Effect of Dietary Pyrroloquinoline Quinone Disodium Salt on Cognitive Function in Healthy Volunteers: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study

The effects of pyrroloquinoline quinone disodium salt on brain function and physiological processes

Pyrroloquinoline quinone disodium salt (PQQ) is a red trihydrate crystal that was approved as a new food ingredient by FDA in 2008. Now, it is approved as a food in Japan and the EU. PQQ has redox properties and exerts antioxidant, neuroprotective, and mitochondrial biogenesis effects. The baseline intake level of PQQ is considered to be 20 mg/day. PQQ ingestion lowers blood lipid peroxide levels in humans, suggesting antioxidant activity. In the field of cognitive function, double-blind, placebo-controlled trials have been conducted. Various improvements have been reported regarding general memory, verbal memory, working memory, and attention. Furthermore, a stratified analysis of a population with a wide range of ages revealed unique effects in young people (20-40 years old) that were not observed in older adults (41-65 years old). Specifically, cognitive flexibility and executive speed improved more rapidly in young people at 8 weeks. Co-administration of PQQ and coenzyme Q10 further enhanced these effects. In an open-label trial, PQQ was shown to improve sleep and mood. Additionally, PQQ was found to suppress skin moisture loss and increase PGC-1α expression. Overall, PQQ is a food with various functions, including brain health benefits. J. Med. Invest. 71 : 23-28, February, 2024.

Pyrroloquinoline Quinone (PQQ) Improves Long-term Survival of Fat Grafts by Alleviating Oxidative Stress and Promoting Angiogenesis During the Early Phase After Transplantation

BACKGROUND

Reducing absorption after autologous fat grafting is a current challenge. Pyrroloquinoline quinone (PQQ) is the strongest known catalyst of redox reactions, which can scavenge reactive oxygen species (ROS) and alleviate oxidative stress.

OBJECTIVES

The aim of this study was to establish an in vivo model of PQQ-assisted lipotransfer and clarify the role of PQQ in reducing oxidative stress, alleviating apoptosis, and promoting angiogenesis during the acute hypoxic phase after grafting. In addition the study was performed to assess whether this intervention would have a positive effect on the improvement of long-term volume retention.

METHODS

Different concentrations of PQQ (low: 10 μM, medium: 100 μM, and high: 1000 μM) were mixed with human adipose tissue and transplanted subcutaneously into nude mice. Meanwhile, a control group of phosphate-buffered saline in an equal volume to PQQ was set up. On the third day after grafting, whole mount fluorescence staining was applied to detect ROS, mitochondrial membrane potential (MMP), apoptosis, adipocyte activity, and angiogenesis. Graft volume retention rate and electron microscopic morphology were evaluated at the third month. Immunohistochemistry and polymerase chain reaction (PCR) were further employed to elucidate the mechanism of action of PQQ.

RESULTS

PQQ-assisted fat grafting improved the long-term volume retention, promoted the quality and viability of the adipose tissue, and reduced the level of fibrosis. The underlying mechanism of PQQ assisted in scavenging the accumulated ROS, restoring MMP, enhancing adipocyte viability, alleviating tissue apoptosis, and promoting timely angiogenesis during the hypoxia stress phase. The most effective concentration of PQQ was 100 μM. Immunohistochemistry and PCR experiments confirmed that PQQ reduced the expression of Bax and cytochrome c in the mitochondrial apoptotic pathway and increased the level of the antiapoptotic molecule Bcl-2.

CONCLUSIONS

PQQ could improve the long-term survival of adipocytes by alleviating hypoxic stress and promoting timely angiogenesis in the early phase following lipotransfer.

LEVEL OF EVIDENCE: 4

Pyrroloquinoline quinone disodium salt improves brain function in both younger and older adults

Brain function is important for a good quality of life. Pyrroloquinoline quinone disodium salt (PQQ) has been proven to improve brain function and cognition in older adults (above 45 years). In this double-blind, placebo-controlled study, we investigated the effects of PQQ on cognitive function in adults aged between 20 and 65 years. PQQ (20 mg per day) was administered for 12 weeks to the participants. After 12 weeks, the participants showed improvements in composite memory and verbal memory. A further age-stratified analysis was performed. In younger adults (aged 20-40 years), PQQ improved cognitive function (cognitive flexibility, processing speed, and execution speed) after 8 weeks. Only older adults (aged 41-65 years) showed improvements in complex and verbal memory after 12 weeks. In the logistic regression analysis that included the results of all cognitive tests, the changes due to PQQ intake were observed at 8 and 12 weeks in the young and old groups, respectively.

Safety Assessment of a Novel, Dietary Pyrroloquinoline Quinone Disodium Salt (mnemoPQQ®)

Pyrroloquinoline quinone (PQQ), a potent coenzyme antioxidant naturally occurring in foods, has been demonstrated to protect brain cells by enhancing the expression of nerve growth factors (NGF) and NGF receptors, and suppressing the fibril formation and aggression of amyloid β. We developed mnemoPQQ^®, a novel PQQ disodium salt and assessed its safety in GLP compliant toxicity studies. Acute toxicity studies of mnemoPQQ^® in Wistar rats revealed that its LD₅₀ was 1825- and 1410 mg/kg body weight (bw) in male and female rats, respectively, while its acute dermal LD₅₀ was >2,000 mg/kg bw mnemoPQQ^® was found to be non-irritant to the skin of rabbit in an acute dermal irritation/corrosion study, and classified mnemoPQQ^® as a non-irritant to the eye of rabbit in an acute eye irritation/corrosion study. Ames bacterial reverse mutation assay and in vitro Mammalian cell gene mutation test exhibited its non-mutagenic potential. In mammalian in vivo erythrocyte micronucleus test, mnemoPQQ^® was classified as non-clastogenic and non-mutagenic. A 90-day sub-chronic toxicity study, conducted at and up to the highest daily dose of 600 mg/kg body weight, revealed no evidence of systemic toxicity. All rats survived the treatment without any significant abnormal clinical signs and alterations in hematology, clinical chemistry, neurological evaluation, thyroid functions, reproductive hormone levels, sperm evaluations, vaginal cytology, endocrine functions, organ weight and gross and microscopic pathology findings. No observed adverse effect level (NOAEL) of mnemoPQQ^® was found to be greater than 600 mg/kg body weight. These studies affirm that mnemoPQQ^® has broad spectrum safety for human consumption.

Pyrroloquinoline Quinone Chemistry, Biology, and Biosynthesis

The widely distributed, essential redox factor pyrroloquinoline quinone (PQQ, methoxatin) (1) was discovered in the mid-1960s. The breadth and depth of its biological effects are steadily being revealed, and understanding its biosynthesis at the genomic level is a continuing process. In this review, aspects of the chemistry, biology, biosynthesis, and commercial production of 1 at the gene level, and some applications, are presented from discovery through to mid-2021.

Pyrroloquinoline-Quinone Is More Than an Antioxidant: A Vitamin-like Accessory Factor Important in Health and Disease Prevention

Pyrroloquinoline quinone (PQQ) is associated with biological processes such as mitochondriogenesis, reproduction, growth, and aging. In addition, PQQ attenuates clinically relevant dysfunctions (e.g., those associated with ischemia, inflammation and lipotoxicity). PQQ is novel among biofactors that are not currently accepted as vitamins or conditional vitamins. For example, the absence of PQQ in diets produces a response like a vitamin-related deficiency with recovery upon PQQ repletion in a dose-dependent manner. Moreover, potential health benefits, such as improved metabolic flexibility and immuno-and neuroprotection, are associated with PQQ supplementation. Here, we address PQQ's role as an enzymatic cofactor or accessory factor and highlight mechanisms underlying PQQ's actions. We review both large scale and targeted datasets demonstrating that a neonatal or perinatal PQQ deficiency reduces mitochondria content and mitochondrial-related gene expression. Data are reviewed that suggest PQQ's modulation of lactate acid and perhaps other dehydrogenases enhance NAD+-dependent sirtuin activity, along with the sirtuin targets, such as PGC-1α, NRF-1, NRF-2 and TFAM; thus, mediating mitochondrial functions. Taken together, current observations suggest vitamin-like PQQ has strong potential as a potent therapeutic nutraceutical.