Antischistosomal and Immune Enhancing Potential of Azadirachta Indica and Ekebergia Capensis in Mice Infected with Schistosoma Mansoni

Abstract

Schistosomiasis is a parasitic disease of great socio-economic and public health importance in tropical and sub-tropical countries. Praziquantel (PZQ) is effective against all schistosome species, it is ineffective on larval stages and concerns of drug resistant strains developing prompts 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. Swiss albino mice were infected with 90 cercariae each and treated orally with aqueous extracts of Ekebergia capensis or 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. Total reduction of worm and egg loads was used as an indicator of drug activity, relative to the infected but untreated control groups. 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. E. capensis was more potent than A. indica in reducing both the worm burden at all the stages and tissue egg load (P<0.05). Immune enhancing potential of the medicinal plants was determined by analyzing the levels of cytokines in serum samples that were collected before and after treatment. A BD-Cytometric Bead Array (CBA) mouse Th1/Th2/Th17 kit was used to quantitate the levels of cytokines using flow cytometer (FACS Calibur) and analysis of the data was done using FCAP software. Results from two doses (400mg/kg and 200mg/kg) in 2 weeks and 7 weeks pi experiments (to represent juvenile and adult worms respectively) indicated that the two medicinal plant extracts have immunomodulatory effect. There was a significant increase (P<0.05) in Th1 cytokines (IL-2, IFN- γ and TNF-α), a decrease in Th2 cytokines (IL-4, IL-6 and IL-10) and an increase in Th17 (IL-17) following treatment with the plant extract at both 2 weeks and 7 weeks pi. These findings confirm the potential use of medicinal plants in the management of schistosomiasis.