NADH and NADPH-dependent reduction of coenzyme Q at the plasma membrane

Coenzyme Q10 Supplementation and Oxidative Stress Parameters: An Updated Systematic Review and Meta-analysis of Randomized Controlled Clinical Trials

Background: Oxidative stress (OS) contributes to the development of some disorders, including malignancies, metabolic diseases, Alzheimer's disease, and Parkinson's disease. Objectives: The effects of coenzyme Q10 (CoQ10) supplementation on OS parameters have been assessed through an updated systematic review and meta-analysis. Methods: SCOPUS, PubMed, Cochrane Library, EMBASE, and Web of Sciences were used for article searching. Standardized mean difference (SMD) and its standard error were calculated using a random-effects DerSimonian and Laird model. All analyses were done using the STATA software version 16.0 (StataCorp, College Station, TX). Results: Based on twenty-five studies which remained to be incorporated in the meta-analysis, a statistically significant decrease in malondialdehyde (MDA) (SMD -2.74; 95% CI -3.89, -1.58; I2 = 96.9%) as well as nitric oxide (NO) (SMD -5.16; 95% CI -7.98, 2.34; I2 = 92.5%) was associated with CoQ10 supplementation, and a significant increase in total antioxidant capacity (TAC) (SMD 3.40; 95% CI 1.98, 4.83; I2 = 97.4%) and superoxide dismutase (SOD) activity (SMD 1.22; 95% CI 0.32, 2.12; I2 = 94.32%). Conclusions: The results showed no significant effect of CoQ10 supplementation on glutathione peroxidase (GPx), catalase (CAT) activities, and glutathione (GSH) levels. CoQ10 supplementation significantly reduced MDA and NO concentrations and increased TAC and SOD activity.

Metabolomic Signatures of Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is associated with many variations in metabolism, but the ex-act correlates of these metabolic disturbances with behavior and development and their links to other core metabolic disruptions are understudied. In this study, large-scale targeted LC-MS/MS metabolomic analysis was conducted on fasting morning plasma samples from 57 children with ASD (29 with neurodevelopmental regression, NDR) and 37 healthy controls of similar age and gender. Linear model determined the metabolic signatures of ASD with and without NDR, measures of behavior and neurodevelopment, as well as markers of oxidative stress, inflammation, redox, methylation, and mitochondrial metabolism. MetaboAnalyst ver 5.0 (the Wishart Research Group at the University of Alberta, Edmonton, Canada) identified the pathways associated with altered metabolic signatures. Differences in histidine and glutathione metabolism as well as aromatic amino acid (AAA) biosynthesis differentiated ASD from controls. NDR was associated with disruption in nicotinamide and energy metabolism. Sleep and neurodevelopment were associated with energy metabolism while neurodevelopment was also associated with purine metabolism and aminoacyl-tRNA biosynthesis. While behavior was as-sociated with some of the same pathways as neurodevelopment, it was also associated with alternations in neurotransmitter metabolism. Alterations in methylation was associated with aminoacyl-tRNA biosynthesis and branched chain amino acid (BCAA) and nicotinamide metabolism. Alterations in glutathione metabolism was associated with changes in glycine, serine and threonine, BCAA and AAA metabolism. Markers of oxidative stress and inflammation were as-sociated with energy metabolism and aminoacyl-tRNA biosynthesis. Alterations in mitochondrial metabolism was associated with alterations in energy metabolism and L-glutamine. Using behavioral and biochemical markers, this study finds convergent disturbances in specific metabolic pathways with ASD, particularly changes in energy, nicotinamide, neurotransmitters, and BCAA, as well as aminoacyl-tRNA biosynthesis.

The Use of the Coenzyme Q10 as a Food Supplement in the Management of Fibromyalgia: A Critical Review

The coenzyme Q₁₀ is a naturally occurring benzoquinone derivative widely prescribed as a food supplement for different physical conditions and pathologies. This review aims to sum up the key structural and functional characteristics of Q₁₀, taking stock of its use in people affected by fibromyalgia. A thorough survey has been conducted, using Pubmed, Scifinder, and ClinicalTrials.gov as the reference research applications and registry database, respectively. Original articles, reviews, and editorials published within the last 15 years, as well as open clinical investigations in the field, if any, were analyzed to point out the lights and shadows of this kind of supplementation as they emerge from the literature.

Central Nervous System Metabolism in Autism, Epilepsy and Developmental Delays: A Cerebrospinal Fluid Analysis

Neurodevelopmental disorders are associated with metabolic pathway imbalances; however, most metabolic measurements are made peripherally, leaving central metabolic disturbances under-investigated. Cerebrospinal fluid obtained intraoperatively from children with autism spectrum disorder (ASD, n = 34), developmental delays (DD, n = 20), and those without known DD/ASD (n = 34) was analyzed using large-scale targeted mass spectrometry. Eighteen also had epilepsy (EPI). Metabolites significantly related to ASD, DD and EPI were identified by linear models and entered into metabolite–metabolite network pathway analysis. Common disrupted pathways were analyzed for each group of interest. Central metabolites most involved in metabolic pathways were L-cysteine, adenine, and dodecanoic acid for ASD; nicotinamide adenine dinucleotide phosphate, L-aspartic acid, and glycine for EPI; and adenosine triphosphate, L-glutamine, ornithine, L-arginine, L-lysine, citrulline, and L-homoserine for DD. Amino acid and energy metabolism pathways were most disrupted in all disorders, but the source of the disruption was different for each disorder. Disruption in vitamin and one-carbon metabolism was associated with DD and EPI, lipid pathway disruption was associated with EPI and redox metabolism disruption was related to ASD. Two microbiome metabolites were also detected in the CSF: shikimic and cis-cis-muconic acid. Overall, this study provides increased insight into unique metabolic disruptions in distinct but overlapping neurodevelopmental disorders.

The effects of coenzyme Q10 supplementation on metabolic profiles and parameters of mental health in women with polycystic ovary syndrome

OBJECTIVE

Evaluating the impact of coenzyme Q10 (CoQ10) supplementation on hormonal indices, mental health, and biomarkers of inflammatory responses and oxidative stress among female patients suffering from polycystic ovary syndrome (PCOS).

METHODS

The present double-blinded, placebo-controlled randomized clinical trial consisted of 55 PCOS women (aged 18-40 years old), who were randomized into groups receiving 100 mg/day of CoQ10 (28 cases) or placebo (27 cases) for 12 weeks.

RESULTS

The supplementation of CoQ10 decreased significantly the scores of Beck Depression Inventory (BDI) (p = .03) and Beck Anxiety Inventory (BAI) (p = .01) and high-sensitivity C-reactive protein (hs-CRP) level (p = .005) when comparing with the placebo group. Moreover, CoQ10 group exhibited a significant drop in total testosterone (p = .004), dehydroepiandrosterone sulfate (DHEAS) (p < .001), hirsutism (p = .002) and malondialdehyde (MDA) (p = .001) levels in the serum, and a significant rise in sex hormone-binding globulin (SHBG) (p < .001) and total antioxidant capacity (TAC) (p < .001) levels in the serum than the placebo group.

CONCLUSIONS

12-week supplementation of CoQ10 to PCOS women showed beneficial impact on BDI, BAI, hs-CRP, total testosterone, DHEAS, hirsutism, SHBG, TAC and MDA levels.

A systematic review for the efficacy of coenzyme Q10 in patients with chronic kidney disease

BACKGROUND

The effects of coenzyme Q10 (CoQ10) supplementation in chronic kidney disease (CKD) patients remain controversial.

OBJECTIVE

A systematic review of current evidence was performed to systematically and comprehensively summarize the effects of CoQ10 on cardiovascular outcomes, oxidative stress, inflammation, lipid profiles, and glucose metabolism.

METHODS

MEDLINE, EMBASE, and the Cochrane Library database (Cochrane Central Register of Controlled Trials) were searched to identify eligible studies investigating the effects of CoQ10 supplementation on patients with CKD.

RESULTS

Twelve independent studies (including seventeen publications) were included in this systematic review. For CKD patients, six studies reported variable cardiovascular outcomes, which yielded inconsistent results. Regarding oxidative stress and inflammation, pooled analysis showed that CoQ10 supplementation significantly reduced malonaldehyde (WMD: - 1.15 95% CI - 1.48 to - 0.81) and high-sensitivity C reactive protein levels (WMD: - 1.18 95% CI - 2.21 to - 0.15). Regarding glucose metabolism, we found that CoQ10 supplementation resulted in significant improvements in HbA1c (WMD: - 0.80; 95% CI: - 1.35 to - 0.24) and QUICKI (WMD: 0.02; 95% CI: 0.01 to 0.03). The pooled results indicated that CoQ10 supplementation had no effects on total cholesterol, or LDL-cholesterol, or on HDL-cholesterol, and triglycerides.

CONCLUSIONS

Our systematic review demonstrated that CoQ10 supplementation might have promising effects on oxidative stress. This work provided some clues that CoQ10 supplementation might have the potential to improve inflammation levels, glucose metabolism, cardiac structure, and cardiac biomarkers. However, the effects of CoQ10 supplementation should be confirmed in larger high-quality studies.

Increasing Nrf2 Activity as a Treatment Approach in Neuropsychiatry

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor encoded by NFE2L2. Under oxidative stress, Nrf2 does not undergo its normal cytoplasmic degradation but instead travels to the nucleus, where it binds to a DNA promoter and initiates transcription of anti-oxidative genes. Nrf2 upregulation is associated with increased cellular levels of glutathione disulfide, glutathione peroxidase, glutathione transferases, thioredoxin and thioredoxin reductase. Given its key role in governing the cellular antioxidant response, upregulation of Nrf2 has been suggested as a common therapeutic target in neuropsychiatric illnesses such as major depressive disorder, bipolar disorder and schizophrenia, which are associated with chronic oxidative and nitrosative stress, characterised by elevated levels of reactive oxygen species, nitric oxide and peroxynitrite. These processes lead to extensive lipid peroxidation, protein oxidation and carbonylation, and oxidative damage to nuclear and mitochondrial DNA. Intake of N-acetylcysteine, coenzyme Q₁₀ and melatonin is accompanied by increased Nrf2 activity. N-acetylcysteine intake is associated with improved cerebral mitochondrial function, decreased central oxidative and nitrosative stress, reduced neuroinflammation, alleviation of endoplasmic reticular stress and suppression of the unfolded protein response. Coenzyme Q₁₀, which acts as a superoxide scavenger in neuroglial mitochondria, instigates mitohormesis, ameliorates lipid peroxidation in the inner mitochondrial membrane, activates uncoupling proteins, promotes mitochondrial biogenesis and has positive effects on the plasma membrane redox system. Melatonin, which scavenges mitochondrial free radicals, inhibits mitochondrial nitric oxide synthase, restores mitochondrial calcium homeostasis, deacetylates and activates mitochondrial SIRT3, ameliorates increased permeability of the blood-brain barrier and intestine and counters neuroinflammation and glutamate excitotoxicity.

The particulars of certain drugs' effect on the endogenous coenzyme Q10 plasma level in patients with cardiovascular diseases

Objectives Coenzyme Q10 (CoQ10) has many vital functions in human body and its endogenous level can be affected either by various diseases or by administrated drugs. This study reveals the effect of atorvastatin, amlodipine and ethoxidol on the endogenous CoQ10 plasma concentration. Methods It was determined the total plasma concentration of endogenous CoQ10 in the plasma of 54 healthy individuals and 62 patients with cardiovascular diseases during treatment with various drugs using high performance liquid chromatography with mass spectrometric detection (HPLC-MS/MS). Results It was found that CoQ10 plasma concentration in patients is statistically significantly lower (on average -49.0 Δ%) than in practically healthy individuals. The total CoQ10 plasma level in patients receiving atorvastatin in the complex therapy is statistically significantly lower (-15.2 Δ%), and in patients taking amlodipine or ethoxidol is statistically significantly higher (+18.2 and +20.2 Δ%, respectively) than in patients of control groups (a group of patients who receive the same drugs, except for the studied one). Conclusions The study showed that in patients with CVDs treated with various drugs the CoQ10 plasma level is statistically significantly lower than in practically healthy individuals. So, to avoid the adverse reactions connected with low CoQ10 plasma levels, it is recommended to adjust the therapy to maintain its constant level.

The interplay between oxidative stress and bioenergetic failure in neuropsychiatric illnesses: can we explain it and can we treat it?

Nitro-oxidative stress and lowered antioxidant defences play a key role in neuropsychiatric disorders such as major depression, bipolar disorder and schizophrenia. The first part of this paper details mitochondrial antioxidant mechanisms and their importance in reactive oxygen species (ROS) detoxification, including details of NO networks, the roles of H₂O₂ and the thioredoxin/peroxiredoxin system, and the relationship between mitochondrial respiration and NADPH production. The second part highlights and identifies the causes of the multiple pathological sequelae arising from self-amplifying increases in mitochondrial ROS production and bioenergetic failure. Particular attention is paid to NAD⁺ depletion as a core cause of pathology; detrimental effects of raised ROS and reactive nitrogen species on ATP and NADPH generation; detrimental effects of oxidative and nitrosative stress on the glutathione and thioredoxin systems; and the NAD⁺-induced signalling cascade, including the roles of SIRT1, SIRT3, PGC-1α, the FOXO family of transcription factors, Nrf1 and Nrf2. The third part discusses proposed therapeutic interventions aimed at mitigating such pathology, including the use of the NAD⁺ precursors nicotinamide mononucleotide and nicotinamide riboside, both of which rapidly elevate levels of NAD⁺ in the brain and periphery following oral administration; coenzyme Q₁₀ which, when given with the aim of improving mitochondrial function and reducing nitro-oxidative stress in the brain, may be administered via the use of mitoquinone, which is in essence ubiquinone with an attached triphenylphosphonium cation; and N-acetylcysteine, which is associated with improved mitochondrial function in the brain and produces significant decreases in oxidative and nitrosative stress in a dose-dependent manner.

Resveratrol Regulates the Expression of Genes Involved in CoQ Synthesis in Liver in Mice Fed with High Fat Diet

Resveratrol (RSV) is a bioactive natural molecule that induces antioxidant activity and increases protection against oxidative damage. RSV could be used to mitigate damages associated to metabolic diseases and aging. Particularly, RSV regulates different aspects of mitochondrial metabolism. However, no information is available about the effects of RSV on Coenzyme Q (CoQ), a central component in the mitochondrial electron transport chain. Here, we report for the first time that RSV modulates COQ genes and parameters associated to metabolic syndrome in mice. Mice fed with high fat diet (HFD) presented a higher weight gain, triglycerides (TGs) and cholesterol levels while RSV reverted TGs to control level but not weight or cholesterol. HFD induced a decrease of COQs gene mRNA level, whereas RSV reversed this decrease in most of the COQs genes. However, RSV did not show effect on CoQ₉, CoQ₁₀ and total CoQ levels, neither in CoQ-dependent antioxidant enzymes. HFD influenced mitochondrial dynamics and mitophagy markers. RSV modulated the levels of PINK1 and PARKIN and their ratio, indicating modulation of mitophagy. In summary, we report that RSV influences some of the metabolic adaptations of HFD affecting mitochondrial physiology while also regulates COQs gene expression levels in a process that can be associated with mitochondrial dynamics and turnover.

Plasma membrane redox enzymes: new therapeutic targets for neurodegenerative diseases

Mitochondrial dysfunction caused by oxidative stress appears at early stages of aging and age-related diseases. Plasma membrane redox enzymes act in a compensatory manner to decrease oxidative stress and supply reductive capacity to ensure cell survival. Plasma membrane redox enzymes transfer electrons from NAD(P)H to oxidized ubiquinone and α-tocopherol, resulting in inhibition of further oxidative damage. Plasma membrane redox enzymes and their partners are affected by aging, leading to progression of neurodegenerative disease pathogenesis. Up-regulating plasma membrane redox enzymes via calorie restriction and phytochemicals make cells more resistant to oxidative damage under stress conditions by maintaining redox homeostasis and improving mitochondrial function. Investigation into plasma membrane redox enzymes can provide mechanistic details underlying the relationships between plasma membrane redox enzymes and mitochondrial complexes and provide a good therapeutic target for prevention and delay of neurodegenerative disorders.

The effects of coenzyme Q10 supplementation on biomarkers of inflammation and oxidative stress in among coronary artery disease: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Systemic inflammation and oxidative stress significantly contribute in developing coronary artery disease (CAD). This systematic review and meta-analysis was aimed to determine the effects of coenzyme Q10 (CoQ10) supplementation on biomarkers of inflammation and oxidative stress among patients with CAD.

METHODS

The electronic databases including MEDLINE, EMBASE, Scopus, Web of Science, and Cochrane Library databases were systematically searched until Oct 2018. The quality assessment and heterogeneity of the selected randomized clinical Trials (RCTs) were examined using the Cochrane Collaboration risk of bias tool, and Q and I² tests, respectively. Given the presence of heterogeneity, random-effects model or fixed-effect model were used to pool standardized mean differences (SMDs) as summary effect sizes.

RESULTS

A total of 13 clinical RCTs of 912 potential citations were found to be eligible for the current meta-analysis. The pooled findings for biomarkers of inflammation and oxidative stress demonstrated that CoQ10 supplementation significantly increased superoxide dismutase (SOD) (SMD 2.63; 95% CI, 1.17, 4.09, P < 0.001; I² = 94.5%) and catalase (CAT) levels (SMD 1.00; 95% CI, 0.57, 1.43, P < 0.001; I² = 24.5%), and significantly reduced malondialdehyde (MDA) (SMD - 4.29; 95% CI - 6.72, - 1.86, P = 0.001; I² = 97.6%) and diene levels (SMD - 2.40; 95% CI - 3.11, - 1.68, P < 0.001; I² = 72.6%). We did not observe any significant effect of CoQ10 supplementation on C-reactive protein (CRP) (SMD - 0.62; 95% CI - 1.31, 0.08, P = 0.08; I² = 87.9%), tumor necrosis factor alpha (TNF-α) (SMD 0.22; 95% CI - 1.07, 1.51, P = 0.73; I² = 89.7%), interleukin-6 (IL-6) (SMD - 1.63; 95% CI - 3.43, 0.17, P = 0.07; I² = 95.2%), and glutathione peroxidase (GPx) levels (SMD 0.14; 95% CI - 0.77, 1.04, P = 0.76; I² = 78.7%).

CONCLUSIONS

Overall, this meta-analysis demonstrated CoQ10 supplementation increased SOD and CAT, and decreased MDA and diene levels, but did not affect CRP, TNF-α, IL-6, and GPx levels among patients with CAD.

Clinical Trial of the Effects of Coenzyme Q10 Supplementation on Biomarkers of Inflammation and Oxidative Stress in Diabetic Hemodialysis Patients

Background

The aim of the study was to determine the effects of coenzyme Q10 (CoQ10) supplementation on biomarkers of inflammation and oxidative stress among diabetic hemodialysis (HD) patients.

Methods

Sixty diabetic HD patients participated in the randomized, double blind, placebo-controlled clinical trial. They were randomly assigned into two groups to intake either 60 mg CoQ10 supplements (n = 30) or placebo (n = 30) twice a day for 12 weeks.

Results

After 12 weeks of intervention, CoQ10 supplementation significantly increased total antioxidant (TAC) (54.921 ± 26.437 vs. -126.781 ± 26.437, P < 0.001) and nitric oxide (NO) levels (4.121 ± 1.314 vs. -1.427 ± 1.314, P = 0.006) and decreased C-reactive protein (CRP) (-1.302 ± 0.583 vs. 0.345 ± 0.583, 0.042) levels compared with the placebo. We did not observe any significant effect of CoQ10 supplementation on malondialdehyde (MDA) and glutathione (GSH) levels compared with the placebo.

Conclusions

Overall, our study showed that CoQ10 supplementation to diabetic HD patients for 12 weeks was associated with increased levels of TAC and NO levels and decreased level of high-sensitivity CRP (hs-CRP) levels, but did not have any beneficial effects on MDA and GSH.

The effects of coenzyme Q10 administration on glucose homeostasis parameters, lipid profiles, biomarkers of inflammation and oxidative stress in patients with metabolic syndrome

BACKGROUND

Limited data are available indicating the effects of coenzyme Q10 (CoQ10) supplementation on metabolic status of patients with metabolic syndrome (MetS).

PURPOSE

The present study was conducted to determine the effects of CoQ10 administration on glucose homeostasis parameters, lipid profiles, biomarkers of inflammation and oxidative stress among patients with MetS.

METHODS

This randomized, double-blind, placebo-controlled trial was performed among 60 overweight or obese and type 2 diabetes mellitus patients with coronary heart disease aged 40-85 years old. Participants were randomly allocated into two groups. Group A (n = 30) received 100 mg CoQ10 supplements and group B (n = 30) received placebo for 8 weeks. Fasting blood samples were taken at the beginning of the study and after 8-week intervention to quantify glucose homeostasis parameters, lipid profiles and biomarkers of inflammation and oxidative stress.

RESULTS

Compared with the placebo, CoQ10 supplementation resulted in a significant reduction in serum insulin levels (-2.1 ± 7.1 vs. +4.1 ± 7.8 µIU/mL, P = 0.002) and homeostasis model of assessment-insulin resistance (-0.7 ± 2.1 vs. +1.0 ± 2.0, P = 0.002) and homeostatic model assessment-beta cell function (-5.9 ± 22.2 vs. +15.9 ± 34.0, P = 0.005). In addition, patients who received CoQ10 supplements had a significant increase in plasma total antioxidant capacity (TAC) concentrations (+26.0 ± 105.0 vs. -162.2 ± 361.8 mmol/L, P = 0.008) compared with the placebo group. However, after adjustment for the baseline levels, age and baseline BMI, the effect on TAC levels (P = 0.08) disappeared. Additionally, compared with the placebo group, a significant positive trends in plasma glutathione (P = 0.06) and a significant reduction in malondialdehyde (P = 0.08) were seen among patients who received CoQ10 supplement. We did not observe any significant changes in fasting plasma glucose, lipid concentrations and inflammatory markers.

CONCLUSIONS

Overall, daily intake of 100 mg CoQ10 supplements among patients with MetS for 8 weeks had beneficial effects on serum insulin levels, HOMA-IR, HOMA-B and plasma TAC concentrations.

CLINICAL TRIAL REGISTRATION NUMBER

www.irct.ir : IRCT201502245623N35.

NRF2 and the Phase II Response in Acute Stress Resistance Induced by Dietary Restriction

Dietary restriction (DR) as a means to increase longevity is well-established in a number of model organisms from yeast to primates. DR also improves metabolic fitness and increases resistance to acute oxidative, carcinogenic and toxicological stressors - benefits with more immediate potential for clinical translation than increased lifespan. While the detailed mechanism of DR action remains unclear, a conceptual framework involving an adaptive, or hormetic response to the stress of nutrient/energy deprivation has been proposed. A key prediction of the hormesis hypothesis of DR is that beneficial adaptations occur in response to an increase in reactive oxygen/nitrogen species (ROS). These ROS may be derived either from increased mitochondrial respiration or increased xenobiotic metabolism in the case of some DR mimetics. This review will focus on the potential role of the redox-sensing transcription factor NF-E2-related factor 2 (NRF2) and its control of the evolutionarily conserved antioxidant/redox cycling and detoxification systems, collectively known as the Phase II response, in the adaptive response to DR.

Trans-plasma membrane electron transport in mammals: functional significance in health and disease

Trans-plasma membrane electron transport (t-PMET) has been established since the 1960s, but it has only been subject to more intensive research in the last decade. The discovery and characterization at the molecular level of its novel components has increased our understanding of how t-PMET regulates distinct cellular functions. This review will give an update on t-PMET, with particular emphasis on how its malfunction relates to some diseases, such as cancer, abnormal cell death, cardiovascular diseases, aging, obesity, neurodegenerative diseases, pulmonary fibrosis, asthma, and genetically linked pathologies. Understanding these relationships may provide novel therapeutic approaches for pathologies associated with unbalanced redox state.

Is coenzyme Q a key factor in aging?

Coenzyme Q (Q) is a key component for bioenergetics and antioxidant protection in the cell. During the last years, research on diseases linked to Q-deficiency has highlighted the essential role of this lipid in cell physiology. Q levels are also affected during aging and neurodegenerative diseases. Therefore, therapies based on dietary supplementation with Q must be considered in cases of Q deficiency such as in aging. However, the low bioavailability of dietary Q for muscle and brain obligates to design new mechanisms to increase the uptake of this compound in these tissues. In the present review we show a complete picture of the different functions of Q in cell physiology and their relationship to age and age-related diseases. Furthermore, we describe the problems associated with dietary Q uptake and the mechanisms currently used to increase its uptake or even its biosynthesis in cells. Strategies to increase Q levels in tissues are indicated.

Highly sensitive sensor for detection of NADH based on catalytic growth of Au nanoparticles on glassy carbon electrode

In this work, an electrochemical dihydronicotinamide adenine dinucleotide (NADH) sensor based on the catalytic growth of Au nanoparticles (Au NPs) on glassy carbon electrode was developed. Catalyzed by Au NPs immobilized on pretreated glassy carbon electrode, the reduction of AuCl(4)(-) in the presence of hydroquinone and cetyltrimethyl ammonium chloride led to the formation of enlarged Au NPs on the electrode surface. Spectrophotometry and high-resolution scanning electronic microscope (SEM) analysis of the sensor morphologies before and after biocatalytic reaction revealed a diameter growth of the nanoparticles. The catalytic growth of Au NPs on electrode surface remarkably facilitated the electron transfer and improved the performance of the sensor. Under optimal conditions, NADH could be detected in the range from 1.25 x 10(-6) to 3.08 x 10(-4) M, and the detection limit was 2.5 x 10(-7) M. The advantages of the proposed sensor, such as high precision and sensitivity, fast response, low cost, and good storage stability, made it suitable for on-line detection of NADH in complex biological systems and contaminant degradation processes.

Evaluation of the mutagenic and genotoxic potential of ubiquinol

Ubiquinol (the reduced form of coenzyme Q(10)) is the two-electron reduction product of ubiquinone (the oxidized form of coenzyme Q(10)), and has been shown to be an integral part of living cells, where it functions as an antioxidant in both mitochondria and lipid membranes. To provide information to enable a Generally Regarded as Safe (GRAS) evaluation for the use of ubiquinol in selected foods, a series of Organisation of Economic Cooperation and Development (OECD) and good laboratory practice (GLP) toxicological studies was conducted to evaluate the mutagenic and genotoxic potential of Kaneka QH brand of ubiquinol. Ubiquinol did not induce reverse mutations in Salmonella typhimurium strains TA100, TA1535, TA98, and TA1537 and Escherichia coli WP2uvrA at concentrations up to 5000 mu g/plate, in either the absence and presence of exogenous metabolic activation by rat liver S9. Likewise, ubiquinol did not induce chromosome aberrations in Chinese hamster lung fibroblast (CHL/IU) cells in short-term (6-h) tests with or without rat liver S9 at concentrations up to 5000 mu g/ml or in a continuous (24-h) treatment test at concentrations up to 1201 mu g/ml. Finally, no mortalities, no abnormal clinical signs, and no significant increase in chromosome damage were observed in an in vivo micronucleus test when administered orally at doses up to 2000 mg/kg/day. Thus, ubiquinol was evaluated as negative in the bacterial reverse mutation, chromosomal aberration, and rat bone marrow micronucleus tests under the conditions of these assays.

Subchronic Oral Toxicity of Ubiquinol in Rats and Dogs

Ubiquinol is the two-electron reduction product of ubiquinone (coenzyme Q10or CoQ10) and functions as an antioxidant in both mitochondria and lipid membranes. In humans and most mammals, including dogs, the predominant form of coenzyme Q is coenzyme Q10, whereas the primary form in rodents is coenzyme Q9(CoQ9). Therefore, the subchronic toxicity of ubiquinol was evaluated and compared in Sprague-Dawley rats and beagle dogs. In the initial rat study, males and females were given ubiquinol at doses of 0, 300, 600, or 1200 mg/kg or ubiquinone at 1200 mg/kg by gavage for 13 weeks. This was followed by the second study, where females were given with doses of 75, 150, 200, or 300 mg/kg/day in order to determine a no observed adverse effect level (NOAEL). In the dog study, the test material was administered to males and females at dose levels of 150, 300, and 600 mg/kg, and ubiquinone was included at 600 mg/kg. Clinical observations, mortality, body weights, food and water consumption, ophthalmoscopy, urinalysis, hematology, blood biochemistry, gross findings, organ weights, and histopathological findings were examined. In both species, determination of plasma and liver ubiquinol concentrations, measured as total coenzyme Q10, were performed. There were no deaths or test article–related effects in body weight, food consumption, ophthalmology, urinalysis, or hematology in rats. Histopathological examinations revealed test article–related effects on the liver, spleen, and mesenteric lymph node in female rats but not in male rats. In the liver, fine vacuolation of hepatocytes was observed in the ubiquinol groups at 200 mg/kg and above. These changes were judged to be of no toxicological significance because they were not considered to induce cytotoxic changes. Microgranuloma and focal necrosis with accumulation of macrophages were observed in the ubiquinol groups at 300 mg/kg and above. These findings were accompanied by slight increases in blood chemistry enzymes (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and lactate dehydrogenase [LDH]), which was suggestive of either potential hepatotoxicity or a normal physiological response to ubiguinol loading. Microgranuloma, and focal necrosis were judged to be only adverse effects induced by test article based on their incidence and pathological characteristics. These changes observed in liver were thought due to uptake of the administered ubiquinol by the liver as an adaptive response to xenobiotics, and the microgranulomas and focal necrosis were considered the results of excessive uptake of ubiquinol, which exceeded the capacity for adaptive response. Based on these findings the NOAEL in rats was conservatively estimated to be 600 mg/kg/day for males and 200 mg/kg/day for females. In dogs, there were no deaths or ubiquinol-related toxicity findings during the administration period. No test article–related effects were observed in body weight, food consumption, ophthalmology, electrocardiogram, urinalysis, hematology, or blood chemistry. Histopathological examination revealed no effects attributable to administration of ubiquinol or ubiquinone in any organs examined. Based on these findings, a NOAEL for ubiquinol in male and female dogs was estimated to be more than 600 mg/kg/day under the conditions of this study.

Study on safety and bioavailability of ubiquinol (Kaneka QH™) after single and 4-week multiple oral administration to healthy volunteers

The safety and bioavailability of ubiquinol (the reduced form of coenzyme Q(10)), a naturally occurring lipid-soluble nutrient, were evaluated for the first time in single-blind, placebo-controlled studies with healthy subjects after administration of a single oral dose of 150 or 300 mg and after oral administration of 90, 150, or 300 mg for 4 weeks. No clinically relevant changes in results of standard laboratory tests, physical examination, vital signs, or ECG induced by ubiquinol were observed in any dosage groups. The C(max) and AUC(0-48 h) derived from the mean plasma ubiquinol concentration-time curves increased non-linearly with dose from 1.88 to 3.19 micro g/ml and from 74.61 to 91.76 micro g h/ml, respectively, after single administration. Trough concentrations had nearly plateaued at levels of 2.61 micro g/ml for 90 mg, 3.66 micro g/ml for 150 mg, and 6.53 micro g/ml for 300 mg at day 14, and increased non-linearly with dose in the 4-week study. In conclusion, following single or multiple-doses of ubiquinol in healthy volunteers, significant absorption of ubiquinol from the gastrointestinal tract was observed, and no safety concerns were noted on standard laboratory tests for safety or on assessment of adverse events for doses of up to 300 mg for up to 2 weeks after treatment completion.

Duroquinone reduction during passage through the pulmonary circulation

The lungs can substantially influence the redox status of redox-active plasma constituents. Our objective was to examine aspects of the kinetics and mechanisms that determine pulmonary disposition of redox-active compounds during passage through the pulmonary circulation. Experiments were carried out on rat and mouse lungs with 2,3,5,6-tetramethyl-1,4-benzoquinone [duroquinone (DQ)] as a model amphipathic quinone reductase substrate. We measured DQ and durohydroquinone (DQH2) concentrations in the lung venous effluent after injecting, or while infusing, DQ or DQH2 into the pulmonary arterial inflow. The maximum net rates of DQ reduction to DQH2 in the rat and mouse lungs were approximately 4.9 and 2.5 micromol. min(-1).g dry lung wt(-1), respectively. The net rate was apparently the result of freely permeating access of DQ and DQH2 to tissue sites of redox reactions, dominated by dicumarol-sensitive DQ reduction to DQH2 and cyanide-sensitive DQH2 reoxidation back to DQ. The dicumarol sensitivity along with immunodetectable expression of NAD(P)H-quinone oxidoreductase 1 (NQO1) in the rat lung tissue suggest cytoplasmic NQO1 as the dominant site of DQ reduction. The effect of cyanide on DQH2 oxidation suggests that the dominant site of oxidation is complex III of the mitochondrial electron transport chain. If one envisions DQ as a model compound for examining the disposition of amphipathic NQO1 substrates in the lungs, the results are consistent with a role for lung NQO1 in determining the redox status of such compounds in the circulation. For DQ, the effect is conversion of a redox-cycling, oxygen-activating quinone into a stable hydroquinone.

Mycosporine-like amino acids and related Gadusols: biosynthesis, acumulation, and UV-protective functions in aquatic organisms

Organisms living in clear, shallow water are exposed to the damaging wavelengths of solar ultraviolet radiation (UVR) coincident with the longer wavelengths of photosynthetically available radiation (PAR) also necessary for vision. With the general exception of bacteria, taxonomically diverse marine and freshwater organisms have evolved the capacity to synthesize or accumulate UV-absorbing mycosporine-like amino acids (MAAs), presumably for protection against environmental UVR. This review highlights the evidence for this UV-protective role while also considering other attributed functions, including reproductive and osmotic regulation and vision. Probing the regulation and biosynthesis of MAAs provides insight to the physiological evolution and utility of UV protection and of biochemically associated antioxidant defenses.

Intracellular redox status affects transplasma membrane electron transport in pulmonary arterial endothelial cells

Pulmonary arterial endothelial cells possess transplasma membrane electron transport (TPMET) systems that transfer intracellular reducing equivalents to extracellular electron acceptors. As one aspect of determining cellular mechanisms involved in one such TPMET system in pulmonary arterial endothelial cells in culture, glycolysis was inhibited by treatment with iodoacetate (IOA) or by replacing the glucose in the cell medium with 2-deoxy-D-glucose (2-DG). TPMET activity was measured as the rate of reduction of the extracellular electron acceptor polymer toluidine blue O polyacrylamide. Intracellular concentrations of NADH, NAD(+), NADPH, and NADP(+) were determined by high-performance liquid chromatography of KOH cell extracts. IOA decreased TPMET activity to 47% of control activity concomitant with a decrease in the NADH/NAD(+) ratio to 34% of the control level, without a significant change in the NADPH/NADP(+) ratio. 2-DG decreased TPMET activity to 53% of control and decreased both NADH/NAD(+) and NADPH/NADP(+) ratios to 51% and 55%, respectively, of control levels. When lactate was included in the medium along with the inhibitors, the effects of IOA and 2-DG on both TPMET activity and the NADPH/NADP(+) ratios were prevented. The results suggest that cellular redox status is a determinant of pulmonary arterial endothelial cell TPMET activity, with TPMET activity more highly correlated with the poise of the NADH/NAD(+) redox pair.

Biochemical functions of coenzyme Q10

Coenzyme Q is well defined as a crucial component of the oxidative phosphorylation process in mitochondria which converts the energy in carbohydrates and fatty acids into ATP to drive cellular machinery and synthesis. New roles for coenzyme Q in other cellular functions are only becoming recognized. The new aspects have developed from the recognition that coenzyme Q can undergo oxidation/reduction reactions in other cell membranes such as lysosomes. Golgi or plasma membranes. In mitochondria and lysosomes, coenzyme Q undergoes reduction/oxidation cycles during which it transfers protons across the membrane to form a proton gradient. The presence of high concentrations of quinol in all membranes provides a basis for antioxidant action either by direct reaction with radicals or by regeneration of tocopherol and ascorbate. Evidence for a function in redox control of cell signaling and gene expression is developing from studies on coenzyme Q stimulation of cell growth, inhibition of apoptosis, control of thiol groups, formation of hydrogen peroxide and control of membrane channels. Deficiency of coenzyme Q has been described based on failure of biosynthesis caused by gene mutation, inhibition of biosynthesis by HMG coA reductase inhibitors (statins) or for unknown reasons in ageing and cancer. Correction of deficiency requires supplementation with higher levels of coenzyme Q than are available in the diet.

Pulmonary reduction of an intravascular redox polymer

Pulmonary endothelial cells in culture reduce external electron acceptors via transplasma membrane electron transport (TPMET). In studying endothelial TPMET in intact lungs, it is difficult to exclude intracellular reduction and reducing agents released by the lung. Therefore, we evaluated the role of endothelial TPMET in the reduction of a cell-impermeant redox polymer, toluidine blue O polyacrylamide (TBOP(+)), in intact rat lungs. When added to the perfusate recirculating through the lungs, the venous effluent TBOP(+) concentration decreased to an equilibrium level reflecting TBOP(+) reduction and autooxidation of its reduced (TBOPH) form. Adding superoxide dismutase (SOD) to the perfusate increased the equilibrium TBOP(+) concentration. Kinetic analysis indicated that the SOD effect could be attributed to elimination of the superoxide product of TBOPH autooxidation rather than of superoxide released by the lungs, and experiments with lung-conditioned perfusate excluded release of other TBOP(+) reductants in sufficient quantities to cause significant TBOP(+) reduction. Thus the results indicate that TBOP(+) reduction is via TPMET and support the utility of TBOP(+) and the kinetic model for investigating TPMET mechanisms and their adaptations to physiological and pathophysiological stresses in the intact lung.