Prodelphinidins and related flavanols in wine

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Abstract
Summary Liquid chromatography coupled to diode array spectrophotometry and mass spectroscopy detection (LC‐DAD‐MS) has been applied to the study of the proanthocyanidin composition of red wine. Analytical conditions were optimized using several flavanols previously isolated from grape seeds and pomegranate peel. Higher sensitivity was obtained in positive than in negative ion mode and electrospray ionization (ESI) proved to be more useful than chemical ionization (APCI) for the identification of flavanols with a higher degree of polymerization, since it always provided the molecular ion. Useful information for the identification of compounds was also obtained from their fragmentation patterns (MS‐MS spectra). The application of the method of LC‐DAD‐MS set up permitted the identification of fourteen flavanols in wine: four monomers (C, catechin; EC, epicatechin; GC, gallocatechin; EGC, epigallocatechin), eight dimers (B1, B2, B3, B4, B7, GC‐4,8‐GC, GC‐4,8‐C and C‐4,8‐GC) and two trimers (EC‐4,8‐EC‐4,8‐C and C1). Two other heterogeneous dimers were detected, which were supposed to possess an epi(gallo)catechin unit. No important peaks corresponding to galloyl derivatives were found. As far as we know, prodelphinidins and flavanols containing GC units were identified in wine for the first time.