Oxidative burden in prediabetic and diabetic individuals: evidence from plasma coenzyme Q(10)

Combined Supplementation of Coenzyme Q10 and Other Nutrients in Specific Medical Conditions

Coenzyme Q10 (CoQ10) is a compound with a crucial role in mitochondrial bioenergetics and membrane antioxidant protection. Despite the ubiquitous endogenous biosynthesis, specific medical conditions are associated with low circulating CoQ10 levels. However, previous studies of oral CoQ10 supplementation yielded inconsistent outcomes. In this article, we reviewed previous CoQ10 trials, either single or in combination with other nutrients, and stratified the study participants according to their metabolic statuses and medical conditions. The CoQ10 supplementation trials in elders reported many favorable outcomes. However, the single intervention was less promising when the host metabolic statuses were worsening with the likelihood of multiple nutrient insufficiencies, as in patients with an established diagnosis of metabolic or immune-related disorders. On the contrary, the mixed CoQ10 supplementation with other interacting nutrients created more promising impacts in hosts with compromised nutrient reserves. Furthermore, the results of either single or combined intervention will be less promising in far-advanced conditions with established damage, such as neurodegenerative disorders or cancers. With the limited high-level evidence studies on each host metabolic category, we could only conclude that the considerations of whether to take supplementation varied by the individuals' metabolic status and their nutrient reserves. Further studies are warranted.

Effects of Coenzyme Q10 Supplementation on Biomarkers of Oxidative Stress in Adults: A GRADE-Assessed Systematic Review and Updated Meta-Analysis of Randomized Controlled Trials

Evidence shows that exogenous CoQ10 supplementation may potentially attenuate oxidative stress status. However, its effective dose and evidence certainty require further evaluation in the general population via more updated randomized controlled trials (RCTs). Databases (PubMed, Embase and Cochrane Library) were searched up to 30 March 2022. Evidence certainty was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Thirty-four RCTs containing 2012 participants were included in this review. Pooled effects of significant increase in total antioxidant capacity (TAC) (standardized mean difference: 1.83, 95%CI: [1.07, 2.59], p < 0.001) and significant reduction in malondialdehyde (MDA) concentrations (−0.77, [−1.06, −0.47], p < 0.001) were shown after CoQ10 supplementation compared to placebo. However, we could not determine that there was a significant increase in circulating superoxide dismutase (SOD) levels yet (0.47, [0.00, 0.94], p = 0.05). Subgroup analyses implied that CoQ10 supplementation was more beneficial to people with coronary artery disease or type 2 diabetes. Additionally, taking 100−150 mg/day CoQ10 supplement had better benefits for the levels of TAC, MDA and SOD (all p < 0.01). These results to a statistically significant extent lent support to the efficacy and optimal dose of CoQ10 supplementation on attenuating oxidative stress status in adults.

Ubiquinol Supplementation Improves Gender-Dependent Cerebral Vasoreactivity and Ameliorates Chronic Inflammation and Endothelial Dysfunction in Patients with Mild Cognitive Impairment

Ubiquinol can protect endothelial cells from multiple mechanisms that cause endothelial damage and vascular dysfunction, thus contributing to dementia. A total of 69 participants diagnosed with mild cognitive impairment (MCI) received either 200 mg/day ubiquinol (Ub) or placebo for 1 year. Cognitive assessment of patients was performed at baseline and after 1 year of follow-up. Patients' cerebral vasoreactivity was examined using transcranial Doppler sonography, and levels of Ub and lipopolysaccharide (LPS) in plasma samples were quantified. Cell viability and necrotic cell death were determined using the microvascular endothelial cell line bEnd3. Coenzyme Q10 (CoQ) levels increased in patients supplemented for 1 year with ubiquinol versus baseline and the placebo group, although higher levels were observed in male patients. The higher cCoQ concentration in male patients improved cerebral vasoreactivity CRV and reduced inflammation, although the effect of Ub supplementation on neurological improvement was negligible in this study. Furthermore, plasma from Ub-supplemented patients improved the viability of endothelial cells, although only in T2DM and hypertensive patients. This suggests that ubiquinol supplementation could be recommended to reach a concentration of 5 μg/mL in plasma in MCI patients as a complement to conventional treatment.

Relationship Between Serum Gamma-Glutamyl Transferase Level and Impaired Fasting Glucose Among Chinese Community-Dwelling Adults: A Follow-Up Observation of 6 Years

Objective: We aimed to investigate the relationship between serum gamma-glutamyl transferase (GGT) and fasting blood glucose (FBG) levels, as well as the cumulative risk of impaired fasting glucose (IFG) regulation in the Chinese adult population after 6 years of follow-up. Methods: A total of 1360 apparently healthy Chinese men and women who completed a community-based health examination survey and did not have IFG in central China in 2010 and 2016 were included in this study. The patients were divided into four groups according to their baseline GGT (in quartiles). The relationship between GGT levels and FBG levels was examined using general linear regression models. The effect of the GGT level on the risk of IFG was analyzed using multivariate logistic regression. The first quartile group of GGT levels was set as the dummy variable in the model, and the odds ratios and 95% confidence intervals of the remaining quartile groups relative to the first quartile group were obtained. Results: After 6 years of follow-up, 16.4% (188/1148) of participants were diagnosed with IFG. The cumulative incidence of IFG in the four groups according to their baseline GGT levels (in quartiles) was 7.7%, 16.1%, 15.8%, and 26.8%, respectively. Based on the Cox multiple regression, the hazard ratio for IFG increased by 28.9% for each unit of increase in the baseline GGT level after adjusting for the confounding factors. The GGT levels of participants in the first quartile were used as the reference group. The relative risks of IFG in the second, third, and fourth quartiles of GGT were 1.70, 1.55, and 2.46, respectively (P = 0.005). Conclusions: GGT was positively associated with the risk of IFG and can be used as an indicator to assess whether a patient may develop prediabetes.

Adjuvant Therapies in Diabetic Retinopathy as an Early Approach to Delay Its Progression: The Importance of Oxidative Stress and Inflammation

Diabetes mellitus (DM) is a progressive disease induced by a sustained state of chronic hyperglycemia that can lead to several complications targeting highly metabolic cells. Diabetic retinopathy (DR) is a multifactorial microvascular complication of DM, with high prevalence, which can ultimately lead to visual impairment. The genesis of DR involves a complex variety of pathways such as oxidative stress, inflammation, apoptosis, neurodegeneration, angiogenesis, lipid peroxidation, and endoplasmic reticulum (ER) stress, each possessing potential therapeutic biomarkers. A specific treatment has yet to be developed for early stages of DR since no management is given other than glycemic control until the proliferative stage develops, offering a poor visual prognosis to the patient. In this narrative review article, we evaluate different dietary regimens, such as the Mediterranean diet, Dietary Pattern to Stop Hypertension (DASH) and their functional foods, and low-calorie diets (LCDs). Nutraceuticals have also been assessed in DR on account of their antioxidant, anti-inflammatory, and antiangiogenic properties, which may have an important impact on the physiopathology of DR. These nutraceuticals have shown to lower reactive oxygen species (ROS), important inflammatory factors, cytokines, and endothelial damage biomarkers either as monotherapies or combined therapies or concomitantly with established diabetes management or nonconventional adjuvant drugs like topical nonsteroidal anti-inflammatory drugs (NSAIDs).

Coenzyme Q10 administration has no effect on sICAM-1 and metabolic parameters of pediatrics with type 1 diabetes mellitus

Background: Endothelial dysfunction (ED) plays a key role in the development and progression of microvascular and macrovascular complications in pediatrics with type 1 diabetes mellitus (T1DM). Coenzyme Q10 (CoQ10) is a nutraceutical with a known anti-inflammatory and anti-oxidant activity. This study was conducted to evaluate the potential effect of CoQ10 on ED and various metabolic parameters. Methods: This prospective randomized open-label pilot study was conducted on 49 T1DM pediatric patients. Seven healthy non-diabetic pediatric subjects who didn't receive treatment were included as a control group. Eligible patients were randomly allocated into either group I (n = 25); received 100 mg of CoQ10 in addition to standard treatment or group II (n = 24); received standard treatment only. The levels of; soluble intracellular adhesion molecule-1 (sICAM-1), glycated hemoglobin (HbA1c), fasting blood glucose (FBG), lipid profile, serum creatinine and liver function tests were assessed for both groups at baseline and after 3 months of treatment. Results: At baseline, compared to an age-matched healthy control group sICAM-1 levels were significantly elevated in group II diabetic patients (276.5 (231.6-320.66) vs 221.8 (177.9-267.1 ng/ml), p = 0.042. After 3 months of treatment no significant difference was observed in sICAM-1, HbA1c, FBG, lipid profile, serum creatinine and liver function tests between the two study groups. A positive correlation was found between sICAM-1 and HbA1c throughout the study (r = 0.308, p = 0.0054). Conclusion: Administration of CoQ10 for 3 months in T1DM pediatric patients was well tolerated but had no favorable effect on ED or metabolic parameters.

Oxidative Stress as the Main Target in Diabetic Retinopathy Pathophysiology

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus (DM) causing vision impairment even at young ages. There are numerous mechanisms involved in its development such as inflammation and cellular degeneration leading to endothelial and neural damage. These mechanisms are interlinked thus worsening the diabetic retinopathy outcome. In this review, we propose oxidative stress as the focus point of this complication onset.

A Mitochondrial Specific Antioxidant Reverses Metabolic Dysfunction and Fatty Liver Induced by Maternal Cigarette Smoke in Mice

Maternal smoking leads to glucose and lipid metabolic disorders and hepatic damage in the offspring, potentially due to mitochondrial oxidative stress. Mitoquinone mesylate (MitoQ) is a mitochondrial targeted antioxidant with high bioavailability. This study aimed to examine the impact of maternal cigarette smoke exposure (SE) on offspring’s metabolic profile and hepatic damage, and whether maternal MitoQ supplementation during gestation can affect these changes. Female Balb/c mice (eight weeks) were either exposed to air or SE for six weeks prior to mating and throughout gestation and lactation. A subset of the SE dams were supplied with MitoQ in the drinking water (500 µmol/L) during gestation and lactation. Intraperitoneal glucose tolerance test was performed in the male offspring at 12 weeks and the livers and plasma were collected at 13 weeks. Maternal SE induced glucose intolerance, hepatic steatosis, mitochondrial oxidative stress and related damage in the adult offspring. Maternal MitoQ supplementation reduced hepatic mitochondrial oxidative stress and improved markers of mitophagy and mitochondrial biogenesis. This may restore hepatic mitochondrial health and was associated with an amelioration of glucose intolerance, hepatic steatosis and pathological changes induced by maternal SE. MitoQ supplementation may potentially prevent metabolic dysfunction and hepatic pathology induced by intrauterine SE.

The antioxidant status of coenzyme Q10 and vitamin E in children with type 1 diabetes

OBJECTIVE

The purpose of this study was to evaluate the antioxidant status of plasma vitamin E and plasma and intracellular coenzyme Q10 in children with type 1 diabetes.

METHOD

This case-control study was conducted on 72 children with type 1 diabetes and compared to 48 healthy children, who were age, sex, and ethnicity-matched. The diabetic children were divided according to their glycosylated hemoglobin (A1c %) into two groups: poor and good glycemic control groups. All children underwent full history taking, clinical examination, and laboratory measurement of complete blood count, A1c %, plasma cholesterol, triglycerides, and vitamin E levels and coenzyme Q10 levels in plasma, erythrocytes, and platelets.

RESULTS

Children with poor glycemic control showed significantly higher plasma vitamin E, coenzyme Q10, triglycerides, low-density lipoproteins, waist circumference/height ratio, cholesterol levels, and lower high-density lipoproteins and platelet coenzyme Q10 redox status in comparison to those with good glycemic control and the control group (p<0.05). Plasma coenzyme Q10 showed a positive correlation with the duration of type 1 diabetes, triglycerides, cholesterol, vitamin E, and A1c %, and negative correlation with the age of the diabetic group (p<0.05). The platelet redox status showed a negative correlation with the A1c % levels (r=-0.31; p=0.022) and the duration of type 1 diabetes (r=-0.35, p=0.012).

CONCLUSION

Patients with type 1 diabetes, especially poorly controlled, had elevation of plasma vitamin E and coenzyme Q10 levels and decreased platelet redox status of coenzyme Q10, which may be an indicator of increased oxidative stress.

Effect of Q10 supplementation on body weight and body mass index: A systematic review and meta-analysis of randomized controlled clinical trials

AIMS

This meta-analysis study was carried out to assess the effects of coenzyme Q10 supplementation on body weight and body mass index of patients in randomized controlled clinical trial studies.

MATERIALS AND METHODS

A comprehensive systematic search of literature was performed through ISI web of sciences, PubMed, Scopus and Cochrane library databases up to February 2018 which was supplemented by manual search of the references list of included studies. From a total of 1579 identified articles, only 17 trials with 14 and 14 effect-sizes were included for pooling the effects of co-enzyme Q10 supplementation on body weight and body mass index, respectively.

RESULTS

Results of random-effect size meta-analysis showed that supplementation with coenzyme Q10 had no significant decreasing effects on body weight (WMD: 0.28 kg; 95% CI = -0.91, 1.47; P = 0.64) and BMI (WMD: -0.03; 95% CI = -0.4, 0.34; P = 0.86) of study participants. Subgroup analysis revealed that dosage of Q10 and trial duration could not differ the results of Q10 supplementation.

CONCLUSION

Results of this meta-analysis study failed to show any beneficial effect of coenzyme Q10 supplementation on body weight and BMI of patients in clinical trial studies.

CoQ10 ameliorates mitochondrial dysfunction in diabetic nephropathy through mitophagy

The molecular signaling mechanisms of Coenzyme Q10 (CoQ10) in diabetic nephropathy (DN) remain poorly understood. We verified that mitochondrial abnormalities, like defective mitophagy, the generation of mitochondrial reactive oxygen species (mtROS) and the reduction of mitochondrial membrane potential, occurred in the glomerulus of db/db mice, accompanied by reduced PINK and parkin expression and increased apoptosis. These changes were partially reversed following oral administration of CoQ10. In inner fenestrated murine glomerular endothelial cells (mGECs), high glucose (HG) also resulted in deficient mitophagy, mitochondrial dysfunction and apoptosis, which were reversed by CoQ10. Mitophagy suppression mediated by Mdivi-1 or siPINK abrogated the renoprotective effects exerted by CoQ10, suggesting a beneficial role for CoQ10-restored mitophagy in DN. Mechanistically, CoQ10 restored the expression, activity and nuclear translocation of Nrf2 in HG-cultured mGECs. In addition, the reduced PINK and parkin expression observed in HG-cultured mGECs were partially elevated by CoQ10. CoQ10-mediated renoprotective effects were abrogated by the Nrf2 inhibitor ML385. When ML385 abolished mitophagy and the renoprotective effects exerted by CoQ10, mGECs could be rescued by treatment with mitoTEMPO, which is a mtROS-targeted antioxidant. These results suggest that CoQ10, as an effective antioxidant in mitochondria, exerts beneficial effects in DN via mitophagy by restoring Nrf2/ARE signaling.

Effect of Monacolin K and COQ10 supplementation in hypertensive and hypercholesterolemic subjects with metabolic syndrome

INTRODUCTION

Metabolic syndrome (MetS) is a world-wide epidemic disease with an increased risk of morbidity and mortality. Treatment strategies of MetS include pharmacologic and non-pharmacologic interventions and in this respect a relevant role has been shown for nutraceutical compounds (NCs). The aim of this study was to investigate the efficacy and safety of NCs incorporated with diet and lifestyle management versus diet alone, in lowering blood pressure (BP) values and improving lipid and glucose profile, in a group of hypertensives and hyper-cholesterolemic patients with MetS.

METHODS

104 subjects with MetS (mean age 57.4 ± 8.8 years, 51% males) without history of cardio-vascular (CV) diseases were enrolled in the study. 52 subjects were treated with a once-daily oral formulation of a NCs containing red yeast rice and coenzyme Q10 added to their diet for 2 months and were compared with the 52 patients following a diet program. Differences in BP, serum total cholesterol (TC), low- and high-density-lipoprotein cholesterol (LDLC and HDLC), triglycerides (TG) and glucose values were compared by analysis of variance.

RESULTS

A significant reduction of BP, TC, TG, LDLC and glucose levels was observed in both treatment groups. However, a greater reduction of systolic BP (-5.2 vs. -3.0 mmHg), diastolic BP (-4.9 vs. 2.9 mmHg), total cholesterol (-17.2%), LDLC (-21.8%), TG (-16.0%) and serum glucose (-3.4%) was observed in the treatment group relative to the control (p < 0.001 for all); HDLC remained unchanged (p = N.S.). Gender difference was not found in either group (p = N.S.).

CONCLUSIONS

In patients with MetS, NC supplementation was safe, well tolerated and effective in improving clinic BP, lipid and glucose profile.

The Effects of Coenzyme Q10 Supplementation on Glucose Metabolism, Lipid Profiles, Inflammation, and Oxidative Stress in Patients With Diabetic Nephropathy: A Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVE

Data on the effects of coenzyme Q10 (CoQ10) supplementation on glucose metabolism, lipid profiles, inflammation, and oxidative stress in subjects with diabetic nephropathy (DN) are scarce. This research was done to determine the effects of CoQ10 supplementation on metabolic status in subjects with DN.

METHODS

This randomized double-blind placebo-controlled clinical trial was done in 50 subjects with DN. Participants were randomly assigned into two groups to intake either 100 mg/day CoQ10 supplements (n = 25) or placebo (n = 25) for 12 weeks. Fasting blood samples were obtained at first and after 12-week intervention to quantify metabolic profiles.

RESULTS

After 12 weeks of treatment, compared with the placebo, CoQ10 supplementation resulted in significant decreases in serum insulin levels (-3.4 ± 6.8 vs +0.8 ± 6.4 µIU/mL, p = 0.02), homeostasis model of assessment-estimated insulin resistance (-1.0 ± 2.0 vs +0.2 ± 1.8, p = 0.03), homeostasis model of assessment-estimated B cell function (-12.3 ± 26.3 vs +3.5 ± 23.1, p = 0.02) and HbA1c (-1.1 ± 1.0 vs -0.1 ± 0.2%, p < 0.001), and a significant improvement in quantitative insulin sensitivity check index (+0.009 ± 0.01 vs -0.006 ± 0.01, p = 0.01). In addition, CoQ10 supplementation significantly decreased plasma malondialdehyde (MDA) (-0.6 ± 0.5 vs +0.5 ± 1.0 µmol/L, p < 0.001) and advanced glycation end products levels (AGEs) (-316.4 ± 380.9 vs +318.6 ± 732.0 AU, p < 0.001) compared with the placebo. Supplementation with CoQ10had no significant impacts on fasting plasma glucose (FPG), lipid profiles, and matrix metalloproteinase-2 (MMP-2) compared with the placebo.

CONCLUSIONS

Taken together, our study demonstrated that CoQ10 supplementation for 12 weeks among DN patients had favorable effects on glucose metabolism, MDA, and AGEs levels, but unchanged FPG, lipid profiles, and MMP-2 concentrations.

Cardamom supplementation improves inflammatory and oxidative stress biomarkers in hyperlipidemic, overweight, and obese pre-diabetic women: a randomized double-blind clinical trial

BACKGROUND

Several preclinical studies have shown that spices may decrease the risk of chronic diseases. However, it has been suggested that more clinical trials be carried out to strengthen this preclinical evidence. The purpose of the present study was to evaluate the effects of cardamom (Elettaria cardamomum) supplementation on inflammation and oxidative stress in hyperlipidemic, overweight, and obese pre-diabetic women.

METHODS

This randomized, placebo-controlled, double-blind clinical trial was conducted on 80 pre-diabetic subjects. They randomly received the cardamom supplement (n = 40, 3 g d^-1 ) or identical inert placebo (n = 40) for 8 weeks. Serum concentrations of high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), tumour necrosis factor α, total antioxidant capacity, malondialdehyde (MDA), protein carbonyl, and erythrocyte superoxide dismutase and glutathione reductase activity were analyzed at the baseline and after intervention.

RESULTS

After the adjustment of some covariates, cardamom supplementation significantly decreased serum hs-CRP (P = 0.02), hs-CRP:IL-6 ratio (P = 0.008), and MDA (P = 0.009) compared with the placebo group.

CONCLUSION

Cardamom could improve some parameters of inflammation and oxidative stress in pre-diabetic subjects. Thus it may be useful in reducing complications associated with inflammation and oxidative stress in these patients. Copyright © 2017 Society of Chemical Industry © 2017 Society of Chemical Industry.

Coenzyme Q and Its Role in the Dietary Therapy against Aging

Coenzyme Q (CoQ) is a naturally occurring molecule located in the hydrophobic domain of the phospholipid bilayer of all biological membranes. Shortly after being discovered, it was recognized as an essential electron transport chain component in mitochondria where it is particularly abundant. Since then, more additional roles in cell physiology have been reported, including antioxidant, signaling, death prevention, and others. It is known that all cells are able to synthesize functionally sufficient amounts of CoQ under normal physiological conditions. However, CoQ is a molecule found in different dietary sources, which can be taken up and incorporated into biological membranes. It is known that mitochondria have a close relationship with the aging process. Additionally, delaying the aging process through diet has aroused the interest of scientists for many years. These observations have stimulated investigation of the anti-aging potential of CoQ and its possible use in dietary therapies to alleviate the effects of aging. In this context, the present review focus on the current knowledge and evidence the roles of CoQ cells, its relationship with aging, and possible implications of dietary CoQ in relation to aging, lifespan or age-related diseases.

Omental adipocyte hypertrophy relates to coenzyme Q10 redox state and lipid peroxidation in obese women

Occurrence of oxidative stress in white adipose tissues contributes to its dysfunction and the development of obesity-related metabolic complications. Coenzyme Q10 (CoQ10) is the single lipophilic antioxidant synthesized in humans and is essential for electron transport during mitochondrial respiration. To understand the role of CoQ10 in adipose tissue physiology and dysfunction, the abundance of the oxidized and reduced (CoQ10red) isoforms of the CoQ10 were quantified in subcutaneous and omental adipose tissues of women covering the full range of BMI (from 21.5 to 53.2 kg/m(2)). Lean women displayed regional variations of CoQ10 redox state between the omental and subcutaneous depot, despite similar total content. Obese women had reduced CoQ10red concentrations in the omental depot, leading to increased CoQ10 redox state and higher levels of lipid hydroperoxide. Women with low omental CoQ10 content had greater visceral and subcutaneous adiposity, increased omental adipocyte diameter, and higher circulating interleukin-6 and C-reactive protein levels and were more insulin resistant. The associations between abdominal obesity-related cardiometabolic risk factors and CoQ10 content in the omental depot were abolished after adjustment for omental adipocyte diameter. This study shows that hypertrophic remodeling of visceral fat closely relates to depletion of CoQ10, lipid peroxidation, and inflammation.

Glutaredoxin mediated redox effects of coenzyme Q10 treatment in type 1 and type 2 diabetes patients

The possible beneficial effects of coenzyme Q10 (CoQ10) supplementation on disease progression and oxidant status in diabetes remains debated. In the present study, patients with type 1 and type 2 diabetes were treated with oral CoQ10, 100 mg twice daily for 12 weeks. We assessed total antioxidant capacity, intra- and extracellular levels of the redox regulating protein glutaredoxin 1 (Grx1), CoQ10, oxidized LDL-cholesterol, lipid profile and HbA1c. We have previously shown that extracellular Grx1 is increased in patients with type 2 diabetes compared to healthy subjects. In the present study, CoQ10 treatment significantly decreased serum Grx1 activity as well as total antioxidant capacity independent of type of diabetes, indicating an improvement to a less oxidized extracellular environment. The effect on serum Grx1 activity was more prominent in patients not on statin treatment. Conversely, intracellular Grx1 activity as well as mRNA levels increased independent of statin treatment. There was a significant improvement in oxidized LDL-cholesterol and lipid profile, with a tendency to improved metabolic control (HbA1c). Additionally, we describe for the first time that CoQ10 is a direct substrate for glutathione, and that Grx1 catalyzes this reaction, thus presenting a novel mechanism for CoQ10 reduction which could explain our findings of an increased intracellular Grx1. In conclusion, 12 weeks CoQ10 treatment significantly improved the extracellular redox balance and lipid profile, indicating that prolonged treatment may have beneficial effects also on clinical outcome in diabetes.

Supplementation of Coenzyme Q10 among Patients with Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a major cause of morbidity and mortality with ever increasing prevalence in the United States and worldwide. There is growing body of evidence suggesting that mitochondrial dysfunction secondary to oxidative stress plays a critical role in the pathogenesis of T2DM. Coenzyme Q10 is an important micronutrient acting on the electron transport chain of the mitochondria with two major functions: (1) synthesis of adenosine triphosphate (ATP); and (2) a potent antioxidant. Deficiency in coenzyme Q10 is often seen in patients with T2DM. Whether restoration of coenzyme Q10 will help alleviate oxidative stress, preserve mitochondrial function, and thus improve glycemic control in T2DM is unclear. This article reviews the relationships among oxidative stress, mitochondrial dysfunction, and T2DM and examines the evidence for potential use of coenzyme Q10 as a supplement for the treatment of T2DM.

Role of dietary and endogenous antioxidants in diabetes

Diabetes affects different people of all ages, race, and sex. This is a condition characterized by a state of chronic hyperglycaemia that leads to an increase of intracellular oxidative stress linked to the overproduction of free radicals. In the present review, we focus our attention on the molecular mechanisms leading to oxidative stress-mediates complications with particular regard to central nervous system (CNS). Furthermore, the present review reports the effects of different kind of antioxidants with enzymatic and nonenzymatic action that may significantly decrease the intracellular free radicals' overproduction and prevents the hyperglycaemia-mediated complications.

Effects of CoQ10 Supplementation on Lipid Profiles and Glycemic Control in Patients with Type 2 Diabetes: a randomized, double blind, placebo-controlled trial

Background

Low grade inflammation and oxidative stress are the key factors in the pathogenesis and development of diabetes and its complications. Coenzyme Q10 (CoQ10) is known as an antioxidant and has a vital role in generation of cellular energy providing. This study was undertaken to evaluate the effects of CoQ10 supplementation on lipid profiles and glycemic controls in patients with diabetes.

Methods

Fifty patients with diabetes were randomly allocated into two groups to receive either 150 mg CoQ10 or placebo daily for 12 weeks. Before and after supplementation, fasting venous blood samples were collected and lipid profiles containing triglyceride, total cholesterol, low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) and glycemic indices comprising of fasting plasma glucose (FPG), insulin and hemoglobin A₁C (HbA₁C) were measured. Insulin resistance was calculated using HOMA-IR index.

Results

Forty patients completed the study. After intervention FPG and HbA₁C were significantly lower in the CoQ10 group compared to the placebo group, but there were no significant differences in serum insulin and HOMA-IR between the two groups. Although total cholesterol did not change in the Q10 group after supplementation, triglyceride and HDL-C significantly decreased and LDL-C significantly increased in the CoQ10 group.

Conclusion

The present study showed that treatment with Q10 may improve glycemic control with no favorable effects on lipid profiles in type 2 patients with diabetes.

Trial registration

IRCT registry number: IRCT138806102394N1

Mitochondrial dysfunction in obesity: potential benefit and mechanism of Co-enzyme Q10 supplementation in metabolic syndrome

Co-enzyme Q10 (Co-Q10) is an essential component of the mitochondrial electron transport chain. Most cells are sensitive to co-enzyme Q10 (Co-Q10) deficiency. This deficiency has been implicated in several clinical disorders such as heart failure, hypertension, Parkinson's disease and obesity. The lipid lowering drug statin inhibits conversion of HMG-CoA to mevalonate and lowers plasma Co-Q10 concentrations. However, supplementation with Co-Q10 improves the pathophysiological condition of statin therapy. Recent evidence suggests that Co-Q10 supplementation may be useful for the treatment of obesity, oxidative stress and the inflammatory process in metabolic syndrome. The anti-inflammatory response and lipid metabolizing effect of Co-Q10 is probably mediated by transcriptional regulation of inflammation and lipid metabolism. This paper reviews the evidence showing beneficial role of Co-Q10 supplementation and its potential mechanism of action on contributing factors of metabolic and cardiovascular complications.

Diabetic cardiomyopathy: mechanisms and new treatment strategies targeting antioxidant signaling pathways

Cardiovascular disease is the primary cause of morbidity and mortality among the diabetic population. Both experimental and clinical evidence suggest that diabetic subjects are predisposed to a distinct cardiomyopathy, independent of concomitant macro- and microvascular disorders. 'Diabetic cardiomyopathy' is characterized by early impairments in diastolic function, accompanied by the development of cardiomyocyte hypertrophy, myocardial fibrosis and cardiomyocyte apoptosis. The pathophysiology underlying diabetes-induced cardiac damage is complex and multifactorial, with elevated oxidative stress as a key contributor. We now review the current evidence of molecular disturbances present in the diabetic heart, and their role in the development of diabetes-induced impairments in myocardial function and structure. Our focus incorporates both the contribution of increased reactive oxygen species production and reduced antioxidant defenses to diabetic cardiomyopathy, together with modulation of protein signaling pathways and the emerging role of protein O-GlcNAcylation and miRNA dysregulation in the progression of diabetic heart disease. Lastly, we discuss both conventional and novel therapeutic approaches for the treatment of left ventricular dysfunction in diabetic patients, from inhibition of the renin-angiotensin-aldosterone-system, through recent evidence favoring supplementation of endogenous antioxidants for the treatment of diabetic cardiomyopathy. Novel therapeutic strategies, such as gene therapy targeting the phosphoinositide 3-kinase PI3K(p110α) signaling pathway, and miRNA dysregulation, are also reviewed. Targeting redox stress and protective protein signaling pathways may represent a future strategy for combating the ever-increasing incidence of heart failure in the diabetic population.

Plasma coenzyme Q10 levels in type 2 diabetic patients with retinopathy

AIM

To determine the relationship between proliferative diabetic retinopathy (PDRP) and plasma coenzyme Q10(CoQ10) concentration.

METHODS

Patients with type 2 diabetes and PDRP were determined to be the case group (n=50). The control group was consist of healthy individuals (n=50). Plasma CoQ10 and malondialdehyde (MDA) levels were measured in both groups.

RESULTS

Ubiquinone-10 (Coenzyme Q10) levels in PDRP and control subjects are 3.81±1.19µmol/L and 1.91±0.62µmol/L, respectively. Plasma MDA levels in PDRP and control subjects were 8.16±2µmol/L and 3.44±2.08µmol/L, respectively. Ratio of Ubiquinol-10/ubiquinone-10 in PDRP and control subjects were 0.26±0.16 and 1.41±0.68, respectively.

CONCLUSION

The ratio of ubiquinol-10/ubiquinone-10 is found lower in patients with PDRP. High levels of plasma ubiquinol-10/ubiquinone-10 ratio indicate the protective effect on diabetic retinopathy.

Comparison study of plasma coenzyme Q10 levels in healthy subjects supplemented with ubiquinol versus ubiquinone

The bioavailability of the reduced form of coenzyme Q10 (ubiquinol) was compared to oxidized coenzyme Q10 (ubiquinone) with identical soft gel capsule excipients by measuring steady state plasma coenzyme Q10 (CoQ10 ) levels in 12 healthy volunteers. After baseline levels of ubiquinol, ubiquinone, total CoQ10 , α-tocopherol, and total cholesterol were obtained, follow-up lab work was performed after 4 weeks of 200 mg/day of ubiquinone, after 4 weeks washout, and after 4 weeks of 200 mg/day of ubiquinol. Plasma total CoQ10 increased from 0.9 to 2.5 µg/mL (P < 0.001) after 4 weeks of ubiquinone and increased from 0.9 to 4.3 µg/mL (P < 0.001) after 4 weeks of ubiquinol. Total CoQ10 /cholesterol ratio increased from 0.2 to 0.7 µmol/mmol after 4 weeks of ubiquinone and increased from 0.2 to 1.2 µmol/mmol after 4 weeks of ubiquinol. Both the increase in plasma CoQ10 and the increase in CoQ10 /cholesterol ratio were significantly better after ubiquinol (P < 0.005 and P < 0.001, respectively) than after ubiquinone indicating superior bioavailability. Plasma ubiquinol/total CoQ10 ratio increased from baseline during ubiquinol supplementation (P < 0.005) and remained unchanged after ubiquinone supplementation. No side effects were noted in this study.

Targeting the upregulation of reactive oxygen species subsequent to hyperglycemia prevents type 1 diabetic cardiomyopathy in mice

Cardiac oxidative stress is an early event associated with diabetic cardiomyopathy, triggered by hyperglycemia. We tested the hypothesis that targeting left-ventricular (LV) reactive oxygen species (ROS) upregulation subsequent to hyperglycemia attenuates type 1 diabetes-induced LV remodeling and dysfunction, accompanied by attenuated proinflammatory markers and cardiomyocyte apoptosis. Male 6-week-old mice received either streptozotocin (55mg/kg/day for 5 days), to induce type 1 diabetes, or citrate buffer vehicle. After 4 weeks of hyperglycemia, the mice were allocated to coenzyme Q10 supplementation (10mg/kg/day), treatment with the angiotensin-converting-enzyme inhibitor (ACE-I) ramipril (3mg/kg/day), treatment with olive oil vehicle, or no treatment for 8 weeks. Type 1 diabetes upregulated LV NADPH oxidase (Nox2, p22(phox), p47(phox) and superoxide production), LV uncoupling protein UCP3 expression, and both LV and systemic oxidative stress (LV 3-nitrotyrosine and plasma lipid peroxidation). All of these were significantly attenuated by coenzyme Q10. Coenzyme Q10 substantially limited type 1 diabetes-induced impairments in LV diastolic function (E:A ratio and deceleration time by echocardiography, LV end-diastolic pressure, and LV -dP/dt by micromanometry), LV remodeling (cardiomyocyte hypertrophy, cardiac fibrosis, apoptosis), and LV expression of proinflammatory mediators (tumor necrosis factor-α, with a similar trend for interleukin IL-1β). Coenzyme Q10's actions were independent of glycemic control, body mass, and blood pressure. Coenzyme Q10 compared favorably to improvements observed with ramipril. In summary, these data suggest that coenzyme Q10 effectively targets LV ROS upregulation to limit type 1 diabetic cardiomyopathy. Coenzyme Q10 supplementation may thus represent an effective alternative to ACE-Is for the treatment of cardiac complications in type 1 diabetic patients.

The reduced form of coenzyme Q10 improves glycemic control in patients with type 2 diabetes: an open label pilot study

Coenzyme Q10 (CoQ10) provides the energy for vital cellular functions and is known to act as an antioxidant. We conducted an open label study to examine the clinical effects of supplementation of the reduced form of CoQ10, ubiquinol, in addition to conventional glucose-lowering agents in patients with type 2 diabetes. Nine subjects (3 males and 6 females) with type 2 diabetes and receiving conventional medication were recruited. The subjects were assigned to receive an oral dose of 200 mg ubiquinol daily for 12 weeks. The effect of ubiquinol on blood pressure, lipid profile, glycemic control, oxidative stress, and inflammation were examined before and after ubiquinol supplementation. In addition, five healthy volunteers were also assigned to receive an oral dose of 200 mg ubiquinol daily for 4 weeks to examine the effects of ubiquinol on insulin secretion. In patients with diabetes, there were no differences with respect to blood pressure, lipid profile, oxidative stress marker, and inflammatory markers. However, there were significant improvements in glycosylated hemoglobin (53.0 ± 4.3 to 50.5 ± 3.7 mmol/mol, P = 0.01) (7.1 ± 0.4 to 6.8 ± 0.4%, P = 0.03). In healthy volunteers, the insulinogenic index (0.65 ± 0.29 to 1.23 ± 0.56, P = 0.02) and the ratio of proinsulin to insulin were significantly improved (3.4 ± 1.8 to 2.1 ± 0.6, P = 0.03). The results of our study are consistent with the suggestion that the supplementation of ubiquinol in subjects with type 2 diabetes, in addition to conventional antihyperglycemic medications, improves glycemic control by improving insulin secretion without any adverse effects

Is there a place for coenzyme Q in the management of metabolic disorders associated with obesity?

Coenzyme Q (CoQ), a lipophilic cofactor of the electron transport chain in the mitochondria, can be synthesized endogenously or provided by food. The aim of this review is to summarize the in vitro cell culture studies, the in vivo animal studies, and the human studies investigating the impact of CoQ supplementation on the occurrence of obesity and related disorders (diabetes, hypertension, lipemia, and atherosclerosis). The antioxidative properties of CoQ have been observed in different experimental models of atherosclerosis, obesity, and diabetes. The recent discovery of the anti-inflammatory effect of CoQ, mostly described in vitro, has generated increased interest in CoQ supplementation, but it needs to be confirmed in vivo in pathological situations. CoQ intervention studies in humans failed to show reproducible effects on body weight, fat mass, or glycemia, but CoQ supplementation does seem to have an antihypertensive effect. The molecular mechanism to explain this effect has only recently been discovered.

Coenzyme Q10 attenuates diastolic dysfunction, cardiomyocyte hypertrophy and cardiac fibrosis in the db/db mouse model of type 2 diabetes

AIMS/HYPOTHESIS

An increase in the production of reactive oxygen species is commonly thought to contribute to the development of diabetic cardiomyopathy. This study aimed to assess whether administration of the antioxidant coenzyme Q(10) would protect the diabetic heart against dysfunction and remodelling, using the db/db mouse model of type 2 diabetes. Furthermore, we aimed to compare the efficacy of coenzyme Q(10) to that of the ACE inhibitor ramipril.

METHODS

Six-week-old non-diabetic db/+ mice and diabetic db/db mice received either normal drinking water or water supplemented with coenzyme Q(10) for 10 weeks. Endpoint cardiac function was assessed by echocardiography and catheterisation. Ventricular tissue was collected for histology, gene expression and protein analysis.

RESULTS

Untreated db/db diabetic mice exhibited hyperglycaemia, accompanied by diastolic dysfunction and adverse structural remodelling, including cardiomyocyte hypertrophy, myocardial fibrosis and increased apoptosis. Systemic lipid peroxidation and myocardial superoxide generation were also elevated in db/db mice. Coenzyme Q(10) and ramipril treatment reduced superoxide generation, ameliorated diastolic dysfunction and reduced cardiomyocyte hypertrophy and fibrosis in db/db mice. Phosphorylation of Akt, although depressed in untreated db/db mice, was restored with coenzyme Q(10) administration. We postulate that preservation of cardioprotective Akt signalling may be a mechanism by which coenzyme Q(10)-treated db/db mice are protected from pathological cardiac hypertrophy.

CONCLUSIONS/INTERPRETATION

These data demonstrate that coenzyme Q(10) attenuates oxidative stress and left ventricular diastolic dysfunction and remodelling in the diabetic heart. Addition of coenzyme Q(10) to the current therapy used in diabetic patients with diastolic dysfunction warrants further investigation.

Plasma coenzyme Q10 is increased during gestational diabetes

OBJECTIVES

To determine plasma CoQ(10) concentration in the course of gestational diabetes mellitus.

STUDY DESIGN

The assessment was provided longitudinally during the third trimester of pregnancy in 40 women with gestational diabetes mellitus (GDM) and 40 normal controls. CoQ(10) was measured with the HPLC method. CoQ(10) results were also normalized to plasma cholesterol concentration (nmoles/mmoles). Plasma samples were collected longitudinally throughout the third trimester.

RESULTS

No statistically significant difference of plasma CoQ(10)/cholesterol levels between GDM patients and controls at 28-32 and 32-36 weeks of gestation, this difference was significant in late pregnancy (36-40 weeks), similarly, in the same gestational period, there was an increased level of HOMA-IR as index of insulin resistance ORAC as index of oxidative stress.

CONCLUSIONS

Since coenzyme Q(10) is believed to be an important cellular antioxidant defence, higher levels of CoQ(10) in GDM patients may be a compensatory mechanism, in response to an activated oxidative stress, probably associated to hyperglycaemia and insulin resistance.

Probucol ameliorates renal and metabolic sequelae of primary CoQ deficiency in Pdss2 mutant mice

Therapy of mitochondrial respiratory chain diseases is complicated by limited understanding of cellular mechanisms that cause the widely variable clinical findings. Here, we show that focal segmental glomerulopathy-like kidney disease in Pdss2 mutant animals with primary coenzyme Q (CoQ) deficiency is significantly ameliorated by oral treatment with probucol (1% w/w). Preventative effects in missense mutant mice are similar whether fed probucol from weaning or for 3 weeks prior to typical nephritis onset. Furthermore, treating symptomatic animals for 2 weeks with probucol significantly reduces albuminuria. Probucol has a more pronounced health benefit than high-dose CoQ₁₀ supplementation and uniquely restores CoQ₉ content in mutant kidney. Probucol substantially mitigates transcriptional alterations across many intermediary metabolic domains, including peroxisome proliferator-activated receptor (PPAR) pathway signaling. Probucol's beneficial effects on the renal and metabolic manifestations of Pdss2 disease occur despite modest induction of oxidant stress and appear independent of its hypolipidemic effects. Rather, decreased CoQ₉ content and altered PPAR pathway signaling appear, respectively, to orchestrate the glomerular and global metabolic consequences of primary CoQ deficiency, which are both preventable and treatable with oral probucol therapy.

α-lipoic acid can improve endothelial dysfunction in subjects with impaired fasting glucose

Several studies showed that impairment of endothelium-dependent arterial dilation (EDAD) exists in subjects with impaired fasting glucose (IFG). The crucial mechanism of this endothelial dysfunction remains unclear. We hypothesized that oxidative stress may be partially responsible for the impairment in EDAD in subjects with IFG. Thus, the present study was designed to assess whether the antioxidant α-lipoic acid can improve endothelial dysfunction in subjects with IFG. Sixty subjects with newly diagnosed IFG and 32 healthy individuals with normal glucose tolerance were enrolled. Subjects were randomized into 2 groups: untreated experimental group (n = 30) and α-lipoic acid treatment group (n = 30, α-lipoic acid 600 mg via intravenous infusion once a day for 3 weeks). We measured EDAD at baseline and after 3 weeks of intervention. At baseline, EDADs in α-lipoic acid and untreated experimental groups were 4.03% and 4.14%, respectively, which were significantly lower than that in controls (5.72%) (P < .001). After 3 weeks of intervention, there was a remarkable increase in EDAD (reaching 5.10%; ΔEDAD, 26.5%) (P < .01) and a significant decrease in plasma thiobarbituric acid reactive substances (TBARS) (29.1%) (P < .05) in IFG subjects treated with α-lipoic acid. Endothelium-dependent arterial dilation and TBARS remained unchanged before and after intervention in the untreated experimental group. The absolute changes in EDAD showed a significant negative correlation with the changes in TBARS (r = -0.444, P = .014). Our data showed that IFG subjects have impaired endothelial function and that antioxidant α-lipoic acid can improve endothelial function through a decrease of oxygen-derived free radicals.

Effects of coenzyme Q10 on salivary secretion

OBJECTIVES

Dry mouth is a condition associated with reduced salivary secretion and is thought to be related to aging. This study was conducted to test whether reduced (ubiquinol) or oxidized (ubiquinone) forms of CoQ10 affect salivary secretion and salivary CoQ10 content before and after treatment.

DESIGN AND METHODS

Sixty-six patients were given either ubiquinol or ubiquinone orally at a dosage of 100 mg/day, or a placebo for 1 month, and salivary secretion and salivary CoQ10 content were analyzed before and after treatment.

RESULTS

Both parameters were significantly improved following treatment with either form of CoQ10, suggesting the effectiveness of CoQ10 in attenuating dry mouth symptoms.

CONCLUSION

CoQ10 was locally detected in salivary glands, suggesting that orally administered CoQ10 was transported to the salivary glands via the blood stream and exerted its activity, improving salivary secretion.

Ubiquinol-10 and ubiquinone-10 levels in umbilical cord blood of healthy foetuses and the venous blood of their mothers

Despite their being good markers of oxidative stress for clinical use, little is known about ubiquinol-10 (reduced coenzyme Q10) and ubiquinone-10 (oxidized coenzyme Q10) levels in foetuses and their mothers. This study investigates oxidative stress in 10 healthy maternal venous, umbilical arterial and venous bloods after vaginal delivery by measuring ubiquinol-10 and ubiquinone-10 levels. Serum ubiquinol-10 and ubiquinone-10 levels were measured by HPLC with a highly sensitive electrochemical detector. Maternal venous ubiquinol-10 and ubiquinone-10 levels were significantly higher than umbilical arterial and venous levels (all p < 0.001). However, the ubiquinone-10/total coenzyme Q10 (CoQ10) ratio, which reflects the redox status, was significantly higher in umbilical arterial and umbilical venous blood compared to maternal venous blood (all p < 0.001). The ubiquinone-10/total CoQ10 ratio was higher in umbilical arterial than in umbilical venous blood (p < 0.01). The present study demonstrated that foetuses were under higher oxidative stress than their mothers.

Renal preservation effect of ubiquinol, the reduced form of coenzyme Q10

BACKGROUND

The aim of this study was to evaluate the renal preservation effect of ubiquinol, the reduced form of coenzyme Q10 (CoQ10).

METHODS

Three-week-old heminephrectomized male Sprague-Dawley rats were divided into three groups (10 animals each): diet with normal (0.3%) salt, high (8%) salt, and high salt plus 600 mg/kg body weight/day of ubiquinol, for 4 weeks. Systolic blood pressure (SBP), urinary albumin (u-alb), superoxide anion generation (lucigenin chemiluminescence) and ubiquinol levels in renal tissues were examined.

RESULTS

Salt loading increased SBP (111.0 ± 3.6 vs. 169.4 ± 14.3 mmHg, p < 0.01) and u-alb (43.8 ± 28.0 vs. 2528.7 ± 1379.0 µg/day, p < 0.02). These changes were associated with stimulation of superoxide generation in the kidney (866.3 ± 102.8 vs. 2721.4 ± 973.3 RLU/g kidney, p < 0.01). However, ubiquinol decreased SBP (143.9 ± 29.0 mmHg, p < 0.05), u-alb (256.1 ± 122.1 µg/day, p < 0.02), and renal superoxide production (877.8 ± 195.6 RLU/g kidney, p < 0.01), associated with an increase in renal ubiquinol levels.

CONCLUSION

Ubiquinol, the reduced form of CoQ10, effectively ameliorates renal function, probably due to its antioxidant effect. Thus, ubiquinol may be a candidate for the treatment of patients with kidney disease.

Antioxidant level and redox status of coenzyme Q10 in the plasma and blood cells of children with diabetes mellitus type 1

Hyperglycaemia has been reported to cause increased production of oxygen free radicals. Oxidative stress may contribute to the pathogenesis of diabetic complications. Coenzyme Q(10) (CoQ(10)) is known for its key role in mitochondrial bioenergetics and is considered as a potent antioxidant and free radical scavenger. This study was conducted to evaluate plasma and blood cell concentrations of CoQ(10) in accordance to its redox capacity in children with diabetes mellitus type 1. CoQ(10) plasma and blood cell concentrations and redox status were measured using high-performance liquid chromatography with electrochemical detection in 43 children with diabetes mellitus type 1 and compared with 39 healthy children. In addition, the diabetic patients were subdivided according to their haemoglobin A1c (HbA1c) values into two groups, that is, those with good control (<8%) and those with poor control (>8%), and the CoQ(10) status was compared between the two groups. Children with type 1 diabetes showed increased plasma levels of CoQ(10) in comparison to healthy children. While CoQ(10) erythrocyte and platelet concentrations did not differ, in the diabetes group, the platelet redox status differed with a significantly increased part of reduced CoQ(10). This difference in concentration and redox status in comparison to healthy controls may be attributed to the subgroup of patients with poor control, as the subdivision of diabetic patients according to their HbA1c values shows. In diabetic children, especially in those with poor control, an increase in plasma concentration and intracellular redox capacity of the antioxidant CoQ(10) may contribute to the body's self-protection during a state of enhanced oxidative stress.