Anti-trypanosomal Activity of Leaf Extracts of Andrographis paniculata in Trypanosoma brucei brucei-infected Mice

Abstract

African Animal Trypanosomiasis is a disease of major economic and public health importance, especially with the current setback in the treatment of cases using synthetic anti-trypanosomal agents. As a result, there is an urgent need to identify alternative compounds for chemotherapy. Therefore, the present study investigated the phytochemical composition, acute oral toxicity, and in vivo antitrypanosomal efficacy of crude methanol, n-hexane fraction, and ethyl acetate fraction of Andrographis paniculata (king of bitters) leaf in Trypanosoma brucei brucei-infected mice. The methanol extract was screened for the presence of secondary metabolites by using standard methods. The crude plant extract and fractions were administered orally to the parasite-infected mice at doses of 300 and 600 mgkg-1 body weight (b. wt) following standard procedures. The result was compared to Diminazine aceturate which was given at the recommended dose of 3.5 mgkg-1 b. wt subcutaneously. Phytochemical screening has revealed the presence of alkaloids, flavonoids, saponins, phenols, glycosides, steroids, tannins, and anthraquinones. Diminazine aceturate gave a 100% parasite clearance, and the mice survived throughout the study period (60.00±0.00) days. A. paniculata extract at 600 mgkg-1 b. wt was found to be effective in reducing the parasite multiplication by 43.58 % and extending the life span of the treated mice to (10.50±0.50) days compared to the untreated control, (7.45±0.55) days. Ethyl acetate fraction on the other hand was found to be more effective in reducing the parasitaemia level (61.33 % and 75.63 %) and extending the life span of the mice to (12.50±0.34) and (15.76±0.23) days for both 300 and 600 mgkg-1 b. wt doses respectively, whereas the n-hexane gave a limited trypanocidal effect of 9.89 % and 21.15 %. The results obtained in the present study suggest the ethnopharmacological usefulness of the plant and necessitate further studies on isolated active substances from this plant.