Molecular Docking Analysis and Anti-trypanosomal Properties of Cymbopogon citratus Ethanol Leaf Extracts

Abstract

African trypanosomiasis, a neglected tropical disease transmitted by tsetse flies and caused by Trypanosoma brucei brucei, poses significant health and economic burdens across sub-Saharan Africa. Conventional treatment methods face challenges, including drug resistance, toxicity, and high costs, underscoring the need for alternative therapies. This study investigates the anti-trypanosomal properties of Cymbopogon citratus (lemongrass) leaf extracts at concentrations ranging from 100 to 400 mg/kg, evaluating their effects on parasitaemia levels in in vivo models and through molecular docking studies. Isometamidium chloride and normal saline served as positive and negative controls, respectively. Phytochemical analysis identified the presence of alkaloids, phenolics, terpenes, anthraquinones, steroids, cardiac glycosides, and tannins in both ethanolic and aqueous extracts of C. citratus. Flavonoids and carbohydrates were exclusively detected in the aqueous extract. In vivo studies showed both extracts significantly reduced parasitaemia in infected mice, with the 200 mg/kg aqueous extract producing the most pronounced suppression by day 4 (p = 0.0105) and outperforming the ethanolic extract (p = 0.0347). The packed cell volume declined over time in all tests, except for the aqueous extract in the suppressive test, which showed a slight increase. No mortality was recorded in acute toxicity tests, indicating both extracts were non-toxic. Furthermore, molecular docking evaluations revealed that compounds like geranyl acetate from C. citratus interact with key residues of the T. brucei brucei L-threonine-3-dehydrogenase enzyme, potentially inhibiting its activity. These findings suggest that C. citratus holds promise as a source of novel anti-trypanosomal agents and may contribute to the development of alternative, plant-based therapies for African trypanosomiasis.