Phytochemical investigation and molluscicidal activity of oreopanax reticulatum Donn

ABSTRACT

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 beta-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 glycosides [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 [LC90= 7 and 6 ppm] after 24 hours exposure whereas the two flavonoid glycosides and four bidesmosidic saponins were inactive up to 50 ppm