ANTI-PLASMODIAL ACTIVITY OF SOME MEDICINAL PLANTS USED FOR TREATMENT OF MALARIA AND SYNERGISM OF METHANOLIC EXTRACTS OF CARISSA EDULIS AND ARTEMISIA ANNUA

Abstract

The increasing prevalence and distribution of malaria has been attributed to a number of factors, one of them being the emergence and spread of drug resistant parasites. Efforts are now being directed towards the discovery and development of new chemically diverse anti-malarial agents. The present study reports on the in vitro anti-plasmodial activity of 15 selected medicinal plants used widely by the traditional healers to treat malaria in the North Rift parts of Kenya. The plant extracts were tested for in vitro activity against chloroquin-senitive (D6) strains of plasmodium falciparum parasites. Of the 15 species assayed, 40% showed promising anti-plasmodial activity of IC₅₀ ≤ 10 µg/ml, while another 40% showed moderate activity of IC₅₀ between 10 – 50 µg/ml and 20% had weak activity of IC₅₀ between 50 – 100 µg/ml. These results justify the correlation between traditional uses of the plants with their bioactivity. Synergism between total extract of Atemisia annua and Carissa edulis ware also analyzed using combination ratios of 10:90 to 90:10 respectively against P.falciparum parasites. This led to the identification of anti-malarial combination therapy of methanolic extracts of the two plants with sum of fraction inhibiting concentration (FIC) of 0.74 at 50% combination ratios. These results support a rational rather than random approach to the selection of anti-plasmodial screening candidates, and identify a number of promising plants for further investigation as plant-based anti-malarial agents.