Consumption of Sylimarin, Pyrroloquinoline Quinone Sodium Salt and Myricetin: Effects on Alcohol Levels and Markers of Oxidative Stress-A Pilot Study.

BACKGROUND: Alcohol abuse is one of the most common causes of mortality worldwide. This study aimed to investigate the efficacy of a treatment in reducing circulating ethanol and oxidative stress biomarkers. METHODS: Twenty wine-drinking subjects were investigated in a randomized controlled, single-blind trial (ClinicalTrials.gov. Identifier: NCT06548503; Ethical Committee of the University of Padova (HEC-DSB/12-2023) to evaluate the effect of the intake of a product containing silymarin, pyrroloquinoline quinone sodium salt, and myricetin (referred to as Si.Pi.Mi. for this project) on blood alcohol, ethyl glucuronide (EtG: marker for alcohol consumption) and markers of oxidative stress levels (Reactive Oxygen Species-ROS, Total Antioxidant Capacity-TAC, CoQ10, thiols redox status, 8-isoprostane, NO metabolites, neopterin, and uric acid). The effects of the treatment versus placebo were evaluated acutely and after 1 week of supplementation in blood and/or saliva and urine samples. RESULTS: Si.Pi.Mi intake reduced circulating ethanol after 120 min (-33%). Changes in oxidative stress biomarkers, particularly a TAC (range +9-12%) increase and an 8-isoprostane (marker of lipidic peroxidation) decrease (range -22-27%), were observed too. CONCLUSION: After the administration of Si.Pi.Mi, the data seemed to suggest a better alcohol metabolism and oxidative balance in response to wine intake. Further verification is requested.

Pyrroloquinoline Quinone Alleviates Intestinal Inflammation and Cell Apoptosis via the MKK3/6-P38 Pathway in a Piglet Model.

This study investigates the underlying mechanism through which dietary supplementation of pyrroloquinoline quinone disodium (PQQ) alleviates intestinal inflammation and cell apoptosis in piglets challenged with lipopolysaccharide (LPS). Seventy-two barrows were divided into three groups: control (CTRL), LPS challenged (LPS), and LPS challenged with PQQ supplementation (PQQ + LPS). On d 7, 11, and 14, piglets received intraperitoneal injections of LPS or 0.9% of NaCl (80 µg/kg). After a 4 h interval following the final LPS injection on d 14, blood samples were obtained, and all piglets were euthanized for harvesting jejunal samples. The results showed that dietary supplementation of PQQ improved the damage of intestinal morphology, increased the down-regulated tight junction proteins, and reduced the increase of serum diamine oxidase activity, the intestinal fatty acid binding protein, and TNF-α levels in piglets challenged with LPS (p < 0.05). The proteomics analysis revealed a total of 141 differentially expressed proteins (DEPs), consisting of 64 up-regulated DEPs and 77 down-regulated DEPs in the PQQ + LPS group compared to the LPS group. The KEGG pathway analysis indicated enrichment of the tight junction pathway and the apoptosis pathway (p < 0.05). Compared to the LPS group, the piglets in the PQQ + LPS group had increased levels of Bcl-2 protein, reduced positive apoptosis signals, and a decrease in the abundance of MKK 3/6 and p-p38 proteins (p < 0.05). In conclusion, dietary supplementation of PQQ could alleviate jejunal inflammatory damage and cell apoptosis in piglets challenged with LPS through the MKK3/6-p38 signaling pathway.

Pyrroloquinoline Quinone Alleviates Mitochondria Damage in Radiation-Induced Lung Injury in a MOTS-c-Dependent Manner.

Radiation-induced lung injury (RILI) is a prevalent complication of thoracic tumor radiotherapy and accidental radiation exposure. Pyrroloquinoline quinone (PQQ), a novel vitamin B, plays a crucial role in delaying aging, antioxidation, anti-inflammation, and antiapoptosis. This study aims to investigate the protective effect and mechanisms of PQQ against RILI. C57BL/6 mice were exposed to a 20 Gy dose of X-ray radiation on the entire thorax with or without daily oral administration of PQQ for 2 weeks. PQQ effectively mitigated radiation-induced lung tissue damage, inflammation, oxidative stress, and epithelial cell apoptosis. Additionally, PQQ significantly inhibited oxidative stress and mitochondrial damage in MLE-12 cells. Mechanistically, PQQ upregulated the mRNA and protein levels of MOTS-c in irradiated lung tissue and MLE-12 cells. Knockdown of MOTS-c by siRNA substantially attenuated the protective effects of PQQ on oxidative stress, inflammation, and apoptosis. In conclusion, PQQ alleviates RILI by preserving mitochondrial function through a MOTS-c-dependent mechanism, suggesting that PQQ may serve as a promising nutraceutical intervention against RILI.

Novel Insights into the Antimicrobial and Antibiofilm Activity of Pyrroloquinoline Quinone (PQQ); In Vitro, In Silico, and Shotgun Proteomic Studies.

Microbial infections pose a significant global health threat, affecting millions of individuals and leading to substantial mortality rates. The increasing resistance of microorganisms to conventional treatments requires the development of novel antimicrobial agents. Pyrroloquinoline quinone (PQQ), a natural medicinal drug involved in various cellular processes, holds promise as a potential antimicrobial agent. In the present study, our aim was, for the first time, to explore the antimicrobial activity of PQQ against 29 pathogenic microbes, including 13 fungal strains, 8 Gram-positive bacteria, and 8 Gram-negative bacteria. Our findings revealed potent antifungal properties of PQQ, particularly against Syncephalastrum racemosum, Talaromyces marneffei, Candida lipolytica, and Trichophyton rubrum. The MIC values varied between fungal strains, and T. marneffei exhibited a lower MIC, indicating a greater susceptibility to PQQ. In addition, PQQ exhibited notable antibacterial activity against Gram-positive and -negative bacteria, with a prominent inhibition observed against Staphylococcus epidermidis, Proteus vulgaris, and MRSA strains. Remarkably, PQQ demonstrated considerable biofilm inhibition against the MRSA, S. epidermidis, and P. vulgaris strains. Transmission electron microscopy (TEM) studies revealed that PQQ caused structural damage and disrupted cell metabolism in bacterial cells, leading to aberrant morphology, compromised cell membrane integrity, and leakage of cytoplasmic contents. These findings were further affirmed by shotgun proteomic analysis, which revealed that PQQ targets several important cellular processes in bacteria, including membrane proteins, ATP metabolic processes, DNA repair processes, metal-binding proteins, and stress response. Finally, detailed molecular modeling investigations indicated that PQQ exhibits a substantial binding affinity score for key microbial targets, including the mannoprotein Mp1P, the transcriptional regulator TcaR, and the endonuclease PvuRTs1I. Taken together, our study underscores the effectiveness of PQQ as a broad-spectrum antimicrobial agent capable of combating pathogenic fungi and bacteria, while also inhibiting biofilm formation and targeting several critical biological processes, making it a promising therapeutic option for biofilm-related infections.

The impact of six-week dihydrogen-pyrroloquinoline quinone supplementation on mitochondrial biomarkers, brain metabolism, and cognition in elderly individuals with mild cognitive impairment: a randomized controlled trial.

OBJECTIVES: To assess the impact of medium-term supplementation with dihydrogen and pyrroloquinoline quinone (PQQ) on mitochondrial biomarkers, brain metabolism, and cognition in elderly individuals diagnosed with mild cognitive impairment. DESIGN: A parallel-group, randomized, placebo-controlled, double-blind experimental design, maintaining a 1:1 allocation ratio between the experimental group (receiving the dihydrogen-producing minerals and PQQ) and the control group (receiving the placebo) throughout the trial. SETTING AND PARTICIPANTS: Thirty-four elderly individuals with mild cognitive impairment (mean age 71.9 ± 3.8 years; 28 females) voluntarily provided written consent to participate in this trial. Participants were assigned in a double-blind parallel-group design to receive either a dihydrogen-PQQ mixture (Alpha Hope®, CalerieLife, Irvine, CA) or placebo twice daily for a 6-week intervention period. METHODS: The primary endpoint was the change in serum brain-derived neurotrophic factor (BDNF) from baseline to the 6-week follow-up; secondary outcomes included cognitive function indices, specific metabolites in brain tissue, brain oxygenation, and the prevalence and severity of side effects. Interaction effects (time vs. intervention) were evaluated using two-way ANOVA with repeated measures and Friedman's 2-way ANOVA by ranks, for normally distributed data with homogeneous variances and non-homogeneous variances, respectively. RESULTS: Dihydrogen-PQQ resulted in a significant elevation in serum BDNF levels at the six-week follow-up (P = 0.01); conversely, no changes in BDNF levels were observed in the placebo group throughout the study duration (P = 0.27). A non-significant trend in the impact of interventions on BDNF levels was observed (treatment vs. time interaction, P = 0.14), suggesting a tendency for dihydrogen-PQQ to upregulate BDNF levels compared to the placebo. A significant interaction effect was observed for the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) scores in the orientation domain (P = 0.03), indicating the superiority of dihydrogen-PQQ over placebo in enhancing this cognitive aspect. Cerebral oxygenation saturation exhibited a significant increase following the administration of the dihydrogen-PQQ mixture, from 48.4 ± 7.2% at baseline to 52.8 ± 6.6% at 6-week post-administration (P = 0.005). In addition, brain N-acetyl aspartate levels significantly increased at seven out of thirteen locations post-intervention in participants receiving the mixture (P ≤ 0.05). CONCLUSIONS: Despite the limited number of participants included in the study for interpreting clinical parameters, the dihydrogen-PQQ mixture blend shows promise as a potential dietary intervention for enhancing mental orientation and brain metabolism in individuals with age-related mild cognitive decline.

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.

Nrf2 activation by pyrroloquinoline quinone inhibits natural aging-related intervertebral disk degeneration in mice.

Age-related intervertebral disk degeneration (IVDD) involves increased oxidative damage, cellular senescence, and matrix degradation. Pyrroloquinoline quinone (PQQ) is a water-soluble vitamin-like compound with strong anti-oxidant capacity. The goal of this study was to determine whether PQQ can prevent aging-related IVDD, and the underlying mechanism. Here, we found that dietary PQQ supplementation for 12 months alleviated IVDD phenotypes in aged mice, including increased disk height index and reduced histological scores and cell loss, without toxicity. Mechanistically, PQQ inhibited oxidative stress, cellular senescence, and senescence-associated secretory phenotype (SASP) in the nucleus pulposus and annulus fibrosus of aged mice. Similarly, PQQ protected against interleukin-1ß-induced matrix degradation, reactive oxygen species accumulation, and senescence in human nucleus pulposus cells (NPCs) in vitro. Molecular docking predicted and biochemical assays validated that PQQ interacts with specific residues to dissociate the Keap1-Nrf2 complex, thereby increasing nuclear Nrf2 translocation and activation of Nrf2-ARE signaling. RNA sequencing and luciferase assays revealed Nrf2 can transcriptionally upregulate Wnt5a by binding to its promoter, while Wnt5a knockdown prevented PQQ inhibition of matrix metalloproteinase-13 in NPCs. Notably, PQQ supplementation failed to alleviate aging-associated IVDD phenotypes and oxidative stress in aged Nrf2 knockout mice, indicating Nrf2 is indispensable for PQQ bioactivities. Collectively, this study demonstrates Nrf2 activation by PQQ inhibits aging-induced IVDD by attenuating cellular senescence and matrix degradation. This study clarifies Keap1-Nrf2-Wnt5a axis as the novel signaling underlying the protective effects of PQQ against aging-related IVDD, and provides evidence for PQQ as a potential agent for clinical prevention and treatment of natural aging-induced IVDD.

Pyrroloquinoline quinone promotes human mesenchymal stem cell-derived mitochondria to improve premature ovarian insufficiency in mice through the SIRT1/ATM/p53 pathway.

BACKGROUND: DNA damage and oxidative stress induced by chemotherapy are important factors in the onset of premature ovarian insufficiency (POI). Studies have shown that mitochondria derived from mesenchymal stem cells (MSC-Mito) are beneficial for age-related diseases, but their efficacy alone is limited. Pyrroloquinoline quinone (PQQ) is a potent antioxidant with significant antiaging and fertility enhancement effects. This study aimed to investigate the therapeutic effect of MSC-Mito in combination with PQQ on POI and the underlying mechanisms involved. METHODS: A POI animal model was established in C57BL/6J mice by cyclophosphamide and busulfan. The effects of MSC-Mito and PQQ administration on the estrous cycle, ovarian pathological damage, sex hormone secretion, and oxidative stress in mice were evaluated using methods such as vaginal smears and ELISAs. Western blotting and immunohistochemistry were used to assess the expression of SIRT1, PGC-1α, and ATM/p53 pathway proteins in ovarian tissues. A cell model was constructed using KGN cells treated with phosphoramide mustard to investigate DNA damage and apoptosis through comet assays and flow cytometry. SIRT1 siRNA was transfected into KGN cells to further explore the role of the SIRT1/ATM/p53 pathway in combination therapy with MSC-Mito and PQQ for POI. RESULTS: The combined treatment of MSC-Mito and PQQ significantly restored ovarian function and antioxidant capacity in mice with POI. This treatment also reduced the loss of follicles at various stages, improving the disrupted estrous cycle. In vitro experiments demonstrated that PQQ facilitated the proliferation of MitoTracker-labelled MSC-Mito, synergistically restoring mitochondrial function and inhibiting oxidative stress in combination with MSC-Mito. Both in vivo and in vitro, the combination of MSC-Mito and PQQ increased mitochondrial biogenesis mediated by SIRT1 and PGC-1α while inhibiting the activation of ATM and p53, consequently reducing DNA damage-mediated cell apoptosis. Furthermore, pretreatment of KGN cells with SIRT1 siRNA reversed nearly all the aforementioned changes induced by the combined treatment. CONCLUSIONS: Our research findings indicate that PQQ facilitates MSC-Mito proliferation and, in combination with MSC-Mito, ameliorates chemotherapy-induced POI through the SIRT1/ATM/p53 signaling pathway.

Pyrroloquinoline quinone ameliorates PM2.5-induced pulmonary fibrosis through targeting epithelial-mesenchymal transition.

Pulmonary fibrosis is a lung disorder affecting the lungs that involves the overexpressed extracellular matrix, scarring and stiffening of tissue. The repair of lung tissue after injury relies heavily on Type II alveolar epithelial cells (AEII), and repeated damage to these cells is a crucial factor in the development of pulmonary fibrosis. Studies have demonstrated that chronic exposure to PM2.5, a form of air pollution, leads to an increase in the incidence and severity of pulmonary fibrosis by stimulation of epithelial-mesenchymal transition (EMT) in lung epithelial cells. Pyrroloquinoline quinone (PQQ) is a bioactive compound found naturally that exhibits potent anti-inflammatory and anti-oxidative properties. The mechanism by which PQQ prevents pulmonary fibrosis caused by exposure to PM2.5 through EMT has not been thoroughly discussed until now. In the current study, we discovered that PQQ successfully prevented PM2.5-induced pulmonary fibrosis by targeting EMT. The results indicated that PQQ was able to inhibit the expression of type I collagen, a well-known fibrosis marker, in AEII cells subjected to long-term PM2.5 exposure. We also found the alterations of cellular structure and EMT marker expression in AEII cells with PM2.5 incubation, which were reduced by PQQ treatment. Furthermore, prolonged exposure to PM2.5 considerably reduced cell migratory ability, but PQQ treatment helped in reducing it. In vivo animal experiments indicated that PQQ could reduce EMT markers and enhance pulmonary function. Overall, these results imply that PQQ might be useful in clinical settings to prevent pulmonary fibrosis.

Deep Learning-Driven Exploration of Pyrroloquinoline Quinone Neuroprotective Activity in Alzheimer's Disease.

Alzheimer's disease (AD) is a pressing concern in neurodegenerative research. To address the challenges in AD drug development, especially those targeting Aß, this study uses deep learning and a pharmacological approach to elucidate the potential of pyrroloquinoline quinone (PQQ) as a neuroprotective agent for AD. Using deep learning for a comprehensive molecular dataset, blood-brain barrier (BBB) permeability is predicted and the anti-inflammatory and antioxidative properties of compounds are evaluated. PQQ, identified in the Mediterranean-DASH intervention for a diet that delays neurodegeneration, shows notable BBB permeability and low toxicity. In vivo tests conducted on an Aß1₋42-induced AD mouse model verify the effectiveness of PQQ in reducing cognitive deficits. PQQ modulates genes vital for synapse and anti-neuronal death, reduces reactive oxygen species production, and influences the SIRT1 and CREB pathways, suggesting key molecular mechanisms underlying its neuroprotective effects. This study can serve as a basis for future studies on integrating deep learning with pharmacological research and drug discovery.

Protective role of pyrroloquinoline quinone against gentamicin induced cochlear hair cell ototoxicity.

Gentamicin (GM) is one of the commonly used antibiotics in the aminoglycoside class but is ototoxic, which constantly impacts the quality of human life. Pyrroloquinoline quinone (PQQ) as a redox cofactor produced by bacteria was found in soil and foods that exert an antioxidant and redox modulator. It is well documented that the PQQ can alleviate inflammatory responses and cytotoxicity. However, our understanding of PQQ in ototoxicity remains unclear. We reported that PQQ could protect against GM-induced ototoxicity in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells in vitro. To evaluate reactive oxygen species (ROS) production and mitochondrial function, ROS and JC-1 staining, oxygen consumption rate (OCR), and extracellular acidification rate (ECAR) measurements in living cells, mitochondrial dynamics analysis was performed. GM-mediated damage was performed by reducing the production of ROS and inhibiting mitochondria biogenesis and dynamics. PQQ ameliorated the cellular oxidative stress and recovered mitochondrial membrane potential, facilitating the recovery of mitochondrial biogenesis and dynamics. Our in vitro findings improve our understanding of the GM-induced ototoxicity with therapeutic implications for PQQ.

Pyrroloquinoline quinone supplementation attenuates inflammatory liver injury by STAT3/TGF-ß1 pathway in weaned piglets challenged with lipopolysaccharide.

This study is aimed to evaluate the effect and underling mechanism of dietary supplementation with pyrroloquinoline quinone (PQQ) disodium on improving inflammatory liver injury in piglets challenged with lipopolysaccharide (LPS). A total of seventy-two crossbred barrows were allotted into four groups as follows: the CTRL group (basal diet + saline injection); the PQQ group (3 mg/kg PQQ diet + saline injection); the CTRL + LPS group (basal diet + LPS injection) and the PQQ + LPS group (3 mg/kg PQQ diet + LPS injection). On days 7, 11 and 14, piglets were challenged with LPS or saline. Blood was sampled at 4 h after the last LPS injection (day 14), and then the piglets were slaughtered and liver tissue was harvested. The results showed that the hepatic morphology was improved in the PQQ + LPS group compared with the CTRL + LPS group. PQQ supplementation decreased the level of serum inflammatory factors, aspartate aminotransferase and alanine transaminase, and increased the HDL-cholesterol concentration in piglets challenged with LPS; piglets in the PQQ + LPS group had lower liver mRNA level of inflammatory factors and protein level of α-smooth muscle actin than in the CTRL + LPS group. Besides, mRNA expression of STAT3/TGF-ß1 pathway and protein level of p-STAT3(Tyr 705) were decreased, and mRNA level of PPARα and protein expression of p-AMPK in liver were increased in the PQQ + LPS group compared with the CTRL + LPS group (P < 0·05). In conclusion, dietary supplementation with PQQ alleviated inflammatory liver injury might partly via inhibition of the STAT3/TGF-ß1 pathway in piglets challenged with LPS.

Pyrroloquinoline quinone inhibits PCSK9-NLRP3 mediated pyroptosis of Leydig cells in obese mice.

Abnormal lipid metabolism and chronic low-grade inflammation are the main traits of obesity. Especially, the molecular mechanism of concomitant deficiency in steroidogenesis-associated enzymes related to testosterone (T) synthesis of obesity dominated a decline in male fertility is still poorly understood. Here, we found that in vivo, supplementation of pyrroloquinoline quinone (PQQ) efficaciously ameliorated the abnormal lipid metabolism and testicular spermatogenic function from high-fat-diet (HFD)-induced obese mice. Moreover, the transcriptome analysis of the liver and testicular showed that PQQ supplementation not only inhibited the high expression of proprotein convertase subtilisin/Kexin type 9 (PCSK9) but also weakened the NOD-like receptor family pyrin domain containing 3 (NLRP3)-mediated pyroptosis, which both played a negative role in T synthesis of Leydig Cells (LCs). Eventually, the function and the pyroptosis of LCs cultured with palmitic acid in vitro were simultaneously benefited by suppressing the expression of NLRP3 or PCSK9 respectively, as well the parallel effects of PQQ were affirmed. Collectively, our data revealed that PQQ supplementation is a feasible approach to protect T synthesis from PCSK9-NLRP3 crosstalk-induced LCs' pyroptosis in obese men.

Protective effects of pyrroloquinoline quinone in brain folate deficiency.

BACKGROUND: Folates (Vitamin B9) are critical for normal neurodevelopment and function, with transport mediated by three major pathways: folate receptor alpha (FRα), proton-coupled folate transporter (PCFT), and reduced folate carrier (RFC). Cerebral folate uptake primarily occurs at the blood-cerebrospinal fluid barrier (BCSFB) through concerted actions of FRα and PCFT, with impaired folate transport resulting in the neurological disorder cerebral folate deficiency (CFD). Increasing evidence suggests that disorders associated with CFD also present with neuroinflammation, oxidative stress, and mitochondrial dysfunction, however the role of brain folate deficiency in inducing these abnormalities is not well-understood. Our laboratory has identified the upregulation of RFC by nuclear respiratory factor 1 (NRF-1) at the blood-brain barrier (BBB) once indirectly activated by the natural compound pyrroloquinoline quinone (PQQ). PQQ is also of interest due to its anti-inflammatory, antioxidant, and mitochondrial biogenesis effects. In this study, we examined the effects of folate deficiency and PQQ treatment on inflammatory and oxidative stress responses, and changes in mitochondrial function. METHODS: Primary cultures of mouse mixed glial cells exposed to folate-deficient (FD) conditions and treated with PQQ were analyzed for changes in gene expression of the folate transporters, inflammatory markers, oxidative stress markers, and mitochondrial DNA (mtDNA) content through qPCR analysis. Changes in cellular reactive oxygen species (ROS) levels were analyzed in vitro through a DCFDA assay. Wildtype (C57BL6/N) mice exposed to FD (0 mg/kg folate), or control (2 mg/kg folate) diets underwent a 10-day (20 mg/kg/day) PQQ treatment regimen and brain tissues were collected and analyzed. RESULTS: Folate deficiency resulted in increased expression of inflammatory and oxidative stress markers in vitro and in vivo, with increased cellular ROS levels observed in mixed glial cells as well as a reduction of mitochondrial DNA (mtDNA) content observed in FD mixed glial cells. PQQ treatment was able to reverse these changes, while increasing RFC expression through activation of the PGC-1α/NRF-1 signaling pathway. CONCLUSION: These results demonstrate the effects of brain folate deficiency, which may contribute to the neurological deficits commonly seen in disorders of CFD. PQQ may represent a novel treatment strategy for disorders associated with CFD, as it can increase folate uptake, while in parallel reversing many abnormalities that arise with brain folate deficiency.

Pyrroloquinoline quinone drives ATP synthesis in vitro and in vivo and provides retinal ganglion cell neuroprotection.

Retinal ganglion cells are highly metabolically active requiring strictly regulated metabolism and functional mitochondria to keep ATP levels in physiological range. Imbalances in metabolism and mitochondrial mechanisms can be sufficient to induce a depletion of ATP, thus altering retinal ganglion cell viability and increasing cell susceptibility to death under stress. Altered metabolism and mitochondrial abnormalities have been demonstrated early in many optic neuropathies, including glaucoma, autosomal dominant optic atrophy, and Leber hereditary optic neuropathy. Pyrroloquinoline quinone (PQQ) is a quinone cofactor and is reported to have numerous effects on cellular and mitochondrial metabolism. However, the reported effects are highly context-dependent, indicating the need to study the mechanism of PQQ in specific systems. We investigated whether PQQ had a neuroprotective effect under different retinal ganglion cell stresses and assessed the effect of PQQ on metabolic and mitochondrial processes in cortical neuron and retinal ganglion cell specific contexts. We demonstrated that PQQ is neuroprotective in two models of retinal ganglion cell degeneration. We identified an increased ATP content in healthy retinal ganglion cell-related contexts both in in vitro and in vivo models. Although PQQ administration resulted in a moderate effect on mitochondrial biogenesis and content, a metabolic variation in non-diseased retinal ganglion cell-related tissues was identified after PQQ treatment. These results suggest the potential of PQQ as a novel neuroprotectant against retinal ganglion cell death.

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.

Pyrroloquinoline quinone alleviates natural aging-related osteoporosis via a novel MCM3-Keap1-Nrf2 axis-mediated stress response and Fbn1 upregulation.

Age-related osteoporosis is associated with increased oxidative stress and cellular senescence. Pyrroloquinoline quinone (PQQ) is a water-soluble vitamin-like compound that has strong antioxidant capacity; however, the effect and underlying mechanism of PQQ on aging-related osteoporosis remain unclear. The purpose of this study was to investigate whether dietary PQQ supplementation can prevent osteoporosis caused by natural aging, and the potential mechanism underlying PQQ antioxidant activity. Here, we found that when 6-month-old or 12-month-old wild-type mice were supplemented with PQQ for 12 months or 6 months, respectively, PQQ could prevent age-related osteoporosis in mice by inhibiting osteoclastic bone resorption and stimulating osteoblastic bone formation. Mechanistically, pharmmapper screening and molecular docking studies revealed that PQQ appears to bind to MCM3 and reduces its ubiquitination-mediated degradation; stabilized MCM3 then competes with Nrf2 for binding to Keap1, thus activating Nrf2-antioxidant response element (ARE) signaling. PQQ-induced Nrf2 activation inhibited bone resorption through increasing stress response capacity and transcriptionally upregulating fibrillin-1 (Fbn1), thus reducing Rankl production in osteoblast-lineage cells and decreasing osteoclast activation; as well, bone formation was stimulated by inhibiting osteoblastic DNA damage and osteocyte senescence. Furthermore, Nrf2 knockout significantly blunted the inhibitory effects of PQQ on oxidative stress, on increased osteoclast activity and on the development of aging-related osteoporosis. This study reveals the underlying mechanism of PQQ's strong antioxidant capacity and provides evidence for PQQ as a potential agent for clinical prevention and treatment of natural aging-induced osteoporosis.

Effects of Pyrroloquinoline Quinone (PQQ) and Coenzyme Q10 on Mitochondrial Genes, MitomiRs and Cellular Properties in HepG2 Cell Line.

Our study aimed to reveal the effects and changes, antioxidant metabolism (Oxidative Stress), inflammatory response, mitochondrial biogenesis and mitochondrial dysfunction characteristics in hepatocellular carcinoma cell line HepG2; that occur in genes (NRF-1, NRF-2, NFκB and PGC-1α) and miRNAs (miR15-a, miR16-1, miR181-c) that can control related features. To investigate the effects of Pyrroloquinoline quinone (PQQ) and Coenzyme Q10 (CoQ10) in HepG2, and their effects on cell viability, lateral cell migration, gene expression and miRNA expression levels were investigated. If the data we have obtained are evaluated in terms of anti-cancer effectiveness, the most effective use of CoQ10 can be defined as the use alone rather than the combined use. According to the results of the wound healing experiment, we determined that Pyrroloquinoline quinone and combined drug application increased the wound closure area and cell proliferation compared to the control group, while CoQ10 application decreased it. We found that Pyrroloquinoline quinone and Coenzyme Q10 exposure in the HepG2 cell line increased Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) expression but not NRF-1 gene expression. We reported only a small increase in expression of the NRF-2 gene in the Pyrroloquinoline quinone application compared to the control group. We found that only Pyrroloquinoline quinone and CoQ10 application caused more expression increase in the Nuclear Factor kappa B (NFκB) gene compared to combined application. Pyrroloquinoline quinone and CoQ10 administration down-regulated the expression levels of miR16-1, miR15a and miR181c. The use of Pyrroloquinoline quinone and CoQ10 is effective on epigenetic factors, miR-15a, miR-16-1 and miR181c are important candidate biomarkers in hepatocellular carcinoma and diseases accompanied by mitochondrial dysfunction.

Oral pyrroloquinoline quinone (PQQ) during pregnancy increases cardiomyocyte endowment in spontaneous IUGR guinea pigs.

BACKGROUND: Intrauterine growth restriction (IUGR) exerts a negative impact on developing cardiomyocytes and emerging evidence suggests activation of oxidative stress pathways plays a key role in this altered development. Here, we provided pregnant guinea pig sows with PQQ, an aromatic tricyclic o-quinone that functions as a redox cofactor antioxidant, during the last half of gestation as a potential antioxidant intervention for IUGR-associated cardiomyopathy. METHODS: Pregnant guinea pig sows were randomly assigned to receive PQQ or placebo at mid gestation and fetuses were identified as spontaneous IUGR (spIUGR) or normal growth (NG) near term yielding four cohorts: NG ± PQQ and spIUGR ± PQQ. Cross sections of fetal left and right ventricles were prepared and cardiomyocyte number, collagen deposition, proliferation (Ki67) and apoptosis (TUNEL) were analyzed. RESULTS: Cardiomyocyte endowment was reduced in spIUGR fetal hearts when compared to NG; however, PQQ exerted a positive effect on cardiomyocyte number in spIUGR hearts. Cardiomyocytes undergoing proliferation and apoptosis were more common in spIUGR ventricles when compared with NG animals, which was significantly reduced with PQQ supplementation. Similarly, collagen deposition was increased in spIUGR ventricles and was partially rescued in PQQ-treated spIUGR animals. CONCLUSION: The negative influence of spIUGR on cardiomyocyte number, apoptosis, and collagen deposition during parturition can be suppressed by antenatal administration of PQQ to pregnant sows. These data identify a novel therapeutic intervention for irreversible spIUGR-associated cardiomyopathy.

Pyrroloquinoline Quinone Administration Alleviates Allergic Airway Inflammation in Mice by Regulating the JAK-STAT Signaling Pathway.

The current asthma therapies are inadequate for many patients with severe asthma. Pyrroloquinoline quinone (PQQ) is a naturally-occurring redox cofactor and nutrient that can exert a multitude of physiological effects, including anti-inflammatory and antioxidative effects. We sought to explore the effects of PQQ on allergic airway inflammation and reveal the underlying mechanisms. In vitro, the effects of PQQ on the secretion of epithelial-derived cytokines by house dust mite- (HDM-) incubated 16-HBE cells and on the differentiation potential of CD4+ T cells were investigated. In vivo, PQQ was administered to mice with ovalbumin- (OVA-) induced asthma, and lung pathology and inflammatory cell infiltration were assessed. The changes in T cell subsets and signal transducers and activators of transcription (STATs) were evaluated by flow cytometry. Pretreatment with PQQ significantly decreased HDM-stimulated thymic stromal lymphopoietin (TSLP) production in a dose-dependent manner in 16-HBE cells and inhibited Th2 cell differentiation in vitro. Treatment with PQQ significantly reduced bronchoalveolar lavage fluid (BALF) inflammatory cell counts in the OVA-induced mouse model. PQQ administration also changed the secretion of IFN-γ and IL-4 as well as the percentages of Th1, Th2, Th17, and Treg cells in the peripheral blood and lung tissues, along with inhibition the phosphorylation of STAT1, STAT3, and STAT6 while promoting that of STAT4 in allergic airway inflammation model mice. PQQ can alleviate allergic airway inflammation in mice by improving the immune microenvironment and regulating the JAK-STAT signaling pathway. Our findings suggest that PQQ has great potential as a novel therapeutic agent for inflammatory diseases, including asthma.