The structure of cotyledoside, a novel toxic bufadienolide glycoside from Tylecodon wallichii(Harv.) Toelken

Abstract

The structure of cotyledoside, the active toxic principle of Tylecodon wallichii(Harv.) Toelken subs. wallichii was assigned as 7β,8-epoxy-14-hydroxy-2α,3β-(tetrahydro-3,5-dihydroxy-4-methoxy-6-methyl-2H-pyran-2,4-diyldioxy)-5α-bufa-20,22-dienolide. The structure is based on a detailed study of the high-field 1H and 13C n.m.r. spectra of cotyledoside. The relative configuration of the metabolite was deduced from the observed proton–proton nuclear Overhauser effects and the magnitude of the proton–proton coupling constants.