The Biomedical Significance of PQQ

This chapter presents an overview of the biomedical significance of Pyrroloquinoline quinone (PQQ). It was first isolated from cultures of methylotrophic bacteria as an acetone adduct and its structure determined by X-ray diffraction and confirmed by organic synthesis. PQQ captures electrons from primary amines, catechols, catecholamines, ascorbic acid, and NAD(P)H to form PQQ-semiquinone and/or PQQ-hydroquinone. In a collaborative study with Dr. Manfred Karnovsky, an expert in respiratory burst biochemistry, they have recently shown that superoxide may be derived from a reaction involving the dioxygen oxidation of a reduced ortho-quinom, probably PQQ, which is present in phorbol myristate acetate-activated guinea pig peritoneal exudate neutrophils. The recent reports on the anti-inflammatory and antioxidant actions of PQQ are discussed. Rats given a variety of hepatotoxins capable of destroying the liver through the induction of oxidative stress injury are protected by PQQ in a dose-dependent manner. PQQ is a potent antioxidant and anti-inflammatory agent, which could be used pharmaceutically.