The ethanol extract of Euphorbia aphylla (Family Euphorbiaceae) was evaluated for molluscicidal activities against Biomphalaria alexandrina and Bulinus truncatus, the snail vectors of Schistosoma mansoni and Schistosoma haematobium in Egypt, respectively. It was also tested for the in-vitro schistosomicidal activity against adult worms and the free- living stages (eggs, miracidia and cercariae) of both species.
This study showed that this extract has a considerable molluscicidal activity on both snail spp. (LC50 7.6 and 0.013 ppm and LC90 16.6 and 0.038 ppm respectively). B. truncatus is much more susceptible to E. aphylla ethanol extract than B. alexandrina. On the other hand, the conventional synthetic molluscicide niclosamide assayed by the same procedure showed LC50 0.2 ppm and LC90 0.6 ppm for both snails respectively. Consequently the molluscicidal effect of this extract against B. truncatus is much higher than that of niclosamide. The in vitro assay of this extract at concentration of 100 ug/ml showed lethal effect on adult worms of S. mansoni and S. haematobium after 3 days. The LC50 was found to be 60.4 ug/ml and 50.8 ug/ml and LC90 to be 90.4 ug/ml and 88.7 ug/ml for these species respectively. However, this effect is still much less than that of the reference drug praziquantel which gave LC50 0.2 ug/ml for both species and LC90 0.6 ug/ml for both species. The corresponding molluscicidal LC50 of ethanol extract of E. aphylla killed all S. mansoni free living stages (eggs, miracidia and cercariae) after 30, 20 and 40 minutes respectively and killed the same stages of S. haematobium after 20, 15 and 30 minutes respectively. Consequently the possibility of utilizing E. aphylla extract as an alternative natural molluscicide and as a potential source for anti-schistosomal drug especially for S. haematobium should be considered for further investigations.