In-vitro Activity of Medicinal Plant Crude Extract and In-vivo Toxicity Testing of Dichloromethane Root Extract of Citrus limon in laboratory Rabbits

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: Achyranthes aspera, Heinsiacrinita, Bridelia cathartica, Citrus limon, Microglossapyrifolia, Vernoniaglabra and Carissa edulis obtained from Kilifi and Homa-Bay counties in Kenya were evaluated for their anti-Plasmodium falciparum potential. Collection of samples and analysis took about three months from April 2018.

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

Results: Four extracts (hexane, dichloromethane (DCM),methanoland 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. Cathertical eaves (methanol) with IC50 value of 15.647 µg/Ml. However, three pure compounds were obtained; suberosin IC5026.7 (Strain W2), 53.1 (Strain D6) and xanthyletin IC501580 (Strain W2) from C. limon (DCM) and spinasterol IC50 43.2 (Strain W2) from M. 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 synthesis of anti- plasmodial drugs as they are active in vitro.