4,4’,5,5’,6,6’-Hexahydroxydiphenic acid dilactone

Ellagic acid (4,4 ,5,5 ,6,6 -hexahydroxydiphenic acid dilactone) (XVH) occurs in nature either in its free form or in the form of ellagitannins or glucosides [93], It is found in dicotyledonous plants of the genera castenea, eucalyptus, eugenia, euphorbia, gerinimum, mangifera, platycarya, quercus, rhus and terminalia [94],... 

Most hydrolyzable tannins contain a central core of glucose or other polyhydric alcohol esterified with gallic acid (gallotannins) or hexahydroxydiphenic acid (ellagitannins) (Fig. 2). The latter is isolated as its stable dilactone, ellagic acid. These Types of tannins are readily hydrolyzed by acids, bases or certain enzymes. 

The hydroxybenzoic acids that are found in various fruits and occur mostly as esters include salicylic acid (2-hydroxybenzoic acid), 4-hydroxybenzoic acid, gentisic acid (2,4-di-hydroxybenzoic acid), protocatechuic acid (3,4-dihydroxybenzoic acid), gallic acid (3,4,5-trihydroxybenzoic acid), vanillic acid (3-methoxy-4-hydroxybenzoic acid) and ellagic acid (IX, Formula 18.13), the dilactone of hexahydroxydiphenic acid (Table 18.19). Table 18.19 shows the most important sources of 4-hydroxybenzoic acid, protocatechuic acid and gallic acid. Strawberries (0.2-0.5), raspberries (1.2) and blackberries (1.9-2.0) contain higher concentrations of free and bound ellagic acid (g/kg). 

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