Bioassay Guided Fractionation and Anti-Trypanosomal Effect of Fractions and Crude Aqueous and Methanolic Extracts of Terminalia Avicennioides (Guill. & Perr.) Parts

In vitro and in vivo anti-trypanosomal effects as well as reagent-based chemical screening of the aqueous and methanolic extracts of the roots, leaves and stem bark of Terminalia avicennioides were undertaken. In vitro, cessation or drop in the parasite motility, compared to the control, was taken as a measure of the anti-trypanasomal efficacy of the extracts following incubation of the parasite, Trypanosoma brucei brucei, with different extract concentrations (0, 5, 10 and 20 mg/ml) in 96-well micro titre plate. In vivo, groups of infected white albino rats were treated with 50, 100 and 200 mg/kg and the effect of treatment on parasitemia, packed cell volume (PCV) and lifespan were monitored. The root and stem bark extracts completely immobilized trypanosomes within 30 minutes of incubation at 20 mg/ml concentration, with the aqueous root extract displaying the highest activity, and the methanol extract of the leaf, the least. This effect compared favorably with that of the standard drug, diminazine aceturate. In vivo, significant (P<0.05) suppression of parasitemia, alleviation of anemia and prolongation of lifespan occurred in a dose dependent fashion with both the crude extracts and the bioassay-guided fractions. Reagent-based chemical analyses of the crude extracts showed presence of anthraquinones, tannins, saponins, flavonoids and cardiac glycosides, but the ethylacetate: methanol fraction which was most active revealed strong presence of saponins. These results suggest that the use of Terminalia avicennioides for management of trypanosomiasis in traditional medicine has scientific basis, and thus warrants further detailed evaluation.