resumo
In this work, procyanidins were extracted with methanol from the seeds of white and red grape varieties, and fractionated using graded methanol/chloroform precipitation in order to obtain the oligomers of lower molecular weight. These were analyzed by electrospray ionization-mass spectrometry (ESI-MS and ESI-NIS/N[S) in the positive mode. Protonated molecules, [M+H](+), of procyanidin species of nongalloylated and monogalloylated type-A and type-B oligomers, with degree of polymerisation 2-5, and digalloylated oligomers, with degree of polymerisation 2-3, were observed in the ESI-MS spectra. Type-A procyanidin abundance accounted for 60-80% of the abundance of the corresponding type-B species. Independent of the interflavanic linkage, the abundance of monogalloylated ditners accounted for 20% of the abundance of the corresponding nongalloylated ones. For the higher degrees of polymerisation, the abundance of galloylated oligomers was shown to reach up to 60% of the abundance of the corresponding nongalloylated oligomers. Thiolytic analyses showed that the type-A interflavanic linkages were present in the terminal units whereas the type-B intertlavanic linkages were present as extension units. Although many reports are already available regarding the analyses of procyanidin polymers and grape seed procyanidins, this is the first report for the occurrence of type-A galloylated procyanidins. The similarity of the relative abundances and structural features observed in the samples of both white and red grape varieties, shows that these are characteristic of grape seeds. (c) 2007 Elsevier Ltd. All rights reserved.
palavras-chave
FLIGHT MASS-SPECTROMETRY; VITIS-VINIFERA; POLYMERIC PROCYANIDINS; STRUCTURAL-CHARACTERIZATION; FLAVAN-3-OL COMPOSITION; LIQUID-CHROMATOGRAPHY; OLIVE PULP; ELECTROSPRAY; PROANTHOCYANIDINS; POLYPHENOLS
categoria
Chemistry; Food Science & Technology; Nutrition & Dietetics
autores
Passos, CP; Cardoso, SM; Domingues, MRM; Domingues, P; Silva, CM; Coimbra, MA
nossos autores
