III and VI) (LC90= 7 and 6 ppm) . . The unsaponifiable part of the petroleum ether fraction of the leaves and stems of Oreopanax reticulatum Donn (Family Araliaceae) was analysed by GLC to reveal the presence of a series of hydrocarbons, cholesterol, stigmasterol and -sitosterol. Also, eight fatty acids were identified on the saponifiable part. The butanolic fraction was chromatographed over silica gel and sephadex-LH20 columns and preparative thin layer chromatography to afford two flavonoid

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... lycosides (I and IV) as well as four bidesmosidic triterpenoidal saponins (II, V, VII and VIII). Alkaline hydrolysis of two bidesmosidic saponins (II and V) gave two monodesmosidic (III and VI). Their structures were elucidated using spectroscopic and chemical techniques. Molluscicidal screening of the isolated compounds (I-VIII) against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni in Egypt revealed that the two monodesmosidic triterpenoidal saponins (III and VI) have strong activities (LC 90 = 7 and 6 ppm) after 24 hours exposure whereas the two flavonoid glycosides and four bidesmosidic saponins were inactive up to 50 ppm.