Potential of some monoterpenoids and their new N-methyl carbamate derivatives against Schistosomiasis snail vector, Biomphalaria alexandrina.

Some monoterpenoids and their corresponding new N-methyl carbamate derivatives were used to study their molluscicidal effect on Biomphalaria alexandrina, the snail-vector of Schistosoma mansoni in Egypt. Improving the efficacy of the tested monoterpenoids and/or their corresponding carbamates by either piperonyl butoxide (PBO) or triton X-100 (TX) was also performed. Thymol, β-citronellol, carvacrol, and geraniol exhibited high molluscicidal activity against the snails. Geraniol, β-citronellol, and carvacrol were strongly synergized by PBO but, an opposite trend was found with TX. The molluscicidal activity of geraniol or β-citronellol when mixed with PBO was as potent as copper sulfate. Another attempt to improve the bioactivity of monoterpenoids was through their structure modifications. Thus, conversion of the tested monoterpenoids into their corresponding carbamates led to enhancement in the activity of aliphatic monoterpenoids and reduction in the aromatics.