Book ChapterDOI
Structural Variations in Proanthocyanidins and Their Derivatives
Reads0
Chats0
TLDR
The structure complexity of condensed tannins (polymeric proanthocyanidins) is centered principally on variations in hydroxylation patterns of the flavan chain extender units, the stereochemistry at the three chiral centers of the heterocyclic ring, the location and type of interflavanoid bond, and the structure of the terminal unit as discussed by the authors.Abstract:
Structural complexity in the condensed tannins (polymeric proanthocyanidins) is centered principally on variations in hydroxylation patterns of the flavan chain extender units, the stereochemistry at the three chiral centers of the heterocyclic ring, the location and type of interflavanoid bond, and the structure of the terminal unit. Superimposed on these basic structural features are derivatizations such as O-methylation, C- and O-glycosylation, and O-galloylation. Because of the strong nucleophilicity of the resorcinolic or phloroglucinolic A-rings, some unusual conjugates linked through the C-6 or C-8 positions have also been found. A further level of structural diversity results from facile rearrangements of these compounds. Although great progress has been made in elucidation of the structure of oligomeric proanthocyanidins, our knowledge of the structure of higher polymers rests primarily on interpretations of their 13C-NMR spectra.read more
Citations
More filters
Journal ArticleDOI
Formation of complexes between polyvinyl pyrrolidones or polyethylene glycols and tannins, and their implication in gas production and true digestibility in in vitro techniques
TL;DR: The increase in gas production was associated with higher production of short-chain fatty acids with little change in their molar proportions, suggesting an increase in organic matter digestibility by inclusion of the PEG in tannin-rich feeds.
Journal ArticleDOI
A review of the effects and mechanisms of polyphenolics in cancer.
TL;DR: The review encompasses the occurrence and bioavailability of the polyphenolics, the in vitro and in vivo evidence for their effects on cancer, both positive and negative, and the various mechanisms by which the chemicals may exert their effects.
Journal ArticleDOI
Red wine astringency: a review
TL;DR: In this paper, a detailed account of the chemical properties of saliva and the possible modes of interaction between these and red wine phenolics that lead to the necessary physical changes in saliva required to elicit astringency are presented and compared.
Journal ArticleDOI
Tannin diagenesis in mangrove leaves from a tropical estuary: a novel molecular approach
Peter J. Hernes,Ronald Benner,Gregory L. Cowie,Miguel A. Goñi,Brian A. Bergamaschi,John I. Hedges +5 more
TL;DR: Molecular-level condensed tannin analyses were conducted on a series of mangrove ( Rhizophora mangle) leaves at various stages of decomposition in a tropical estuary.
Journal ArticleDOI
Specificity of Tannin Binding Salivary Proteins Relative to Diet Selection by Mammals
TL;DR: The tannin-binding specificity of salivary proteins in several mammals was investigated as a possible explanation for observed food habits in Moose and beaver.
References
More filters
Journal ArticleDOI
Proanthocyanidin dimers and polymers from Quercus dentata
TL;DR: In this paper, the proanthocyanidin polymers also isolated from the same extract have been shown to consist of monomeric and terminal units identifiable with the corresponding units of all the five co-occurring polymers.
Journal ArticleDOI
High-resolution 13C NMR studies of proanthocyanidin polymers (condensed tannins)
TL;DR: In this paper, high-resolution 13C NMR spectra of some proanthocyanidin polymers were presented, and the chemical shifts of selected resonances in these spectra were compared with those of structurally related monomers and oligomers.
Journal ArticleDOI
Tannins and other phenolics from Myrica esculenta bark
TL;DR: In this article, an investigation of the bark of Myrica esculenta has led to the isolation and identification of gallic acid, myricanol, myricanone, epigallocatechin 3- O -gallate, two prodelphinidin dimers epigallocin-(4β → 8)- epigallaocatechin(4β) 3-O-gallate and3-O -galloylepigallocin( 4β→8)-epigalla-3- O-galloyle, and the hydrolysable
Journal ArticleDOI
Flavanol digallates in green tea leaf
TL;DR: In this paper, the authors extended the flavanol class to include the natural natural flavanol-3,5-digallates III and IX in addition to the flavan-3-ols I, VI, VII, and XII.
Journal ArticleDOI
Loblolly pine bark polyflavanoids
TL;DR: The inner bark of Pinus taeda L. contains (+ )-catechin, the procyanidin 8.1 (a C-4 to C-8 linked (-)-epicatechin to (+)-catechine dimer), and three polymeric procyclanidins with distinctly different solubility and chromatographic properties.