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Competition between (+)-catechin and (-)-epicatechin in acetaldehyde-induced polymerization of flavanols

Author:
Es-Safi, N.E., Fulcrand, H., Cheynier, V., Moutounet, M.
Source:
Journal of agricultural and food chemistry 1999 v.47 no.5 pp. 2088-2095
ISSN:
0021-8561
Subject:
catechin, epicatechin, polymerization, acetaldehyde, pH, acidity, chemical structure, chemical reactions
Abstract:
The reactions of (+)-catechin and (-)-epicatechin in the presence of acetaldehyde were studied in model solution systems. When incubated separately with acetaldehyde and at pH values varying from 2.2 to 4.0, reactions were faster with (-)-epicatechin than with (+)-catechin. In mixtures containing both (+)-catechin and (-)-epicatechin with acetaldehyde, new compounds besides the homogeneous bridged derivatives were detected. These compounds were concluded to be heterooligomers consisting of (+)-catechin and (-)-epicatechin linked with an ethyl bridge. In this case, the reaction of (-)-epicatechin was faster than that of (+)-catechin. This was also observed in solutions containing the two flavanols and the (+)-catechin-ethanol intermediate. Under these conditions, the homogeneous (+)-catechin bridged dimers and heterogeneous dimers were obtained by action of the intermediate on (+)-catechin and (-)-epicatechin, respectively. In addition, the homogeneous (-)-epicatechin ethyl-bridged dimers were also detected, showing that ethyl linkages underwent depolymerization and recombination reactions.
Agid:
1371763