Pyrroloquinoline quinone (PQQ) is a quinone described as a cofactor for many bacterial dehydrogenases and reported to have effects on mammalian cell/tissue metabolism. Pyrroloquinoline quinone is found in foods, so dietary supplementation of this compound is possible. The nutritional role of Pyrroloquinoline quinone in mammalian health is supported by the severe defects in reproduction, growth and immunity caused by dietary Pyrroloquinoline quinone deficiency, so Pyrroloquinoline quinone is considered a "new vitamin".

Food sources

Pyrroloquinoline quinone is found in common foods such as tea, papaya, kiwi fruit and B. natto fermented soybeans. Fruits and vegetables contain 7-34 μg/kg; legume seeds 18.24 μg/kg; fermented products 60-800 μg/kg; milk 3.4 μg/kg; egg yolk 7 μg/kg; human milk 140-180 μg/kg. It is estimated that most people consume 1-2 mg of PQQ per day from food.

Benefits

Neuroprotective properties

Pyrroloquinoline quinone can improve clinical deficits by modulating different metabolic mechanisms, where dysfunctional metabolism and mitochondrial activity can lead to cell damage and death. PQQ has been shown to have neuroprotective properties in different experimental models of neurodegenerative diseases, although the link between PQQ-promoted metabolism and improved neuronal viability in some cases remains to be fully elucidated. It affects the activity of the "Parkinson's disease protein" DJ-1, a peptidase involved in androgen receptor-regulated transcription leading to mitochondrial biogenesis. Studies have also shown that PQQ can stimulate mitochondrial biogenesis by stimulating the activation of the peroxisome proliferator-activated receptor-γ-coactivator-1α (PGC-1α) promoter through phosphorylation.

Antioxidant protection

Pyrroloquinoline quinone is a cofactor found in bacteria and is associated with various bacterial soluble and membrane enzymes that directly oxidize sugars, alcohols, and aldehydes. In higher organisms, PQQ has been reported to be a potent free radical scavenger that appears to intervene in different processes, with significant effects in preventing disease and maintaining human health. Animal studies have shown that PQQ treatment has antioxidant effects, including protection against carbon tetrachloride hepatotoxicity, inhibition of glucocorticoid-induced glutathione depletion, and cataracts.

Anticancer

PQQ can induce apoptosis in different cancer cell lines. PQQ has been shown to affect the activity of the oncogene ras, which is important in signal transduction pathways involved in growth and development.

Side Effects

Common side effects of Pyrroloquinoline quinone include headache, drowsiness, and fatigue. Extremely high doses of PQQ can also be dangerous. High doses of PQQ have been found to cause nephrotoxicity and oxidative DNA damage. This effect is thought to be due to its ability to undergo redox cycling, which may be pro-oxidative.

References:

[1] CANOVAI A, WILLIAMS P A. Pyrroloquinoline quinone: a potential neuroprotective compound for neurodegenerative diseases targeting metabolism[J]. ACS Applied Materials & Interfaces, 2024, 50 3. DOI:10.4103/nrr.nrr-d-23-01921.

[2] FLORES-ENCARNACION. An Innovative Quinone (Pyrroloquinoline Quinone) and its Antiproliferative Effects[J]. International Journal of Current Research and Review, 2019, 18 1. DOI:10.31782/IJCRR.2019.1122.