Tannins and related compounds. Part 13. Isolation and structures of trimeric, tetrameric, and pentameric proanthicyanidins from cinnamon

Gen Ichiro Nonaka, Satoshi Morimoto, Itsuo Nishioka

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Abstract

A proanthocyanidin trimer, two tetramers, and a pentamer have been isolated in their free phenolic forms from cinnamon, the bark of Cinnamomum zeylanicum (Lauraceae). Partial acid-catalysed degradation of these tannins with phenylmethanethiol, in conjunction with 1H- and 13C-n.m.r. analysis, has unequivocally established their structures as epicatechin-(4β→8, 2β→7)epicatechin-(4α→8)- epicatechin (5); epicatechin-(4β→8)epicatechin-(4β→8, 2β→7)-epicatechin-(4α→8)-epicatechin (6); epicatechin-(4β→6)-epicatechin-(4β→8, 2β→7)- epicatechin-(4α→8)-epicatechin (7); and epicatechin-(4β→8)- epicatechin-(4β→8)epicatechin-(4β-→8, 2β→7)- epicatechin-(4α→8)-epicatechin (8).

Original languageEnglish
Pages (from-to)2139-2145
Number of pages7
JournalJournal of the Chemical Society, Perkin Transactions 1
Publication statusPublished - 1983

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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