Comparative study on the phytometabolites, antimalarial activity and β-hematin inhibitory potential of methanol extracts of <i>Moringa oleifera</i> leaf and stembark

Almost half of the world’s population remains at risk of malaria; a devastating infectious disease that has afflicted mankind for years. A good proportion of individuals in malarious regions rely on medicinal plants for managing malaria. Moringa oleifera is one such plant. In this study, the phytochemical profiling, acute toxicity and antimalarial activity of its leaf and stembark were conducted. Furthermore, their ability to inhibit β-hematin formation was explored as a possible mechanism of Moringa oleifera’s antimalarial action. Phytochemical screening revealed that both plant parts do not contain similar phytochemicals. This was corroborated by their TLC metabolite fingerprints. Both plant parts were non-toxic to mice at 2 g/kg b.wt. The stembark suppressed malaria parasite growth (IC50: 84.44 ± 5.02 mg/kg b.wt.) more than the leaf (IC50: 126.43 ± 2.86 mg/kg b.wt.). Untreated mice, stembark, leaf and chloroquine treated mice survived up to 11, 21, 19 and 30 days respectively. The stembark, leaf and chloroquine suppressed β-hematin formation with IC50 values of 102 ± 5.48 µg/ml, > 500 µg/ml and <25 µM respectively. Moringa oleifera stembark may thus possess hemozoin inhibitory property. Assessment of the in vitro antiplasmodial activity of the stembark against chloroquine sensitive and chloroquine resistant strains of the malaria parasite as well as its potential to inhibit heme complexation in cultured Plasmodium falciparum parasites is advocated as it may guide the discovery of antimalarial compounds with novel scaffolds that are capable of inhibiting heme detoxification while not sharing crossresistance with chloroquine.