Screening of estrogenic and antiestrogenic activities from medicinal plants

The medicinal plant extracts commercially used in Asia were screened for their estrogenic and antiestrogenic activities in a recombinant yeast system featuring both a human estrogen receptor (ER) expression plasmid and a reporter plasmid. Pueraria lobata (flower) had the highest estrogenic relative potency (RP, 7.75 × 10−3; RP of 17β-estradiol = 1), followed by Amomum xanthioides (1.25 × 10−3). Next potent were a group consisting of Glycyrrhiza uralensis, Zingiber officinale, Rheum undulatum, Curcuma aromatica, Eriobotrya japonica, Sophora flavescens, Anemarrhena asphodeloides, Polygonum multiflorum, and Pueraria lobata (root) (ranging from 9.5 × 10−4 to 1.0 × 10−4). Least potent were Prunus persica, Lycoppus lucidus, and Adenophora stricta (ranging from 9.0 × 10−5 to 8.0 × 10−5). The extracts exerting antiestrogenic effects, Cinnamomum cassia and Prunus persica, had relative potencies of 1.14 × 10−3 and 7.4 × 10−4, respectively (RP of tamoxifen = 1). The solvent fractions from selected estrogenic or antiestrogenic herbs had higher estrogenic relative potencies, with their RP ranging from 9.3 × 10−1 to 2.7 × 10−4 and from 8.2 × 10−1 to 9.1 × 10−3, respectively. These results support previous reports on the efficacy of Oriental medicinal plants used or not used as phytoestrogens for hormone replacement therapy.