In vivo antitrypanosomal activities of Acacia nilotica stem bark methanol extract in Wistar rats infected with Trypanosoma brucei brucei

Background: Trypanosomiasis is a disease of vertebral animals caused by parasitic protozoa of the genus Trypanosoma. It is one of the neglected tropical diseases (NTDs) affecting about 36 countries of Sub-saharan Africa, threatening more than 60 million people and 70 million animals. Chemotherapy is the major means of controlling African trypanosomiasis is limited by rapid drug resistance, toxicity and high cost. There is an urgent need for therapeutic agents that are effective, affordable, and accessible to the rural poor people in Africa who are greatly affected by the disease. This study aimed to determine the in vivo effect of stem bark methanol extract of Acacia nilotica (A. nilotica) on experimental Trypanosoma brucei brucei infection in Wistar rats. Methods: Phytochemical analysis, and LD50 determination were carried out using standard procedures. Three (3) days pre-patent period was observed after inoculating the rats with the parasite. Parasitemia was monitored daily while the Parked Cell Volume (PCV) was determined at one-day intervals during the infection course. Results: The phytochemical analysis showed the presence of carbohydrates, steroid/triterpenes, saponin, alkaloid, flavonoid, tannin, glycosides, and anthraquinones. The toxicity of the stem bark methanol extract was tolerable at 1200 mg/kg body weight. Methanol extract of A. nilotica (stem bark) showed promising curative potential in vivo against Trypanosoma brucei brucei at 300, 400 and 500 mg/kg body weight. These doses completely cured the experimental T.b.b infection in Wistar rats after 3 days of treatment. Significant reduction (p<0.05) in the parasite burden confirmed by the absence of anaemia (PCV 48.1% ±1.5% and 46.4% ±1.3% respectively) was observed when compared with the “infected but not treated” control group (normal saline group). Conclusion: Based on these observations, it was therefore deduced that the methanol extract of Acacia nilotica stem bark extract possessed the active ingredient that cures experimental T. brucei brucei infections in Wistar rats.