Antitrypanosomal Evaluation of Methanol Fractions of Stem Bark Extract of Acacia nilotica (Linn) against Trypanosoma congolense Infection in Albino Mice

Abstract

Trypanosomiasis is considered a plague in sub-Saharan Africa and chemotherapy of the disease is unsatisfactory. This study was conducted to explore an alternative source of an antitrypanosomal agent from the stem bark of Acacia nilotica. The methanol extract of A. nilotica stem bark was subjected to a qualitative phytochemical screening and fractionation by column chromatography using gradient elution with hexane, ethyl acetate, and methanol solvent mixtures. The acute toxicity of the crude extract was evaluated. The antitrypanosomal assay was performed on the column fractions (coded 1-9). Fifty-eight albino mice were used with diminazene aceturate as a standard drug for the in vivo assay. The mice were divided into eleven groups and the effect of each fraction on parasitaemia, packed cell volume (PCV), white blood count (WBC), red blood cell (RBC), body weight, and percentage survival of the animals were monitored over a period of 21 weeks. Treatment with fractions 4 and 5 of the ethyl acetate: methanol (90:10 and 70:30, respectively) resulted in prolonged infection, extension of life, and recovery 14 weeks beyond the negative control. Meanwhile, treatment with other fractions showed lower potency. The animals treated with fractions 4 and 5 also showed higher levels of PCV, RBC, and WBC. It was also observed that 20 and 40 % of mice treated with fractions 4 and 5 appeared to have recovered. The findings of this study revealed that fractions 4 and 5 can control anaemia, boost immunity, and prolong the life of infected mice beyond the standard drug, indicating that they offer promising prospect for lead compounds in the chemotherapy of trypanosomiasis.