Antiplasmodial and Antioxidant Activity of Vernonia blumeoides: A Medicinal Plant Used in Cameroon to Treat Malaria

Background: Malaria is a parasitic disease that affects many parts of the globe, especially sub-Saharan Africa. Over time, malaria parasites have become resistant to most antimalarial drugs, including artemisinin. Medicinal plants, which are used in the traditional treatment of malaria can afford effective drugs against this notorious disease. One such plant includes Vernonia blumeoides, which is used in the treatment of parasitic diseases, including malaria. Thus the scientific validation of the use of Vernonia blumeoides in ethnomedicine is of outstanding importance.

Objectives: This study sought to investigate the antiplasmodial and antioxidant activity of extracts from Vernonia blumeoides.

Methods: Vernonia blumeoides ethanol extract was obtained by maceration, and then subjected to phytochemical screening using standard protocols. The as-prepared extract was partitioned using solvents of increasing polarity to afford hexane, ethyl acetate, n-butanol fractions, and the water residue. The antiplasmodial potential of extract and fractions was determined by the Sybr green method. Antioxidant activity of V. blumeoides extracts was evaluated using DPPH, ABTS and FRAP assays. Cytotoxicity test was performed on murine macrophage Raw cells using the resazurin test.

Results: The ethanol extract was obtained as a brown powder and the yield of extraction was found to be 43.95%. The phytochemical screening of this extract revealed the presence of tannins, alkaloids, flavonoids, phenolic compounds, and glycosides. Upon antiplasmodial screening against P. falciparum Dd2 and 3D7, the median inhibitory concentrations (IC50) of extract and fractions from V. blumeoides ranged from 4.70 to >100 µg/ml, with ethyl acetate extract having the lowest IC50 value and highest activity. Vernonia blumeoides extracts exhibited antioxidant activity with median scavenging concentrations ranging from 31.17 to 124.1 µg/mL, 50.84 to 500 µg/mL, and 33.95 to 500 µg/mL for ABTS, DPPH and FRAP assays, respectively. Cytotoxicity test of V. blumeoides extracts on Raw cells revealed non toxicity.

Conclusions: This novel contribution demonstrated the antiplasmodial activity of V. blumeoides extracts, thus validating the ethnopharmacological use of this plant in the treatment of malaria symptoms. Nonetheless, in depth studies on the mechanisms of action, in vivo toxicity, as well as pharmacokinetic experiments are warranted for the successful utilization of this plant in ethnomedicine.