Procyanidin dimers and trimers from grape seeds
1991
Ricardo da Silva, J.M. | Rigaud, J. | Cheynier, V. | Cheminat, A. | Moutounet, M.
Fractionation of a grape (Vitis vinifera) seed extract yielded various natural procyanidin dimers and trimers isolated and identified for the first time in grapes: procyanidin dimers B5 [epicatechin-(4 beta leads to 6)-epicatechin], B6 [catechin-(4 alpha leads to 6)-catechin] and B8 catechin-(4 alpha leads to 6)-epicatechin]; four procyanidin trimers [epicatechin-4 beta leads to 6)-epicatechin-(4 beta leads to 8)-epicatechin], [epicatechin-(4 beta leads to 8)-epicatechin-(4 beta leads to 6)-catechin], [epicatechin-(4 beta leads to 8)-epicatechin-(4 beta leads to 6)-epicatechin], [epicatechin-(4 beta leads to 6)-epicatechin-(4 beta leads to 8)-catechin] along with five galloyl procyanidins: B2 3-O-gailate, B1 3-O-gailate, B4 3'-O-gailate, B2 3,3'-di-O-gatiate and [epicatechin-(4 beta leads to 8)-epicatechin 3-O-gailate-(4 beta leads to 8)-catechin]. The presence of (+)-catechin, (-)-epicatechin, (-)-epicatechin 3-O-gailate, procyanidins dimers B1, B2, B3, B4, B7, B2 3'-O-gallate and procyanidin trimers C1 and [epicatechin-(4 beta leads to 8)-epicatechin-(4 beta leads to 8)-catechin] was also confirmed. The structures of all these compounds were elucidated by enzymatic hydrolysis, complete acid hydrolysis, partial acid-catalysed degradation with phloroglucinol and phenylmethanethiol, FABMS and 1H NMR. Separation of procyanidins and of their phloroglucinol or phenylmethanethiol adducts was achieved by TLC on silica plates and HPLC.
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