Evaluation of medicinal plants from Mali for their in vitro and in vivo trypanocidal activity.

Water, methanol and dichloromethane extracts prepared from various parts of 40 medicinal plant species from Mali were investigated for their trypanocidal activity against Trypanosoma brucei brucei. Of a total of 165 extracts tested in vitro in the Low Inoculation Long Incubation Test (LILIT), 24 extracts showed a high trypanocidal activity. Using the Long-Term Viability Assay (LtVA) for corroboration of the results of the 24 extracts, it was found that 15 samples had minimum inhibitory concentration (MIC) values > 10 microg/ml, eight MIC values of 100 microg/ml and one MIC values of 50-100 microg/ml. So far, four extracts with MIC values < or = 100 microg/ml were tested for antitrypanosomal activity in mice, experimentally infected with Trypanosoma brucei brucei. Only, the aqueous extracts of the leaves of Terminalia avicennioides Guill. and Perr. (Combretaceae) and the stem bark of Ceiba pentandra (L.) Gaertn. (Bombacaceae) were able to reduce the parasitaemia in animals treated at the dose of 100 mg/kg b.w. (intraperitoneally, two times daily for 3 days) and of 150 mg/kg b.w. (per os, two times daily for 3 days), respectively. The reduction of parasitaemia was, however, statistically significant (p=0.002) only in case of treatment with Terminalia avicennioides.