Artemether administered together with haemin damages schistosomes in vitro

We conducted experiments in vitro to assess the effect of artemether in com bination with haemin on adult Schistosoma japonicum, S. mansoni and S. haem atobium. When schistosomes were maintained in a medium containing artemethe r at concentrations of 20 mug/mL or less for 72 h, no apparent effect on th e schistosomes was seen. When the medium contained 50 or 100 mug/mL haemin as well as artemether, the schistosomes showed decreased motor activity 2-2 4 h after exposure, which was followed by the staining of the whole worm bo dy a reddish-yellow colour, dilatation of the intestine, and extensive vesi culation of the tegument. Some of the schistosomes died 24 h after exposure , and almost all died within 48-72 h. When schistosomes were exposed to the same concentrations of haemin alone, they were stained a light yellow colo ur but there was no apparent effect on their survival. Our findings suggest that artemether interacts with haemin to exert a toxic effect on the worms , which might be of importance in the further elucidation of the mechanism of action of artemether on schistosomes.