In Vitro Comparison of Estrogenic Activities of Popular Women’s Health Botanicals

Hormone therapy (HT) used in the treatment of menopausal symptoms has been associated with an increased incidence of hormone dependent cancers. Therefore, many women turned to botanical dietary supplements. Previous studies have shown that estrogen receptor alpha (ERα) activation initiates cell proliferation, potentially leading to the development of cancer. It is believed that ERβ agonists do not initiate cell proliferation suggesting a better safety profile. The primary goal of this study was to compare the ERα and ERβ activities of popular botanicals such as: hops (Humulus lupulus), red clover (Trifolium pratense), and licorice (Glycyrrhiza glabra (GG), G. uralensis (GU), G. inflata (GI)), along with their respective active compounds, 8-prenylnaringenin, genistein, liquiritigenin(LigF)/isoliquiritigenin (LigC) [GG,GU, GI], and licochalcone A (LicA) [GI]. In ERα Ishikawa endometrial cells, hops and red clover induced estrogen responsive alkaline phosphatase (AP) activity and act as full ERα agonists. The three licorice species also induced AP activity; however, they exhibited partial agonist effects with GI being the most potent. Similarly,8-PN showed the highest ERα potency and full agonist activity followed by genistein, LigF/LigC,and LicA. Among the extracts, red clover and GI showed 10 times better potency in the ERE-luciferase assay in ERβ MDA-MB-231/B41 cells compared to ERα cells. While LigF, and LicA were partial ERβ agonists, 8-PN had no ERβ activity. Genistein is the most potent ERβ phytoestrogen and is a full agonist. These data suggest that while hops and 8-PN, have highly potent ERα effects, licorice and its compounds have partial effects for ERα and ERβ. The most potent licorice species, GI, displayed selectivity for ERβ warranting further studies to determine the presence of an unknown ERβ agonist. The ERβ selectivity and the potency of genistein in red clover suggest that red clover may be a relatively safe menopausal remedy.