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.
2-776: 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 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
4-458: The order Myrtales , such as the pomegranate . Hexahydroxydiphenic acid Hexahydroxydiphenic acid is an organic compound with the formula [(HO) 3 C 6 HCO 2 H] 2 . It is the oxidatively coupled derivative of gallic acid It is a white solid, although samples are typically brown owing to oxidation. Luteic acid and ellagic acid are the mono- and di lactone of hexahydroxydiphenic acid, respectively. Hexahydroxydiphenic acid
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