Antiplasmodial Activity of Aqueous and Ethanolic Extracts of Anacardium Occidentale and Cymbopogon Citratus

Abstract

The search for antimalarial compounds was necessitated by Plasmodium falciparum resistance to most antimalarial drugs. In endemic countries where malaria is prevalent, medicinal plants are often used to treat malaria. In this study, the in vitro antimalarial activities of crude aqueous and ethanolic extracts of Anacardium occidentale and Cymbopogon citratus, were evaluated against P. falciparum. Fourteen fresh blood samples obtained from infected children and adults aged 15 to 25 years were tested against the plant extracts. Standard microtest technique of schizont maturation and parasite growth assay was used to culture fresh isolates. Acute toxicity of the aqueous and ethanolic extracts A. occidentale and C. citratus was tested on albino rats. Anti-inflammatory activity was determined using xylene induced ear oedema and the analgesic properties of plants’ extracts were evaluated using acetic acid-induced writhing in mice. The SSPS Statistical tool was used to calculate mean parasite growth and percentage parasite inhibition. The t-test was used to analyse the data. There was a significant (p = 0.05) reduction in the number of parasitized cells relative to the control. Ethanol extract of A. occidentale exhibited higher antimalarial activity of 75.6% than aqueous IC50 of 11.7μg/ml followed by aqueous extract of A. occidentale with 72.4% activity and IC50 of 16.0μg/ml. The aqueous extract of C. citratus had an activity of 69.0%, IC50 of 23μg/ml. Ethanol extract of C. citratus had the lowest antimalarial activity of 67.9%, IC50 of 30μg/ml. All the four extracts showed moderate antimalarial activity. None of the extracts exhibited any sign of toxicity in rats, and all showed a good measure of anti-inflammatory activity. The extracts at doses 50mg/kg and 100mg/kg body weight produced various analgesics responses in a dose dependent manner. There was a significant (P < 0.05) reduction in writhing at 100mg/kg body weight in both aqueous and ethanolic extracts of A. occidentale and C. citratus. This result shows that the aqueous and ethanolic extracts of A. occidentale and C. citratus possess promising antimalarial activities which can be exploited for malaria therapy, and also justifies the traditional use of the plants in malaria treatment. Further work is suggested to isolate, identify and characterize the active constituents from the plants.