Polymeric proanthocyanidins. Stereochemistry, structural units, and molecular weight
- 1 January 1980
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 10,p. 2278-2286
- https://doi.org/10.1039/p19800002278
Abstract
Homogeneous polymeric proanthocyanidins have been isolated from 22 plant sources and all are based on a C(4)–C(8)[or C(6)] linked polyflavan-3-ol structure. 13C N.m.r, spectroscopy in 2[H6]acetone–water is used to calculate the ratio of procyanidin to prodelphinidin monomer units, the average heterocyclic ring stereochemistry of the monomers, and the ratio of monomers to chain-terminating units. The majority of polymers isolated in this study possess monomers with predominantly a 2,3-cis stereochemistry [the same configuration as (–)-epicatechin]. The number-average molecular weight, calculated from monomer to terminal unit ratios, of the polymers is 1 500–5 000. The structure of the chain-terminating group is established by thiolysis degradation and g.l.c. analysis of the products.Keywords
This publication has 4 references indexed in Scilit:
- Compositional changes in lower molecular weight flavans during grape maturationPhytochemistry, 1979
- Direct proof of a homogeneous polyflavan-3-ol structure for polymeric proanthocyanidinsJournal of the Chemical Society, Chemical Communications, 1979
- Condensed tannins. Circular dichroism method of assessing the absolute configuration at C-4 of 4-arylflavan-3-ols, and stereochemistry of their formation from flavan-3,4-diolsJournal of the Chemical Society, Chemical Communications, 1978
- The condensed tannins of pasture legume speciesPhytochemistry, 1976