Antisweet Natural Products. XIII. Structures of Alternosides I-X from Gymnema alternifolium

Abstract

From the dried roots of Gymnema alternifolium, ten new oleanane-type triterpenoid glycosides, named alternosides I-X (1-10), were isolated, as well as two artifactual compounds, 11 and 12. Their structures were determined on the basis of spectroscopic data and chemical evidence. Compounds 1-5, and 6, 8 and 10 are 3, 28-bis-O-glycosides of chichipegenin having an acyl group at position 16 or 18, and no acyl group, respectively.Compound 7 is 3-O-glycoside of chichipegenin. Compound 9 consists of the 3, 28-bis-O-glycosides of longispinogenin.Compounds 1-5 and 11, having an acyl group, showed antisweet activity.