PQQ is a tricyclic ortho-quinone that serves as a redox cofactor for bacterial dehydrogenases and has been identified as an important nutrient for mammalian health. It is notable for its exceptional stability and ability to carry out repeated catalytic oxidation-reduction cycles. Research has demonstrated that PQQ stimulates mitochondrial biogenesis through activation of the PGC-1α signaling pathway and supports nerve growth factor (NGF) synthesis. PQQ is produced commercially via bacterial fermentation and has received GRAS status in the US and Novel Food approval in the EU.