Identification of plumbagin and sanguinarine as effective chemotherapeutic agents for treatment of schistosomiasis.

Schistosomiasis, a snail-borne parasitic disease, affects more than 200 million people worldwide. Currently the treatment of schistosomiasis relies on a single therapy of praziquantel, a drug developed over 30 years ago. Thus, there is an urgent need to develop alternative antischistosomal drugs. In the pursuit of novel antischistosomal drugs, we examined the antischistosomal activities of 45 compounds that had been reported to exhibit antimicrobial and/or antiparasitic activities. Two plant-derived compounds, plumbagin and sanguinarine, were found to possess potent antischistosomal activities in vitro. For both the compounds, a concentration of 10 μM (equivalent to 1.88 μg/ml for plumbagin and 3.68 μg/ml for sanguinarine) resulted in 100% mortality at 48 h, which meets the World Health Organization's (WHO) criterion of "hit" compounds for the control of schistosomiasis. Morphological changes and tegumental alterations of the dead worms treated by the two compounds were quite different. The significant morphological changes of worms after treatment by the two compounds suggest the two compounds target different biological pathways, both of which result in parasite's death. This study provides evidence to suggest plumbagin and sanguinarine have real potential as effective alternative chemotherapeutic agents for the treatment of schistosomiasis.