A New Class of Blue Anthocyanin-Derived Pigments Isolated from Red Wines

TLDR

Two novel anthocyanin‑derived pigments with UV–vis absorption at 575 nm were isolated from aged Port wine using TSK Toyopearl HW‑40 (S) gel chromatography and semipreparative HPLC. These pigments represent a new class of pyranoanthocyanin–flavanol hybrids linked by a vinyl bridge, whose extended π‑conjugation likely imparts high stability and intense blue color, and they form via reactions between anthocyanin‑pyruvic acid and vinyl‑flavanol adducts. Keywords: pyranoanthocyanin, flavanols, red wine, aging, blue color.

Abstract

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 (1H, 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 π 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. Keywords: Pyranoanthocyanin; flavanols; red wine; aging; blue color