Acetylated saponins with molluscicidal activity from Sapindus rarak : Unambiguous structure determination by proton nuclear magnetic resonance and quantitative analysis

Abstract Four monodesmosidic triglycosides, bearing up to two acetyl moieties on the terminal sugar, have been isolated from the pericarp of fruits of Sapindus rarak DC (Sapindaceae). The positions of the acetyl groups and interglycosidic linkages have been established by proton nuclear magnetic resonance spectroscopy, including double‐quantum filtered phase‐sensitive COSY and homonuclear Overhauser enhancement difference measurements. A method for the qualitative analysis of saponins by reversed phase high pressure liquid chromatography (HPLC) has been developed. The total saponin content was determined by HPLC analysis of hederagenin liberated by acidic hydrolysis of the methanolic extract. The molluscicidal activity (LC 100/24h ) of the saponins ranges from 6.25 to 12.5 ppm.