Détail de la notice
Titre du Document
Tandem mass spectrometry of the B-type procyanidins in wine and B-type dehydrodicatechins in an autoxidation mixture of (+)-catechin and (-)-epicatechin
Auteur(s)
WEIXING SUN ; MILLER Jack M.
Résumé
We describe the characterization of the B-type procyanidins in wine and the B-type dehydrodicatechins (dimeric flavan-3-ols) obtained for the autoxidation of (+)-catechin and (-)-epicatechin by tandem mass spectrometry (MS/MS) coupled to reversed-phase high-performance liquid chromatography (HPLC). The MS/MS analysis demonstrates that the interesting major fragments derive from the dissociations of the C-ring on the catechin or epicatechin unit, such as retro-Diels-Alder reactions. The two kinds of dimers give completely different fragmentations because of the striking effect of the C-C interflavan linkage (IFL). For the natural dimers in wine, a catechin or epicatechin unit linking to the C-4 position stabilizes the product ions by forming a large n-n hyperconjugated system, whereas a similar π-π system is formed within dehydrodicatechin B through the C-C IFL. Thus dissociation in MS/MS experiments was inhibited. Apparently, the fragmentations of the dimers differ from that of the monomer, which is very important in the study of the gas-phase ion behaviour of the polymeric flavan-3-ols. In addition, two specific fragment ions at m/z 451 for native dimers and at m/z 393 for autoxidation species in HPLC/MS/MS were found to be very useful for analysing mixtures of B-type procyanidins and B-type dehydrodicatechins in food and beverages.
Editeur
Wiley
Identifiant
PMID : 12717756 ISSN : 1076-5174
Source
Journal of mass spectrometry A. 2003, vol. 38, n° 4, pp. 438-446 [9 pages] [bibl. : 20 ref.]
Langue
Anglais
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