On the molluscicidal activity of tannin containing plants.

The aqueous and methanolic extracts of a series of typical tannin containing plants exhibit strong molluscicidal properties against the freshwater snail biomphalaria glabrata, which is the intermediate host of schistosomiasis. The crude extracts of Krameria triandra (Krameriaceae) and Arctostaphylos uvaursi (Ericaceae) were active at concentrations of 50 ppm. Hydrolyzable and condensed tannins are responsable for the molluscicidal activity. This report indicates a new class of plant derived compounds which may have important practical application for the control of schistosomiasis in endemic areas.