Mass Spectrometric Evidence for the Existence of Oligomeric Anthocyanins in Grape Skins
Stéphane Vidal, Emmanuelle Meudec, Véronique Cheynier, George K. Skouroumounis, Yoji Hayasaka
Journal of Agricultural and Food Chemistry
Abstract
The fractionation of a grape skin extract by multilayer countercurrent chromatography coupled with step gradient elution allowed the preparation of a fraction almost devoid of free anthocyanins. This fraction appeared to be almost exclusively polymeric, as judged by liquid chromatographic-mass spectrometric (LC-MS) analysis, color-bleaching tests with sulfur dioxide, and thiolysis. Electrospray mass spectrometric analysis indicated that the pigmented material in this fraction was chiefly composed of direct condensation products of anthocyanin extending up to trimers. With regard to their linkages, the anthocyanin units in the oligomers were possibly linked by either an A-type (by both carbon-carbon and ether bonds) or B-type (by carbon-carbon bond) linkage, like proanthocyanidins. The terminal anthocyanin unit of the oligomers is consistently in the flavylium form but the extension units are in the flavan form for the A-type oligomers and in the flavene form for the B-type oligomers. Although their linkages still need to be defined rigorously, this is the first mass spectrometric evidence confirming the existence of anthocyanin oligomers in the grape skin extract.
Extracted Claims
2 claims extracted from this paper into the knowledge graph
anthocyanin oligomers exist grape skin extract
“This is the first mass spectrometric evidence confirming the existence of anthocyanin oligomers in the grape skin extract.”
anthocyanin units link A-type or B-type linkage
“With regard to their linkages, the anthocyanin units in the oligomers were possibly linked by either an A-type (by both carbon-carbon and ether bonds) or B-type (by carbon-carbon bond) linkage, like p...”