Structure elucidation and absolute configuration of the tyledosides, bufadienolide glycosides from Tylecodon grandiflorus

Abstract

The isolation and characterization of six related bufadienolide glycosides, tyledosides A, B, C, D, F, and G from Tylecodon grandiflorus(Burm. F) Toelken are reported. The structure elucidation of these metabolites is based on a detailed study of their highfield ¹H and ¹³C n.m.r. spectra. Extensive use was made of two-dimensional homonuclear and heteronuclear correlation experiments in the assignment of the n.m.r. spectra. The results obtained upon chemical derivatization of tyledosides A, C, and D are in agreement with the assigned structures.