In vitro Antiplasmodial and Cytotoxic activity of Three Medicinal Plants used Traditionally for Treatment of Malaria

Abstract

Introduction: Reports of emergence of Artemisinin Combination Therapies (ACTs) resistant malaria parasites in Greater Mekong region and Equatorial Guinea, is a strong reason necessitating increased efforts to discover new antimalarial compounds with novel mechanisms of action. Plants have potential to yield new antiplasmodial compounds. This study investigated the safety and efficacy of three plants; Bersama abyssinica Fresen, Rubus keniensis Standl and Hypoestes verticillaris (L.f.) Sol. ex Roem. and Schult that are used by the Ogiek community of Kenya for treatment of malaria. Methodology: The crude extracts were tested for in vitro antimalarial activity using Plasmodium falciparum strains W2 (chloroquine resistant) and D6 (chloroquine sensitive). Safety evaluation was done using monkey kidney Vero cells and the brine shrimp lethality test. Results: Dichloromethane: methanol (1:1) and 5% aqueous methanol extracts of the three plants exhibited in vitro antiplasmodial activity against the W2 and D6 Plasmodium falciparum strains with IC50= 12.11–19.18 µg/mL, 5.46-7.04 µg/mL and 9.82 – 34.52 µg/mL, respectively. H. verticillaris extracts were the most active against the two Plasmodium falciparum strains. The dichloromethane: methanol extracts of the three plants exhibited lower toxicity on monkey kidney Vero cells relative to antiplasmodial activity as compared to the 5% aqueous methanol extracts. The mean Vero cells: parasite selectivity index of the dichloromethane: methanol extracts was (4.8), B. abyssinica (3.75) and R. keniensis (1.9), while for the 5% aqueous methanol extracts they were H. verticillaris (1.0), B. abyssinica (1.95) and R. keniensis (1.75). A similar toxicity profile was exhibited by brine shrimp lethality results. Conclusion: The results support the use of the three plants for the treatment of malaria. Therefore, they have potential to yield safe and effective compounds targeting P. falciparum malaria.