RESUMO
OBJECTIVE: To extract and purify the active component from Solanum for Oncomelania snail control, evaluate its effect against the snails and determine its chemical structure. METHODS: Pedicel and seed were moved and the remaining part of the Solanum xanthocarpum fruit was torrefied and ground into powder. The powder was soaked into 95% ethanol and extracted. The residue was treated by ethyl acetate. 7 components were separated by methods of thin layer chromatography (TLC) and column chromatography (CCL). 4 main components were observed for the effect of snail-killing by immersion method. An alkaloid with Rf = 0. 58, named as component A, was confirmed as one of the effective components for Oncomelania snail control. The component A was further purified and received Al and A2 by proper elusion, and their effect was re-tested. The molecular weight and chemical structure of A2 were determined by MS, NMR and IR respectively. RESULTS: The death rate of Oncomelania snails was 94.2% when the concentration of component A was 2.50 mg/L1(28 C ). The flow liquid system (ethyl acetate: chloroform: methanol 11:11:35) applied was the best reagent for separating component A. The death rate of Oncomelania snails in solution of A2 (0.2 mg/L) was 100% (28 degrees C). The molecular weight of A2 was 867 with an mp 298-305 C. CONCLUSION: The effective agent (A2),one of the active components from the fruit of Solanum xanthocar pum, is alpha-solamargine which shows an excellent effect in killing Oncomelania snails.