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Condensed tannins (proanthocyanidins, polyflavonoid tannins, catechol-type tannins, pyrocatecollic type tannins, non-hydrolyzable tannins or flavolans) are polymers formed by the condensation of flavans. They do not contain sugar residues. They are called proanthocyanidins as they yield anthocyanidins when depolymerized under oxidative conditions. Different types of condensed tannins exist, such as the procyanidins, propelargonidins, prodelphinidins, profisetinidins, proguibourtinidins or prorobinetidins, formed from flavonoids structures corresponding to the related anthocyanins. One particular type of condensed tannin, found in grape, are procyanidins, which are polymers of 2 to 50 (or more) flavan-3-ol units joined by carbon-carbon bonds. These are not susceptible to being cleaved by hydrolysis. While many hydrolyzable tannins and most condensed tannins are water-soluble, several tannins are also highly octanol-soluble.〔Mueller-Harvey, I., Mlambo, V., Sikosana, J.L.N., Smith, T., Owen, E., Brown, R.H. Octanol-water partition coefficients for predicting the effects of tannins in ruminant nutrition. ''J. Agric. Food Chem''. 2007, vol. 55, 5436-5444. 10.1021/jf070308a〕〔Mueller-Harvey, I. Unravelling the conundrum of tannins in animal nutrition and health. J. Sci. Food Agric. 86, 2006, 2010-2037. DOI: 10.1002/jsfa.2577〕 Some large condensed tannins are insoluble. Differences in solubilities are likely to affect their biological functions. == Natural occurrences == Tannins of tropical woods tend to be of a catechin nature rather than of the gallic type present in temperate woods.〔(Les tannins dans les bois tropicaux (Tannin in tropical woods), by Jacqueline Doat, Revue bois et forêts des tropiques, 1978, n° 182 (French) )〕 Condensed tannins can be recovered from ''Lithocarpus glaber'' or can be found in ''Prunus'' sp. The bark of ''Commiphora angolensis'' contains condensed tannins.〔Chemical study of bark from Commiphora angolensis Engl. Cardoso Do Vale, J., Bol Escola Farm Univ Coimbra Edicao Cient, 1962, volume 3, page 128 ((abstract ))〕 Commercial sources of condensed tannins are plants such as quebracho wood (''Schinopsis lorentzii''), mimosa bark (''Acacia mollissima''), grape seeds (''Vitis vinifera''), pine barks and spruce barks.〔(''Haslam E. Plant Polyphenols, Vegetable Tannins Revisited. Cambridge University Press, Cambridge, UK (1989)'' ).〕〔Extraction of condensed tannins from grape pomace for use as wood adhesives. Ping L, Laurent Chrusciel L, Navarrete P and Pizzi A, Industrial Crops and Products, Volume 33, Issue 1, January 2011, Pages 253–257. 〕 Condensed tannins are formed in tannosomes, specialized organelles, in Tracheophytes, i.e. vascular plants.〔http://aob.oxfordjournals.org/content/early/2013/09/11/aob.mct168.full.pdf Annals of Botany: The tannosome is an organelle forming condensed tannins in the chlorophyllous organs of Tracheophyta〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Condensed tannin」の詳細全文を読む スポンサード リンク
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