Anthocyanone A: a quinone methide derivative resulting from malvidin 3-O-glucoside degradation.

A new compound resulting from the oxidative degradation of maldivin 3-O-glucoside under acid conditions was detected in a wine model solution stored under 90 and 25 degrees C. It was isolated by semipreparative HPLC, and its structure was elucidated by UV-vis spectra, mass spectrometry (LC/MS), and NMR spectroscopy (1-D and 2-D). The compound was identified as 8-beta-d-glucopyranosyl-2,4-dihydroxy-6-oxo-cyclohexa-2,4-dienyl acetic acid (anthocyanone A), which results from nucleophilic attack of hydrogen peroxide to maldivin 3-O-glucoside through a Baeyer-Villiger oxidation followed by other oxidations steps.