Ca<Superscript>2+</Superscript> increases the specific coenzyme Q<Subscript>10</Subscript> content in <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

Of various metal ions (Ca²⁺, Cr³⁺, Cu²⁺, Fe²⁺, Mg²⁺, Mn²⁺, Ni²⁺ and Zn²⁺) added to the culture medium of Agrobacterium tumefaciens at 1 mM, only Ca²⁺ increased Coenzyme Q10 (CoQ₁₀) content in cells without the inhibition of cell growth. In a pH-stat fed-batch culture, supplementation with 40 mM of CaCO₃ increased the specific CoQ₁₀ content and oxidative stress by 22.4 and 48%, respectively. Also, the effect of Ca²⁺ on the increase of CoQ₁₀ content was successfully verified in a pilot-scale (300 L) fermentor. In this study, the increased oxidative stress in A. tumefaciens culture by the supplementation of Ca²⁺ is hypothesized to stimulate the increase of specific CoQ₁₀ content in order to protect the membrane against lipid peroxidation. Our results improve the understanding of Ca²⁺ effect on CoQ₁₀ biosynthesis in A. tumefaciens and should contribute to better industrial production of CoQ₁₀ by biological processes.     

Impact of Carrier Systems on the Interactions of Coenzyme Q<Subscript>10</Subscript> with Model Lipid Membranes

We investigated the influence of carrier systems for different commercially available water-soluble formulations for coenzyme Q₁₀ on structural changes of model lipid membranes formed by 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and by a mixture of phosphatidylcholine and sphingomyelin (2.4:1). Structural changes in the membranes were measured using fluorescence anisotropy, electron paramagnetic resonance, and differential scanning calorimetry. Two fluorophores and two spin probes were used to monitor membrane characteristics close to the water-lipid interface and in the middle of the bilayer of the model lipid membranes. Different water-soluble carrier systems were tested. These data show that different systems can facilitate penetration of CoQ₁₀ in the lipid membranes, where an increase in the lipid order parameter was observed. In addition, water soluble CoQ₁₀ formulations better protect lipids from oxidation in liposome solution. With the exception of the carriers in an emulsified formulation of CoQ₁₀, those in the other samples did not have any significant effects on membrane fluidity.     

A water soluble CoQ10 formulation improves intracellular distribution and promotes mitochondrial respiration in cultured cells

Background

Mitochondria are both the cellular powerhouse and the major source of reactive oxygen species. Coenzyme Q₁₀ plays a key role in mitochondrial energy production and is recognized as a powerful antioxidant. For these reasons it can be argued that higher mitochondrial ubiquinone levels may enhance the energy state and protect from oxidative stress. Despite the large number of clinical studies on the effect of CoQ₁₀ supplementation, there are very few experimental data about the mitochondrial ubiquinone content and the cellular bioenergetic state after supplementation. Controversial clinical and in vitro results are mainly due to the high hydrophobicity of this compound, which reduces its bioavailability.

Principal Findings

We measured the cellular and mitochondrial ubiquinone content in two cell lines (T67 and H9c2) after supplementation with a hydrophilic CoQ₁₀ formulation (Qter®) and native CoQ₁₀. Our results show that the water soluble formulation is more efficient in increasing ubiquinone levels. We have evaluated the bioenergetics effect of ubiquinone treatment, demonstrating that intracellular CoQ₁₀ content after Qter supplementation positively correlates with an improved mitochondrial functionality (increased oxygen consumption rate, transmembrane potential, ATP synthesis) and resistance to oxidative stress.

Conclusions

The improved cellular energy metabolism related to increased CoQ₁₀ content represents a strong rationale for the clinical use of coenzyme Q₁₀ and highlights the biological effects of Qter®, that make it the eligible CoQ₁₀ formulation for the ubiquinone supplementation.     

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.     

Coenzyme Q and vitamin E need each other as antioxidants

Summary Both vitamin E and coenzyme Q possess distinct lipoprotective antioxidant properties in biological membranes. Their combined antioxidant activity, however, is markedly synergistic when both are present together. While it is likely that vitamin E represents the initial chain-breaking antioxidant during lipid peroxidation, both fully reduced CoQH₂ (ubiquinol) and semireduced CoQH^. (ubisemiquinone) appear to efficiently recycle the resultant vitamin E phenoxyl radical back to its biologically active reduced form. We describe and support a potential kinetic mechanism whereby vitamin E and coenzyme Q interact in such a way as to usurp the prooxidant effects of O ₂ ^−. . Physical interactions of vitamin E and coenzyme Q within the environment of the membrane lipid bilayer facilitate the recycling of vitamin E by ubisemiquinone and ubiquinol. Lastly, data are linked into a catalytic cycle that serves to connect normal electron transport mechanisms within biological membranes to the maintenance of lipoprotective antioxidant mechanisms.     

Distribution of Coenzyme Q Homologues in Brain

Ubiquinone (coenzyme Q₁₀), in addition to its function as an electron and proton carrier in mitochondrial electron transport coupled to ATP synthesis, acts in its reduced form (ubiquinol) as an antioxidant, inhibiting lipid peroxidation in biological membranes and protecting mitochondrial inner-membrane proteins and DNA against oxidative damage accompanying lipid peroxidation. Tissue ubiquinone levels are subject to regulation by physiological factors that are related to the oxidative activity of the organism: they increase under the influence of oxidative stress, e.g. physical exercise, cold adaptation, thyroid hormone treatment, and decrease during aging. In the present study, coenzyme Q homologues were separated and quantified in the brains of mice, rats, rabbits, and chickens using high-performance liquid chromatography. In addition, the coenzyme Q homologues were measured in cells such as NG-108, PC-12, rat fetal brain cells and human SHSY-5Y and monocytes. In general, Q₁ content was the lowest among the coenzyme homologues quantified in the brain. Q₉ was not detectable in the brains of chickens and rabbits, but was present in the brains of rats and mice. Q₉ was also not detected in human cell lines SHSY-5Y and monocytes. Q₁₀ was detected in the brains of mice, rats, rabbits, and chickens and in cell lines. Since both coenzyme Q and vitamin E are antioxidants, and coenzyme Q recycles vitamins E and C, vitamin E was also quantified in mice brain using HPLC-electrochemical detector (ECD). The quantity of vitamin E was lowest in the substantia nigra compared with the other brain regions. This finding is crucial in elucidating ubiquinone function in bioenergetics; in preventing free radical generation, lipid peroxidation, and apoptosis in the brain; and as a potential compound in treating various neurodegenerative disorders.     

Enhancement of antibody production by the addition of Coenzyme-Q<Subscript>10</Subscript>

Recently, there has been a growing demand for therapeutic monoclonal antibodies (MAbs) on the global market. Because therapeutic MAbs are more expensive than low-molecular-weight drugs, there have been strong demands to lower their production costs. Therefore, efficient methods to minimize the cost of goods are currently active areas of research. We have screened several enhancers of specific MAb production rate (SPR) using a YB2/0 cell line and found that coenzyme-Q₁₀ (CoQ₁₀) is a promising enhancer candidate. CoQ₁₀ is well known as a strong antioxidant in the respiratory chain and is used for healthcare and other applications. Because CoQ₁₀ is negligibly water soluble, most studies are limited by low concentrations. We added CoQ₁₀ to a culture medium as dispersed nanoparticles at several concentrations (Q-Media) and conducted a fed-batch culture. Although the Q-Media had no effect on cumulative viable cell density, it enhanced SPR by 29%. In addition, the Q-Media had no effect on the binding or cytotoxic activity of MAbs. Q-Media also enhanced SPR with CHO and NS0 cell lines by 30%. These observations suggest that CoQ₁₀ serves as a powerful aid in the production of MAbs by enhancing SPR without changing the characteristics of cell growth, or adversely affecting the quality or biological activity of MAbs.     

A role for reduced coenzyme Q in atherosclerosis?

Substantial evidence implicates oxidative modification of low density lipoprotein (LDL) as an important event contributing to atherogenesis. As a result, the elucidation of the molecular mechanisms by which LDL is oxidized and how such oxidation is prevented by antioxidants has been a significant research focus. Studies on the antioxidation of LDL lipids have focused primarily on alpha-tocopherol (alpha-TOH), biologically and chemically the most active form of vitamin E and quantitatively the major lipid-soluble antioxidant in extracts prepared from human LDL. In addition to alpha-TOH, plasma LDL also contains low levels of ubiquinol-10 (CoQ10H2; the reduced form of coenzyme Q10). Recent studies have shown that in oxidizing plasma lipoproteins alpha-TOH can exhibit anti- or pro-oxidant activities for the lipoprotein's lipids exposed to a vast array of oxidants. This article reviews the molecular action of alpha-TOH in LDL undergoing "mild" radical-initiated lipid peroxidation, and discusses how small levels of CoQ10H2 can represent an efficient antioxidant defence for lipoprotein lipids. We also comment on the levels alpha-TOH, CoQ10H2 and lipid oxidation products in the intima of patients with coronary artery disease and report on preliminary studies examining the effect of coenzyme Q10 supplementation on atherogenesis in apolipoprotein E knockout mice.     

CoQ10 supplementation rescues nephrotic syndrome through normalization of H2S oxidation pathway

Nephrotic syndrome (NS), a frequent chronic kidney disease in children and young adults, is the most common phenotype associated with primary coenzyme Q₁₀ (CoQ₁₀) deficiency and is very responsive to CoQ₁₀ supplementation, although the pathomechanism is not clear. Here, using a mouse model of CoQ deficiency-associated NS, we show that long-term oral CoQ₁₀ supplementation prevents kidney failure by rescuing defects of sulfides oxidation and ameliorating oxidative stress, despite only incomplete normalization of kidney CoQ levels and lack of rescue of CoQ-dependent respiratory enzymes activities. Liver and kidney lipidomics, and urine metabolomics analyses, did not show CoQ metabolites. To further demonstrate that sulfides metabolism defects cause oxidative stress in CoQ deficiency, we show that silencing of sulfide quinone oxido-reductase (SQOR) in wild-type HeLa cells leads to similar increases of reactive oxygen species (ROS) observed in HeLa cells depleted of the CoQ biosynthesis regulatory protein COQ8A. While CoQ₁₀ supplementation of COQ8A depleted cells decreases ROS and increases SQOR protein levels, knock-down of SQOR prevents CoQ₁₀ antioxidant effects. We conclude that kidney failure in CoQ deficiency-associated NS is caused by oxidative stress mediated by impaired sulfides oxidation and propose that CoQ supplementation does not significantly increase the kidney pool of CoQ bound to the respiratory supercomplexes, but rather enhances the free pool of CoQ, which stabilizes SQOR protein levels rescuing oxidative stress.     

Localization of coenzyme Q10 in the center of a deuterated lipid membrane by neutron diffraction

Quinones (e.g., coenzyme Q, CoQ₁₀) are best known as carriers of electrons and protons during oxidative phosphorylation and photosynthesis. A myriad of mostly more indirect physical methods, including fluorescence spectroscopy, electron-spin resonance, and nuclear magnetic resonance, has been used to localize CoQ₁₀ within lipid membranes. They have yielded equivocal and sometimes contradictory results. Seeking unambiguous evidence for the localization of ubiquinone within lipid bilayers, we have employed neutron diffraction. CoQ₁₀ was incorporated into stacked bilayers of perdeuterated dimyristoyl phosphatidyl choline doped with dimyristoyl phosphatidyl serine containing perdeuterated chains in the natural fluid-crystalline state. Our data show CoQ₁₀ at the center of the hydrophobic core parallel to the membrane plane and not, as might be expected, parallel to the lipid chains. This localization is of importance for its function as a redox shuttle between the respiratory complexes and, taken together with our recent result that squalane is in the bilayer center, may be interpreted to show that all natural polyisoprene chains lie in the bilayer center. Thus ubiquinone, in addition to its free radical scavenging and its well-known role in oxidative phosphorylation as a carrier of electrons and protons, might also act as an inhibitor of transmembrane proton leaks.     

Protective effects of coenzyme Q10 and α-tocopherol against free radical-mediated liver cell injury

In an attempt to provide further confirmation of the antioxidant role of reduced form of coenzyme Q homologue (CoQ_nH₂) and α-tocopherol (α-Toc), we incubated isolated rat hepatocytes with a water-soluble radical initiator, 2,2′-azobis(2-amidinopropane)dihydrochloride (AAPH) in the presence or absence of exogenously added coenzyme Q₁₀ (CoQ₁₀) or α-Toc for 3 h at 37°C under an atmosphere of 95% oxygen and 5% carbon dioxide. In the control experiment without adding AAPH it was confirmed that added CoQ₁₀ and α-Toc were incorporated into the cells and some CoQ₁₀ were converted to CoQ₁₀H₂. Incubation of hepatocytes with 50 mM AAPH resulted in the formation of thiobarbituric acid-reactive substances and the decrease in cell viability and both were inhibited by exogenously added CoQ₁₀ or α-Toc in a dose-dependent manner. The decrease in endogenous CoQ₉H₂ and α-Toc levels was observed by the addition of AAPH. Addition of CoQ₁₀ inhibited the oxidation of CoQ₉H₂ to CoQ₉ dose-dependently while the addition of α-Toc did not. These data suggest that both CoQ_nH₂ and α-Toc act as antioxidants and can inhibit free radical-mediated cell injury.     

Therapeutic targeting of oxidative stress with coenzyme Q10 counteracts exaggerated diabetic cardiomyopathy in a mouse model of diabetes with diminished PI3K(p110α) signaling

Diabetes-induced cardiac complications include left ventricular (LV) dysfunction and heart failure. We previously demonstrated that LV phosphoinositide 3-kinase p110α (PI3K) protects the heart against diabetic cardiomyopathy, associated with reduced NADPH oxidase expression and activity. Conversely, in dominant negative PI3K(p110α) transgenic mice (dnPI3K), reduced cardiac PI3K signaling exaggerated diabetes-induced cardiomyopathy, associated with upregulated NADPH oxidase. The goal was to examine whether chronic supplementation with the antioxidant coenzyme Q₁₀ (CoQ₁₀) could attenuate LV superoxide and diabetic cardiomyopathy in a setting of impaired PI3K signaling. Diabetes was induced in 6-week-old nontransgenic and dnPI3K male mice via streptozotocin. After 4 weeks of diabetes, CoQ₁₀ supplementation commenced (10 mg/kg ip, 3 times/week, 8 weeks). At study end (12 weeks of diabetes), markers of LV function, cardiomyocyte hypertrophy, collagen deposition, NADPH oxidase, oxidative stress (3-nitrotyrosine), and concentrations of CoQ₉ and CoQ₁₀ were determined. LV NADPH oxidase (Nox2 gene expression and activity, and lucigenin-enhanced chemiluminescence), as well as oxidative stress, were increased by diabetes, exaggerated in diabetic dnPI3K mice, and attenuated by CoQ₁₀. Diabetes-induced LV diastolic dysfunction (prolonged deceleration time, elevated end-diastolic pressure, impaired E/A ratio), cardiomyocyte hypertrophy and fibrosis, expression of atrial natriuretic peptide, connective tissue growth factor, and β-myosin heavy chain were all attenuated by CoQ₁₀. Chronic CoQ₁₀ supplementation attenuates aspects of diabetic cardiomyopathy, even in a setting of reduced cardiac PI3K protective signaling. Given that CoQ₁₀ supplementation has been suggested to have positive outcomes in heart failure patients, chronic CoQ₁₀ supplementation may be an attractive adjunct therapy for diabetic heart failure.     

Optimization of culture conditions and scale-up to pilot and plant scales for coenzyme Q<Subscript>10</Subscript> production by <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

This report describes the optimization of culture conditions for coenzyme Q₁₀ (CoQ₁₀) production by Agrobacterium tumefaciens KCCM 10413, an identified high-CoQ₁₀-producing strain (Kim et al., Korean patent. 10-0458818, 2002b). Among the conditions tested, the pH and the dissolved oxygen (DO) levels were the key factors affecting CoQ₁₀ production. When the pH and DO levels were controlled at 7.0 and 0–10%, respectively, a dry cell weight (DCW) of 48.4 g l⁻¹ and a CoQ₁₀ production of 320 mg l⁻¹ were obtained after 96 h of batch culture, corresponding to a specific CoQ₁₀ content of 6.61 mg g-DCW⁻¹. In a fed-batch culture of sucrose, the DCW, specific CoQ₁₀ content, and CoQ₁₀ production increased to 53.6 g l⁻¹, 8.54 mg g-DCW⁻¹, and 458 mg l⁻¹, respectively. CoQ₁₀ production was scaled up from a laboratory scale (5-l fermentor) to a pilot scale (300 l) and a plant scale (5,000 l) using the impeller tip velocity (V _tip) as a scale-up parameter. CoQ₁₀ production at the laboratory scale was similar to those at the pilot and plant scales. This is the first report of pilot- and plant-scale productions of CoQ₁₀ in A. tumefaciens.     

Treatment of CoQ10 Deficient Fibroblasts with Ubiquinone,CoQ Analogs,and Vitamin C: Time- and Compound-Dependent Effects

Background

Coenzyme Q₁₀ (CoQ₁₀) and its analogs are used therapeutically by virtue of their functions as electron carriers, antioxidant compounds, or both. However, published studies suggest that different ubiquinone analogs may produce divergent effects on oxidative phosphorylation and oxidative stress.

Methodology/Principal Findings

To test these concepts, we have evaluated the effects of CoQ₁₀, coenzyme Q₂ (CoQ₂), idebenone, and vitamin C on bioenergetics and oxidative stress in human skin fibroblasts with primary CoQ₁₀ deficiency. A final concentration of 5 µM of each compound was chosen to approximate the plasma concentration of CoQ₁₀ of patients treated with oral ubiquinone. CoQ₁₀ supplementation for one week but not for 24 hours doubled ATP levels and ATP/ADP ratio in CoQ₁₀ deficient fibroblasts therein normalizing the bioenergetics status of the cells. Other compounds did not affect cellular bioenergetics. In COQ2 mutant fibroblasts, increased superoxide anion production and oxidative stress-induced cell death were normalized by all supplements.

Conclusions/Significance

These results indicate that: 1) pharmacokinetics of CoQ₁₀ in reaching the mitochondrial respiratory chain is delayed; 2) short-tail ubiquinone analogs cannot replace CoQ₁₀ in the mitochondrial respiratory chain under conditions of CoQ₁₀ deficiency; and 3) oxidative stress and cell death can be counteracted by administration of lipophilic or hydrophilic antioxidants. The results of our in vitro experiments suggest that primary CoQ₁₀ deficiencies should be treated with CoQ₁₀ supplementation but not with short-tail ubiquinone analogs, such as idebenone or CoQ₂. Complementary administration of antioxidants with high bioavailability should be considered if oxidative stress is present.     

Intracellular cholesterol accumulation and coenzyme Q10 deficiency in Familial Hypercholesterolemia

Familial Hypercholesterolemia (FH) is an autosomal co-dominant genetic disorder characterized by elevated low-density lipoprotein (LDL) cholesterol levels and increased risk for premature cardiovascular disease. Here, we examined FH pathophysiology in skin fibroblasts derived from FH patients harboring heterozygous mutations in the LDL-receptor.Fibroblasts from FH patients showed a reduced LDL-uptake associated with increased intracellular cholesterol levels and coenzyme Q₁₀ (CoQ₁₀) deficiency, suggesting dysregulation of the mevalonate pathway.Secondary CoQ₁₀ deficiency was associated with mitochondrial depolarization and mitophagy activation in FH fibroblasts. Persistent mitophagy altered autophagy flux and induced inflammasome activation accompanied by increased production of cytokines by mutant cells. All the pathological alterations in FH fibroblasts were also reproduced in a human endothelial cell line by LDL-receptor gene silencing.Both increased intracellular cholesterol and mitochondrial dysfunction in FH fibroblasts were partially restored by CoQ₁₀ supplementation. Dysregulated mevalonate pathway in FH, including increased expression of cholesterogenic enzymes and decreased expression of CoQ₁₀ biosynthetic enzymes, was also corrected by CoQ₁₀ treatment.Reduced CoQ₁₀ content and mitochondrial dysfunction may play an important role in the pathophysiology of early atherosclerosis in FH. The diagnosis of CoQ₁₀ deficiency and mitochondrial impairment in FH patients may also be important to establish early treatment with CoQ₁₀.     

The importance of plasma membrane coenzyme Q in aging and stress responses

The plasma membrane of eukaryotic cells is the limit to interact with the environment. This position implies receiving stress signals that affects its components such as phospholipids. Inserted inside these components is coenzyme Q that is a redox compound acting as antioxidant. Coenzyme Q is reduced by diverse dehydrogenase enzymes mainly NADH-cytochrome b₅ reductase and NAD(P)H:quinone reductase 1. Reduced coenzyme Q can prevent lipid peroxidation chain reaction by itself or by reducing other antioxidants such as α-tocopherol and ascorbate. The group formed by antioxidants and the enzymes able to reduce coenzyme Q constitutes a plasma membrane redox system that is regulated by conditions that induce oxidative stress. Growth factor removal, ethidium bromide-induced ρ° cells, and vitamin E deficiency are some of the conditions where both coenzyme Q and its reductases are increased in the plasma membrane. This antioxidant system in the plasma membrane has been observed to participate in the healthy aging induced by calorie restriction. Furthermore, coenzyme Q regulates the release of ceramide from sphingomyelin, which is concentrated in the plasma membrane. This results from the non-competitive inhibition of the neutral sphingomyelinase by coenzyme Q particularly by its reduced form. Coenzyme Q in the plasma membrane is then the center of a complex antioxidant system preventing the accumulation of oxidative damage and regulating the externally initiated ceramide signaling pathway.     

Coenzyme Q10 enrichment decreases oxidative DNA damage in human lymphocytes

Ubiquinol-10, the reduced form of coenzyme Q10, is a powerful antioxidant in plasma and lipoproteins. It has been suggested that endogenous ubiquinol-10 also exerts a protective role even towards DNA oxidation mediated by lipid peroxidation. Even though the antioxidant activity of coenzyme Q10 is mainly ascribed to ubiquinol-10, a role for ubiquinone-10 (the oxidized form), has been suggested not only if appropriate reducing systems are present. To investigate whether the concentration of ubiquinol-10 or ubiquinone-10 affects the extent of DNA damage induced by H2O2, we supplemented in vitro human lymphocytes with both forms of coenzyme Q10 and evaluated the DNA strand breaks by Comet assay. The exposure of lymphocytes to 100 microM H2O2 resulted in rapid decrease of cellular ubiquinol-10 content both in ubiquinol-10-enriched and in control cells, whereas alpha-tocopherol and beta-carotene concentration were unchanged. After 30 min from H2O2 exposure, the amount of DNA strand breaks was lower and cells' viability was significantly higher in ubiquinol-10-enriched cells compared with control cells. A similar trend was observed in ubiquinone-10-enriched lymphocytes when compared with control cells. Our experiments suggest that coenzyme Q10 in vitro supplementation enhances DNA resistance towards H2O2-induced oxidation, but it doesn't inhibit directly DNA strand break formation.     

Dietary supplementation with coenzyme Q10 results in increased levels of ubiquinol-10 within circulating lipoproteins and increased resistance of human low-density lipoprotein to the initiation of lipid peroxidation.

Ubiquinol-10 (CoQH2, the reduced form of coenzyme Q10) is a potent antioxidant present in human low-density lipoprotein (LDL). Supplementation of humans with ubiquinone-10 (CoQ, the oxidized coenzyme) increased the concentrations of CoQH2 in plasma and in all of its lipoproteins. Intake of a single oral dose of 100 or 200 mg CoQ increased the total plasma coenzyme content by 80 or 150%, respectively, within 6 h. Long-term supplementation (three times 100 mg CoQ/day) resulted in 4-fold enrichment of CoQH2 in plasma and LDL with the latter containing 2.8 CoQH2 molecules per LDL particle (on day 11). Approx. 80% of the coenzyme was present as CoQH2 and the CoQH2/CoQ ratio was unaffected by supplementation, indicating that the redox state of coenzyme Q10 is tightly controlled in the blood. Oxidation of LDL containing various [CoQH2] by a mild, steady flux of aqueous peroxyl radicals resulted immediately in very slow formation of lipid hydroperoxides. However, in each case the rate of lipid oxidation increased markedly with the disappearance of 80-90% CoQH2. Moreover, the cumulative radical dose required to reach this 'break point' in lipid oxidation was proportional to the amount of CoQH2 incorporated in vivo into the LDL. Thus, oral supplementation with CoQ increases CoQH2 in the plasma and all lipoproteins thereby increasing the resistance of LDL to radical oxidation.     

Preparation and characterization of novel coenzyme Q<Subscript>10</Subscript> nanoparticles engineered from microemulsion precursors

The purpose of these studies was to prepare and characterize nanoparticles into which Coenzyme Q₁₀ (CoQ₁₀) had been incorporated (CoQ₁₀-NPs) using a simple and potentially scalable method. CoQ₁₀-NPs were prepared by cooling warm microemulsion precursors composed of emulsifying wax, CoQ₁₀, Brij 78, and/or Tween 20. The nanoparticles were lyophilized, and the stability of CoQ₁₀-NPs in both lyophilized form and aqueous suspension was monitored over 7 days. The release of CoQ₁₀ from the nanoparticles was investigated at 37°C. Finally, an in vitro study of the uptake of CoQ₁₀-NPs by mouse macrophage, J774A.1, was completed. The incorporation efficiency of CoQ₁₀ was approximately 74%±5%. Differential Scanning Calorimetry (DSC) showed that the nanoparticle was not a physical mixture of its individual components. The size of the nanoparticles increased over time if stored in aqueous suspension. However, enhanced stability was observed when the nanoparticles were stored at 4°C. Storage in lyophilized form demonstrated the highest stability. The in vitro release profile of CoQ₁₀ from the nanoparticles showed an initial period of rapid release in the first 9 hours followed by a period of slower and extended release. The uptake of CoQ₁₀-NPs by the J774A.1 cells was over 4-fold higher than that of the CoQ₁₀-free nanoparticles (P<.05). In conclusion, CoQ₁₀-NPs with potential application for oral CoQ₁₀ delivery were engineered readily from microemulsion precursors.     

Age-related changes in brain mitochondrial DNA deletion and oxidative stress are differentially modulated by dietary fat type and coenzyme Q₁₀

Mitochondria-related oxidative damage is a primary event in aging and age-related neurodegenerative disorders. Some dietary treatments, such as antioxidant supplementation or the enrichment of mitochondrial membranes with less oxidizable fatty acids, reduce lipid peroxidation and lengthen life span in rodents. This study compares life-long feeding on monounsaturated fatty acids (MUFAs), such as virgin olive oil, and n-6 polyunsaturated fatty acids, such as sunflower oil, with or without coenzyme Q₁₀ supplementation, with respect to age-related molecular changes in rat brain mitochondria. The MUFA diet led to diminished age-related phenotypic changes, with lipoxidation-derived protein markers being higher among the older animals, whereas protein carbonyl compounds were lower. It is noteworthy that the MUFA diet prevented the age-related increase in levels of mitochondrial DNA deletions in the brain mitochondria from aged animals. The findings of this study suggest that age-related oxidative stress is related, at the mitochondrial level, to other age-related features such as mitochondrial electron transport and mtDNA alterations, and it can be modulated by selecting an appropriate dietary fat type and/or by suitable supplementation with low levels of the antioxidant/electron carrier molecule coenzyme Q.