In vitro screening of medicinal plants with estrogen receptor modulating activity

Yeast-based estrogenicity assay is the simplest and useful for the assay and the discovery of novel estrogenic substances in natural specimens. The estrogen receptor (ER) modulating activity of 50% EtOH extracts of 101 traditional medicinal herbs was assessed using a recombinant yeast assay system with both a human estrogen receptor expression plasmid and a receptor plasmid. Among them, 14 species proved to be active. Pureariae Flos (flower of Puerraria thunbergiana BENTH.) had the highest estrogenic relative potency (7.75×10^-3) (EC₅₀=9.39 μg/ml). The EC₅₀ value of 17β-estradiol used as the positive control was 0.073 μg/ml (Relative Potency=1.00). These results demonstrated that some of the traditional medical herbs may be useful in the therapy of estrogen replacement.