In vitro antiplasmodial activity of methanol stem extract of costus afer ker gawl. (costaceae) and its residual aqueous fraction against some drug-sensitive and drug-resistant plasmodium falciparum strains

Abstract

Malaria remains a major public health problem in many countries in the tropical and sub-tropical regions of the world. The resistance of malaria parasites to commonly used antimalarial drugs including artemisinin-combination therapies in some Southeast Asian countries poses a great challenge to malaria control programmes. The aim of this study was to investigate the in vitro antiplasmodial activity of the methanol stem extract of Costus afer and its residual aqueous fraction against chloroquine-sensitive, chloroquine-resistant and artemether-resistant Plasmodium falciparum strains. Methanol stem extract of the plant was obtained by maceration of the powdered stem in 70% v/v methanol and residual aqueous fraction was obtained by successive solvent fractionation with dichloromethane, ethylacetate and finally n-butanol. In-vitro antiplasmodial activity was assessed using the candle jar method with some slight modifications. The methanol stem extract of Costus afer and its residual aqueous fraction produced significant and dose-dependent inhibitions of schizont growth in all the three Plasmodium strains with IC50 values of 8.86 and 10.51, 11.27 and 15.05, and 10.30 and 11.23 µg/mL against chloroquine-sensitive, chloroquine-resistant and artemether-resistant strains, respectively. Chloroquine phosphate was the most potent against chloroquine-sensitive strain (IC50 = 0.81 µg/mL) and Quinine sulphate was the most active against both chloroquine-resistant and artemether-resistant strains (IC50 values of 8.6 and 1.45 µg/mL, respectively). This study has shown that Costus afer stem extracts possess in-vitro antiplasmodial activity and it may be a good remedy for both chloroquine-sensitive, chloroquine-resistant and artemether-resistant falciparum malaria or a source of lead compounds for new antimalarial drugs.