Estrogenic and anti-estrogenic properties of tropical African plants traditionally used in folk medicine

An amazing diversity of traditionally used plants is found in the tropical areas of Africa and many of these plants have not or only insufficiently been studied. The purpose of this study was to evaluate eight African tropical plants, belonging to miscellaneous plant families, for estrogenic and anti-estrogenic properties and to isolate and characterize single compounds obtained from these herbal extracts.

Plant materials of Brillantaisia owariensis (BO), Palisota schweinfurthii (PS), Ricinodendron heudelotii ssp. africanum (RH), Thonningia sanguinea (TS), Hymenocardia ulmoides (HS), Garcinia mannii (GM), Alchornae cordifolia (AC), and Xylopium aethiopicum (XA) were extracted by methanol after defatting with petroleum ether. Experimentally, all extracts were tested using estrogen receptor subtype specific transactivation assays in human bone-derived U2OS cells. Cytotoxicity was measured by using MTT assay in U2OS cells. Overall, we identified two of the herbal extracts (RH, TS) with high and one (AC) with moderate estrogenic activities, three (BO, PS, HS) with moderate anti-estrogenic properties. One extract (GM) showed preferential estrogen receptor subtype specific anti-estrogenic properties. A strong cytotoxicity was detected for one extract (XA).

With this study on the estrogenic properties of plants of tropical origin, we provide evidence for agonistic activity of three plant extracts and antagonistic properties in four cases which support the traditional use for gynecological or reproductive purposes of some investigated plants. In order to prevent intoxications of the local population the observed cytotoxic extract has to be investigated in detail.

Acknowledgements: We thank Dr. Thea Lautenschläger and Prof. Christoph Neinhuis in collaboration with their partners in Angola for collecting and providing the plant material.