PQQ Joins B Vitamin Family

TOKYO--Pyrroloquinoline quinone (PQQ) is definitely a vitamin and is likely a member of the B vitamin family, according to Tadafumi Kato, M.D., Ph.D., and researchers from the Aging and Psychiatric Research Group of the Brian Science Institute. PQQ is the first new vitamin to be discovered since 1948, when vitamin B12 was found.

Kato and his team published a paper in the April 2003 issue of Nature (422, 6934:832, 2003) (www.nature.com) noting PQQ, which was first isolated from bacteria, is likely important to mammals, although its biological pathways are unknown. They added that PQQ, which must be supplied by the diet, acts as a cofactor in enzyme-catalyzed reduction-oxidation (redox) reactions, much as nicotinamides and flavins. As a mammalian redox cofactor necessary for the degradation of the amino acid lysine, PQQ qualifies as a member of the B vitamin family, the researchers concluded.

Investigators at the University of California (UC), Davis, also published a paper on PQQ's necessity in mammalian health. Their study, which appeared in the February 2003 issue of Experimental Biology & Medicine (228, 2:160-6, 2003) (www.ebmonline.org), demonstrated PQQ supplementation improved reproductive performance and growth in mice. The UC Davis researchers fed mice chemically defined, amino acid-based diets with or without 6 mcg/kg of PQQ for eight weeks before breeding. At weaning, the pups were fed the same diets as their mothers. Researchers noted decreased conception and fertility in PQQ-deficient mice, and the babies born to PQQ-deprived mothers grew at slower rates than offspring from mice given supplemental PQQ.

Previous in vitro research conducted with PQQ has demonstrated it may act as an antioxidant. Researchers at the University of Michigan, Ann Arbor, found PQQ protected isolated rabbit heart cells against oxidative damage (Biochem Biophys Res Commun, 193, 1:434-9, 1993), while a team out of the University of Otago in New Zealand concluded the reactivities of PQQ are dependent on its environment, and the vitamin can act as an antioxidant or pro-oxidant in different biological systems (Biochem Pharmacol, 65, 1:67-74, 2003). Another study, conducted at Harvard Medical School in Boston, demonstrated PQQ's superoxide scavenging abilities, leading researchers to conclude this may be its mechanism of action for protecting against stroke (Eur J Neurosci, 16, 6:1015-24, 2002).