The ellagitannins are a diverse class of hydrolyzable tannins , a type of polyphenol formed primarily from the oxidative linkage of galloyl groups in 1,2,3,4,6-pentagalloyl glucose . Ellagitannins differ from gallotannins , in that their galloyl groups are linked through C-C bonds, whereas the galloyl groups in gallotannins are linked by depside bonds.
3-517: Grandinin is an ellagitannin . It can be found in Melaleuca quinquenervia leaves and in oaks species like the North American white oak ( Quercus alba ) and European red oak ( Quercus robur ). It shows antioxydant activity. It is an astringent compound. It is also found in wine, red or white , aged in oak barrels. It is a castalagin glycoside by binding of the pentose lyxose . It contains
6-466: A nonahydroxytriphenic acid moiety. It suppresses the phosphorylation of the epidermal growth factor receptor in human colon carcinoma cells. Ellagitannin Ellagitannins contain various numbers of hexahydroxydiphenoyl units, as well as galloyl units and/or sanguisorboyl units bounded to sugar moiety. In order to determine the quantity of every individual unit, the hydrolysis of
9-547: The extracts with trifluoroacetic acid in methanol /water system is performed. Hexahydroxydiphenic acid, created after hydrolysis, spontaneously lactonized to ellagic acid , and sanguisorbic acid to sanguisorbic acid dilactone, while gallic acid remains intact. Ellagitannins generally form macrocycles , whereas gallotannins do not. Urolithins , such as urolithin A , are microflora human metabolites of dietary ellagic acid derivatives. Ellagitannins are reported in dicotyledoneous angiospermes, and notably in species in
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