Vol. 15 No. 174 - 189 (2024): Molluscicidal activity of Toad (Bufo Spp.) venom crude extract on the multi-species of Snail intermediate hosts of Schistosoma

Schistosomiasis remains a significant public health concern in many developing nations,
particularly in tropical and subtropical regions. While synthetic compounds such as
Niclosamide have been developed to combat snail-borne diseases, these synthetic
molluscicides are either scarce, expensive or toxic to non-target organisms in the snail habitat.
In contrast, plant-derived products have been extensively studied for their molluscicidal
properties, whereas animal-derived compounds, notably toad venom, have received less
attention. This study explores the potential of toad venom as an alternative molluscicide for
controlling snail intermediate hosts of Schistosoma. Toad venom was extracted and analyzed
for zoochemicals and Gas Chromatography-Mass Spectrometry (GC-MS) Analysis.
Molluscicidal evaluation of toad venom crude extract was conducted following World Health
Organization (WHO) guidelines. Adult snails of Biomphalaria pfeifferi, Bulinus forskalii, and
Bulinus globosus species were exposed to graded concentrations (200, 100, 50, 25, 12.5, and
6.5 mg/L) of the toad venom crude extract. Analysis of results was performed using ANOVA
and Probit Regression analysis. Results on qualitative zoochemical screening of crude extract
of toad venom revealed the presence of cardiac glycoside, carbohydrate, saponins, steroids
IJABR Vol. 15(1): 174 - 189 (2024)

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and terpenoids. GCMS analysis of crude toad venom revealed 30 peaks representing 25
bioactive compounds, with 9-Octadecenoic acid, methyl ester being the most abundant

constituents in the crude toad venom. The toad venom extract showed a dose and time-
dependent activity against the exposed mollusks. Exposure of B. pfeifferi, B. globosus, and B.

forskalii to 100 mg/L concentrations resulted in mortality rates of 73.3%, 66.6%, and 60%,
respectively, after 24 hours. After 24 hours of exposure period, the lethal concentrations
required to kill 50% (LC50) of B. pfeifferi, B. globosus, and B. forskalii snails were 46.77, 70.79,
and 79.43 mg/L, respectively. Notably, the effective doses of toad venom against the three snail
species exhibited minor variations despite their coexistence in common habitats. In
conclusion, this study underscores the molluscicidal potential of toad venom as a promising
lead agent for controlling snail intermediate hosts of Schistosoma.