Dehydrohexahydroxydiphenic acid is a group found in dehydroellagitannins. It is formed from hexahydroxydiphenic acid (HHDP) through oxidation of the plant hydrolysable tannins. It is found in ellagitannins such as euphorbin A, geraniin or mallotusinic acid. In geraniin, it is forming an equilibrium mixture of six-membered hemi-ketal and five-membered hemi-ketal forms. References Ellagitannins Carboxylic acids Heterocyclic compounds with 3 rings Oxygen heterocycles