Antisweet natural products. XIV - Structures of alternosides XI-XIX from Gymnema alternifolium

From the fresh roots of Gymnema alternifolium, nine new oleanane-type trite rpenoid glycosides, named alternosides XI-XIX (1-9), were isolated, togethe r with two artificial compounds 10 and 11, and two known compounds, sitakis osides X (12) and XVII (13). Their structures were determined on the basis of spectroscopic data and chemical evidence, Compounds 1-3 are 3-O-glycosid es of chichipegenin having a tigloyl group at C-22, 28 and 16, respectively . Compounds 4-7 are 3,28-bis-O-glycosides of chichipegenin having a tigloyl group at C-22. Compounds 8 and 9 are 3,28-bis-O-glycosides of longispinoge nin, Compounds 1-7 having an acyl group showed antisweet activity.