期刊
FOOD CHEMISTRY
卷 114, 期 3, 页码 874-880出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.foodchem.2008.10.056
关键词
Proanthocyanidins; Depolymerisation; Thiolysation; Mangosteen pericarp; Epicatechin
资金
- Ministry of Education of Singapore [R-143-000-299-112]
- Faculty of Science, National University of Singapore through the International Collaborative Fund
- National University of Singapore
Reaction of dried mangosteen pericarps powders with mercaptoacetic acid in the presence of hydrochloric acid in methanol afforded 4 beta-(carboxymethyl)sulphanyl-(-)-epicatechin methyl ester, 1. in 4.5% yield. The structure of 1 was characterised by H-1, C-13 NMR, and mass spectra. Two protons on the prochiral methylene carbon next to sulphur atom give rise to characteristic AB pattern peaks indicating its association to chiral environment as is the case in 1. Compound 1 is a potential synthon towards other epicatechin derivatives due to its labile C-S bond under weakly basic conditions. Reaction 1 with epicatechin gave B2. If 3,5-dimethoxyaniline was used, 4 beta-(2'-amino-4',6'-dimethoxyphenyl)epicatechin, 2, was isolated in moderate yield. Reaction of I with mercaptoethanol leads to synthesis of 4 beta-(2-hydroxyethylthio)epicatechin, 3, in good yield. Finally mercaptoacetic acid was used as an alternative for successful determination of mean degree of polymerisation of PAs isolated from pine bark, grape seeds, cocoa bean, and mangosteen. (C) 2008 Elsevier Ltd. All rights reserved.
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