Effects of the extracts of some tropical medicinal plants on estrogen inducible yeast and Ishikawa screens, and on ovariectomized Wistar rats.

A total of 33 extracts from 18 Cameroonians plants were studied in two in vitro test systems to determine potential estrogenic activities. The estrogenic activities of the extracts, which have shown promising activity on both in vitro screens were further investigated in vivo on ovariectomized Wistar rats. All 33 extracts were screened in the yeast test-system. Five of these extracts, namely the ethyl acetate extract of the stem bark of Millettia conraui, the ethyl acetate extract of the stem bark of Millettia drastica, the methanol extract of the leaves of Bridelia ferruginea, the methanol extract of the roots of Pseudarthria hookeri and the methanol extract of the roots of Nauclea latifolia showed interesting estrogenic properties, and were therefore further investigated on alkaline Phosphase induction in Ishikawa cells. The extracts of Millettia conraui, Millettia drastica, Pseudarthria hoockeri and Nauclea latifolia showed significant stimulatory effects at 10 and 100 mg/ml doses. The extract of Bridelia ferruginea was not further evaluated because of its toxicity on Ishikawa cells. This stimulatory effect was completely inhibited by a combined treatment with the pure antiestrogen ICI (Faslodex, 5 x 10(-7) M). In vivo experiments showed that per os administration of 200 mg/kg bw of the extracts of Millettia conraui and Bridelia ferruginea significantly increased uterine epithelial height by 17.93% and 28.08% respectively compared with uteri of ovariectomized controls after 7 days of treatment. Uterine epithelial height of animals treated with 100 rg/kg bw/d of ethinylestradiol increased by 242.3% in the same experiment. Extracts of Nauclea latifolia and Millettia drastica had no effect on the uterine epithelial height of ovariectomised rats. 200 mg/kg bw/d of the extracts of Nauclea latifolia, Millettia drastica, Bridelia ferruginea and Millettia conraui given orally significantly increased vaginal epithelial height by 15.64%, 24.06%, 51.02% and 58.12% following the same treatment regiment compared to untreated controls. In line with these data was the finding that vaginal epithelial height and vaginal cornification in the presence of each of these extracts was more advanced than in ovariectomized controls although not as prominent as in response to ethinylestradiol treatment. These results suggest that some constituents of the extracts of Millettia conraui, Millettia drastica, Pseudarthria hookeri, Nauclea latifolia and Bridelia ferruginea may have estrogenic activity.