A two-step screening method, using estrogen receptor-mediated transactivation, to measure estrogenicity in edible plants

Estrogenic activity in 88 edible plants was screened using a human ovarian carcinoma cell line stably transformed with estrogen-responsive elements (ERE) fused to a luciferase (luc) reporter gene (BG1Luc4E(2)). We found 18 plants (ashitaba, avocados, chinese mustard, chinese chive (yellow), chrysanthemum, dokudami, shantung greens, green soybeans, soybean seeds, soybean sprouts, hop, japanese pepper, kidney beans, kuromame, perilla, peas (immature), plantain, and pomegranate juice) expressing estrogenic activity in BG1Luc4E(2) cells. To confirm that the phytoestrogenic activity occurred via estrogen receptors (ER), the reporter vector (ERE-tk-luc) and an expression vector, containing either ERα or ERβ, were used to transiently transfect 293T cells. Extracts from avocados, plantain and dokudami did not activate ERα- and ERβ-mediated transcription. In conclusion, we report a simple and quick screening method for phytoestrogenic activity in plant extracts using BG1Luc4E(2) cells and confirmation of the results by ERα- or ERβ-transfected 293T cells. This two-step screening method has a practical application in screening estrogenic substances in edible plants.