Antileishmanial Activity of Fractions of Calotropis procera Latex Against Leishmania donovani: Implications for Management in North East Nigeria

Visceral leishmaniasis (kala-azar), caused by Leishmania donovani, is endemic in parts of North East Nigeria, particularly in the semi-arid zones of Borno and Yobe States, where diagnosis and treatment infrastructure is severely constrained. Calotropis procera, a common shrub in the Sahel belt, is used by traditional healers in these communities for fever and skin conditions, and its cytotoxic latex has received preliminary attention for antiprotozoal potential. This study evaluates the antileishmanial activity of fractionated Calotropis procera latex extracts against promastigote and amastigote forms of Leishmania donovani. Latex was collected from Maiduguri, fractionated by solvent partitioning, and subjected to silica gel column chromatography. Antileishmanial activity was assessed in promastigote viability assays and an intracellular amastigote model using THP-1 differentiated macrophages. Cytotoxicity was evaluated against Vero cells to determine selectivity index. Cardiac glycoside-rich and terpenoid-rich fractions demonstrated potent promastigote inhibition with IC50 values of 3.4 and 7.8 ug/mL respectively. Amastigote inhibition in the macrophage model was significant at 10 ug/mL without marked host cell toxicity, yielding selectivity indices above 15. A partially purified calotropin-containing fraction was the most active sub-fraction. These findings advance the case for systematic investigation of Calotropis procera as a natural product source for antileishmanial drug development in North East Nigeria. Keywords: Calotropis procera, antileishmanial, Leishmania donovani, calotropin, North East Nigeria