Risk assessment for coenzyme Q10 (Ubiquinone)

Involvement of Coenzyme Q10 in Various Neurodegenerative and Psychiatric Diseases

Coenzyme Q10 (CoQ10), commonly known as ubiquinone, is a vitamin-like component generated in mitochondrial inner membranes. This molecule is detected broadly in different parts of the human body in various quantities. This molecule can be absorbed by the digestive system from various nutritional sources as supplements. CoQ10 exists in three states: in a of reduced form (ubiquinol), in a semiquinone radical form, and in oxidized ubiquinone form in different organs of the body, playing a crucial role in electron transportation and contributing to energy metabolism and oxygen utilization, especially in the musculoskeletal and nervous systems. Since the early 1980s, research about CoQ10 has become the interest for two reasons. First, CoQ10 deficiency has been found to have a link with cardiovascular, neurologic, and cancer disorders. Second, this molecule has an antioxidant and free-radical scavenger nature. Since then, several investigations have indicated that the drug may benefit patients with cardiovascular, neuromuscular, and neurodegenerative illnesses. CoQ10 may protect the neurological system from degeneration and degradation due to its antioxidant and energy-regulating activity in mitochondria. This agent has shown its efficacy in preventing and treating neurological diseases such as migraine, Parkinson's disease, Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis, and Friedreich's ataxia. This study reviews the literature to highlight this agent's potential therapeutic effects in the mentioned neurological disorders.

Homozygous COQ7 mutation: a new cause of potentially treatable distal hereditary motor neuropathy

Distal hereditary motor neuropathy represents a group of motor inherited neuropathies leading to distal weakness. We report a family of two brothers and a sister affected by distal hereditary motor neuropathy in whom a homozygous variant c.3G>T (p.1Met?) was identified in the COQ7 gene. This gene encodes a protein required for coenzyme Q10 biosynthesis, a component of the respiratory chain in mitochondria. Mutations of COQ7 were previously associated with severe multi-organ disorders characterized by early childhood onset and developmental delay. Using patient blood samples and fibroblasts derived from a skin biopsy, we investigated the pathogenicity of the variant of unknown significance c.3G>T (p.1Met?) in the COQ7 gene and the effect of coenzyme Q10 supplementation in vitro. We showed that this variation leads to a severe decrease in COQ7 protein levels in the patient's fibroblasts, resulting in a decrease in coenzyme Q10 production and in the accumulation of 6-demethoxycoenzyme Q10, the COQ7 substrate. Interestingly, such accumulation was also found in the patient's plasma. Normal coenzyme Q10 and 6-demethoxycoenzyme Q10 levels were restored in vitro by using the coenzyme Q10 precursor 2,4-dihydroxybenzoic acid, thus bypassing the COQ7 requirement. Coenzyme Q10 biosynthesis deficiency is known to impair the mitochondrial respiratory chain. Seahorse experiments showed that the patient's cells mainly rely on glycolysis to maintain sufficient ATP production. Consistently, the replacement of glucose by galactose in the culture medium of these cells reduced their proliferation rate. Interestingly, normal proliferation was restored by coenzyme Q10 supplementation of the culture medium, suggesting a therapeutic avenue for these patients. Altogether, we have identified the first example of recessive distal hereditary motor neuropathy caused by a homozygous variation in the COQ7 gene, which should thus be included in the gene panels used to diagnose peripheral inherited neuropathies. Furthermore, 6-demethoxycoenzyme Q10 accumulation in the blood can be used to confirm the pathogenic nature of the mutation. Finally, supplementation with coenzyme Q10 or derivatives should be considered to prevent the progression of COQ7-related peripheral inherited neuropathy in diagnosed patients.

Efficacy and Optimal Dose of Coenzyme Q10 Supplementation on Inflammation-Related Biomarkers: A GRADE-Assessed Systematic Review and Updated Meta-Analysis of Randomized Controlled Trials

SCOPE

Coenzyme Q10 (CoQ10) has become a popular nutritional supplement due to its wide range of beneficial biological effects. Previous meta-analyses show that the attenuation of CoQ10 on inflammatory biomarkers remains controversial. This meta-analysis aims to assess the efficacy and optimal dose of CoQ10 supplementation on inflammatory indicators in the general population.

METHODS AND RESULTS

Databases are searched up to December 2022 resulting in 6713 articles, of which 31 are retrieved for full-text assessment and included 1517 subjects. Double-blind randomized controlled trials (RCTs) of CoQ10 supplementation are eligible if they contain C reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). CoQ10 supplementation can significantly reduce the levels of circulating CRP (SMD: -0.40, 95% CI: [-0.67 to -0.13], p = 0.003), IL-6 (SMD: -0.67, 95% CI: [-1.01 to -0.33], p < 0.001), and TNF-α (SMD: -1.06, 95% CI: [-1.59 to -0.52], p < 0.001) and increase the concentration of circulating CoQ10.

CONCLUSION

This meta-analysis provides evidence for CoQ10 supplementation to reduce the level of inflammatory mediators in the general population and proposes that daily supplementation of 300-400 mg CoQ10 show superior inhibition of inflammatory factors.

Neuroprotective effects of coenzyme Q10 on neurological diseases: a review article

Neurological disorders affect the nervous system. Biochemical, structural, or electrical abnormalities in the spinal cord, brain, or other nerves lead to different symptoms, including muscle weakness, paralysis, poor coordination, seizures, loss of sensation, and pain. There are many recognized neurological diseases, like epilepsy, Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), stroke, autosomal recessive cerebellar ataxia 2 (ARCA2), Leber's hereditary optic neuropathy (LHON), and spinocerebellar ataxia autosomal recessive 9 (SCAR9). Different agents, such as coenzyme Q10 (CoQ10), exert neuroprotective effects against neuronal damage. Online databases, such as Scopus, Google Scholar, Web of Science, and PubMed/MEDLINE were systematically searched until December 2020 using keywords, including review, neurological disorders, and CoQ10. CoQ10 is endogenously produced in the body and also can be found in supplements or foods. CoQ10 has antioxidant and anti-inflammatory effects and plays a role in energy production and mitochondria stabilization, which are mechanisms, by which CoQ10 exerts its neuroprotective effects. Thus, in this review, we discussed the association between CoQ10 and neurological diseases, including AD, depression, MS, epilepsy, PD, LHON, ARCA2, SCAR9, and stroke. In addition, new therapeutic targets were introduced for the next drug discoveries.

Beneficial antioxidant effects of Coenzyme Q10 on reproduction

This chapter focuses on preclinical and clinical studies conducted in recent years that contribute to increasing knowledge on the role of Coenzyme Q10 in female reproductive health. General aspects of CoQ10, such as its role as an antioxidant and in mitochondrial bioenergetics are considered. The age-dependent decline in human female reproductive potential is associated with cellular mitochondrial dysfunction and oxidative stress, and in some cases accompanied by a decrease in CoQ10 levels. Herein, we discuss experimental and clinical evidence on CoQ10 protective effects on reproductive health. We also address the potential of supplementation with this coenzyme to rescue reprotoxicity induced by exposure to environmental xenobiotics. This review not only contributes to our general understanding of the effects of aging on female reproduction but also provides new insights into strategies promoting reproductive health. The use of CoQ10 supplementation can improve reproductive performance through the scavenging of reactive oxygen species and free radicals. This strategy can constitute a low-risk and low-cost strategy to attenuate the impact on fertility related to aging and exposure to environmental chemicals.

Coenzyme Q10 Attenuates Human Platelet Aggregation Induced by SARS-CoV-2 Spike Protein via Reducing Oxidative Stress In Vitro

Platelet hyperreactivity and oxidative stress are the important causes of thrombotic disorders in patients with COVID-19. Oxidative stress, induced by the excessive generation of reactive oxygen species (ROS), could increase platelet function and the risk of thrombus formation. Coenzyme Q10 (CoQ10), exhibits strong antioxidative activity and anti-platelet effect. However, the effects and mechanisms of CoQ10 on attenuating platelet aggregation induced by spike protein have never been studied. This study aims to investigate whether the SARS-CoV-2 spike protein potentiates human platelet function via ROS signaling and the protective effect of CoQ10 in vitro. Using a series of platelet function assays, we found that spike protein potentiated platelet aggregation and oxidative stress, such as ROS level, mitochondrial membrane potential depolarization, and lipid damage level (MDA and 8-iso-PGF2α) in vitro. Furthermore, CoQ10 attenuated platelet aggregation induced by spike protein. As an anti-platelet mechanism, we showed that CoQ10 significantly decreased the excess production of ROS induced by spike protein. Our findings show that the protective effect of CoQ10 on spike protein-potentiated platelet aggregation is probably associated with its strong antioxidative ability.

Dose-Response Effect of Coenzyme Q10 Supplementation on Blood Pressure among Patients with Cardiometabolic Disorders: A Grading of Recommendations Assessment, Development, and Evaluation (GRADE)-Assessed Systematic Review and Meta-Analysis of Randomized Controlled Trials

Previous studies have shown beneficial effects of coenzyme Q10 (CoQ10) supplementation on blood pressure (BP). However, the optimal intake of CoQ10 for BP regulation in patients with cardiometabolic disorders is unknown, and its effect on circulating CoQ10 is also unclear. We aimed to assess the dose-response relation between CoQ10 and BP, and quantify the effect of CoQ10 supplementation on the concentration of circulating CoQ10 by synthesizing available evidence from randomized controlled trials (RCTs). A comprehensive literature search was performed in 3 databases (PubMed/MEDLINE, Embase, and Cochrane Library) to 21 March, 2022. A novel 1-stage restricted cubic spline regression model was used to evaluate the nonlinear dose-response relation between CoQ10 and BP. Twenty-six studies comprising 1831 subjects were included in our meta-analysis. CoQ10 supplementation significantly reduced systolic blood pressure (SBP) (-4.77 mmHg, 95% CI: -6.57, -2.97) in patients with cardiometabolic diseases; this reduction was accompanied by a 1.62 (95% CI: 1.26, 1.97) μg/mL elevation of circulating CoQ10 compared with the control group. Subgroup analyses revealed that the effects of reducing SBP were more pronounced in patients with diabetes and dyslipidemia and in studies with longer durations (>12 wk). Importantly, a U-shaped dose-response relation was observed between CoQ10 supplementation and SBP level, with an approximate dose of 100-200 mg/d largely reducing SBP (χ2 = 10.84, Pnonlinearity = 0.004). The quality of evidence was rated as moderate, low, and very low for SBP, diastolic blood pressure (DBP), and circulating CoQ10 according to the Grading of Recommendations, Assessment, Development, and Evaluation approach (GRADE), respectively. The current finding demonstrated that the clinically beneficial effects of CoQ10 supplementation may be attributed to the reduction in SBP, and 100-200 mg/d of CoQ10 supplementation may achieve the greatest benefit on SBP in patients with cardiometabolic diseases. This study was registered on PROSPERO as CRD42021252933.

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.

Using a neonatal rat model to explore the therapeutic potential of coenzyme Q10 in prematurity under hyperoxia

Hyperoxia, is often used in preterm supportive care, leading to high oxygen exposure in neonates. Coenzyme Q10 (CoQ10) is a free radical scavenger that has been studied in older children but never be investigated for its role in preterm care. We hypothesize that the administration of exogenous CoQ10 would raise serum concentrations of CoQ10 and mitigate the adverse effects of hyperoxia on the organs by reducing oxygen-free radicals and inflammation. The aim of this study was to evaluate the effects of oxidative stress, inflammatory response, and survival in neonatal rats after CoQ10 treatment. Neonatal rats delivered from four pregnant Wistar rats were randomly divided into four groups: (a) control, (b) CoQ10, (c) hyperoxia (O₂ group), and (d) treatment (CoQ10 + O₂ ) groups. The dose of CoQ10 injected was 30 mg/kg. The CoQ9, CoQ10, cytokines, oxidative stress, and antioxidant enzyme activity were measured. Tissue samples were histologically examined and mortality was monitored for 16 days. The level of CoQ9 significantly increased in the liver, kidney, and plasma, while the level of CoQ10 significantly increased in most organ tissues in the CoQ10 + O₂ group. Additionally, CoQ10 decrease oxidative stress in the liver, increase antioxidant enzyme activity in the heart, kidney, and brain, and reverse an inclined level of hematopoietic growth factors. However, CoQ10 had no effect on inflammation, organ damage, or mortality. Therefore, the use of CoQ10 in potential adjuvant therapy for neonatal hyperoxia requires further research.

Reactive Oxygen Species Induced Pathways in Heart Failure Pathogenesis and Potential Therapeutic Strategies

With respect to structural and functional cardiac disorders, heart failure (HF) is divided into HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Oxidative stress contributes to the development of both HFrEF and HFpEF. Identification of a broad spectrum of reactive oxygen species (ROS)-induced pathways in preclinical models has provided new insights about the importance of ROS in HFrEF and HFpEF development. While current treatment strategies mostly concern neuroendocrine inhibition, recent data on ROS-induced metabolic pathways in cardiomyocytes may offer additional treatment strategies and targets for both of the HF forms. The purpose of this article is to summarize the results achieved in the fields of: (1) ROS importance in HFrEF and HFpEF pathophysiology, and (2) treatments for inhibiting ROS-induced pathways in HFrEF and HFpEF patients. ROS-producing pathways in cardiomyocytes, ROS-activated pathways in different HF forms, and treatment options to inhibit their action are also discussed.

Coenzyme Q10 effects in neurological diseases

Coenzyme Q10 (CoQ10), a lipophilic substituted benzoquinone, is present in animal and plant cells. It is endogenously synthetized in every cell and involved in a variety of cellular processes. CoQ10 is an obligatory component of the respiratory chain in inner mitochondrial membrane. In addition, the presence of CoQ10 in all cellular membranes and in blood. It is the only endogenous lipid antioxidant. Moreover, it is an essential factor for uncoupling protein and controls the permeability transition pore in mitochondria. It also participates in extramitochondrial electron transport and controls membrane physicochemical properties. CoQ10 effects on gene expression might affect the overall metabolism. Primary changes in the energetic and antioxidant functions can explain its remedial effects. CoQ10 supplementation is safe and well-tolerated, even at high doses. CoQ10 does not cause any serious adverse effects in humans or experimental animals. New preparations of CoQ10 that are less hydrophobic and structural derivatives, like idebenone and MitoQ, are being developed to increase absorption and tissue distribution. The review aims to summarize clinical and experimental effects of CoQ10 supplementations in some neurological diseases such as migraine, Parkinson´s disease, Huntington´s disease, Alzheimer´s disease, amyotrophic lateral sclerosis, Friedreich´s ataxia or multiple sclerosis. Cardiovascular hypertension was included because of its central mechanisms controlling blood pressure in the brainstem rostral ventrolateral medulla and hypothalamic paraventricular nucleus. In conclusion, it seems reasonable to recommend CoQ10 as adjunct to conventional therapy in some cases. However, sometimes CoQ10 supplementations are more efficient in animal models of diseases than in human patients (e.g. Parkinson´s disease) or rather vague (e.g. Friedreich´s ataxia or amyotrophic lateral sclerosis).

Effects of coenzyme Q10 on reproductive performance of laying Japanese quail (Coturnix japonica) under cadmium challenge

Japanese quail is an increasingly important bird of economic importance for commercial egg and meat production, particularly in developing countries. There is a need for research aimed at improving efficiency of these birds during stressful challenges, such as oxidative stress. Coenzyme Q10 (CoQ10), a highly functional antioxidant, protects cells against oxidative stress. This study was conducted to determine the effects of CoQ10 on reproductive performance of Japanese quail under cadmium (Cd) challenge. A total of 216 six-wk-old Japanese quail were randomly allocated into 3 groups for an 8 wk experimental trial. The treatments include a negative control (NC): feeding basal diet; a positive control (PC): feeding basal diet and cadmium administration (1 mg/100 g BW, at 10 and 11 wk of age), and (CdQ10): feeding CoQ10 supplemented (900 mg/kg diet) basal diet and Cd administration. At 11 and 13 wk of age, egg production, body weight, mortality, oviduct, and ovarian biometry, were recorded. Histology and histopathology of isthmus and magnum, fertility, hatchability, hatchling quality, and HSP70 mRNA transcript abundance in the utero-vaginal junction (UVJ) were evaluated. Positive control and CdQ10 group had no significant effect on live body weight, stroma weight, follicle size, hatchability, and fertility; however, Cd administration increased (P < 0.01) mortality rate in the PC group compared to the NC and CdQ10 groups. CdQ10 quail produced more eggs and had a higher hatchling quality compared to the PC group (P < 0.01). The thickness and height of isthmus and magnum folds in the CdQ10 group was increased compared to the PC group (P < 0.01) and overall oviduct weight was increased with CoQ10 supplementation (P < 0.01). Compared to PC, the CdQ10 group had a reduction in infiltration of inflammatory cells. Relative abundance of HSP70 mRNA in UVJ was influenced by interactive effect of treatment × time (P < 0.05). In conclusion, dietary supplementation of CoQ10 showed beneficial effects on some reproduction characteristics of female Japanese quail under Cd-induced oxidative stress.

Coenzyme Q10 supplementation - In ageing and disease

Coenzyme Q₁₀ (CoQ₁₀) is an essential component of the mitochondrial electron transport chain. It is also an antioxidant in cellular membranes and lipoproteins. All cells produce CoQ₁₀ by a specialized cytoplasmatic-mitochondrial pathway. CoQ₁₀ deficiency can result from genetic failure or ageing. Some drugs including statins, widely used by inter alia elderly, may inhibit endogenous CoQ₁₀ synthesis. There are also chronic diseases with lower levels of CoQ₁₀ in tissues and organs. High doses of CoQ₁₀ may increase both circulating and intracellular levels, but there are conflicting results regarding bioavailability. Here, we review the current knowledge of CoQ₁₀ biosynthesis and primary and acquired CoQ₁₀ deficiency, and results from clinical trials based on CoQ₁₀ supplementation. There are indications that supplementation positively affects mitochondrial deficiency syndrome and some of the symptoms of ageing. Cardiovascular disease and inflammation appear to be alleviated by the antioxidant effect of CoQ₁₀. There is a need for further studies and well-designed clinical trials, with CoQ₁₀ in a formulation of proven bioavailability, involving a greater number of participants undergoing longer treatments in order to assess the benefits of CoQ₁₀ treatment in neurodegenerative disorders, as well as in metabolic syndrome and its complications.

Primary Coenzyme Q deficiencies: A literature review and online platform of clinical features to uncover genotype-phenotype correlations

Primary Coenzyme Q (CoQ) deficiencies are clinically heterogeneous conditions and lack clear genotype-phenotype correlations, complicating diagnosis and prognostic assessment. Here we present a compilation of all the symptoms and patients with primary CoQ deficiency described in the literature so far and analyse the most common clinical manifestations associated with pathogenic variants identified in the different COQ genes. In addition, we identified new associations between the age of onset of symptoms and different pathogenic variants, which could help to a better diagnosis and guided treatment. To make these results useable for clinicians, we created an online platform (https://coenzymeQbiology.github.io/clinic-CoQ-deficiency) about clinical manifestations of primary CoQ deficiency that will be periodically updated to incorporate new information published in the literature. Since CoQ primary deficiency is a rare disease, the available data are still limited, but as new patients are added over time, this tool could become a key resource for a more efficient diagnosis of this pathology.

Therapeutic Potential and Immunomodulatory Role of Coenzyme Q10 and Its Analogues in Systemic Autoimmune Diseases

Coenzyme Q₁₀ (CoQ₁₀) is a mitochondrial electron carrier and a powerful lipophilic antioxidant located in membranes and plasma lipoproteins. CoQ₁₀ is endogenously synthesized and obtained from the diet, which has raised interest in its therapeutic potential against pathologies related to mitochondrial dysfunction and enhanced oxidative stress. Novel formulations of solubilized CoQ₁₀ and the stabilization of reduced CoQ₁₀ (ubiquinol) have improved its bioavailability and efficacy. Synthetic analogues with increased solubility, such as idebenone, or accumulated selectively in mitochondria, such as MitoQ, have also demonstrated promising properties. CoQ₁₀ has shown beneficial effects in autoimmune diseases. Leukocytes from antiphospholipid syndrome (APS) patients exhibit an oxidative perturbation closely related to the prothrombotic status. In vivo ubiquinol supplementation in APS modulated the overexpression of inflammatory and thrombotic risk-markers. Mitochondrial abnormalities also contribute to immune dysregulation and organ damage in systemic lupus erythematosus (SLE). Idebenone and MitoQ improved clinical and immunological features of lupus-like disease in mice. Clinical trials and experimental models have further demonstrated a therapeutic role for CoQ₁₀ in Rheumatoid Arthritis, multiple sclerosis and type 1 diabetes. This review summarizes the effects of CoQ₁₀ and its analogs in modulating processes involved in autoimmune disorders, highlighting the potential of these therapeutic approaches for patients with immune-mediated diseases.

Effects of Coenzyme Q10 Supplementation on Anthropometric Indices in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background:

Obesity is related to increase in the incidence of morbidity and mortality. Previous studies have led to conflicting results regarding the effect of coenzyme Q10 (CoQ10) supplementation on anthropometric indices. This study aimed to evaluate the efficacy of CoQ10 supplementation on body weight, body mass index (BMI), and waist circumference (WC) through a systematic review and meta-analysis of randomized controlled trials (RCTs).

Methods:

PubMed, Scopus, Web of Science, and Cochrane Library as well as the reference lists of the identified relevant RCTs were searched up to March 2019, and weighted mean differences (WMDs) were pooled by using the random-effects model.

Results:

Twenty RCTs (976 participants) were eligible to be included in the systematic review. The meta-analysis revealed that CoQ10 supplementation had no effect on body weight (WMD = −0.04 kg; 95% confidence interval [CI]: −1.96, 1.6; I² = 0.0%), BMI (WMD = −0.06 kg/m²; 95% CI: −0.54, 0.42; I² = 0.0%), and WC (WMD = 0.79 cm; 95% CI: −2.83, 0.04; I² = 0.0%).

Conclusions:

CoQ10 supplementation might not improve anthropometric indices. Future well-designed trials are still needed to confirm these results.

Micellization of coenzyme Q by the fungicide caspofungin allows for safe intravenous administration to reach extreme supraphysiological concentrations

Coenzyme Q₁₀ (CoQ₁₀; also known as ubiquinone) is a vital, redox-active membrane component that functions as obligate electron transporter in the mitochondrial respiratory chain, as cofactor in other enzymatic processes and as antioxidant. CoQ₁₀ supplementation has been widely investigated for treating a variety of acute and chronic conditions in which mitochondrial function or oxidative stress play a role. In addition, it is used as replacement therapy in patients with CoQ deficiency including inborn primary CoQ₁₀ deficiency due to mutations in CoQ₁₀-biosynthetic genes as well as secondary CoQ₁₀ deficiency, which is frequently observed in patients with mitochondrial disease syndrome and in other conditions. However, despite many tests and some promising results, whether CoQ₁₀ treatment is beneficial in any indication has remained inconclusive. Because CoQ₁₀ is highly insoluble, it is only available in oral formulations, despite its very poor oral bioavailability. Using a novel model of CoQ-deficient cells, we screened a library of FDA-approved drugs for an activity that could increase the uptake of exogenous CoQ₁₀ by the cell. We identified the fungicide caspofungin as capable of increasing the aqueous solubility of CoQ₁₀ by several orders of magnitude. Caspofungin is a mild surfactant that solubilizes CoQ₁₀ by forming nano-micelles with unique properties favoring stability and cellular uptake. Intravenous administration of the formulation in mice achieves unprecedented increases in CoQ₁₀ plasma levels and in tissue uptake, with no observable toxicity. As it contains only two safe components (caspofungin and CoQ₁₀), this injectable formulation presents a high potential for clinical safety and efficacy.

•

Coenzyme Q₁₀ (CoQ₁₀) can be solubilized by the antifungal drug caspofungin (CF).

•

CF is a mild surfactant and solubilizes CoQ₁₀ in water by forming micellar structures with a high CoQ₁₀ content.

•

CF/CoQ₁₀ micelles have unique properties favoring rapid and efficient uptake into cells and mitochondria.

•

CF/CoQ₁₀ micelles can be intravenously administrated without signs of toxicity.

•

Intravenous administration of CF/CoQ₁₀ in mice achieves unprecedented elevation of CoQ₁₀ plasma levels and tissue uptake.

Comparative Bioavailability of Different Coenzyme Q10 Formulations in Healthy Elderly Individuals

Coenzyme Q10 (CoQ10) plays a central role in mitochondrial oxidative phosphorylation. Several studies have shown the beneficial effects of dietary CoQ10 supplementation, particularly in relation to cardiovascular health. CoQ10 biosynthesis decreases in the elderly, and consequently, the beneficial effects of dietary supplementation in this population are of greater significance. However, most pharmacokinetic studies have been conducted on younger populations. The aim of this study was to investigate the single-dose bioavailability of different formulations of CoQ10 in a healthy geriatric population. A randomized, three-period, crossover bioavailability study was conducted on 21 healthy older adults (aged 65–74). The treatment was a single dose with a one-week washout period. Three different formulations containing the equivalent of 100 mg of CoQ10 were used: Q10Vital^® water-soluble CoQ10 syrup (the investigational product—IP); ubiquinol capsules (the comparative product—CP); and ubiquinone capsules (the standard product—SP). Ubiquinone/ubiquinol was followed in the plasma for 48 h. An analysis of the ratio of the area under the baseline-corrected concentration curve (ΔAUC₄₈) for total CoQ10 and a comparison to SP yielded the following: The bioavailability of CoQ10 in the IP was 2.4-fold higher (95% CI: 1.3–4.5; p = 0.002), while the bioavailability of ubiquinol (CP) was not significantly increased (1.7-fold; 95% CI: 0.9–3.1, p = 0.129). No differences in the redox status of the absorbed coenzyme Q10 were observed between formulations, showing that CoQ10 appeared in the blood mostly as ubiquinol, even if consumed as ubiquinone.

The Effect of Coenzyme Q10 Supplementation on Vascular Endothelial Growth Factor and Serum Levels of Interleukin 6 and 8 in Women with Breast Cancer: A Double-Blind, Placebo-Controlled, Randomized Clinical Trial

Background

To better evaluate the efficacy of CoQ10 on the inflammatory markers in breast cancer patients, we conducted a clinical study of patients with breast cancer undergoing tamoxifen therapy. CoQ10 serves as an antioxidant and inhibits oxidation caused by reactive oxygen species. The aim of the current study was to assess the effect of coenzyme Q10 supplementation on serum levels of interleukin 6, 8, and vascular endothelial growth factor (VEGF) in patients with breast cancer undergoing tamoxifen therapy by a double-blind, placebo-controlled, randomized clinical trial.

Methods

In the study, 30 breast cancer patients and 29 healthy subjects were randomized into four groups. Two groups of intervention received 100 mg CoQ10, and two control groups took placebo once a day for 2 months. Blood draws were obtained at baseline and at the end of the study. Serum levels of IL-6, IL-8 and VEGF were analyzed using ELISA kits.

Results

The data of the 59 participants were analyzed. Supplementation with CoQ10 demonstrated a significant decrease in IL-8 and IL-6 serum levels compared to placebo (P< 0.05). Although the downward trend was evident, CoQ10 supplementation did not reveal any significant effect on serum VEGF concentration. The group of patients who received supplements showed the most reduction in serum levels of cytokines among other groups.

Conclusion

CoQ10 supplementation could be effective in ameliorating inflammatory cytokine levels, thereby reducing the consequences of inflammation caused by breast cancer. To generalize the results, larger and longer intervention studies with higher safe doses are needed and should take account of possible costs and harms as well as benefits (registration number: IRCT2015042021874N1).

The Paradox of Coenzyme Q10 in Aging

Coenzyme Q (CoQ) is an essential endogenously synthesized molecule that links different metabolic pathways to mitochondrial energy production thanks to its location in the mitochondrial inner membrane and its redox capacity, which also provide it with the capability to work as an antioxidant. Although defects in CoQ biosynthesis in human and mouse models cause CoQ deficiency syndrome, some animals models with particular defects in the CoQ biosynthetic pathway have shown an increase in life span, a fact that has been attributed to the concept of mitohormesis. Paradoxically, CoQ levels decline in some tissues in human and rodents during aging and coenzyme Q₁₀ (CoQ₁₀) supplementation has shown benefits as an anti-aging agent, especially under certain conditions associated with increased oxidative stress. Also, CoQ₁₀ has shown therapeutic benefits in aging-related disorders, particularly in cardiovascular and metabolic diseases. Thus, we discuss the paradox of health benefits due to a defect in the CoQ biosynthetic pathway or exogenous supplementation of CoQ₁₀.

The footprints of mitochondrial impairment and cellular energy crisis in the pathogenesis of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and Fanconi's syndrome: A comprehensive review

Fanconi's Syndrome (FS) is a disorder characterized by impaired renal proximal tubule function. FS is associated with a vast defect in the renal reabsorption of several chemicals. Inherited and/or acquired conditions seem to be connected with FS. Several xenobiotics including many pharmaceuticals are capable of inducing FS and nephrotoxicity. Although the pathological state of FS is well described, the exact underlying etiology and cellular mechanism(s) of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and FS are not elucidated. Constant and high dependence of the renal reabsorption process to energy (ATP) makes mitochondrial dysfunction as a pivotal mechanism which could be involved in the pathogenesis of FS. The current review focuses on the footprints of mitochondrial impairment in the etiology of xenobiotics-induced FS. Moreover, the importance of mitochondria protecting agents and their preventive/therapeutic capability against FS is highlighted. The information collected in this review may provide significant clues to new therapeutic interventions aimed at minimizing xenobiotics-induced renal injury, serum electrolytes imbalance, and FS.

CoQ10 and Aging

The aging process includes impairment in mitochondrial function, a reduction in anti-oxidant activity, and an increase in oxidative stress, marked by an increase in reactive oxygen species (ROS) production. Oxidative damage to macromolecules including DNA and electron transport proteins likely increases ROS production resulting in further damage. This oxidative theory of cell aging is supported by the fact that diseases associated with the aging process are marked by increased oxidative stress. Coenzyme Q10 (CoQ₁₀) levels fall with aging in the human but this is not seen in all species or all tissues. It is unknown whether lower CoQ₁₀ levels have a part to play in aging and disease or whether it is an inconsequential cellular response to aging. Despite the current lay public interest in supplementing with CoQ₁₀, there is currently not enough evidence to recommend CoQ₁₀ supplementation as an anti-aging anti-oxidant therapy.

Effect of Coenzyme Q10 Supplementation on Testosterone

Enhancing testosterone production in males is a continuous research direction for many scientists in the field, due to its role as a principal sex hormone and as a crucial modulator of well-being and general health in humans. Since 1978, there have been more than 30 studies that have connected coenzyme Q₁₀ and testosterone. Such a link is attributable to the vigorous biological role of coenzyme Q₁₀ as a crucial member in the energy production route in humans and animals, which is thought to have a positive influence on testosterone production, and hence on infertility, particularly male infertility. However, this connection has not yet been deliberated. The present work systematically reviews and summarizes the influence of coenzyme Q₁₀ supplementation on testosterone. To accomplish this purpose, the Scopus, PubMed, and Web of Science databases were searched using the keywords “coenzyme Q₁₀” versus “testosterone” for English language papers from November 1978 through October 2018. Relevant articles were also discussed and included to address an integral discussion. In summary, to date the studies conducted on human males reveal insignificant effects of coenzyme Q₁₀ supplementation on testosterone. Similarly, rather than the reproductive toxicity studies, the studies conducted on animals did not show any positive influence of coenzyme Q₁₀ on testosterone. However, coenzyme Q₁₀ supplementation was found to ameliorate the reduction in testosterone induced by chemical reproductive toxicants, mainly by neutralizing the damaging effect of the generated free radicals. However, collectively these findings require further confirmation by additional research studies.

Coenzyme Q10 Supplementation in Aging and Disease

Coenzyme Q (CoQ) is an essential component of the mitochondrial electron transport chain and an antioxidant in plasma membranes and lipoproteins. It is endogenously produced in all cells by a highly regulated pathway that involves a mitochondrial multiprotein complex. Defects in either the structural and/or regulatory components of CoQ complex or in non-CoQ biosynthetic mitochondrial proteins can result in a decrease in CoQ concentration and/or an increase in oxidative stress. Besides CoQ₁₀ deficiency syndrome and aging, there are chronic diseases in which lower levels of CoQ₁₀ are detected in tissues and organs providing the hypothesis that CoQ₁₀ supplementation could alleviate aging symptoms and/or retard the onset of these diseases. Here, we review the current knowledge of CoQ₁₀ biosynthesis and primary CoQ₁₀ deficiency syndrome, and have collected published results from clinical trials based on CoQ₁₀ supplementation. There is evidence that supplementation positively affects mitochondrial deficiency syndrome and the symptoms of aging based mainly on improvements in bioenergetics. Cardiovascular disease and inflammation are alleviated by the antioxidant effect of CoQ₁₀. There is a need for further studies and clinical trials involving a greater number of participants undergoing longer treatments in order to assess the benefits of CoQ₁₀ treatment in metabolic syndrome and diabetes, neurodegenerative disorders, kidney diseases, and human fertility.

Effects of coenzyme Q10 supplementation on metabolic profile in diabetes: a systematic review and meta-analysis

WHAT IS KNOWN AND OBJECTIVE

CoenzymeQ10 (CoQ10 ), or ubiquinone, is an endogenous enzyme cofactor produced by most human cells. It is a potent antioxidant and is necessary for energy production in mitochondria. Diabetes mellitus is a chronic disease with multiple metabolic abnormalities, principally resulting from the inflammation and oxidative stress associated with mitochondrial dysfunctions. Clinical trials of the effects of supplementary CoQ10 on metabolic control in diabetes have reported inconsistent results. We undertook a systematic review and meta-analysis of randomized controlled trials to assess the effects of CoQ10 supplementation on glycaemic control, lipid profile and blood pressure in patients with diabetes.

METHODS

A systematic search was conducted on MEDLINE, The Cochrane Library, CINAHL, NCCAM, Web of Science, Scopus, ClinicalTrials.gov and historical search of reference lists of relevant articles. The bibliographic databases were searched from inception to February 2015. We included randomized, placebo-controlled trials of CoQ10 in diabetes lasting at least 12 weeks. HbA1c or fasting plasma glucose had to be reported. Primary outcome was glycemic control, and secondary outcomes were lipid profile and blood pressure. Treatment effect was estimated with mean difference.

RESULTS AND DISCUSSION

Seven trials were included in the meta-analysis, involving 356 patients. Neither CoQ10 alone nor CoQ10 plus fenofibrate improved glycemic control. In addition, CoQ10, alone or in combination with fenofibrate, did not alter LDL-C, HDL-C and blood pressure. Triglycerides levels were significantly reduced with CoQ10 (mean difference -0·26 mmol/L, 95% CI -0·05 mmol/L to -0·47 mmol/L, P = 0·02) and CoQ10 plus fenofibrate (mean difference -0·72 mmol/L, 95% CI -0·32 mmol/L to -1·12 mmol/L, P = 0·0004). CoQ10 plus fenofibrate also effectively reduced total cholesterol (mean difference: -0·45 mmol/L, 95% CI -0·06 mmol/L to -0·84 mmol/L, P = 0·02).

WHAT IS NEW AND CONCLUSIONS

CoQ10 supplementation has no beneficial effects on glycemic control, lipid profile or blood pressure in patients with diabetes. However, it may reduce triglycerides levels. Due to limited data availability, well-powered and well-designed randomized controlled trials are needed to clearly determine the effect of CoQ10 on metabolic profile in diabetes. Dosage effects should also be explored.

Strategies for oral delivery and mitochondrial targeting of CoQ10

Coenzyme Q10 (CoQ10), also known as ubiquinone or ubidecarenone, is a powerful, endogenously produced, intracellularly existing lipophilic antioxidant. It combats reactive oxygen species (ROS) known to be responsible for a variety of human pathological conditions. Its target site is the inner mitochondrial membrane (IMM) of each cell. In case of deficiency and/or aging, CoQ10 oral supplementation is warranted. However, CoQ10 has low oral bioavailability due to its lipophilic nature, large molecular weight, regional differences in its gastrointestinal permeability and involvement of multitransporters. Intracellular delivery and mitochondrial target ability issues pose additional hurdles. To maximize CoQ10 delivery to its biopharmaceutical target, numerous approaches have been undertaken. The review summaries the current research on CoQ10 bioavailability and highlights the headways to obtain a satisfactory intracellular and targeted mitochondrial delivery. Unresolved questions and research gaps were identified to bring this promising natural product to the forefront of therapeutic agents for treatment of different pathologies.

Oral coenzyme Q10 supplementation in patients with nonalcoholic fatty liver disease: effects on serum vaspin, chemerin, pentraxin 3, insulin resistance and oxidative stress

BACKGROUNDS AND AIMS

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver injury. Chronic exposure to oxidative stress leads to depletion of liver antioxidants and abnormal cytokine production; antioxidant therapy is one of the main therapeutic lines in NAFLD. In the current study we aimed to investigate the effect of coenzyme Q10 (coQ10) therapy on several adipocytokines and insulin resistance in patients with NAFLD.

METHODS

In the current randomized double-blind placebo controlled trial 44 NAFLD patients were enrolled. After randomization into two groups, 22 patients received 100 mg/day coQ10 capsules and 22 patients received placebo daily for 4 weeks. BMI and WHR were calculated for patients at the beginning and end of the study and blood samples were obtained from the patients to measure serum concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), fasting serum glucose (FSG), insulin resistance (IR), vaspin, chemerin, pentraxin 3 (PTX3) and markers of oxidative stress including total antioxidant capacity (TAC) and malondialdehyde (MDA).

RESULTS

After 4 weeks of coQ10 supplementation, waist circumference (WC) and serum AST and TAC concentrations significantly decreased in intervention group (p <0.05) but no significant changes occurred in placebo-treated group. In stepwise multivariate linear regression model, change in serum FSG was a significant predictor of changes in serum vaspin, chemerin and pentraxin 3 (p <0.001).

CONCLUSIONS

The present study showed a potential for coQ10 therapy in improving several anthropometric and biochemical variables in NAFLD. Longer studies with higher doses of coQ10 are required to further evaluate this potential benefit.

Coenzyme q10 therapy

For a number of years, coenzyme Q10 (CoQ10) was known for its key role in mitochondrial bioenergetics; later studies demonstrated its presence in other subcellular fractions and in blood plasma, and extensively investigated its antioxidant role. These 2 functions constitute the basis for supporting the clinical use of CoQ10. Also, at the inner mitochondrial membrane level, CoQ10 is recognized as an obligatory cofactor for the function of uncoupling proteins and a modulator of the mitochondrial transition pore. Furthermore, recent data indicate that CoQ10 affects the expression of genes involved in human cell signaling, metabolism and transport, and some of the effects of CoQ10 supplementation may be due to this property. CoQ10 deficiencies are due to autosomal recessive mutations, mitochondrial diseases, aging-related oxidative stress and carcinogenesis processes, and also statin treatment. Many neurodegenerative disorders, diabetes, cancer, and muscular and cardiovascular diseases have been associated with low CoQ10 levels as well as different ataxias and encephalomyopathies. CoQ10 treatment does not cause serious adverse effects in humans and new formulations have been developed that increase CoQ10 absorption and tissue distribution. Oral administration of CoQ10 is a frequent antioxidant strategy in many diseases that may provide a significant symptomatic benefit.

Overcoming toxicity and side-effects of lipid-lowering therapies

Lowering serum lipid levels is part of the foundation of treating and preventing clinically significant cardiovascular disease. Recently, the American Heart Association/American College of Cardiology released cholesterol guidelines which advocate for high efficacy statins rather than LDL-c goals for five patient subgroups at high risk for cardiovascular disease. Therefore, it is critical that clinicians have an approach for managing side-effects of statin therapy. Statins are associated with myopathy, transaminase elevations, and an increased risk of incident diabetes mellitus among some patients; connections between statins and other processes, such as renal and neurologic function, have also been studied with mixed results. Statin-related adverse effects might be minimized by careful assessment of patient risk factors. Strategies to continue statin therapy despite adverse effects include switching to another statin at a lower dose and titrating up, giving intermittent doses of statins, and adding non-statin agents. Non-statin lipid-lowering drugs have their own unique limitations. Management strategies and algorithms for statin-associated toxicities are available to help guide clinicians. Clinical practice should emphasize tailoring therapy to address each individual's cholesterol goals and risk of developing adverse effects on lipid-lowering drugs.

Coenzyme Q10 prevents accelerated cardiac aging in a rat model of poor maternal nutrition and accelerated postnatal growth

Studies in human and animals have demonstrated that nutritionally induced low birth-weight followed by rapid postnatal growth increases the risk of metabolic syndrome and cardiovascular disease. Although the mechanisms underlying such nutritional programming are not clearly defined, increased oxidative-stress leading to accelerated cellular aging has been proposed to play an important role. Using an established rodent model of low birth-weight and catch-up growth, we show here that post-weaning dietary supplementation with coenzyme Q10, a key component of the electron transport chain and a potent antioxidant rescued many of the detrimental effects of nutritional programming on cardiac aging. This included a reduction in nitrosative and oxidative-stress, telomere shortening, DNA damage, cellular senescence and apoptosis. These findings demonstrate the potential for postnatal antioxidant intervention to reverse deleterious phenotypes of developmental programming and therefore provide insight into a potential translatable therapy to prevent cardiovascular disease in at risk humans.

Nutrient reference values for bioactives: new approaches needed? A conference report

Nutrients can be classified as either “essential” or “non-essential,” the latter are also termed bioactive substances. Whereas the absence of essential nutrients from the diet results in overt deficiency often times with moderate to severe physiological decrements, the absence of bioactive substances from the diet results in suboptimal health. Nutrient reference values are set by Codex Alimentarius and regulatory bodies in many countries, mostly for essential nutrients with recommended daily intakes. The IOM in the United States has defined a set of four DRIs that, when data are appropriate, include an EAR, a RDA that is derived from the EAR, an AI for nutrients without appropriate data to identify an EAR, and an UL. From the RDA, the United States derives a labeling value called the DV, which applies to older children and most adults. In Codex, the equivalents of the DVs are the NRVs to be used in calculating percentage values on food labels. Nothing in the IOM documents specifies that labeling values can be set only for what have been defined to date as essential nutrients. Indeed, the US Food and Drug Administration sets a labeling value for dietary fiber based on the IOM AI for this ingredient. This conference explores the definitions, concepts, and data on two of the best examples of bioactive substances that, perhaps, should have NRVs: lutein and zeaxanthin, and n-3 long-chain polyunsaturated fatty acids.

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.

Primary and secondary coenzyme Q10 deficiency: the role of therapeutic supplementation

Coenzyme Q10 (CoQ10) is the only lipid-soluble antioxidant that animal cells synthesize de novo. It is found in cell membranes and is particularly well known for its role in the electron transport chain in mitochondrial membranes during aerobic cellular respiration. A deficiency in either its bioavailability or its biosynthesis can lead to one of several disease states. Primary deficiency has been well described and results from mutations in genes involved in CoQ10 biosynthesis. Secondary deficiency may be linked to hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins), which are used for the treatment of hypercholesterolemia. Dietary contributions of CoQ10 are very small, but supplementation is effective in increasing plasma CoQ10 levels. It has been clearly demonstrated that treatment with CoQ10 is effective in numerous disorders and deficiency states and that supplementation has a favorable outcome. However, CoQ10 is not routinely prescribed in clinical practice. This review explores primary as well as statin-induced secondary deficiency and provides an overview of the benefits of CoQ10 supplementation.

Lack of effect of coenzyme q10 on doxorubicin cytotoxicity in breast cancer cell cultures

BACKGROUND/HYPOTHESES: Doxorubicin is a standard adjuvant therapy for early-stage breast cancer, and it significantly improves disease-free and overall survival. However, 3% to 20% of breast cancer patients develop chronic cardiomyopathic changes and congestive heart failure because of doxorubicin therapy. Doxorubicin-induced cardiotoxicity is thought to be due to the increased generation of reactive oxygen species within cardiac myocyte mitochondria. Coenzyme Q10 (CoQ10) is a lipid-soluble antioxidant that may protect against mitochondrial reactive oxygen species and thus prevent doxorubicin-induced cardiotoxicity. Despite the potential benefits of CoQ10 in preventing cardiotoxicity, it is not known if CoQ10 diminishes the antineoplastic effects of doxorubicin therapy.

STUDY DESIGN

In vitro cell culture experiments.

METHODS

Breast cancer cell lines (MDA-MB-468 and BT549) were tested for their ability to uptake exogenous CoQ10 using high-performance liquid chromatography. Breast cancer cell lines were then treated with doxorubicin and a range of CoQ10 concentrations to determine the effect of CoQ10 on doxorubicin's cytotoxicity.

RESULTS

This study demonstrated that intracellular and mitochondrial CoQ10 concentrations increased substantially as higher exogenous concentrations were administered to breast cancer cells. CoQ10 had no effect on the ability of doxorubicin to induce apoptosis or inhibit growth or colony formation in both the cell lines tested when applied over a wide dose range, which encompassed typical basal plasma levels and plasma levels above those typically achieved by supplemented patients.

CONCLUSION

The clinical testing of CoQ10 as a supplement to prevent doxorubicin-induced cardiotoxicity requires confidence that it does not decrease the efficacy of chemotherapy. These results support the hypothesis that CoQ10 does not alter the antineoplastic properties of doxorubicin. Further in vivo studies, as well as combination chemotherapy studies, would be reassuring before a large-scale clinical testing of CoQ10 as a cardioprotective drug.

Oral repeated-dose toxicity studies of coenzyme Q10 in beagle dogs

To support phase III testing of coenzyme Q10 (CoQ₁₀) in humans, we conducted pharmacokinetic and toxicology studies in beagle dogs. Following single gavage administration of CoQ₁₀ at 600, 1200, 1800, or 2400 mg/kg per d no obvious dose response was observed in maximum concentration (C(max)) or area under the curve (AUC) versus time curve at the 3 highest dosages. In a repeated-dose study of CoQ₁₀ at 600, 1200, 1800, or 2400 mg/kg per d for 4 weeks, CoQ₁₀ reached steady state in plasma by 2 weeks at all dosages. Both C (max) and AUC increased with increasing dosage of CoQ₁₀. The highest plasma levels were recorded at 1800 mg/kg per d. In a 39-week chronic toxicity study of CoQ₁₀ at 1200 and 1800 mg/kg per d or placebo, CoQ₁₀ reached steady state in plasma by 13 weeks. Behaviors, blood chemistries, and detailed histopathology were normal. No deaths occurred. These results support the use of a 2400 mg/d dosage of CoQ₁₀ in human clinical trials.

Micronutrient special issue: coenzyme Q(10) requirements for DNA damage prevention

Coenzyme Q(10) (CoQ(10)) is an essential component for electron transport in the mitochondrial respiratory chain and serves as cofactor in several biological processes. The reduced form of CoQ(10) (ubiquinol, Q(10)H(2)) is an effective antioxidant in biological membranes. During the last years, particular interest has been grown on molecular effects of CoQ(10) supplementation on mechanisms related to DNA damage prevention. This review describes recent advances in our understanding about the impact of CoQ(10) on genomic stability in cells, animals and humans. With regard to several in vitro and in vivo studies, CoQ(10) provides protective effects on several markers of oxidative DNA damage and genomic stability. In comparison to the number of studies reporting preventive effects of CoQ(10) on oxidative stress biomarkers, CoQ(10) intervention studies in humans with a direct focus on markers of DNA damage are limited. Thus, more well-designed studies in healthy and disease populations with long-term follow up results are needed to substantiate the reported beneficial effects of CoQ(10) on prevention of DNA damage.