Pyrroloquinoline quinone is a pyrroloquinoline having oxo groups at the 4- and 5-positions and carboxy groups at the 2-, 7- and 9-positions. It has a role as a water-soluble vitamin (role), a cofactor, an antioxidant and an anti-inflammatory agent. It is a member of orthoquinones, a tricarboxylic acid and a pyrroloquinoline cofactor. It is a conjugate acid of a pyrroloquinoline quinone(3-).A pyrrolo-quinoline having two adjacent keto-groups at the 4 and 5 positions and three acidic carboxyl groups. It is a coenzyme of some DEHYDROGENASES.