Antischistosomal Activity of Azadirachta indica and Ekebergia capensis in Mice Infected with Schistosoma mansoni

Aims: Schistosomiasis is a parasitic disease of great socio-economic and public health importance in tropical and sub-tropical countries. Praziquantel (PZQ) is the drug of choice for treatment of schistosomiasis since it is effective against all species of schistosomes. However, PZQ is less efficacious against larval stages of the parasite and there are recent concerns that long term mass drug treatment could lead to development of drug resistant strains thus prompting the need for alternative antischistosomal drugs. Plants have over the years provided a rich source of novel drugs for a wide range of diseases afflicting man and domestic animals.

Study Design: Swiss albino mice were infected and randomized into groups of five for plant extract treated groups, positive control groups treated with conventional drugs PZQ and artemether, as well as infected but untreated (negative control) groups.

Place and Duration of Study: The study was done at the Animal Facility in the Centre for Biotechnology Research and Development, Kenya Medical Research Institute from July 2013 to July 2014.

Methodology: Swiss albino mice were infected with 90 cercariae each and treated orally with varying doses of aqueous extracts of Ekebergia capensis and Azadirachta indica at doses of 25, 50, 100, 200 and 400 mg/kg at 2 weeks (juvenile worms), 4 weeks (immature worms) and 7 weeks (adult worms) post infection. PZQ and artemether were used as positive controls while infected untreated group was used as negative controls. Total reduction of worm load as well as egg load in the liver and intestine was used as an indicator of drug activity, relative to the infected but untreated control groups.

Results: Both E. capensis and A. indica showed significant dose-dependent percentage worm load reduction (P<0.05) at different doses ranging from 100 mg/kg to 400 mg/kg. These extracts also significantly reduced tissues (liver and intestine) egg load counts at doses ranging from 50 mg/kg to 400 mg/kg which was also dose-dependent.

Conclusion: The antischistosomal activity of the two plant extracts was dose dependent with E. capensis being more potent in reducing both the worm burden at all the stages and tissue egg load. These findings validate the potential use of medicinal plants in the management of schistosomiasis and provide a basis for exploring medicinal plants as sources for new antischistosomal agents.