Evaluation of antiplasmodial activity and inhibitions of lipid peroxidation and parasite haem polymerization activity by medicinal phytochemicals of Phyllanthus amarus

Despite the dedicated struggle to eliminate malaria, the current trend of the infection, particularly, in sub-Saharan Africa remains worrisome due to failing control and treatment approaches caused by a myriad of factors. Therefore, the search for new, affordable, and more potent antimalarial drugs, from plants especially, have become the frontline in recent times. This study thus, evaluates the in vitro antiplasmodial, cytotoxic and antioxidant activities of the phytochemical (alkaloids, flavonoids, tannins, saponins, cardiac glycosides and anthraquinones) extracts of Phyllanthus amarus using documented methods. Antiplasmodial and cytotoxic activities were determined by parasite growth inhibition assay and microassay technique by the lactate dehydrogenase method, respectively. Antioxidant activities were determined by measuring inhibition of both lipid peroxidation and heam polymerization by extracts. Results show that the alkaloid extract was noncytotoxic (CC = 60.26 μg/mL) and most selectable (SI = 125.5) with the highest antiplasmodial (IC = 0.48 μg/mL) and 50 50 haem polymerization inhibition (IC = 0.63 μg/mL) activities, but moderate antioxidant lipid peroxidation inhibition, (LPI; 50 IC = 500μg/mL) capacity. However, the ethanol and flavonoid phytochemical extracts displayed the highest antioxidant 50 activity in inhibition of heam polymerization (IC = 0.46 μg/mL) and lipid peroxidation (IC = 218.78 μg/mL), respectively, 50 50 with significant antiplasmodial activity (IC = 0.48 μg/mL and 1.10 μg/mL, respectively). Our results show that all 50s phytochemical extracts studied were non-cytotoxic. Although the antioxidant activities of the flavonoid and ethanol phytochemical extracts were greater in comparison to the alkaloid phytochemical, alkaloid was the most selectable active antiplasmodial phytochemical of P. amarus and one of its mechanisms of action is by inhibiting parasite haem detoxification.