STRUCTURE INVESTIGATION AND PROTON AND C-13 ASSIGNMENTS OF DIGITONIN AND CHOLESTEROL USING MULTIDIMENSIONAL NMR TECHNIQUES

Digitonin, a spirostanolglycoside from the seeds of Digitalis purpurea L., is a highly haemolytically active saponin. This effect is conside red to be based on complex formation between cholesterin and digitonin . Against the background of investigations concerning the interaction between glycosides and membrane components, and the determination of t he structure of the digitonin-cholesterol complex, a detailed NMR spec troscopic investigation of the complex-forming compounds was carried o ut. Assignment of the H-1 and C-13 spectra of digitonin was made by us ing one- and two-dimensional NMR techniques (1D TOCSY, 2D TOCSY, HMQC and HMBC); 3D TOCSY-ROESY, 1D ROESY and HMBC experiments provided info rmation about the sequence of the oligosaccharide chain and the positi on of glycosidations. The precise analysis of the COSY, HMQC und HMBC spectra made the assignment of all proton resonance signals of cholest erol possible for the first time.