title: In vitro estrogenic activity of two major compounds from the stem bark of Erythrina lysistemon (Fabaceae).
abstract: Plant-derived estrogen-like compounds, so called phytoestrogens, are given much attention due to their potential therapeutic use. In our previous work the ethylacetate extract of Erythrina lysistemon stem bark showed estrogenic effects on cell culture systems and ovariectomized Wistar rats. Using classical chromatographic methods, two constituents of Erythrina lysistemon have been isolated, referred to here as compounds 1 (alpinumisoflavone) and 2 (abyssinone V-4'-methyl-ether), and their structures successfully determined using spectroscopic techniques. To test their binding affinity, the ligand binding assay has been used on estrogen α receptor, and estrogen β receptor. Furthermore, transactivation assay in stably or transiently transfected human osteosarcoma (U2OS-estrogen α receptor and estrogen β receptor) cells were used to examine their estrogenic activity. The regulations of some estrogen receptor target genes were also investigated. Both compounds bind to estrogen α and β receptors. They significantly increased luciferase activity in a dose-dependent manner and induced the endogenous estrogen receptor-estrogen response element (ERE) interaction in U2OS-estrogen α receptor and estrogen β receptor cells. In contrast, when co-treated with E2, compound 2 did not antagonize E2 activity in both systems whereas, 1 significantly suppressed E2 activity despite its low binding affinity to estrogen β receptor. This result suggests a non-competitive mechanism. Both compounds also altered the expression of estrogen receptor target genes such as growth regulation by estrogen in breast cancer 1 (GREB1) and Cyclin D1 in breast cells. These results suggest that compounds 1 and 2 endow estrogenic activity and may be the active principles of Erythrina lysistemon.
authors.affiliation: Prince Henry Institute for Medical Research, PO Box 5152, Clayton, 3168 VIC, Melbourne, Australia. chantal.nde@princehenrys.org
authors.forename: Chantal Beatrice
authors.initials: CB
authors.lastname: Magne Nde
authors.forename: Dieudonne
authors.initials: D
authors.lastname: Njamen
authors.forename: Stephen
authors.initials: S
authors.lastname: Tanee Fomum
authors.forename: Jean
authors.initials: J
authors.lastname: Wandji
authors.forename: Evan
authors.initials: E
authors.lastname: Simpson
authors.forename: Colin
authors.initials: C
authors.lastname: Clyne
authors.forename: Günter
authors.initials: G
authors.lastname: Vollmer
mesh_terms: D045744:Cell Line, Tumor; D004895:Erythrina / Q000737:chemistry*; D004967:Estrogens / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D008024:Ligands; D024301:Plant Bark / Q000737:chemistry*; D010936:Plant Extracts / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology*; D018547:Plant Stems / Q000737:chemistry*; D011960:Receptors, Estrogen / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D004967:Estrogens; D008024:Ligands; D010936:Plant Extracts; D011960:Receptors, Estrogen