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 IL10) 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.
