Coenzyme Q10 in plasma and erythrocytes: comparison of antioxidant levels in healthy probands after oral supplementation and in patients suffering from sickle cell anemia

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.

Comparison between Sickle Cell Disease Patients and Healthy Donors: Untargeted Lipidomic Study of Erythrocytes

Sickle cell disease (SCD) is one of the most common severe monogenic disorders in the world caused by a mutation on HBB gene and characterized by hemoglobin polymerization, erythrocyte rigidity, vaso-occlusion, chronic anemia, hemolysis, and vasculopathy. Recently, the scientific community has focused on the multiple genetic and clinical profiles of SCD. However, the lipid composition of sickle cells has received little attention in the literature. According to recent studies, changes in the lipid profile are strongly linked to several disorders. Therefore, the aim of this study is to dig deeper into lipidomic analysis of erythrocytes in order to highlight any variations between healthy and patient subjects. 241 lipid molecular species divided into 17 classes have been annotated and quantified. Lipidomic profiling of SCD patients showed that over 24% of total lipids were altered most of which are phospholipids. In-depth study of significant changes in lipid metabolism can give an indication of the enzymes and genes involved. In a systems biology scenario, these variations can be useful to improve the understanding of the biochemical basis of SCD and to try to make a score system that could be predictive for the severity of clinical manifestations.

Is plasma concentration of coenzyme Q10 a predictive marker for left ventricular remodelling after revascularization for ST-segment elevation myocardial infarction?

BACKGROUND

Left ventricular remodelling that frequently occurs after acute myocardial infarction is associated with an increased risk of heart failure and cardiovascular death. Although several risk factors have been identified, there is still no marker in clinical use to predict left ventricular remodelling. Plasma concentration of coenzyme Q10, which plays a key role in mitochondrial energy production and as an antioxidant, seems to be negatively correlated with left ventricular function after acute myocardial infarction.

OBJECTIVE

The goal of our study was to determine whether the plasma coenzyme Q10 baseline concentrations at time of the ST-elevation myocardial infarction (STEMI) could predict left ventricular remodelling at six months' follow-up.

METHODS

Sixty-eight patients who were admitted to hospital for STEMI and successfully revascularized with primary percutaneous coronary intervention were recruited. All patients underwent a 3D-echocardiography examination within the first four days after percutaneous coronary intervention and six months later then divided into two groups based on the presence or not of left ventricular remodelling. Plasma coenzyme Q10 concentration at the time of percutaneous coronary intervention was determined using high-performance liquid chromatography-tandem mass spectrometry.

RESULTS

While we found similar plasma coenzyme Q10 concentrations compared with other studies, no association was evidenced between coenzyme Q10 concentrations and left ventricular remodelling (P = 0.89).

CONCLUSION

We found no evidence for using plasma coenzyme Q10 concentration as an early prediction marker of left ventricular remodelling after STEMI.

Atorvastatin impairs liver mitochondrial function in obese Göttingen Minipigs but heart and skeletal muscle are not affected

Statins lower the risk of cardiovascular events but have been associated with mitochondrial functional changes in a tissue-dependent manner. We investigated tissue-specific modifications of mitochondrial function in liver, heart and skeletal muscle mediated by chronic statin therapy in a Göttingen Minipig model. We hypothesized that statins enhance the mitochondrial function in heart but impair skeletal muscle and liver mitochondria. Mitochondrial respiratory capacities, citrate synthase activity, coenzyme Q10 concentrations and protein carbonyl content (PCC) were analyzed in samples of liver, heart and skeletal muscle from three groups of Göttingen Minipigs: a lean control group (CON, n = 6), an obese group (HFD, n = 7) and an obese group treated with atorvastatin for 28 weeks (HFD + ATO, n = 7). Atorvastatin concentrations were analyzed in each of the three tissues and in plasma from the Göttingen Minipigs. In treated minipigs, atorvastatin was detected in the liver and in plasma. A significant reduction in complex I + II-supported mitochondrial respiratory capacity was seen in liver of HFD + ATO compared to HFD (P = 0.022). Opposite directed but insignificant modifications of mitochondrial respiratory capacity were seen in heart versus skeletal muscle in HFD + ATO compared to the HFD group. In heart muscle, the HFD + ATO had significantly higher PCC compared to the HFD group (P = 0.0323). In the HFD group relative to CON, liver mitochondrial respiration decreased whereas in skeletal muscle, respiration increased but these changes were insignificant when normalizing for mitochondrial content. Oral atorvastatin treatment in Göttingen Minipigs is associated with a reduced mitochondrial respiratory capacity in the liver that may be linked to increased content of atorvastatin in this organ.

Clinical Evidence for Q10 Coenzyme Supplementation in Heart Failure: From Energetics to Functional Improvement

Oxidative stress and mitochondrial dysfunction are hallmarks of heart failure (HF). Coenzyme Q10 (CoQ10) is a vitamin-like organic compound widely expressed in humans as ubiquinol (reduced form) and ubiquinone (oxidized form). CoQ10 plays a key role in electron transport in oxidative phosphorylation of mitochondria. CoQ10 acts as a potent antioxidant, membrane stabilizer and cofactor in the production of adenosine triphosphate by oxidative phosphorylation, inhibiting the oxidation of proteins and DNA. Patients with HF showed CoQ10 deficiency; therefore, a number of clinical trials investigating the effects of CoQ10 supplementation in HF have been conducted. CoQ10 supplementation may confer potential prognostic advantages in HF patients with no adverse hemodynamic profile or safety issues. The latest evidence on the clinical effects of CoQ10 supplementation in HF was reviewed.

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.

Bioavailability of coenzyme Q10 supplements depends on carrier lipids and solubilization

OBJECTIVES

Bioavailability of supplements with coenzyme Q10 (CoQ₁₀) in humans seems to depend on the excipients of formulations and on physiological characteristics of the individuals. The aim of this study was to determine which factors presented in CoQ₁₀ supplements affect the different response to CoQ₁₀ in humans.

METHODS

We tested seven different supplement formulations containing 100 mg of CoQ₁₀ in 14 young, healthy individuals. Bioavailability was measured as area under the curve of plasma CoQ₁₀ levels over 48 h after ingestion of a single dose. Measurements were repeated in the same group of 14 volunteers in a double-blind crossover design with a minimum of 4 wk washout between intakes.

RESULTS

Bioavailability of the formulations showed large differences that were statistically significant. The two best absorbable formulations were soft-gel capsules containing ubiquinone (oxidized CoQ₁₀) or ubiquinol (reduced CoQ₁₀). The matrix used to dissolve CoQ₁₀ and the proportion and addition of preservatives such as vitamin C affected the bioavailability of CoQ₁₀. Although control measurements documented that all formulations contained 100 mg of either CoQ₁₀ or ubiquinol, some of the participants showed high and others lower capacity to reach high increase of CoQ₁₀ in blood, indicating the participation of individual unknown physiological factors.

CONCLUSION

This study highlights the importance of individually adapted selection of best formulations to reach the highest bioavailability of CoQ₁₀ in humans.

Highly sensitive and selective determination of redox states of coenzymes Q9 and Q10 in mice tissues: Application of orbitrap mass spectrometry

Coenzyme Q (CoQ) is a redox active molecule that plays a fundamental role in mitochondrial energy generation and functions as a potent endogenous antioxidant. Redox ratio of CoQ has been suggested as a good marker of mitochondrial dysfunction and oxidative stress. Nevertheless, simultaneous measurement of redox states of CoQ is challenging owing to its hydrophobicity and instability of the reduced form. In order to improve the analytical methodology, paying special attention to this instability, we developed a highly sensitive and selective high-resolution/accurate-mass (HR/AM) UHPLC-MS/MS method for the rapid determination of redox states of CoQ₉ and CoQ₁₀ by ultra-performance liquid chromatography-hybrid quadrupole-Orbitrap mass spectrometry. CoQs were extracted using hexane with the addition of butylated hydroxytoluene to limit oxidation during sample preparation. Chromatographic separation of the analytes was achieved on a Kinetex C₁₈ column with the isocratic elution of 5 mM ammonium formate in 2-propanol/methanol (60:40) within 4 min. A full MS/all ion fragmentation (AIF) acquisition mode with mass accuracy < 5 ppm was used for detection and determination of redox states of CoQ₉ and CoQ₁₀ in healthy mice tissues using reduced and oxidized CoQ₄ as internal standards. The validated method showed good linearity (r² ≥ 0.9991), intraday, inter-day precision (CVs ≤ 11.9%) and accuracy (RE ≤±15.2%). In contrast to existing methods, the current method offers enhanced sensitivity (up to 52 fold) with LOD and LOQ ranged from 0.01 to 0.49 ng mL^-1 and 0.04-1.48 ng mL^-1, respectively. Moreover, we evaluated various diluents to investigate bench top stability (at 4 °C) of targeted analytes in tissue samples during LC-MS assay up to 24 h. Ethanol was determined to be an optimum diluent without any significant oxidation of reduced CoQ up to 24 h. The developed method offers a rapid, highly sensitive and selective strategy for the measurement of redox states of CoQs in clinical studies.

Coenzyme Q10 and Heart Failure: A State-of-the-Art Review

Heart failure (HF) with either preserved or reduced ejection fraction is associated with increased morbidity and mortality. Evidence-based therapies are often limited by tolerability, hypotension, electrolyte disturbances, and renal dysfunction. Coenzyme Q10 (CoQ10) may represent a safe therapeutic option for patients with HF. CoQ10 is a highly lipophilic molecule with a chemical structure similar to vitamin K. Although being a common component of cellular membranes, CoQ10's most prominent role is to facilitate the production of adenosine triphosphate in the mitochondria by participating in redox reactions within the electron transport chain. Numerous trials during the past 30 years examining CoQ10 in patients with HF have been limited by small numbers and lack of contemporary HF therapies. The recent publication of the Q-SYMBIO randomized controlled trial demonstrated a reduction in major adverse cardiovascular events with CoQ10 supplementation in a contemporary HF population. Although having limitations, this study has renewed interest in evaluating CoQ10 supplementation in patients with HF. Current literature suggests that CoQ10 is relatively safe with few drug interactions and side effects. Furthermore, it is already widely available as an over-the-counter supplement. These findings warrant future adequately powered randomized controlled trials of CoQ10 supplementation in patients with HF. This state-of-the-art review summarizes the literature about the mechanisms, clinical data, and safety profile of CoQ10 supplementation in patients with HF.

Analytical problems with the determination of coenzyme Q10 in biological samples

The article discusses analytical problems related to the determination of coenzyme Q10 in biological samples. The assaying of coenzyme Q10 in complex samples, such as plasma, tissues, or food items requires meticulous sample preparation prior to final quantification. The process typically consists of the following steps: deproteinization, extraction, and ultimately reduction of extract volumes. At times drying under a gentle stream of neutral gas is applied. In the case of solid samples, a careful homogenization is also required. Each step of the sample preparation process can be a source of analytical errors that may lead to inaccurate results. The main aim of this work is to point to sources of analytical errors in the preparation process and their relation to physicochemical properties of coenzyme Q10. The article also discusses ways of avoiding and reducing the errors.

Measurement of oxidized and reduced coenzyme Q in biological fluids, cells, and tissues: an HPLC-EC method

Direct measure of coenzyme Q (CoQ) in biological specimens may provide important advantages. Precise and selective high-performance liquid chromatography (HPLC) methods with electrochemical (EC) detection have been developed for the measurement of reduced (ubiquinol) and oxidized (ubiquinone) CoQ in biological fluids, cells, and tissues. EC detection is preferred for measurement of CoQ because of its high sensitivity. Reduced and oxidized CoQ are first extracted from biological specimens using 1-propanol. After centrifugation, the 1-propanol supernatant is directly injected into HPLC and monitored at a dual-electrode. The EC reactions occur at the electrode surface. The first electrode transforms ubiquinone into ubiquinol, and the second electrode measures the current produced by the oxidation of the hydroquinone group of ubiquinol. The methods described provide rapid, precise, and simple procedures for determination of reduced and oxidized CoQ in biological fluids, cells, and tissues. The methods have been successfully adapted to meet regulatory requirements for clinical laboratories, and have been proven reliable for analysis of clinical and research samples for clinical trials and animal studies involving large numbers of specimens.

Coenzyme Q10 concentration in plasma and blood cells of juvenile patients hospitalized for anorexia nervosa

The antioxidant status of coenzyme Q10 (CoQ10) was investigated in plasma, erythrocytes, and platelets of juvenile patients with anorexia nervosa. Blood for analysis of the CoQ10 status was taken from 16 juvenile patients suffering from anorexia nervosa (restricting form) at the time point of admission to the hospital and at discharge after about 12 weeks. Plasma and blood cells isolated by a density gradient were stored at -84 °C until analysis. CoQ10 concentration and redox status were measured by high pressure liquid chromatography with electrochemical detection and internal standardization. The improvement of physical health during the hospital refeeding process was followed up by the body mass index (BMI). The antioxidant status of plasma CoQ10 in juvenile patients suffering from anorexia nervosa indicated no abnormalities in comparison to healthy controls. However, the decreased concentration of CoQ10 observed in platelets at the time point of hospital admission may represent mitochondrial CoQ10 depletion. This initial deficit improved during the hospital refeeding process. The platelet CoQ10 concentration showed a positive correlation to the BMI of the patients.

Coenzyme Q(10) is decreased in fibroblasts of patients with methylmalonic aciduria but not in mevalonic aciduria

The content of coenzyme Q(10) (CoQ(10)) was examined in skin fibroblasts of 10 patients with mevalonic aciduria (MVA) and of 22 patients with methylmalonic aciduria (MMA). Patients with these inborn errors of metabolism are thought to be at risk for CoQ(10) depletion either by direct inhibition of the proximal pathway of CoQ(10) synthesis (MVA) or indirectly by inhibition of mitochondrial energy metabolism (MMA). We demonstrated that CoQ(10) concentrations were not significantly different from controls in MVA patients, suggesting that there may be upregulatory effects. On the other hand the CoQ(10) content in fibroblasts of patients with MMA was significantly reduced.

Effects of ubiquinol-10 on microRNA-146a expression in vitro and in vivo

MicroRNAs (miRs) are involved in key biological processes via suppression of gene expression at posttranscriptional levels. According to their superior functions, subtle modulation of miR expression by certain compounds or nutrients is desirable under particular conditions. Bacterial lipopolysaccharide (LPS) induces a reactive oxygen species-/NF-kappaB-dependent pathway which increases the expression of the anti-inflammatory miR-146a. We hypothesized that this induction could be modulated by the antioxidant ubiquinol-10. Preincubation of human monocytic THP-1 cells with ubiquinol-10 reduced the LPS-induced expression level of miR-146a to 78.9 +/- 13.22%. In liver samples of mice injected with LPS, supplementation with ubiquinol-10 leads to a reduction of LPS-induced miR-146a expression to 78.12 +/- 21.25%. From these consistent in vitro and in vivo data, we conclude that ubiquinol-10 may fine-tune the inflammatory response via moderate reduction of miR-146a expression.

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.

Analysis of coenzyme Q in human blood and tissues

The major coenzyme Q species in humans is the decaprenyl quinoid derivative coenzyme Q10 (CoQ10), and its measurement is somewhat challenging owing to its hydrophobicity and tendency to be oxidized. There are three major methods which are suited for analysis of CoQ10: HPLC-coupled UV or electrochemical detection, and tandem mass spectrometry. The techniques are discussed, and results of these applications to determine CoQ10 concentrations in various human fluids and tissues are summarized.

Enrichment of coenzyme Q10 in plasma and blood cells: defense against oxidative damage

Coenzyme Q10 (CoQ10) concentration in blood cells was analyzed by HPLC and compared to plasma concentration before, during, and after CoQ10 (3 mg/kg/day) supplementation to human probands. Lymphocyte DNA 8-hydroxydeoxy-guanosine (8-OHdG), a marker of oxidative stress, was analyzed by Comet assay.

Subjects supplemented with CoQ10 showed a distinct response in plasma concentrations after 14 and 28 days. Plasma levels returned to baseline values 12 weeks after treatment stopped. The plasma concentration increase did not affect erythrocyte levels. However, after CoQ10 supplementation, the platelet level increased; after supplementation stopped, the platelet level showed a delayed decrease. A positive correlation was shown between the plasma CoQ10 level and platelet and white blood cell CoQ10 levels. During CoQ10 supplementation, delayed formation of 8-OHdG in lymphocyte DNA was observed; this effect was long-lasting and could be observed even 12 weeks after supplementation stopped. Intracellular enrichment may support anti-oxidative defense mechanisms.

Coenzyme Q10 concentration in the plasma of children suffering from acute lymphoblastic leukaemia before and during induction treatment

Coenzyme Q10 (CoQ10) is used by the body as an endogenous antioxidant. This property combined with its essential function in mitochondrial energy production suggests that it may have therapeutic potential in cancer treatment. As part of the body's antioxidant defence against free radical production, CoQ10 concentrations may change during anti-cancer chemotherapy. Our study measured CoQ10 concentration in the plasma of 27 children with acute lymphoblastic leukaemia (ALL) at the time of diagnosis, during induction (protocol ALL-BFM 2000), and post induction treatment. The starting values were compared to the CoQ10 concentrations in 92 healthy children. The total CoQ10 concentration and its redox status were measured by HPLC using electrochemical detection and internal standardisation. While the CoQ10 concentration in the plasma of children with ALL was within a normal range at the time of diagnosis (0.99 +/- 0.41 pmol/microl), a drastic increase was observed during induction treatment (2.19 +/- 1.01 pmol/mul on day 33). This increase was accompanied by shift in the redox status in favour of the reduced form of CoQ10. The increase in CoQ10 concentration during induction treatment may be attributed to the activation of a natural antioxidative defence mechanism, endocrine influence on CoQ10 synthesis from steroid treatment, or a shift in CoQ10 from the damaged cells to the plasma after cell lysis.

Risk assessment for coenzyme Q10 (Ubiquinone)

Coenzyme Q10 (CoQ10) widely occurs in organisms and tissues, and is produced and used as both a drug and dietary supplement. Increasing evidence of health benefits of orally administered CoQ10 are leading to daily consumption in larger amounts, and this increase justifies research and risk assessment to evaluate the safety. A large number of clinical trials have been conducted using a range of CoQ10 doses. Reports of nausea and other adverse gastrointestinal effects of CoQ10 cannot be causally related to the active ingredient because there is no dose-response relationship: the adverse effects are no more common at daily intakes of 1200 mg than at a 60 mg. Systematic evaluation of the research designs and data do not provide a basis for risk assessment and the usual safe upper level of intake (UL) derived from it unless the newer methods described as the observed safe level (OSL) or highest observed intake (HOI) are utilized. The OSL risk assessment method indicates that the evidence of safety is strong at intakes up to 1200 mg/day, and this level is identified as the OSL. Much higher levels have been tested without adverse effects and may be safe, but the data for intakes above 1200 mg/day are not sufficient for a confident conclusion of safety.

HPLC method for simultaneous determination of retinol, alpha-tocopherol and coenzyme Q10 in human plasma

A simple HPLC method with UV detection is proposed for the simultaneous determination of three lipophilic vitamins: all-trans-retinol, alpha-tocopherol and coenzyme Q(10) (ubiquinone) in human plasma. The following chromatographic conditions were used: RP-18 column, a mobile phase consisted of methanol -n-hexane 72:28 (v/v) and UV detector set at 324, 292 and 276 nm for all-trans-retinol, alpha-tocopherol and coenzyme Q(10), respectively. The linearity range was 0.35-70 microM for all-trans-retinol, 0.23-44 microM for alpha-tocopherol and 0.12-23 microM for coenzyme Q(10). Deproteinised plasma samples were extracted with n-hexane prior to the analysis. The within-day and between day reproducibilities were 1.5 and 3.7% for all-trans-retinol, 4.0 and 5.8% for alpha-tocopherol and 2.3 and 3.1% for coenzyme Q(10), respectively. Using the proposed method the following recoveries were achieved: 91% for all-trans-retinol, 86% for alpha-tocopherol and 88% for coenzyme Q(10). The method was applied to the determination of the levels of retinol, tocopherol and coenzyme Q(10) in plasma of healthy children and children treated by elimination diet.

Coenzyme Q10 concentration in plasma and blood cells: what about diurnal changes?

Coenzyme Q10 (CoQ10) is used by the body as an endogenous antioxidant and performs essential functions in mitochondrial energy production. The value of CoQ10 as a biomarker for oxidative stress will be severely restricted if there are huge individual daily variations in its concentration. For analysis of diurnal changes in CoQ10 plasma and blood cell concentrations, blood was collected from nine healthy adults (at two- or three-hour intervals for plasma, and three times a day for blood cells). CoQ10 was analysed by HPLC using electrochemical detection and internal standardisation. Daytime variations in CoQ10 concentration in plasma are maintained within narrow limits and show no statistically significant difference (Kruskal-Wallis). However, a drop at night-time (0300 h) is accompanied by a drop in total cholesterol concentration. Remarkable inter-individual differences in blood cell (erythrocytes, platelets, white blood cells) content of CoQ10 occur with only slight intra-individual daily variations. A correlation (Spearman) is found for cholesterol and CoQ10 content in circulation which may be explained by the carrier capacity of blood for this highly lipophilic substance. Moreover, a diurnal change in hepatic HMG-CoA reductase activity may suggest a common diurnal regulation of synthesis of both CoQ10 and cholesterol.

Simultaneous analysis of coenzyme Q10 in plasma, erythrocytes and platelets: comparison of the antioxidant level in blood cells and their environment in healthy children and after oral supplementation in adults

BACKGROUND

Coenzyme Q10 (CoQ10) originates from food intake as well as from endogenous synthesis. While plasma concentrations may be influenced by dietary uptake, little is known whether concentrations in plasma reflect or influence intracellular concentrations.

METHODS

For clinical routine investigation of intracellular CoQ10 contents, blood erythrocytes and platelets were isolated by Ficoll separating solution and CoQ10 analysed using HPLC. The intracellular concentrations were compared to environmental plasma concentrations of 50 clinically healthy infants and additionally after exogenous pharmaceutical supplementation of CoQ10 (3 mg/kg/day) to 12 adult probands for 14 days.

RESULTS

In healthy children, no correlation between plasma concentration and content in blood cells was found. A negative correlation exists between the year of life of the infants and CoQ10 concentrations in plasma correlated to cholesterol content. Probands supplemented with CoQ10 showed a distinct response in plasma concentrations after 14 days. While excessive environmental supplementation was without influence on erythrocyte concentrations, a positive correlation exists between plasma content and concentrations in platelets as mitochondria containing cell lines.

CONCLUSIONS

Under physiologically normal conditions, blood cells or organs may regulate their CoQ10 content independently from environmental supply. Effects may be expected in situations of deficiency or excessive supply. Erythrocyte concentration of CoQ10 keeps independent from environmental supply. Thus incorporation into outer cell membranes may be limited. However, an excessive environmental supply may influence inner compartments like mitochondrial membranes.

Coenzyme Q10 in maternal plasma and milk throughout early lactation

In contrast to other lipophilic antioxidants Coenzyme Q10 originates from food intake as well as from endogenous synthesis. The CoQ10 concentration and lipid content of maternal milk and maternal plasma was investigated during early lactation. Breast milk was obtained from 23 women: A: colostrums (24-48 hours postpartum), B: transitional milk (day 7 pp), C: mature milk (day 14 pp). At the same time capillary blood specimens were collected. Milk and plasma were stored at -84 degrees C until CoQ10 was analysed after hexane extraction by HPLC. The lipid content was determined by PAP-analysis of cholesterol. The plasma content of CoQ10 was the highest soon after delivery (A: 1.29, B:1.20, C:1.07 pmol/microl; Wilcoxon p < 0.05 A vs. C and B vs. C). This tendency was still evident after lipid-adjustment (A:209, B:180, C:175 micromol CoQ10/mol cholesterol; Wilcoxon p < 0.01 A vs. B and C). The level of CoQ10 in milk showed a gradual decline during early lactation (A:0.80, B:0.57, C:0.44 pmol/microl; Wilcoxon p < 0.02 A vs. B and C). After lipid-adjustment this tendency became even more evident (A: 137, B:86, C:67 micromol CoQ10/mol cholesterol; Wilcoxon p < 0.002 A vs. B and C, p < 0.05 B vs. C). The content of CoQ10 in plasma and milk showed a correlation with early milk (Spearman p < 0.005) but not with mature milk. Although lipid content is low the colostrums is a rich source for the lipophilic antioxidant CoQ10.

Coenzyme Q10 is increased in placenta and cord blood during preeclampsia

Preeclampsia is a common (approximately 7% of all pregnancies) disorder of pregnancy in which the normal hemodynamic response to pregnancy is compromised. Despite many years of intensive research, the pathogenesis of preeclampsia is still not fully understood. The objective of the present study was to investigate the levels of coenzyme Q(10) (CoQ(10)) in placental tissue compared to maternal and umbilical cord levels both during normal pregnancy and in those complicated with preeclampsia. Pregnant women (n = 30) and women with preeclampsia (n = 30) were included. Maternal, newborn cord blood levels and placental content of coenzyme Q(10) were measured by high performance liquid chromatography (HPLC). Plasma coenzyme Q(10) levels were significantly higher in normal pregnant women than in women with preeclampsia. CoQ(10) content in placenta from women with preeclampsia (mean 0.28 SEM 0.11 nmol/mg protein) was significantly higher compared to normal pregnancy (mean 0.09 SEM 0.01 nmol/mg protein; p = 0.05). Levels of CoQ(10) in cord blood from normal pregnant women (mean 0.30 SEM 0.05 micromol/l) were significantly lower than in preeclamptic women (mean 4.03 SEM 2.38 micromol/l). In conclusion, these data indicate a possible involvement of CoQ(10) in preeclampsia that might bear deep physiopathological significance and deserve to be further elucidated.

Age-related changes in plasma coenzyme Q10 concentrations and redox state in apparently healthy children and adults

BACKGROUND

Coenzyme Q10 (CoQ) is an endogenous enzyme cofactor, which may provide protective benefits as an antioxidant. Because age-related CoQ changes and deficiency states have been described, there is a need to establish normal ranges in healthy children. The objectives of this study are to determine if age-related differences in reduced CoQ (ubiquinol), oxidized CoQ (ubiquinone), and CoQ redox state exist in childhood, and to establish reference intervals for these analytes in healthy children.

METHODS

Apparently healthy children (n=68) were selected from individuals with no history of current acute illness, medically diagnosed disease, or current medication treatment. Self-reported healthy adults (n=106) were selected from the ongoing Princeton Follow-up Study in greater Cincinnati. Participants were assessed for lipid profiles, ubiquinol concentration, ubiquinone concentration, total CoQ concentration, and CoQ redox ratio.

RESULTS

Mean total CoQ and ubiquinol concentrations are similar in younger children (0.2-7.6 years) and adults (29-78 years); however, lipid-adjusted total CoQ concentrations are significantly increased in younger children. Also CoQ redox ratio is significantly increased in younger and older children compared with adults.

CONCLUSIONS

Elevated CoQ and redox ratios in children may be an indication of oxidative stress effects, which are associated with early development of coronary heart disease.

Comparison of coenzyme Q10 plasma levels in obese and normal weight children

BACKGROUND

Childhood obesity is associated with lower plasma levels of lipophilic antioxidants which may contribute to a deficient protection of low-density lipoproteins (LDL). An increased plasma level of oxidized LDL in obese people with insulin resistance has been demonstrated. The lipophilic antioxidant coenzyme Q10 (CoQ10) is known as an effective inhibitor of oxidative damage in LDL as well. The aim of the present study was to compare the CoQ10 levels in obese and normal weight children.

METHODS

The CoQ10 plasma concentrations were measured in 67 obese children (BMI>97th percentile) and related to their degree of insulin resistance. Homeostasis model assessment (HOMA) was used to detect the degree of insulin resistance. The results were compared to a control group of 50 normal weight and apparently healthy children. The results of the CoQ10 levels were related to the plasma cholesterol concentrations.

RESULTS

After adjustment to plasma cholesterol, no significant difference in the CoQ10 levels between obese and normal weight children could be demonstrated. Furthermore, there was no difference between insulin-resistant and non-insulin-resistant obese children.

CONCLUSION

CoQ10 plasma levels are not reduced in obese children and are not related to insulin resistance.

Plasma levels and redox status of coenzyme Q10 in infants and children

INTRODUCTION

Increased attention has been paid to the role of lipophilic antioxidants in childhood nutrition and diseases during recent years. The lipophilic antioxidant coenzyme Q10 (CoQ10) is known as an effective inhibitor of oxidative damage. In contrast to other lipophilic antioxidants like alpha-tocopherol the plasma concentrations of CoQ10 in childhood are poorly researched. The aim of this study was to determine plasma level and redox status (oxidized form in total CoQ10 in %) of CoQ10 in clinically healthy infants, preschoolers and school-aged children.

METHODS

Plasma level and redox status of CoQ10 were measured by HPLC in 199 clinically healthy children, three groups of infants [1st-4th month (n = 35), 5th-8th month (n = 25), 9th-12th month (n = 25) ], preschoolers (n = 60) and school-aged children (n = 54). The CoQ10 plasma levels were related to plasma cholesterol concentrations. The median and the 5th and 95th percentile were calculated.

RESULTS

Plasma levels and redox status of CoQ10 in infants were significantly higher than in preschoolers and school-aged children. The CoQ10 redox status in the 1st-4th month was significantly increased when compared to the remaining subgroups of infants. In elder children the CoQ10 redox status stabilized.

CONCLUSIONS

This is the first study concerning age-related values of plasma level and redox status of CoQ10 in apparently healthy children. Decreased CoQ10 values could be involved in various pathological conditions affecting childhood. Therefore, the application of age-adjusted reference values may provide more specific criteria to define threshold values for CoQ10 deficiency in plasma.

Plasma coenzyme Q10 reference intervals, but not redox status, are affected by gender and race in self-reported healthy adults

BACKGROUND

Abnormal concentrations of coenzyme Q(10) have been reported in many patient groups, including certain cardiovascular, neurological, hematological, neoplastic, renal, and metabolic diseases. However, controls in these studies are often limited in number, poorly screened, and inadequately evaluated statistically. The purpose of this study is to determine the reference intervals of plasma concentrations of ubiquinone-10, ubiquinol-10, and total coenzyme Q(10) for self-reported healthy adults.

METHODS

Adults (n=148), who were participants in the Princeton Prevalence Follow-up Study, were identified as healthy by questionnaire. Lipid profiles, ubiquinone-10, ubiquinol-10, and total coenzyme Q(10) concentrations were measured in plasma. The method used to determine the reference intervals is a procedure incorporating outlier detection followed by robust point estimates of the appropriate quantiles.

RESULTS

Significant differences between males and females were present for ubiquinol-10 and total coenzyme Q(10). Blacks had significantly higher Q(10) measures than whites in all cases except for the ubiquinol-10/total Q(10) fraction.

CONCLUSIONS

The fraction of ubiquinol-10/total coenzyme Q(10) is a tightly regulated measure in self-reported healthy adults, and is independent of sex and racial differences. Different reference intervals for certain coenzyme Q(10) measures may need to be established based upon sex and racial characteristics.

Coenzyme Q10 reduces the toxicity of rotenone in neuronal cultures by preserving the mitochondrial membrane potential

Defects in mitochondrial energy metabolism due to respiratory chain disorders lead to a decrease in mitochondrial membrane potential (DeltaPsim) and induce apoptosis. Since coenzyme Q10 (CoQ10) plays a dual role as an antioxidant and bioenergetic agent in the respiratory chain, it has attracted increasing attention concerning the prevention of apoptosis in mitochondrial diseases. In this study the potential of CoQ10 to antagonize the apoptosis-inducing effects of the respiratory chain inhibitor rotenone was explored by video-enhanced microscopy in SH-SY5Y neuroblastoma cells. The cationic fluorescent dye JC-1 which exhibits potential-dependent accumulation in mitochondria was used as an indicator to monitor changes in DeltaPsim. The relative changes in fluorescence intensity after incubation with rotenone for 15 minutes were calculated. Pre-treatment with CoQ10 (10 or 100 microM) for 48 h led to a significant reduction of rotenone-induced loss of DeltaPsim. These results suggest, that cytoprotection by CoQ10 may be mediated by raising cellular resistance against the initiating steps of apoptosis, namely the decrease of DeltaPsim. Whether these data may provide new directions for the development of neuroprotective strategies has to be investigated in future studies.