Pregnane Glycosides, Gymnepregosides A-F from the Roots of Gymnema alternifolium

Abstract

The structural elucidation of six new related polyoxypregnane glycosides, gymnepregosides A (1), B (2), C (3), D (4), E (5) and F (6), together with two known compounds, from the roots of Gymnema alternifolium (Asclepiadaceae) was achieved through on a detailed study of ¹H- and <13>C-NMR spectral data and chemical means. The results obtained for new compounds, 1-6, show that they are (20S)-pregn-6-ene-3β, 5α, 8β, 12β, 14β, 17β, 20-heptaol or sarcostin 3-O-glycosides, and all the sugars at C-3 are β(1→4)-linked. Some of them possessed benzoyl, cinnamoyl and tigloyl residues as the ester linkages located at C-12 and/or C-20 of the aglycon.