Evidence for Estrogen Receptor β-Selective Activity of Vitex agnus-castus and Isolated Flavones

Abstract

Recent cell culture experiments indicated that extracts of Vitex agnus-castus (VAC) may contain yet unidentified phytoestrogens. Estrogenic actions are mediated via estrogen receptors (ER). To investigate whether VAC compounds bind to the currently known isoforms ERα or ERß, ligand binding assays (LBA) were performed. Subtype specific ER-LBA revealed a binding of VAC to ERß only. To isolate the ERß-selective compounds, the extract was fractionated by bio-guidance. The flavonoid apigenin was isolated and identified as the most active ERß-selective phytoestrogen in VAC. Other isolated compounds were vitexin and penduletin. These data demonstrate that the phytoestrogens in VAC are ERß-selective.

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