Exploring the conformations of polyflavanoids – an approach to understanding the significance of tannins

Title:	Exploring the conformations of polyflavanoids – an approach to understanding the significance of tannins
Author(s):	Hemingway, R.W.
Date:	1998
Source:	[Proceedings] Polyphenols 96; 1996 July 15-18; Bordeaux, France. Paris: INRA: 81-103.
Description:	Reflection on 25 years of research at the USDA Forest Service Laboratory in Pineville, LA suggests that at least a third and possibly closer to half of the research done on polyflavanoids is in one or another way connected with attempts to understand the conformational properties of these compounds. The concentration on definition of the preferred conformations and conformational flexibility of polyflavanoids is due to the belief that both the commercial and ecological significance of polyflavanoids rest, to large degree, on the relationship of conformation with the complexation of these compounds with other biopolymers (particularly proteins and carbohydrates). This review is not prompted by the notion that all the problems have been solved but rather that scientists have entered a new and exciting phase of tannin chemistry where both NMR and computational approaches have grown to considerable power at the same time when tannin research is increasingly being focused more on the biological significance of these compounds. In this review, Hemingway has summarized both the research conducted at the Forest Service’s Pineville laboratory and the work done by partners and colleagues who have collaborated at various laboratories around the world. The author limits this review to milestones that he considers to be the most important parts of that effort, what he thinks is now known, and some discussion of what he believes are priority issues that need attention. If scientists are to more fully understand the biological significance of condensed tannins, and particularly their complexation with other biopolymers, they must continue to advance the understanding of the conformational preferences and flexibility of these compounds, particularly the free phenols in water, for which only limited data are now available.
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