hydropiperoides complex in the nrITS tree (Kim and Donoghue, 2008) , may have arisen through hybridization between an unknown diploid lineage or possibly a tetraploid in the P. hydropiperoides complex and the diploid P. hydropiper. It is not entirely clear that P. hydropiper served as the maternal parent, since the relationship between P. hydropiper and P. minor is weakly supported in the cpDNA tree (Figure 12.4b) .

Morphologically, P. minor is more similar to the diploid P. foliosa (P. foliosum), which should also be considered as a possible diploid maternal lineage for P. minor (Kim and Donoghue, 2008) .

The pollen apertures likely evolved in parallel in the Aconogonon-Koenigia-Bistorta clade and Persicaria clade (Fan et al., 2013a,b) , and tricolpate pollen is probably the ancestral one. Quincuncial aestivation likely evolved during the early evolution of Koenigia and its close relatives. The uplift of the Himalayas has played a vital role in promoting species diversification of Koenigia. K. islandica expanded its range during Pleistocene glacial cycles by tracking changes in newly available habitats.

There is little study addressing chemotaxonomy and metabolomics of Polygonum and related genera, although such studies can provide vital information for sustainable utilization of Polygonaceae medicinal resources. The family Polygonaceae has been supported as monophyletic, but the circumscription of some subgroups, especially Polygonum and related taxa, has been controversial. The use of population genetic approaches, sampling from multiple populations, would shed light on this issue. More extensive sampling inside and outside the Himalayas and Hengduan Mountains is indispensable to explore the phylogenetic hypothesis and facilitate species diversity conservation.

Xanthone and lignan glycosides from the aerial parts of Polygonum bellardii all growing in Egypt

Polyphenols from aerial parts of Polygonum bellardii and their biological activities

Distribution of drimane sesquiterpenoids and tocopherols in liverworts, ferns and higher plants: Polygonaceae, Canellaceae and Winteraceae species

In vitro biological effects of two anti-diabetic medicinal plants used in Benin as folk medicine

Protective effect of Polygonum orientale L. extracts against Clavibater michiganense subsp. sepedonicum, the causal agent of bacterial ring rot of potato

Polygonum viviparum L. induces vasorelaxation in the rat thoracic aorta via activation of nitric oxide synthase in endothelial cells

Active neuraminidase constituents of Polygonum cuspidatum against influenza A(H1N1) influenza virus

Polygonum viviparum L. inhibits the lipopolysaccharide-induced inflammatory response in RAW264.7 macrophages through haem oxygenase-1 induction and activation of the Nrf2 pathway

Tyrosinase inhibitory activity of a glucosylated hydroxystilbene in mouse melan-a melanocytes

A new herb-drug interaction of Polygonum cuspidatum, a resveratrol-rich nutraceutical, with carbamazepine in rats

Studies on genetic diversity among populations of Persicaria barbata (L.) H. Hara from India based on internal transcribed spacer sequences of nuclear ribosomal DNA

Phylogeny and systematics of Indian Polygonum sensu lato in the subfamily Polygonoideae based on ITS sequences of nuclear ribosomal DNA

Quercetin 3-O-(6 00 -galloyl)-beta-D-galactoside from Polygonum viscosum (Polygonaceae)

Polydatin attenuates cardiac hypertrophy through modulation of cardiac Ca 2+ handling and calcineurin-NFAT signaling pathway

Transcriptome profiling of genes induced by salicylic acid and methyl jasmonate in Polygonum minus

Screening of biological activities of Polygonum maritimum L. from Algerian coast. Asian Pac

Molecular phylogeny of Koenigia L. (Polygonaceae: Persicarieae): implications for classification, character evolution and biogeography

Anti-inflammatory activity of the invasive neophyte Polygonum cuspidatum Sieb. and Zucc. (Polygonaceae) and the chemical comparison of the invasive and native varieties with regard to resveratrol

In vitro and ex-vivo cellular antioxidant protection and cognitive enhancing effects of an extract of Polygonum minus Huds (Line-minus™) demonstrated in a Barnes Maze animal model for memory and learning

Antioxidant and antiinflammatory flavonol glucuronides from Polygonum aviculare L

Anti-atherosclerotic effects of Polygonum aviculare L. ethanol extract in ApoE knock-out mice fed a Western diet mediated via the MAPK pathway

Genuine traditional Korean medicine, Naju Jjok (Chung-Dae, Polygonum tinctorium) improves 2,4-dinitrofluorobenzene-induced atopic dermatitis-like lesional skin

De novo characterization of the root transcriptome of a traditional Chinese medicinal plant Polygonum cuspidatum

Emodin blocks the SARS coronavirus spike protein and angiotensin-converting enzyme 2 interaction

Prescription parsing of miao medicine Polygonum capitatum and kelintong capsule

Phytochemical and biological research of Polygoneae medicinal resources 525

Inhibition of DNA topoisomerases I and II of compounds from Reynoutria japonica

Gastroprotective activity of Polygonum chinense aqueous leaf extract on ethanol-induced hemorrhagic mucosal lesions in rats

Inhibition of IL-32 and TSLP production through the attenuation of caspase-1 activation in an animal model of allergic rhinitis by Naju Jjok (Polygonum tinctorium)

Resveratrol inhibits invasion and metastasis of colorectal cancer cells via MALAT1 mediated Wnt/b-catenin signal pathway

8-Hydroxycalamenene isolated from the rhizomes of Reynoutria elliptica exerts neuroprotective effects both in vitro and in vivo

Incongruence between cpDNA and nrITS trees indicates extensive hybridization within Eupersicaria (Polygonaceae)

A new stilbene glucoside gallate from the roots of Polygonum multiflorum

Allopolyploid speciation in Persicaria (Polygonaceae): insights from a low-copy nuclear region

Polygonum cuspidatum inhibits pancreatic lipase activity and adipogenesis via attenuation of lipid accumulation

Botanical DNA evidence in criminal cases: knotgrass (Polygonum aviculare L.) as a model species

2-Methoxystypandrone inhibits signal transducer and activator of transcription 3 and nuclear factor-kB signaling by inhibiting Janus kinase 2 and IkB kinase

Content of resveratrol and glycoside and its contribution to the antioxidative capacity of Polygonum cuspidatum (Itadori) harvested in Kochi

Inhibition of G protein-activated inwardly rectifying K + channels by extracts of Polygonum persicaria and isolation of new flavonoids from the chloroform extract of the herb

Antiproliferative activity of polygonaceae species from the Carpathian Basin against human cancer cell lines

Hexane extracts of Polygonum multiflorum improve tissue and functional outcome following focal cerebral ischemia in mice

Polyflavanostilbene A, a new flavanol-fused stilbene glycoside from Polygonum cuspidatum

Five new stilbene glycosides from the roots of Polygonum multiflorum

Emodin inhibits tonic tension through suppressing PKCd-mediated inhibition of myosin phosphatase in rat isolated thoracic aorta

Chemical constituents in herbs of Polygonum jucundum

Resveratrol attenuates oxidative damage and ameliorates cognitive impairment in the brain of senescence-accelerated mice

Small-molecule STAT3 signaling pathway modulators from Polygonum cuspidatum

In vitro and in vivo studies of the inhibitory effects of emodin isolated from Polygonum cuspidatum on Coxsackievirus B₄

Resveratrol reverses the effects of chronic unpredictable mild stress on behavior, serum corticosterone levels and BDNF expression in rats

Purification, antioxidant activity and antiglycation of polysaccharides from Polygonum multiflorum Thunb

Stilbene glucoside inhibits the glucuronidation of emodin in rats through the down-regulation of UDP-glucuronosyltransferases 1A8: application to a drug-drug interaction study in Radix Polygoni Multiflori

CYP1A2 polymorphism in Chinese patients with acute liver injury induced by Polygonum multiflorum

Effect of Polygonum hydropiper L. against dengue vector mosquito Aedes albopictus L

Genetic diversity and population structure in Polygonum cespitosum: insights to an ongoing plant invasion

Apoptosis induction by Polygonum minus is related to antioxidant capacity, alterations in expression of apoptotic-related genes, and S-phase cell cycle arrest in HepG2 cell line

In vitro a-glucosidase inhibitory activity of phenolic constituents from aerial parts of Polygonum hyrcanicum

Simultaneous quantification and peroxynitrite-scavenging activities of flavonoids in Polygonum aviculare L. herb

Flavonoid biosynthesis genes putatively identified in the aromatic plant Polygonum minus via expressed sequences tag (EST) analysis

Age estimates for the buckwheat family Polygonaceae based on sequence data calibrated by fossils and with a focus on the amphi-Pacific Muehlenbeckia

8-Methyltryptanthrin-induced differentiation of P19CL6 embryonal carcinoma cells into spontaneously beating cardiomyocyte-like cells

Flavonoid glucuronides with anti-leukaemic activity from Polygonum amphibium L

Phytochemical and biological research of Polygoneae medicinal resources 527

Authentication of the family Polygonaceae in Chinese pharmacopoeia by DNA barcoding technique

Effect of Nrf2 activators on release of glutathione, cysteinylglycine and homocysteine by human U373 astroglial cells

Piceid presents antiproliferative effects in intestinal epithelial Caco-2 cells, effects unrelated to resveratrol release

Analysis of head volatile constituents of Polyonum cuspidatum flower by HS-GC/MS

Promotion effect of constituents from the root of Polygonum multiflorum on hair growth

MEGA6: Molecular Evolutionary Genetics Analysis version 6.0

Resveratrol and cardiovascular health -promising therapeutic or hopeless illusion?

6-Dihydropyranobenzopyrone: a previously undetermined antioxidant isolated from Polygonum amplexicaule. Chin

Resveratrol ameliorates high-glucose-induced hyperpermeability mediated by caveolae via VEGF/KDR pathway

Effects of a proprietary freeze-dried water extract of Eurycoma longifolia (Physta) and Polygonum minus on sexual performance and well-being in men: a randomized, double-blind, placebo-controlled study

A recent review on phytochemical constituents and medicinal properties of kesum (Polygonum minus Huds.). Asian Pac

Characterization of proanthocyanidins in stems of Polygonum multiflorum Thunb as strong starch hydrolase inhibitors

Antidepressant-like activity of resveratrol treatment in the forced swim test and tail suspension test in mice: the HPA axis, BDNF expression and phosphorylation of ERK

In vitro effects of active components of Polygonum Multiflorum Radix on enzymes involved in the lipid metabolism

A potential antitumor ellagitannin, davidiin, inhibited hepatocellular tumor growth by targeting EZH2

Study on chemical composition of ethylacetate fraction from Polygonum amplexicaule var. sinense

-tetrahydroxystilbene-2-O-b-D-glucoside (THSG) attenuates human platelet aggregation, secretion and spreading in vitro

A bioactivity-guided study on the anti-diarrheal activity of Polygonum chinense Linn

Resveratrol-4-O-D-(2 0 -galloyl)-glucopyranoside isolated from Polygonum cuspidatum exhibits anti-hepatocellular carcinoma viability by inducing apoptosis via the JNK and ERK pathway

A new stilbene glucoside from the roots of Polygonum multiflorum Thunb

Inhibitory effects of 2,3,4 0 ,5-tetrahydroxystilbene-2-O-b-D-glucoside on angiotensin II-induced proliferation of vascular smooth muscle cells

The effect of 2, 3, 4 0 , 5-tetrahydroxystilbene-2-O-b-D-glucoside on pressure overload-induced cardiac remodeling in rats and its possible mechanism

Genetic variation and identification of cultivated Fallopia multiflora and its wild relatives by using chloroplast matK and 18S rRNA gene sequences

Polygonumosides A-D, stilbene derivatives from processed roots of Polygonum multiflorum

Inhibitory effects of (À)-loliolide on cellular senescence in human dermal fibroblasts

Quercetin-3-O-b-D-glucuronide isolated from Polygonum aviculare inhibits cellular senescence in human primary cells

Proteomic analysis for anti-atherosclerotic effect of tetrahydroxystilbene glucoside in rats

Inhibition of Epstein-Barr virus lytic cycle by an ethyl acetate subfraction separated from Polygonum cuspidatum root and its major component, emodin

Protective effects of polydatin from Polygonum cuspidatum against carbon tetrachloride-induced liver injury in mice

Protective effect of tetrahydroxystilbene glucoside against hydrogen peroxide-induced dysfunction and oxidative stress in osteoblastic MC3T3-E1 cells

Study on the chemical constituents of the active fraction of Polygonum capitatum

Tetrahydroxystilbene glucoside attenuates neuroinflammation through the inhibition of microglia activation

A review of the pharmacological effects of the dried root of Polygonum cuspidatum (Hu Zhang) and its constituents

Polydatin inhibits growth of lung cancer cells by inducing apoptosis and causing cell cycle arrest

A new chromone glycoside from roots of Polygonum multiflorum

Molecular authentication of the traditional medicinal plant Fallopia multiflora

Genetic diversity of Polygonum capitatum from Guizhou populations by ISSR markers

Study on sequence characterized amplified region (SCAR) markers of Polygonum capitatum