title: 2,3-cis-2R,3R-(-)-epiafzelechin-3-O-p-coumarate, a novel flavan-3-ol isolated from Fallopia convolvulus seed, is an estrogen receptor agonist in human cell lines.
abstract: BACKGROUND
  The plant genus Fallopia is well-known in Chinese traditional medicine and includes many species that contain bioactive compounds, namely phytoestrogens. Consumption of phytoestrogens may be linked to decreased incidence of breast and prostate cancers therefore discovery of novel phytoestrogens and novel sources of phytoestrogens is of interest. Although phytoestrogen content has been analyzed in the rhizomes of various Fallopia sp., seeds of a Fallopia sp. have never been examined for phytoestrogen presence.
  
  
  METHODS
  Analytical chemistry techniques were used with guidance from an in vitro estrogen receptor bioassay (a stably transfected human ovarian carcinoma cell line) to isolate and identify estrogenic components from seeds of Fallopia convolvulus. A transiently transfected human breast carcinoma cell line was used to characterize the biological activity of the isolated compounds on estrogen receptors (ER) α and β.
  
  
  RESULTS
  Two compounds, emodin and the novel flavan-3-ol, (-)-epiafzelechin-3-O-p-coumarate (rhodoeosein), were identified to be responsible for estrogenic activity of F. convolvulus seed extract. Absolute stereochemistry of rhodoeosein was determined by 1 and 2D NMR, optical rotation and circular dichroism. Emodin was identified by HPLC/DAD, LC/MS/MS, and FT/ICR-MS. When characterizing the ER specificity in biological activity of rhodoeosein and emodin, rhodoeosein was able to exhibit a four-fold greater relative estrogenic potency (REP) in breast cells transiently-transfected with ERβ as compared to those transfected with ERα, and emodin exhibited a six-fold greater REP in ERβ-transfected breast cells. Cell type-specific differences were observed with rhodoeosein but not emodin; rhodoeosein produced superinduction of reporter gene activity in the human ovarian cell line (> 400% of maximum estradiol [E2] induction) but not in the breast cell line.
  
  
  CONCLUSIONS
  This study is the first to characterize the novel flavan-3-ol compound, rhodoeosein, and its ability to induce estrogenic activity in human cell lines. Rhodoeosein and emodin may have potential therapeutic applications as natural products activating ERβ, and further characterization of rhodoeosein is necessary to evaluate its selectivity as a cell type-specific ER agonist.
authors.affiliation: Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, CA 95616, USA. jcbrennan@ucdavis.edu
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Brennan
authors.forename: Michael S
authors.initials: MS
authors.lastname: Denison
authors.forename: Dirk M
authors.initials: DM
authors.lastname: Holstege
authors.forename: Prokopios
authors.initials: P
authors.lastname: Magiatis
authors.forename: Jerry L
authors.initials: JL
authors.lastname: Dallas
authors.forename: Elisa G
authors.initials: EG
authors.lastname: Gutierrez
authors.forename: Anatoly A
authors.initials: AA
authors.lastname: Soshilov
authors.forename: James R
authors.initials: JR
authors.lastname: Millam
mesh_terms: D045744:Cell Line, Tumor; D004365:Drugs, Chinese Herbal / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D005419:Flavonoids / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D015394:Molecular Structure; D048789:Phytoestrogens / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D019664:Polygonaceae / Q000737:chemistry*; D011485:Protein Binding; D012639:Seeds / Q000737:chemistry*
chemical_list: D004365:Drugs, Chinese Herbal; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D005419:Flavonoids; D048789:Phytoestrogens; C404987:flavan-3-ol