Testing of the estrogenic activity and toxicity of Stephania venosa herb in ovariectomized rats.

Stephania venosa Spreng is a traditional herb which has been used for cancer treatment as well as an aphrodisiac. The scientific literature strongly supports its in vitro antiproliferative effects on cancer cell lines and has suggested developing this plant as a potential anticancer drug. However, the in vivo steroidogenic activity and toxicity of this plant have never been tested. We analyzed the levels of five key isoflavones in the plant extract by quantitative HPLC and then evaluated the in vivo estrogenic activity and toxicity in ovariectomized rats, in comparison with the phytoestrogen-rich plant, Pueraria mirifica. Twenty rats were first ovariectomized, and then seven days later divided into four groups and gavaged daily with 0, 10 and 100 mg/kg body weight/day of S. venosa, or 100 mg/kg body weight/day of P. mirifica for 28 days. A trace amount of puerarin, daidzin and daidzein with a subtle amount of genistein and genistin were isolated from the S. venosa tuber extract. S. venosa tuber powder, at both doses, did not exhibit any detectable estrogenic activity in ovariectomized rats, as assessed by the vaginal cytology and uterotropic assays, whilst P. mirifica induced a remarkable vaginal and uterine proliferation. S. venosa induced a toxicological effect on the hematological values and histopathological appearance of metabolic organs. Taken together, these results suggest that S. venosa has no discernable estrogenic activity but that it is toxic, at least to ovariectomized rats. Thus, the use of this plant for anticancer treatment needs to be reassessed or used with caution.