Evaluation of estrogenic activity of plant extracts for the potential treatment of menopausal symptoms

Eight botanical preparations that are commonly used for the treatment of me nopausal symptoms were tested for estrogenic activity. Methanol extracts of red clover (Trifolium pratense L.), chasteberry (Vitex agnus-castus L.), a nd hops (Humulus lupulus L.) showed significant competitive binding to estr ogen receptors alpha (ER alpha) and beta (ER beta). With cultured Ishikawa (endometrial) cells, red clover and hops exhibited estrogenic activity as i ndicated by induction of alkaline phosphatase (AP) activity and up-regulati on of progesterone receptor (PR) mRNA. Chasteberry also stimulated PR expre ssion, but no induction of AP activity was observed. In S30 breast cancer c ells, pS2 (presenelin-2), another estrogen-inducible gene, was up-regulated in the presence of red clover, hops, and chasteberry. Interestingly, extra cts of Asian ginseng (Panax ginseng C.A. Meyer) and North American ginseng (Panax quinquefolius L.) induced pS2 mRNA expression in S30 cells, but no s ignificant ER binding affinity, AP induction, or PR expression was noted in Ishikawa eels. Dong quai [Angelica sinensis (Oliv.) Diels] and licorice (G lycyrrhiza glabra L.) showed only weak ER binding and PR and pS2 mRNA induc tion. Black cohosh [Cimicifuga racemosa (L.) Nutt.] showed no activity in a ny of the above in vitro assays. Bioassay-guided isolation utilizing ER com petitive binding as a monitor and screening using ultrafiltration LC-MS rev ealed that genistein was the most active component of red clover. Consisten t with this observation, genistein was found to be the most effective of fo ur red clover isoflavones tested in the above in vitro assays. Therefore, e strogenic components of plant extracts can be identified using assays for e strogenic activity along with screening and identification of the active co mponents using ultrafiltration LC-RIS. These data suggest a potential use f or some dietary supplements, ingested by human beings, in the treatment of menopausal symptoms.