Dehydrohexahydroxydiphenic acid is a group found in dehydroellagitannins. It is formed from hexahydroxydiphenic acid (HHDP) through oxidation of the plant hydrolysable tannins.[1] 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.