IN VITRO ANTITRYPANOSOMAL ACTIVITY OF METHANOLIC LEAF EXTRACT OF SENNA OCCIDENTALIS AGAINST TRYPANOSOMA BRUCEI-BRUCEI

Abstract

African trypanosomiasis remains a major constraint to human and livestock health, and existing trypanocides are compromised by toxicity, cost, and increasing drug resistance, creating a need for alternative agents from medicinal plants. This study evaluated the phytochemical constituents and in vitro antitrypanosomal activity of the methanolic leaf extract of Senna occidentalis against Trypanosoma brucei. Fresh leaves were collected from Samaru, Zaria, dried, and extracted by maceration in absolute methanol. Phytochemical screening was conducted using standard methods, and antitrypanosomal activity was assessed using the Drug Incubation Survival Test against graded extract concentrations (0.16-10 mg/ml), with Diminazene aceturate as the reference drug. The extract yielded 7.0 g of a dark green, gummy residue and tested positive for flavonoids, tannins, alkaloids, saponins, and steroids/terpenes, but negative for cardiac glycosides. Trypanosome survival declined significantly with increasing extract concentration (p < 0.05), with complete loss of motility at 5.0 and 10 mg/ml six hours post-incubation; the median lethal concentration (LC₅₀) of the extract was 0.71 ± 0.04 mg/ml, lower than 0.10 ± 0.02 mg/ml for the reference drug. These findings indicate that the methanolic leaf extract of S. occidentalis possesses an appreciable antitrypanosomal activity attributable to its phytochemical constituents, supporting its potential as a natural source for trypanocidal drug development, pending further in vivo evaluation.