Kalaic acid, a new ursane-type saponin from Musanga cecropioides

Six pentacyclic triterpenes were isolated from the methylated stembark polar extracts of Musanga cecropioides. One of them, methyl kalaate, is a new saponin. The known compounds were methyl ursolate, methyl oleanolate, methyl 2alpha-hydroxyursolate, methyl 2alpha-hydroxyoleanolate, and methyl pomolate. Their structures have been elucidated from 2D-NMR spectroscopic data. A complete (1)H- and (13)C-NMR spectral assignment of methyl pomolate as well as those of the new saponin have been achieved from 2D-COSY.