Total Coenzyme Q10 Research Articles

Increased oxidative stress and coenzyme Q10 deficiency in centenarians.

Aging populations are expanding worldwide, and the increasing requirement for nursing care has become a serious problem. Furthermore, successful aging is one of the highest priorities for individuals and societies. Centenarians are an informative cohort to study and inflammation has been found to be a key factor in predicting cognition and physical capabilities. Inflammation scores have been determined based on the levels of cytokines and C-reactive protein, however, serum antioxidants and lipid profiles have not been carefully examined. We found that the redox balance of coenzyme Q10 significantly shifted to the oxidized form and levels of strong antioxidants, such as ascorbic acid and unconjugated bilirubin, decreased significantly compared to 76-year-old controls, indicating an increased oxidative stress in centenarians. Levels of uric acid, an endogenous peroxynitrite scavenger, remained unchanged, suggesting that centenarians were experiencing moderate, chronic inflammatory conditions. Centenarians exhibited a hypocholesterolemic condition, while an increase in the ratio of free cholesterol to cholesterol esters suggests some impairment of liver function. Serum free fatty acids and monoenoic acid composition, markers of tissue oxidative damage, were significantly decreased in centenarians, indicating an impairment in the tissue repair system. Despite an elevation of the coenzyme Q10 binding protein Psap, serum total coenzyme Q10 levels decreased in centenarians. This suggests a serious deficiency of coenzyme Q10 in tissues, since tissue levels of coenzyme Q10 significantly decrease with age. Therefore, coenzyme Q10 supplementation could be beneficial for centenarians.

Increased oxidative stress and renal injury in patients with sepsis.

Sepsis remains one of the leading causes of death in intensive care units. The early phase of sepsis is characterized by a massive formation of reactive oxygen and nitrogen species such as superoxide and nitric oxide. However, few comprehensive studies on plasma antioxidants have been reported. Increased oxidative stress was confirmed in sepsis patients (n = 18) at the time of hospitalization by a significant decrease in plasma ascorbic acid and a significant increase in the percentage of oxidized form of coenzyme Q10 in total coenzyme Q10 compared to age-matched healthy controls (n = 62). Tissue oxidative damage in patients was suggested by a significant decrease in polyunsaturated fatty acid contents and a significant increase in oleic acid contents in total free fatty acids. Thus, it is reasonable that plasma uric acid (end product of purines) would be significantly elevated. However, uric acid levels were continuously decreased during hospitalization for 7 days, indicating a continuous formation of peroxynitrite. A greater decrease in free cholesterol (FC) compared to cholesterol esters (CE) was observed. Thus, the FC/CE ratio significantly increased, suggesting deficiency of lecithin-cholesterol acyltransferase secreted from the liver. Plasma levels of prosaposin, a coenzyme Q10 binding protein, significantly decreased as compared to healthy controls. This may be correlated with renal injury in sepsis patients, since the kidney is thought to be a major secretor of prosaposin.

Three-Year Follow-Up of High-Dose Ubiquinol Supplementation in a Case of Familial Multiple System Atrophy with Compound Heterozygous COQ2 Mutations

We report a 3-year follow-up of high-dose ubiquinol supplementation in a case of familial multiple system atrophy (MSA) with compound heterozygous nonsense (R387X) and missense (V393A) mutations in COQ2. A high-dose ubiquinol supplementation substantially increased total coenzyme Q10 levels in cerebrospinal fluid as well as in plasma. The patient was at the advanced stage of MSA, and the various scores of clinical rating scales remained stable without changes during the 3 years. The cerebral metabolic ratio of oxygen measured by 15O2 PET, however, increased by approximately 30% after administration of ubiquinol, suggesting that ubiquinol can improve mitochondrial oxidative metabolism in the brain. It also suggests the therapeutic potential of ubiquinol for patients with MSA with COQ2 mutations. Further clinical trials of administration of high-dose ubiquinol to MSA patients are warranted.

Effects of Treated Palm Oil Mill Effluent Application on the Soil Microbial Community Structure and Oil Palm Plantation Productivity

The palm oil mill effluent (POME) is generally treated using biological anaerobic treatment and then utilized for POME land application. This research aimed to study the effect of treated POME land application on soil microbial community structure in oil palm plantation and their impact to the oil palm productivity. The results showed that ubiquinone (UQ) and menaquinone (MK) contents in soils without treated POME application were 0.045 and 0.204 μmol/kg-dry soils, respectively. These were much lower than the UQ and MK contents in soils with treated POME application which were 0.074 and 0.301 μmol/ kg-dry soils, respectively. The diversity quinone (DQ) and bioenergetic divergence quinone (BDq) in soils without treated POME application were 11.21 and 0.86, respectively, while in soils with treated POME application were 11.32 and 0.87, respectively. These results indicate that the treated POME application increased the amount of microorganisms but did not change the diversity of microorganisms. Treated POME application also increased the domination of aerobic bacteria in soils. The total UQ, MK, and UQ/MK ratio of soils with treated POME application are higher than those of soils without treated POME application and the application of POME is generally able to increase oil palm productivity.

Oxidative stress and abnormal cholesterol metabolism in patients with post-cardiac arrest syndrome.

Patients with post-cardiac arrest syndrome (PCAS) suffer from whole body ischemia/reperfusion injury similar to that experienced by newborn babies. Increased oxidative stress was confirmed in PCAS patients (n = 40) at the time of hospitalization by a significant increase in the percentage of the oxidized form of coenzyme Q10 in total coenzyme Q10 compared to age-matched healthy controls (n = 55). Tissue oxidative damage in patients was suggested by the significant increase in plasma levels of free fatty acids (FFA) and the significant decrease in polyunsaturated fatty acid contents in total FFA. A greater decrease in free cholesterol (FC) compared to cholesterol esters (CE) was observed. Therefore, the FC/CE ratio significantly increased, suggesting deficiency of lecithin-cholesterol acyltransferase secreted from the liver. Time course changes of the above parameters were compared among 6 groups of patients divided according to outcome severity. Rapid declines of FC and CE were observed in patients who died within a day, while levels remained unchanged in patients discharged in a week. These data suggest that liver function is one of the key factors determining the survival of patients. Interestingly, therapeutic hypothermia treatment enhanced the increment of plasma ratio of coenzyme Q10 to total cholesterol at the end of rewarming.

142 - Alterations of Endogenous Coenzyme Q10 Levels in Human Cells after the Induction of Lipid Peroxidation by an Organic Peroxide

Coenzyme Q10 (CoQ10) is an essential electron carrier in the mitochondrial electron transport chain and also an endogenously synthesized lipid-soluble antioxidant. We have previously demonstrated that hydrogen peroxide increased CoQ10 levels, but disruption of mitochondrial membrane potential by the chemical uncoupler FCCP suppressed CoQ10 levels in the human 143B cells. Mor bioeover, we have also shown that the COQ5 protein, which is required for CoQ biosynthesis in yeast, is essential for maintaining CoQ10 levels in 143B cells. In this study, we investigated how the condition of enhanced lipid peroxidation affected levels of the reduced form (ubiquinol-10) and oxidized form (ubiquinone-10) of CoQ10. The organic peroxide tert-butyl hydroperoxide (TBHP) was used to induce lipid peroxidation in 143B cells. Levels of esterified F2-isoprostanes (F2-IsoPs) in cells, detected by the gas chromatography/mass spectrometry method, were confirmed to be elevated by a low, medium, or high dose of TBHP as early as after 4 h of treatment. The levels remained augmented after 18 h of TBHP treatment but the degree of the increase was less. Only the medium-dose and high-dose TBHP treatments enhanced total CoQ10 levels after 18 h or 24 h of treatment, but the high-dose TBHP treatment also enhanced ubiquinol-10 levels after 4 h of treatment. Transient knockdown of COQ5, which decreased CoQ10 levels, suppressed the increase of both ubiquinol-10 and ubiquinone-10 levels after 24-h TBHP treatment. These results demonstrate for the first time that specific augmentation of lipid peroxidation could up-regulate formation of endogenous CoQ10 levels and ubiquinol-10 could be the initially generated form.

Electrochemical Measurement of Coenzyme Q10 Using Disposable Interdigitatad Array Electrode

Introduction Coenzyme Q10 (CoQ10) is an important component of the mitochondrial respiratory chain which exists as both oxidized form, CoQ10, and reduced form, CoQ10H2. CoQ10 is also known as an antioxidant in plasma, binding with lipoproteins during circulation. The antioxidative activity of CoQ10 depends on total CoQ10 concentration and percentage of CoQ10H2 in total CoQ10 in plasma. Since the ratio of CoQ10H2 is lower in patients with oxidative stress related diseases, it is considered to be an important marker for oxidative stress. At present, plasma CoQ10 and CoQ10H2 are usually determined by LC-electrochemical detector or LC-MS1,2) which are time-consuming, professional use and expensive analyzers. Considering the development of point of care (POCT) or on site sensor, simple, reliable, economical handy-type disposable test strip for CoQ10is favorable. Interdigitated array electrodes (IDAE) have excellent performances, such as high current density and high sensitivity, due to their hemisphere diffusion and array configuration. In this study, we will present electrochemical measurement of CoQ10using disposable IDAE for POCT or on site sensor. Methods Various concentrations of CoQ10 or CoQ10H2solution were prepared in mixture of 2-propanol and ammonium acetate aqueous solution . Amperometric measurements were performed by single mode or dual mode using IDAE. All solutions were bubbled with Ar before use. Results We first measured the dual mode redox current of working electrode 1 (collector electrode) and working electrode 2 (generator electrode), which were applied oxidizing potential and reducing potential, respectively. When CoQ10 solution was applied to sensor strip, faradaic signal from both generator and collector electrodes were soon reached to steady-state value. The response current on both generator and collector electrodes showed positive correlation with CoQ10 concentration. When CoQ10 oxidized form was applied to the strip, oxidation current was observed, indicating that CoQ10oxidized form was reduced onto the generator electrode and diffused and re-oxidized onto the collector electrode, thus redox cycle occurred successfully. Next, we measured the single mode redox current of working electrode 1 by applying reduction potential or oxidation potential. Reduction current was observed for CoQ10 and oxidation current was observed for CoQ10H2 and both of them exhibit steady- state currents soon after the potential application. The response current detected on working electrode 1 when reduction potential was applied to CoQ10 solution, oxidized form, showed positive correlation with CoQ10 concentration. When the oxidation potential was applied to CoQ10H2 solution, positive correlation with CoQ10H2concentration was observed. These results indicate that using IDAE, total CoQ10 concentration can be determined by dual mode amperometry and CoQ10 oxidized form or CoQ10H2can be determined by single mode amperometry (1) P. H. Tang et al., Clin. Chem. 2, 47 (2001) (2) J. Lagendijk, J. B. Ubbink, and W. J. H. Vermaak, J. Lipid Res. 1, 37 (1996) Figure 1

Serum Levels of Coenzyme Q10 in Patients with Multiple System Atrophy.

The COQ2 gene encodes an essential enzyme for biogenesis, coenzyme Q10 (CoQ10). Recessive mutations in this gene have recently been identified in families with multiple system atrophy (MSA). Moreover, specific heterozygous variants in the COQ2 gene have also been reported to confer susceptibility to sporadic MSA in Japanese cohorts. These findings have suggested the potential usefulness of CoQ10 as a blood-based biomarker for diagnosing MSA. This study measured serum levels of CoQ10 in 18 patients with MSA, 20 patients with Parkinson’s disease and 18 control participants. Although differences in total CoQ10 (i.e., total levels of serum CoQ10 and its reduced form) among the three groups were not significant, total CoQ10 level corrected by serum cholesterol was significantly lower in the MSA group than in the Control group. Our findings suggest that serum CoQ10 can be used as a biomarker in the diagnosis of MSA and to provide supportive evidence for the hypothesis that decreased levels of CoQ10 in brain tissue lead to an increased risk of MSA.

Coenzyme Q10 serum concentration and redox status in European adults: influence of age, sex, and lipoprotein concentration.

Coenzyme Q10 (CoQ10) is synthesized in almost all human tissues and presumably involved in age-related alterations and diseases. Here, we examined the impact of aging and sex on the serum CoQ10 status in 860 European adults ranging in age from 18 to 82 years. We identified an inverse U-shaped relationship between CoQ10 concentration and age. Women showed lower cholesterol-adjusted CoQ10 levels than men, irrespective of age. As observed in both sexes, the decrease in CoQ10 concentration in older subjects was accompanied by a shift in the redox status in favour of the oxidized form. A strong positive correlation was found for total CoQ10 and cholesterol concentrations (Spearman’s, p≤1E-74). We found strong negative correlations between total (Spearman’s, p≤1E-07) and between cholesterol-adjusted CoQ10 concentration (Spearman’s, p≤1E-14) and the proportion of the oxidized form of CoQ10. These correlations were not dependent on age and sex and were attenuated by supplementation with 150 mg/day reduced CoQ10 for 14 days. Overall, our results are useful to define risk groups with critical CoQ10 status in humans. In particular, older subjects were characterized by impaired CoQ10 status due to their lowered serum CoQ10 concentration and concomitant decrease of CoQ10 redox capacity.

Stability of ubiquinol-10 (reduced form of coenzyme Q10 ) in human blood.

The ratio of ubiquinol-10 in total coenzyme Q10 (TQ10 ) in human plasma has been proposed as a useful biomarker of oxidative stress. Since ubiquinol-10 is easily oxidized in air, it is necessary to perform suitable processing at medical institutions prior to analysis. To establish stable storage conditions for blood to determine the ubiquinol-10/TQ10 ratios properly, the effects of temperature conditions on the stability of ubiquinol-10 were studied. Blood samples were collected from nine male Japanese volunteers. Changes in ubiquinol-10/TQ10 ratios in blood samples were evaluated under three temperature conditions (room temperature, refrigerated and ice-cooled). Plasma levels of ubiquinol-10 and ubiquinone-10 were determined by an HPLC system with electrochemical detection and the ubiquinol-10/TQ10 ratios were calculated. We found that the ubiquinol-10/TQ10 ratio was stable up to 8 or 4 h when blood samples were stored in refrigerator or ice-cold container, respectively, and its decreases during these periods were <1.0%. We conclude that, in order to evaluate ubiquinol-10/TQ10 ratios, blood samples should be stored in a refrigerator or an ice-cold container, and processed for plasma separation within 4 h.

Dietary restriction decreases coenzyme Q and ubiquinol potentially via changes in gene expression in the model organism C. elegans.

Dietary restriction (DR) is a robust intervention that extends both health span and life span in many organisms. Ubiquinol and ubiquinone represent the reduced and oxidized forms of coenzyme Q (CoQ). CoQ plays a central role in energy metabolism and functions in several cellular processes including gene expression. Here we used the model organism Caenorhabditis elegans to determine level and redox state of CoQ and expression of genes in response to DR. We found that DR down-regulates the steady-state expression levels of several evolutionary conserved genes (i.e. coq-1) that encode key enzymes of the mevalonate and CoQ-synthesizing pathways. In line with this, DR decreases the levels of total CoQ and ubiquinol. This CoQ-reducing effect of DR is obvious in adult worms but not in L4 larvae and is also evident in the eat-2 mutant, a genetic model of DR. In conclusion, we propose that DR reduces the level of CoQ and ubiquinol via gene expression in the model organism C. elegans.

Redox status and pharmacokinetics of coenzyme Q10 in rat plasma after its single intravenous administration

Q10 corresponds to a onecompartment model ( R 2 = 0.9932), while the corresponding curve of its oxidized form fits to the twocompartment model. During the fi rst minutes after the injection a significant portion of plasma ubiquinone undergoes reduction, and after 7 h the concentration of ubiquinol predominates. The decrease in total plasma coenzyme Q10 content was accompanied by the gradual increase in plasma ubiquinol, which represented about 90% of total plasma CoQ10 by the end of the first day. The results of this study demonstrate the ability of the organism to transform high concentrations of the oxidized form of CoQ10 into the effective antioxidant (reduced) form and justify prospects of the development of parenteral dosage forms of CoQ10 for the use in the treatment of acute pathological conditions.

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

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

Culture Conditions Affect the Category and Production of Ubiquinones in a Recombinant Escherichia Coli with an Exogenous Decaprenyl Diphosphate Synthase

Ubiquinones (UQ) are important electron transporters and play lot of important roles in most organisms. In different species, UQ was classified to be UQ-6, 7, 8, 9, 10 according to their polyprenyl side chain length. The side chain's length is determined by the enzyme named Poly-Prenyl diphosphate synthases (PPPS). Bacteria are usually reconstructed to producing UQ-10 used in human's food additive, medicine or cosmetics, such as using decaprenyl Diphosphate Synthase (DPS) gene from R. radiobacter to substitute E.coli's octaprenyl diphosphate synthase gene , just like E. coli BL21 (�� ispB::ddsA) used in this study. It is interesting that not only in these reconstructed bacteria, but in human-being, DPS can synthesize UQ-9 besides UQ-10. The mechanism of this phenomenon is still unknown. In this study, the effects of culture conditions, including the temperature, dissolved oxygen, pH and culture medium, on the DPS characteristics in E. coli BL21 (�� ispB::ddsA) were examined. Results show that temperature greatly affects the ratio of UQ-9/UQ-10, but not the total ubiquinone's production. Increasing dissolved oxygen and protein concentration in culture medium can promote total ubiquinone's production, but not the ratio of UQ-9/UQ-10. These results may give reference for UQ-10's industrial produce and the mechanism of these conditions' effect on DPS will be discussed.

Culture Conditions affect the Category and Production of Ubiquinones in a Recombinant Escherichia Coli with an Exogenous Decaprenyl Diphosphate Synthase

Ubiquinones (UQ) are important electron transporters and play lot of important roles in most organisms. In different species, UQ was classified to be UQ-6, 7, 8, 9, 10 according to their polyprenyl side chain length. The side chain’s length is determined by the enzyme named Poly-Prenyl diphosphate synthases (PPPS). Bacteria are usually reconstructed to producing UQ-10 used in human’s food additive, medicine or cosmetics, such as using decaprenyl Diphosphate Synthase (DPS) gene from R. radiobacter to substitute <em>E.coli’s</em> octaprenyl diphosphate synthase gene , just like <em>E. coli</em> BL21 (△ispB::ddsA) used in this study. It is interesting that not only in these reconstructed bacteria, but in human-being, DPS can synthesize UQ-9 besides UQ-10. The mechanism of this phenomenon is still unknown. In this study, the effects of culture conditions, including the temperature, dissolved oxygen, pH and culture medium, on the DPS characteristics in <em>E. coli</em> BL21 (△ispB::ddsA) were examined. Results show that temperature greatly affects the ratio of UQ-9/UQ-10, but not the total ubiquinone’s production. Increasing dissolved oxygen and protein concentration in culture medium can promote total ubiquinone’s production, but not the ratio of UQ-9/UQ-10. These results may give reference for UQ-10’s industrial produce and the mechanism of these conditions’ effect on DPS will be discussed.

Determination of coenzyme Q10 tissue status via high-performance liquid chromatography with electrochemical detection in swine tissues (Sus scrofa domestica)

Swine tissues were used as surrogates for human tissues with coenzyme Q10 (CoQ10) as the primary endogenous quinoid to establish a reliable method for the analysis of total CoQ10 concentration and redox status using the reduced and oxidized forms of CoQ9 as internal standards. Specimens of frozen swine tissues were disrupted by bead milling using 2-propanol as the homogenization medium supplemented with the internal standards. After hexane extraction, CoQ10 was analyzed via high-performance liquid chromatography with electrochemical detection. The method is linear (12–60mg fresh muscle tissue/sample), sensitive (∼200pmol CoQ10/sample), and reproducible (coefficients of variation of 6.0 and 3.2% for total CoQ10 and 2.4 and 3.2% for the redox status of within-day and day-to-day precision, respectively), with analytic recoveries for ubiquinone-10, ubihydroquinone-10, and total Q10 of 91, 104, and 94%, respectively. The concentration and redox status were stable for at least 3months at −84°C. The total CoQ10 concentrations (pmol/mg fresh tissue) in swine tissues were as follows: lung (17.4±1.42), skeletal muscle (26.7±2.57), brain (40.7±4.02), liver (62.1±31.0), kidney (111.7±37.08), and heart muscle (149.1±36.78). Significant tissue-specific variations were also found for the redox status (% oxidation of total): swine liver (∼28), lung (∼36), kidney (∼37), heart muscle (∼57), skeletal muscle (∼61), and brain (∼67).

Increased oxidative stress and coenzyme Q10 deficiency in juvenile fibromyalgia: amelioration of hypercholesterolemia and fatigue by ubiquinol-10 supplementation

Fibromyalgia (FM) is characterized by generalized pain and chronic fatigue of unknown etiology. To evaluate the role of oxidative stress in this disorder, we measured plasma levels of ubiquinone-10, ubiquinol-10, free cholesterol (FC), cholesterol esters (CE), and free fatty acids (FFA) in patients with juvenile FM (n = 10) and in healthy control subjects (n = 67). Levels of FC and CE were significantly increased in juvenile FM as compared with controls, suggesting the presence of hypercholesterolemia in this disease. However, plasma level of ubiquinol-10 was significantly decreased and the ratio of ubiquinone-10 to total coenzyme Q10 (%CoQ10) was significantly increased in juvenile FM relative to healthy controls, suggesting that FM is associated with coenzyme Q10 deficiency and increased oxidative stress. Moreover, plasma level of FFA was significantly higher and the content of polyunsaturated fatty acids (PUFA) in total FFA was significantly lower in FM than in controls, suggesting increased tissue oxidative damage in juvenile FM. Interestingly, the content of monoenoic acids, such as oleic and palmitoleic acids, was significantly increased in FM relative to controls, probably to compensate for the loss of PUFA. Next, we examined the effect of ubiquinol-10 supplementation (100 mg/day for 12 weeks) in FM patients. This resulted in an increase in coenzyme Q10 levels and a decrease in %CoQ10. No changes were observed in FFA levels or their composition. However, plasma levels of FC and CE significantly decreased and the ratio of FC to CE also significantly decreased, suggesting that ubiquinol-10 supplementation improved cholesterol metabolism. Ubiquinol-10 supplementation also improved chronic fatigue scores as measured by the Chalder Fatigue Scale.

Pediatric reference intervals for muscle coenzyme Q10

Coenzyme Q10 (CoQ10) is present in humans in both the reduced (ubiquinol, CoQ10H2) and oxidized (ubiquinone, CoQ10) forms. CoQ10 is an essential cofactor in mitochondrial oxidative phosphorylation, and is necessary for ATP production. Total, reduced and oxidized CoQ10 levels in skeletal muscle of 148 children were determined by HPLC coupled with electrochemical detection, and we established three level thresholds for total CoQ10 in muscle. We defined as “severe deficiency”, CoQ10 levels falling in the range between 0.82 and 4.88 μmol/g tissue; as “intermediate deficiency”, those ranging between 5.40 and 9.80 μmol/g tissue, and as “mild deficiency”, the amount of CoQ10 included between 10.21 and 19.10 μmol/g tissue. Early identification of CoQ10 deficiency has important implications in children, not only for those with primary CoQ10 defect, but also for patients with neurodegenerative disorders, in order to encourage earlier supplementation with this agent also in mild and intermediate deficiency.

Coenzyme Q10 in Equine Serum: Response to Supplementation

Although the importance of coenzyme Q10 (CoQ10) in health and disease and its critical role in cellular bioenergetics have been well established in various species, there is a total lack of information on the role of CoQ10 in horses. Therefore, the present study was undertaken first to ascertain the occurrence of CoQ10 and/or possibly other homologs of coenzyme Q (CoQ) in horse serum, and then to examine the response to CoQ10 supplementation on serum CoQ10 concentration. The study was carried out with 2-year-old Thoroughbred horses. Total CoQ (reduced and oxidized forms) in serum was assayed by high-performance liquid chromatography. The data show that horse serum contains CoQ as CoQ10, at a much lower concentration as compared with that of humans and several other species. There is no evidence for the presence of coenzyme Q9 or other homologs of CoQ. On supplementation with CoQ10 at 800 mg a day (1.47 mg/kg body weight), there was a significant increase in serum CoQ10 concentration, approximately 2.7-fold at 60 days. CoQ10 supplementation at this dosage was found to be safe and well tolerated. Additional studies are needed to examine whether maintaining higher serum CoQ10 concentrations is of potential health benefit to the horses, as assessed by selected biochemical markers and also in terms of performance.

Coenzyme Q10, Hyperhomocysteinemia and MTHFR C677T Polymorphism in Levodopa-treated Parkinson’s Disease Patients

There is evidence that increased homocysteine (Hcy) levels might accelerate dopaminergic cell death in Parkinson's disease (PD) through neurotoxic effects. Homocysteine neurotoxicity mainly relies on redox state alterations. The present work was aimed at investigating the relationships between plasma Hcy concentrations and percent content of oxidized versus total Coenzyme Q10 (%CoQ10) in 60 PD patients and 82 healthy subjects. Both groups were screened for plasma levels of Hcy, vitamin B12, folate, %CoQ10 and C677T methylenetetrahydrofolate reductase (MTHFR) gene polymorphism. The MTHFR TT677 mutated genotype was found more frequently in patients than in controls (p = 0.01). In a multivariate analysis, Hcy levels and %CoQ10 were associated with the case/control category (p < 0.0001), MTHFR genotype (p < 0.0001) and their interaction term (p = 0.0015), even after adjusting for age, sex, folate and vitamin B12. Patients carrying the TT677 genotype exhibited the highest values of Hcy and %CoQ10 (p < 0.0001). Structural equation modelling evidenced that the TT677 genotype and levodopa daily dose were independently and directly correlated with Hcy (p < 0.0001, and p = 0.003, respectively), which, in turn, showed a significant correlation (p < 0.0001) with the %CoQ10 in PD patients. Our results suggest that increased Hcy levels act as mediator of the systemic oxidative stress occurring in PD, and %CoQ10 determination might be regarded as a predictor of toxic Hcy effects.