Estrogenic activity of a Rhus verniciflua extract and its major components

Rhus verniciflua Stokes has been used as a traditional herbal medicine, a food additive, and a material for lacquer in Korea. In this study, hot water extracts of R. verniciflua Stokes xylem (RVE) and purified compounds were examined for estrogenic activity. RVE showed estrogenic activity mediated by estrogen receptors (ER) with a higher binding affinity and activity to ERβ than to ERα in ERα- or ERβ-transfected cells. It also exhibited estrogenic activity in a uterotrophic assay using rats. All of RVE compounds had high affinity to ERβ compared with ERα in reporter gene assay and ER binding assay. Among seven RVE compounds, butin, butein, sulfuretin, and garbanzol had a strong estrogenic activity in ERE-mediated reporter gene assay. Butein and sulfuretin had stronger ERβ binding affinity compared with others. Collectively, these results demonstrate an estrogenic activity of RVE and suggest its potential value for postmenopausal women.