H-1 AND C-13 NMR ASSIGNMENT OF THEAFLAVIN, THEAFLAVIN MONOGALLATE AND THEAFLAVIN DIGALLATE

Theaflavin, theaflavin monogallate and theaflavin digallate were isolated from black tea leaves and studied by 1D and 2D NMR techniques, thus allowing unambiguous assignment of the H-1 and C-13 resonances of these complexes. Earlier studies have not yielded C-13 data of equal reliability, especially for the benzotropolone moiety of these molecules, and consequently the data given here will be of use in future studies of natural products isolated from tea. The utility of the 2D proton detected long-range C-13-H-1 correlation experiment (HMBC) in the study of polyphenolic complexes is demonstrated by these results.