Assessment of estrogenic activity of flavonoids from Mediterranean plants using an in vitro short-term test

Six isoflavones, daidzein (4′,7,-dihydroxyisoflavone), genistein (4′,5,7-trihydroxyisoflavone), genistin (genistein 7-O-β-D-glucopyranoside), isoprunetin (4′,7-dihydroxy, 5-metoxyisoflavone), isoprunetin 7-O-β-D-glucopyranoside, isoprunetin 4′,7-di-O-β-D-glucopyranoside and four flavones, luteolin (3′,4′,5,7-tetrahydroxyflavone), luteolin 7-O-β-D-glucopyranoside, luteolin 4′-O-β-D-glucopyranoside, licoflavone C (4′,5,7-trihydroxy,8-isoprenylflavone) were purified from Mediterranean plants (Genista morisii and Genista ephedroides) and their estrogenic activity was assessed by a yeast reporter gene assay (Saccharomyces cerevisiae RMY326 ER-ERE). Licoflavone C showed a powerful estrogenic activity at 10−7 M (0.0338 μg/ml) and it was 47.45% than 10−8 M 17β-estradiol (0.00272 μg/ml). The estrogenicity of this flavone was found to be comparable to the activity showed by genistein at 10−6 M (0.27 μg/ml). This study points out that a glucose substituent in flavones and isoflavones modulates the hormone-like activity in a different way. Isoflavone aglycones showed a more estrogenic activity than the corresponding glucosides. Conversely, the glucosidation made estrogenic the flavone luteolin and the position of substitution differently influenced the estrogenic activity of compounds.