Estrogenic activities of Psoralea corylifolia L. seed extracts and main constituents

Estrogenic activities of ethanol extract and its active components from Psoralea corylifolia L. were studied using various in vitro assays. The main components from ethanol extract were analyzed to be bakuchiol, psoralen, isobavachalcone, isobavachromene, and bavachinin. In a fractionation procedure, hexane and chloroform fractions showed estrogenic activity in yeast transactivation assay and E-screen assay. In yeast transactivation assay, ethanol extract, hexane, and chloroform fractions showed significantly higher activities at a concentration of 1.0 ng/ml, and bakuchiol at the concentration of 10⁻⁶ M was showed the highest activity, especially, which was higher than genistein at the same concentration. In E-screen assay, cell proliferation of bakuchiol (10⁻⁶ M) showed similar estrogenic activity with genistein (10⁻⁶ M). In ER binding assay, bakuchiol displayed the strongest ER-binding affinity (IC₅₀ for ERα = 1.01 × 10⁻⁶ M, IC₅₀ for ERβ = 1.20 × 10⁻⁶ M) and bakuchiol showed five times higher affinity for ERα than for ERβ.