In vivo effects of black cohosh and genistein on estrogenic activity and lipid peroxidation in Japanese Medaka (Oryzias latipes).

This study was designed to assay the estrogenic activities and the antioxidant potential of ethanol extracts from the herbal dietary supplement black cohosh (Cimicifuga racemosa) relative to the natural phytoestrogen genistein. The in vivo mechanisms of action of these two natural products have not been completely elucidated, and Japanese medaka (Oryzias latipes) provides a useful organism for initial in vivo screening of natural products. While both genistein and estradiol altered ovarian and testicular steroid release and decreased circulating testosterone levels in males, neither black cohosh total extract (75-30,000 ng/fish), cimiracemoside A, 25-O-methyl-cimigenoside, actein, nor 26-deoxy-actein caused any differences in estrogenic activity compared to control fish. To assess antioxidant potential, animals were treated with natural products then challenged with 2-acetylaminofluorene (2-AAF) to induce lipid peroxidation (LPO) in the liver. Neither the total ethanol extracts from black cohosh nor its individual components showed an inhibitory effect in 2-AAF induced LPO. However, genistein manifested potent antioxidative activity in the LPO assay, with similar potency to a high dose of á-tocopherol. In contrast to genistein, black cohosh did not exhibit traditional estrogenic effects nor significant in vivo anti-oxidant potential in this fish model system.