Characterization of a colorless anthocyanin-flavan-3-ol dimer containing both carbon-carbon and ether interflavanoid linkages by NMR and mass spectrometry.
Direct addition of anthocyanins and flavan-3-ols was investigated in a model system by incubating malvidin 3-glucoside and (-)-epicatechin in ethanol. Analysis of reaction products by high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC/ESI-MS) before and after thiolysis showed the formation of colorless dimers detected at m/z 781 in the negative ion mode, with retention times and spectroscopic characteristics identical to those of compounds detected in wine, which contain one malvidin 3-glucoside unit and one flavanol unit. On the basis of their resistance to thiolysis, these compounds were postulated to be bicyclic dimers linked with both carbon-carbon and ether bonds as observed in the case of A type proanthocyanidins. The major dimer analyzed by NMR experiments was identified as malvidin 3-glucoside(C2-O-C7,C4-C8)epicatechin, confirming this hypothesis. A similar assay was performed with (+)-catechin instead of (-)-epicatechin, and the formation of bicyclic dimers was also observed.
Remy-Tanneau
Sophie
S
INRA-UMR Sciences pour l'OEnologie, 2 Place Viala, 34060 Montpellier, France.
Le Guernevé
Christine
C
Meudec
Emmanuelle
E
Cheynier
Veronique
V
D000872:Anthocyanins / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D004987:Ethers / Q000737:chemistry*; D005960:Glucosides; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D021241:Spectrometry, Mass, Electrospray Ionization
D000872:Anthocyanins; D004987:Ethers; D005960:Glucosides; C458419:malvidin-3-glucoside; D002244:Carbon; D002392:Catechin