PQQ is a neuro-protective compound. The label states to take one tablet daily.
From Wikipedia:
Neuroprotection
PQQ is a neuroprotective compound that has been shown in a small
number of preliminary studies to protect memory and cognition in aging
animals and humans.[17][18]
It has been shown to reverse cognitive impairment caused by chronic
oxidative stress in animal models and improve performance on memory
tests.[19] PQQ supplementation stimulates the production and release of nerve growth factors in cells that support neurons in the brain,[20] a possible mechanism for the improvement of memory function it appears to produce in aging humans and rats.
PQQ has also been shown to safeguard against the self-oxidation of
the DJ-1 protein, an early step in the onset of some forms of
Parkinson's disease.[21]
PQQ protects brain cells against oxidative damage following
ischemia-reperfusion injury - the inflammation and oxidative damage that
result from the sudden return of blood and nutrients to tissues deprived
of them by stroke.[22]Reactive nitrogen species
(RNS) arise spontaneously following stroke and spinal cord injuries and
impose severe stresses on damaged neurons, contributing to subsequent
long-term neurological damage.[23] PQQ suppresses RNS in experimentally induced strokes,[24]
and provides additional protection following spinal cord injury by
blocking inducible nitric oxide synthase (iNOS), a major source of RNS.[25]
In animal models, administration of PQQ immediately prior to
induction of stroke significantly reduces the size of the damaged brain
area.[26]
These observations have been compounded by the observation in vivo that
PQQ protects against the likelihood of severe stroke in an experimental
animal model for stroke and brain hypoxia.[22]
PQQ also affects some of the brain's neurotransmitter systems. It protects neurons by modulating the properties of the N-methyl-D-aspartate (NMDA) receptor,[27][28]
and so reducing icity - the damaging consequence of long-term
overstimulation of neurons that is associated with many
neurodegenerative diseases and seizures.[29][30][31][32]
PQQ also protects the brain against neurotoxicity induced by other powerful toxins, including mercury[33](a suspected factor in the development of Alzheimer’s disease[34]) and oxidopamine[35]
(a potent neurotoxin used by scientists to induce Parkinsonism in
laboratory animals by destroying dopaminergic and noradrenergic neurons.[36])
PQQ prevents aggregation of alpha-synuclein, a protein associated with Parkinson’s disease.[37] PQQ also protects nerve cells from the toxic effects of the amyloid-beta protein linked with Alzheimer's disease,[38] and reduces the formation of new amyloid beta aggregates.[39]
References
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Nakano M, Ubukata K, Yamamoto T, Yamaguchi H. (2009). "Effect of pyrroloquinoline quinone (PQQ) on mental status of middle-aged and elderly persons". Food Style 2113 (7): 50-52.
Murase, K; Hattori, A; Kohno, M; Hayashi, K (1993). "Stimulation of nerve growth factor synthesis/secretion in mouse astroglial cells by coenzymes". Biochemistry and molecular biology international30 (4): 615-21. PMID8401318.
Nunome, K; Miyazaki, S; Nakano, M; Iguchi-Ariga, S; Ariga, H (2008). "Pyrroloquinoline quinone prevents oxidative stress-induced neuronal death probably through changes in oxidative status of DJ-1". Biological & Pharmaceutical Bulletin31 (7): 1321-6. doi:10.1248/bpb.31.1321. PMID18591768.
Jensen, FE; Gardner, GJ; Williams, AP; Gallop, PM; Aizenman, E; Rosenberg, PA (1994). "The putative essential nutrient pyrroloquinoline quinone is neuroprotective in a rodent model of hypoxic/ischemic brain injury". Neuroscience62 (2): 399-406. doi:10.1016/0306-4522(94)90375-1. PMID7830887.
Zhang, Y; Rosenberg, PA (2002). "The essential nutrient pyrroloquinoline quinone may act as a neuroprotectant by suppressing peroxynitrite formation". The European Journal of Neuroscience16 (6): 1015-24. doi:10.1046/j.1460-9568.2002.02169.x. PMID12383230.
Zhang, Y.; Feustel, P.; Kimelberg, H. (2006-06-13). "Neuroprotection by pyrroloquinoline quinone (PQQ) in reversible middle cerebral artery occlusion in the adult rat". Brain Research1094 (1): 200-206. doi:10.1016/j.brainres.2006.03.111. PMID16709402.
Aizenman, E; Hartnett, KA; Zhong, C; Gallop, PM; Rosenberg, PA (1992). "Interaction of the putative essential nutrient pyrroloquinoline quinone with the N-methyl-D-aspartate receptor redox modulatory site". Journal of Neuroscience12 (6): 2362-9. PMID1318959.
Aizenman, E; Jensen, FE; Gallop, PM; Rosenberg, PA; Tang, LH (1994). "Further evidence that pyrroloquinoline quinone interacts with the N-methyl-D-aspartate receptor redox site in rat cortical neurons in vitro". Neuroscience letters168 (1-2): 189-92. doi:10.1016/0304-3940(94)90447-2. PMID7518062.
Scanlon, JM; Aizenman, E; Reynolds, IJ (1997). "Effects of pyrroloquinoline quinone on glutamate-induced production of reactive oxygen species in neurons". European Journal of Pharmacology326 (1): 67-74. doi:10.1016/S0014-2999(97)00137-4. PMID9178657.
Breese, G. R.; Knapp, D. J.; Criswell, H. E.; Moy, S. S.; Papadeas, S. T.; Blake, B. L. (February 2005). "The neonate-6-hydroxydopamine-lesioned rat: a model for clinical neuroscience and neurobiological principles". Brain Research Reviews48 (1): 57-73. doi:10.1016/j.brainresrev.2004.08.004. PMID15708628.
Zhang, J. J.; Zhang, R. F.; Meng, X. K. (2009-10-30). "Protective effect of pyrroloquinoline quinone against Abeta-induced neurotoxicity in human neuroblastoma SH-SY5Y cells". Neuroscience Letters464 (3): 165-169. doi:10.1016/j.neulet.2009.08.037. PMID19699263.