Book ChapterDOI
Structural Variations in Proanthocyanidins and Their Derivatives
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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
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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.
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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.
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Red wine astringency: a review
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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.
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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
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Journal ArticleDOI
Synthesis of condensed tannins. Part 13. The first 2,3-trans-3,4-cis-procyanidins: sequence of units in a ‘trimer’ of mixed stereochemistry
TL;DR: In this paper, the bonding patterns in the products, and also the sequence of units in one of the trimers of mixed stereochemistry, are resolved by 1H n.m. spectroscopy through selective use of solvents at elevated temperatures.
Journal ArticleDOI
Zur kenntnis der catechin-gerbstoffe
TL;DR: In this paper, the Ubersicht uber die erweiterte Reihe der Hydroxyflavane I-XVIII, zu denen die Catechine (z. B. XIII) gehoren, zeigt erneut, das die gleichzeitige Anwesenheit von Hydroxylen in 7-and 4′-Stellung (IV) fur die Selbstkondensation notwendig ist.
Journal ArticleDOI
Oligomeric flavanoids. Part 3. Structure and synthesis of phlobatannins related to (–)-fisetinidol-(4α,6)- and (4α,8)-(+)-catechin profisetinidins
J. P. Steynberg,Johann F. W. Burger,Desmond A. Young,E. V. Brandt,Jacobus A. Steenkamp,Daneel Ferreira +5 more
TL;DR: In this article, a class of phlobaphene condensed tannins, representing the products of c-ring isomerization of 2,3-trans-3,4-trans-(−)-fisetinidol units present in (4,6)- and (4 8)-biflavanoid profisetsinidins, have been characterized by 1H n.m.n.o.
Journal ArticleDOI
Synthesis of condensed tannins. Part 14. Biflavanoid profisetinidins as synthons. The Acid-induced ‘phlobaphene’ reaction
TL;DR: In this article, acid-induced transformations of the predominant [4,8]-all-trans isomer, illustrative of the well-known ‘phlobaphene reaction of condensed tannins, are shown to include ring-isomerization and fission of the inter-flavanoid bond, followed in the latter instance by the alternatives of anthocyanidin formation, positional rearrangement and self-condensation.
Journal ArticleDOI
Condensed tannins: co-occurrence of procyanidins, prodelphinidins and profisetinidins in the heartwood of Acacia baileyana
TL;DR: In this paper, the hydroxylation pattern of the flavonoids and condensed tannins of the heartwood of Acacia baileyana var. purpurea is described.