In vitro activity of Extract and Fractions of Albizia chevalieri Harms (Mimosaceae) Stem Bark against Trypanosoma brucei brucei

African trypanosomiasis is a parasitic infection that adversely affects man and livestock in sub-Saharan Africa. In addition to the lack of vaccines or drugs for prophylaxis, existing chemotherapies are toxic, expensive, and have developed resistance to trypanosomes. The study investigated the in vitroactivity of Albizia chevalieri stem bark extract and fractions against Trypanosoma brucei brucei. The methanol extract was partitioned successively in graded solvents to obtain n-hexane, n-butanol, ethyl acetate and aqueous fractions. The phytochemical, acute toxicity, and in vitroanti-trypanosomal assays were conducted following the Harbone, Lorke and Drug Incubation Survival Test (DIST) methods respectively. Albizia chevalieri stem bark extractwas found tobe considerably safe, and rich in important bioactive phytoconstituents such as alkaloids, terpenoids, flavonoids and glycosides. The in vitroactivity against T. brucei brucei showed that 0.3125 μg/mL of the extract, butanol fraction and diminazene aceturate standard caused 96.0 ± 2.51, 96.50 ± 1.70 and 93.40 ± 3.24 % inhibition of parasites motility respectively; corresponding to 1.00 ± 0.63, 0.83 ± 0.48 and 1.69 ± 0.82 trypanosomes/field. The strong inhibition of T. bruceimotility by the extract and its butanol fraction has contributed significantly to knowledge as the first report of the anti-trypanosomal activity of A. chevalieri against Trypanosoma brucei brucei.