In vitro Antiplasmodial Activities of Crude Extracts and Compounds Derived from Selected Indigenous Medicinal Plants used Traditionally to Treat Malaria in Kenya

Aims: To identify viable phytomedicines traditionally employed for the treatment of malaria in Kenya that could be developed into antimalarial agents.

Study Design: Quantitative analysis of antiplasmodial activities and brine shrimp bioassays were carried out using standard procedures. The experiment was set in duplicate for each concentration of the drug and average IC50 determined.

Place and Duration of Study: Seven indigenous plants: Achyranthesaspera, Heinsiacrinita, Brideliacathartica, Citrus limon, Microglossapyrifolia, Vernoniaglabra and Carissa edulis obtained from Kilifi and Homa-Bay counties in Kenya were evaluated for their anti-Plasmodium falciparumpotential.Collection of samples and analysis took about three months.

Methodology: Both Chemical and aqueous crude extraction methods were carried out to identify the most active extracts against P. Falciparum and thenisolatepureactive phytochemicals. Pure compounds were subjected to Nuclear Magnetic Resonance (NMR), Infra-Red (IR) and Mass Spectroscopy (MS) analyses for structure elucidation.

Results: Four extracts of hexane, dichloromethane (DCM), methanol and water of seven different species of plants were analyzed for their anti-plasmodial activities.W2 and D6 strains of Falciparum were tested. However, the three most active extracts were from Citrus lemon roots (DCM) with IC50 value of 7.017 µg/mL, C. edulis root (aqueous) with IC50 value of 8.054 µg/Ml and B. Cathertica leaves (methanol) with IC50 value of 15.647 µg/Ml. However, three pure compounds were obtained; suberosinIC5026.7 (Strain W2), 53.1 (Strain D6) and xanthyletin IC501580 (Strain W2) from C. Limon (DCM) and spinasterolIC5043.2 (Strain W2) fromM. pyrifolia (hexane).

Conclusion: The three different species of plants with most active compounds have demonstrated their potentiality in treatment for falciparum malaria. Structures of the isolated three compounds can be modelled to synthesise anti- plasmodial drugs as they are active in vitro.