Plasma coenzyme Q10 response to oral ingestion of coenzyme Q10 formulations

Plasma coenzyme Q10 (CoQ10) response to oral ingestion of various CoQ10 formulations was examined. Both total plasma CoQ10 and net increase over baseline CoQ10 concentrations show a gradual increase with increasing doses of CoQ10. Plasma CoQ10 concentrations plateau at a dose of 2400 mg using one specific chewable tablet formulation. The efficiency of absorption decreases as the dose increases. About 95% of circulating CoQ10 occurs as ubiquinol, with no appreciable change in the ratio following CoQ10 ingestion. Higher plasma CoQ10 concentrations are necessary to facilitate uptake by peripheral tissues and also the brain. Solubilized formulations of CoQ10 (both ubiquinone and ubiquinol) have superior bioavailability as evidenced by their enhanced plasma CoQ10 responses.     

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.     

Primary coenzyme Q10 deficiency and the brain

Our findings in 19 new patients with cerebellar ataxia establish the existence of an ataxic syndrome due to primary CoQ10 deficiency and responsive to CoQ10 therapy. As all patients presented cerebellar ataxia and cerebellar atrophy, this suggests a selective vulnerability of the cerebellum to CoQ10 deficiency. We investigated the regional distribution of coenzyme Q10 in the brain of adult rats and in the brain of one human subject. We also evaluated the levels of coenzyme Q9 (CoQ9) and CoQ10 in different brain regions and in visceral tissues of rats before and after oral administration of CoQ10. Our results show that in rats, amongst the seven brain regions studied, cerebellum contains the lowest level of CoQ. However, the relative proportion of CoQ10 was the same (about 30% of total CoQ) in all regions studied. The level of CoQ10 is much higher in brain than in blood or visceral tissue, such as liver, heart, or kidney. Daily oral administration of CoQ10 led to substantial increases of CoQ10 concentrations only in blood and liver. Of the four regions of one human brain studied, cerebellum again had the lowest CoQ10y concentration.     

Effects of coenzyme Q10 and alpha-tocopherol administration on their tissue levels in the mouse: elevation of mitochondrial alpha-tocopherol by coenzyme Q10.

Coenzyme Q (CoQ) was previously demonstrated in vitro to indirectly act as an antioxidant in respiring mitochondria by regenerating alpha-tocopherol from its phenoxyl radical. The objective of this study was to determine whether CoQ has a similar sparing effect on alpha-tocopherol in vivo. Mice were administered CoQ10 (123 mg/kg/day) alone, or alpha-tocopherol (200 mg/kg/day) alone, or both, for 13 weeks, after which the amounts of CoQ10, CoQ9 and alpha-tocopherol were determined by HPLC in the serum as well as homogenates and mitochondria of liver, kidney, heart, upper hindlimb skeletal muscle and brain. Administration of CoQ10 and alpha-tocopherol, alone or together, increased the corresponding levels of CoQ10 and alpha-tocopherol in the serum. Supplementation with CoQ10 also elevated the amounts of the predominant homologue CoQ9 in the serum and the mitochondria. A notable effect of CoQ10 intake was the enhancement of alpha-tocopherol in mitochondria. alpha-Tocopherol administration resulted in an elevation of alpha-tocopherol content in the homogenates of nearly all tissues and their mitochondria. Results of this study thus indicate that relatively long-term administration of CoQ10 or alpha-tocopherol can result in an elevation of their concentrations in the tissues of the mouse. More importantly, CoQ10 intake has a sparing effect on alpha-tocopherol in mitochondria in vivo.     

Biotechnological production and applications of coenzyme Q10

An efficient whole cell biotransformation process using Lactobacillus kefir was developed for the asymmetric synthesis of tert-butyl (3R, 5S) 6-chloro-dihydroxyhexanoate, a chiral building block for the HMG-CoA reductase inhibitor. The effects of buffer concentration, temperature, pH and oxygen on the asymmetric reduction were investigated in batch reactions. Improvements in final product concentration and yields of 153% (120 mM) and 79% (0.85 mol/mol) with respect to the batch-process were achieved in an optimised fed-batch process. The pure substrate tert-butyl-6-chloro-3,5-dioxohexanoate was dispersed as microdroplets into the reaction system. This resulted in a space-time yield of 4.7 mmol l⁻¹ h⁻¹. A diastereomeric excess of >99% was measured for (3R, 5S) and (3S, 5S) tert-butyl 6-chloro-dihydroxyhexanoate.     

Recombinant expression of His-tagged saposin B and pH-dependent binding to the lipid coenzyme Q10

The use of coenzyme Q10 (CoQ10) has been increasing rapidly during recent years due to its postulated beneficial properties in human health, providing energy and antioxidant protection. There are no known negative side effects of CoQ10 even at very high levels. Recently, native saposin B (sapB) has been shown to bind CoQ10 and subsequently be excreted. It is thought that this interaction between sapB and CoQ10 could be a mechanism to avoid any possible CoQ10 toxicity. The interaction between sapB and CoQ10 is poorly understood. Here we present an increased fermentative yield of recombinant sapB and demonstrate that recombinant sapB will bind CoQ10 in a pH-dependent manner similar to sapB binding with other lipids. SapB was coated onto an IMAC (immobilized metal affinity chromatography) resin and successfully bound CoQ10 at pH 5.0 with release of the CoQ10 at pH 9.0.     

Plasma membrane coenzyme Q10 and growth control

Summary Coenzyme Q is distributed among cellular membranes and it has a significant concentration at the plasma membrane. The plasma membrane contains a trans-membrane electron transport system, which is centered on coenzyme Q. This molecule is maintained reduced by NAD(P)H-dependent enzymes and can reduce other antioxidants such as tocopheroxyl quinone and ascorbate free radical. Its antioxidant property and its ability to maintain in the reduced state the other antioxidants offers a system to protect membrane components against oxidations and prevents oxidative-stress-dependent cellular damage. Growth factor withdrawal induces cell growth arrest and apoptosis through an oxidative-stress-induced pathway. Coenzyme Q can stimulate growth of different cell lines under serum deficiency, mainly by preventing apoptosis. The protection caused by coenzyme Q is independent of the Bcl-2 protein. Plasma membrane coenzyme Q appears to be essential in the regulation of the redox equilibrium of the cell and redox-dependent pathways.     

Characterization of cellular uptake and distribution of coenzyme Q10 and vitamin E in PC12 cells

Coenzyme Q (CoQ) is a well-known electron transporter in the mitochondrial respiratory chain. Furthermore, ubiquinol (UQH(2))--a reduced form of ubiquinone (UQ)--has been shown to act as a radical-scavenging antioxidant. Some studies have reported the beneficial effect of CoQ addition to cultured cells; however, the cellular uptake and distribution of CoQ have not been elucidated. In the present study, we used rat pheochromocytoma PC12 cells to investigate and compare the cellular uptake and distribution of CoQ(10) and alpha-tocopherol (alphaT). UQ(10) or UQ(10)H(2) treatment resulted in an increase in the cellular content of both CoQ(10) in a time- and concentration-dependent manner. A subcellular fractionation study revealed that the added UQ(10) as well as UQ(10)H(2) mainly localized in the mitochondrial fraction, which is similar to the localization of endogenous CoQ but different from that of alphaT. The cellular distribution of alphaT directly corresponded to the lipid distribution, while the CoQ distribution did not show any relationship with the lipid distribution, particularly in the mitochondrial and microsomal fractions. These results indicate that the cellular distribution of CoQ is completely different from that of alphaT; moreover, a certain system which accumulates CoQ preferentially in mitochondria may be suggested.     

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

The pharmacokinetics of the total pool of coenzyme Q₁₀ (CoQ₁₀), its oxidized (ubiquinone) and reduced (ubiquinol, CoQ₁₀H₂) forms have been investigated in rats plasma during 48 h after a single intravenous injection of a solution of solubilized CoQ₁₀ (10 mg/kg) to rats. Plasma levels of CoQ₁₀ were determined by HPLC with spectrophotometric and coulometric detection. In plasma samples taken during the first minutes after the CoQ₁₀ intravenous injection, the total pool of coenzyme Q₁₀ and proportion of CoQ₁₀H₂ remained unchanged during two weeks of storage at ?20°C. The kinetic curve of the total pool of coenzyme Q₁₀ corresponds to a one-compartment model (R ₂ = 0.9932), while the corresponding curve of its oxidized form fits to the two-compartment model. During the first 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.     

Effect of coenzyme Q10 and vitamin E on brain energy metabolism in the animal model of Huntington's disease

The neuropathological and clinical symptoms of Huntington's disease (HD) can be simulated in animal model with systemic administration of 3-nitropropionic acid (3-NP). Energy defects in HD could be ameliorated by administration of coenzyme Q(10) (CoQ(10)), creatine, or nicotinamid. We studied the activity of creatine kinase (CK) and the function of mitochondrial respiratory chain in the brain of aged rats administered with 3-NP with and without previous application of antioxidants CoQ(10)+vitamin E. We used dynamic and steady-state methods of in vivo phosphorus magnetic resonance spectroscopy ((31)P MRS) for determination of the pseudo-first order rate constant (k(for)) of the forward CK reaction, the phosphocreatine (PCr) to adenosinetriphosphate (ATP) ratio, intracellular pH(i) and Mg(i)(2+) content in the brain. The respiratory chain function of isolated mitochondria was assessed polarographically; the concentration of CoQ(10) and alpha-tocopherol by HPLC. We found significant elevation of k(for) in brains of 3-NP rats, reflecting increased rate of CK reaction in cytosol. The function of respiratory chain in the presence of succinate was severely diminished. The activity of cytochromeoxidase and mitochondrial concentration of CoQ(10) was unaltered; tissue content of CoQ(10) was decreased in 3-NP rats. Antioxidants CoQ(10)+vitamin E prevented increase of k(for) and the decrease of CoQ(10) content in brain tissue, but were ineffective to prevent the decline of respiratory chain function. We suppose that increased activity of CK system could be compensatory to decreased mitochondrial ATP production, and CoQ(10)+vitamin E could prevent the increase of k(for) after 3-NP treatment likely by activity of CoQ(10) outside the mitochondria. Results of our experiments contributed to elucidation of mechanism of beneficial effect of CoQ(10) administration in HD and showed that the rate constant of CK is a sensitive indicator of brain energy disorder reflecting therapeutic effect of drugs that could be used as a new in vivo biomarker of neurodegenerative diseases.     

Cardiac performance and coenzyme Q10 in thyroid disorders

To investigate the relationship between serum levels of Coenzyme Q10 and cardiac performance in thyroid disorders, we studied the cardiac performance and assessed serum levels of thyroid hormones and Coenzyme Q10 in 20 patients with hyperthyroidism, 5 patients with hypothyroidism and 10 normal subjects. A significant inverse correlation between thyroid hormones and Coenzyme Q10 levels was found by performing partial correlation analysis. Because low serum levels of Coenzyme Q10 were found in thyrotoxic patients and congestive heart failure may occur as a result of severe hyperthyroidism, 120 mg of Coenzyme Q10 was administered daily for one week to 12 hyperthyroid patients and the change in cardiac performance was assessed. Further augmentation of cardiac performance was found in hyperthyroid hearts, which were already augmented, after the administration of Coenzyme Q10. It appears, therefore, that the Coenzyme Q10 dose actually has a therapeutic value for congestive heart failure induced by severe thyrotoxicosis.     

The uptake and distribution of coenzyme Q(10)

This review describes recent advances in our understanding of the uptake and distribution of coenzyme Q10 (CoQ10) in cells, animals, and humans. These advances have provided evidence of important pharmacokinetic factors, such as non-linear absorption and enterohepatic recirculation, and may facilitate the development of new CoQ10 formulations. Studies providing data which support the claim of tissue uptake of exogenous CoQ10 are also discussed. Improved CoQ10 dosing and drug level monitoring guidelines are suggested for adult and pediatric patient populations. Future CoQ10 research should consider uptake and distribution factors to determine cost-benefit relationships.     

Preparation and quality evaluation of coenzyme Q10 long-circulating liposomes

The aim of this work was to prepare coenzyme Q10 (CoQ10) long-circulating liposomes, and establish the quality standard to determine the content and entrapment efficiency. CoQ10 long-circulating liposomes were prepared by the film dispersion method, HPLC assay for the determination of CoQ10 was developed. Free drugs and liposomes were separated using the protamine aggregation method and entrapment efficiency was determined. The liposomes were homogeneous and the mean diameter was 166.0 nm, Zeta potential was −22.2 mV. The content and entrapment efficiency of CoQ10 were 98.2% and 93.2% for three batches of liposomes, respectively. The lyophilized form of liposomes prepared by freeze-drying showed stable quality characteristics during storage. The formulation and preparative method can be used to prepare CoQ10 long-circulating liposomes with high entrapment efficiency and high quality, the determination method of drug content and entrapment efficiency were effective and rapid and can be used for quality evaluation of liposomes.