A new class of blue anthocyanin-derived pigments isolated from red wines

Two newly formed anthocyanin-derived pigments that revealed unique spectroscopic features, showing maximum absorption in their UV-vis spectra at 575 nm, were isolated by TSK Toyopearl HW-40 (S) gel column chromatography and semipreparative HPLC from an aged Port red wine. Further characterization by ESI/MS and NMR (H-1, gCOSY) showed them to belong to a new class of pigments described here for the first time, the structure of which consisted of a pyranoanthocyanin moiety linked to a flavanol by a vinyl bridge. The extended conjugation of the is electrons throughout all the pigment molecule is likely to confer a higher stability on it and is probably the origin of the intense blue color. The formation of these pigments was found to arise from the reaction between anthocyanin-pyruvic acid adducts and vinyl-flavanol adducts.