Effects of oxidative stress on the Dolichol content of isolated rat liver cells

Dolichol, a long-chain polyisoprenoid broadly distributed in all tissues and cellular membranes with unknown function(s), might have a role in free radical metabolism [it accumulates in older tissues and decreases after CCl₄ (in liver) or phenylhydrazine (in spleen and liver) administration]. The effects of the NADPH-ADP-Fe system on Dolichol levels in isolated hepatocytes were explored and the time-course of changes was compared with the release of MDA in the incubation medium and the decrease in CoQ 9 and 10 and Vitamin E levels. Results showed that the system increased lipid peroxidation and decreased Dolichol and CoQ levels in_parallel fashions and lowered Vitamin E levels with shorter latency. Meanwhile, no increase in dead cells and no Dolichol release in the medium were detected. In conclusion, an increase in oxidative stress possibly caused a rapid degradation of dolichol by the same (unknown) mechanism responsible for the breakdown of_Ubiquinone isoprenoid chains.     

The combined use of oral and topical lipophilic antioxidants increases their levels both in sebum and stratum corneum

The concentration of Vitamin E (vit E) and ubiquinone (CoQ10), which together with squalene (SQ), play a key role against external oxidative insult, has been shown to decrease significantly during ageing. The aim of the present study is to inquire the effect of the combined use of topical bio-cosmetics containing natural active principles (including sebum-like lipid fractions, sebum and epidermal lipophilic and hydrophilic antioxidants), and oral antioxidant supplements on the antioxidant content of sebum and stratum corneum. We therefore treated the face and the back of 50 female volunteers aged 21-40, daily for two months, with a base cream containing 0.05% ubiquinone, 0.1% vit E, and 1% squalene. In addition 50 mg of CoQ10 + 50 mg of d-RRR-alpha-tocopheryl acetate + 50 microg of selenium were administered orally to half of the volunteers (Group A). Group B was represented by 25 volunteers who were treated only topically. Every 15 days during treatment the levels of CoQ10, vit E and SQ were verified in sebum, stratum corneum, and plasma. The daily topical application of the cream led to a significant increase, that peaked after 60 days, of the levels of CoQ10, d-RRR-alpha-tocopherol and SQ in the sebum (Group B), without significantly affecting the stratum corneum or plasma concentrations of the redox couple CoQ10H2/CoQ10 and vit E. The concomitant oral admistration of antioxidants produced in Group A a significant increase of the levels of CoQ10H2/CoQ10 and vit E both in plasma and stratum corneum after 15 and 30 days treatment respectively, compared to Group B. However the sebum levels of lipophilic antioxidants and SQ did not show a significant increase. After the treatments, the levels of CoQ10H2/CoQ10, vit E and SQ went back to basal levels within 6-8 days in sebum, 12-16 days in the stratum corneum, and 3-6 days in plasma. Therefore topical application of the antioxidants was able to increase their level in sebum, while the concomitant oral administration also affected the levels of vit E and CoQ10 in the stratum corneum.     

Effects of coenzyme Q(10) administration on its tissue concentrations,mitochondrial oxidant generation,and oxidative stress in the rat

Coenzyme Q (CoQ(10)) is a component of the mitochondrial electron transport chain and also a constituent of various cellular membranes. It acts as an important in vivo antioxidant, but is also a primary source of O(2)(-*)/H(2)O(2) generation in cells. CoQ has been widely advocated to be a beneficial dietary adjuvant. However, it remains controversial whether oral administration of CoQ can significantly enhance its tissue levels and/or can modulate the level of oxidative stress in vivo. The objective of this study was to determine the effect of dietary CoQ supplementation on its content in various tissues and their mitochondria, and the resultant effect on the in vivo level of oxidative stress. Rats were administered CoQ(10) (150 mg/kg/d) in their diets for 4 and 13 weeks; thereafter, the amounts of CoQ(10) and CoQ(9) were determined by HPLC in the plasma, homogenates of the liver, kidney, heart, skeletal muscle, brain, and mitochondria of these tissues. Administration of CoQ(10) increased plasma and mitochondria levels of CoQ(10) as well as its predominant homologue CoQ(9). Generally, the magnitude of the increases was greater after 13 weeks than 4 weeks. The level of antioxidative defense enzymes in liver and skeletal muscle homogenates and the rate of hydrogen peroxide generation in heart, brain, and skeletal muscle mitochondria were not affected by CoQ supplementation. However, a reductive shift in plasma aminothiol status and a decrease in skeletal muscle mitochondrial protein carbonyls were apparent after 13 weeks of supplementation. Thus, CoQ supplementation resulted in an elevation of CoQ homologues in tissues and their mitochondria, a selective decrease in protein oxidative damage, and an increase in antioxidative potential in the rat.     

Statins lower plasma and lymphocyte ubiquinol/ubiquinone without affecting other antioxidants and PUFA

It has been shown that treating hypercholesterolemic patients (HPC) with statins leads to a decrease, at least in plasma, not only in cholesterol, but also in important non-sterol compounds such as ubiquinone (CoQ10), and possibly dolichols, that derive from the same biosynthetic pathway. Plasma CoQ10 decrease might result in impaired antioxidant protection, therefore leading to oxidative stress. In the present paper we investigated the levels in plasma, lymphocytes and erythrocytes, of ubiquinol and ubiquinone, other enzymatic and non-enzymatic lipophilic and hydrophilic antioxidants, polyunsaturated fatty acids of phosfolipids and cholesterol ester fractions, as well as unsaturated lipid and protein oxidation in 42 hypercholesterolemic patients treated for 3 months. The patients were treated with different doses of 3 different statins, i.e. atorvastatin 10 mg (n = 10) and 20 mg (n = 7), simvastatin, 10 mg (n = 5) and 20 mg (n = 10), and pravastatin, 20 mg (n = 5) and 40 mg (n = 5). Simvastatin, atorvastatin and pravastatin produced a dose dependent plasma depletion of total cholesterol (t-CH), LDL-C, CoQ10H2, and CoQ10, without affecting the CoQ10H2/CoQ10 ratio. The other lipophilic antioxidants (d-RRR-alpha-tocopherol-vit E-, gamma-tocopherol, vit A, lycopene, and beta-carotene), hydrophilic antioxidants (vit C and uric acid), as well as, TBA-RS and protein carbonyls were also unaffected. Similarly the erythrocyte concentrations of GSH and PUFA, and the activities of enzymatic antioxidants (Cu,Zn-SOD, GPx, and CAT) were not significantly different from those of the patients before therapy. In lymphocytes the reduction concerned CoQ10H2, CoQ10, and vit E; other parameters were not investigated. The observed decline of the levels of CoQ10H2 and CoQ10 in plasma and of CoQ10H2, CoQ10 and vit E in lymphocytes following a 3 month statin therapy might lead to a reduced antioxidant capacity of LDL and lymphocytes, and probably of tissues such as liver, that have an elevated HMG-CoA reductase enzymatic activity. However, this reduction did not appear to induce a significant oxidative stress in blood, since the levels of the other antioxidants, the pattern of PUFA as well as the oxidative damage to PUFA and proteins resulted unchanged. The concomitant administration of ubiquinone with statins, leading to its increase in plasma, lymphocytes and liver may cooperate in counteracting the adverse effects of statins, as already pointed out by various authors on the basis of human and animal studies.     

Vitamin E supplementation for the ruminant

Vitamin E is essential for such body functions as growth, reproduction, prevention of various diseases, and for integrity of tissues. The most significantly important result of selenium and vitamin E deficiency is tissue degeneration (e.g. white muscle disease). Vitamin E does not cross the placenta in any appreciable amounts; however, it is concentrated in colostrum. Supplemental vitamin E can greatly increase colostral tocopherol. The importance of providing colostrum rich in vitamin E is essential as both calves and lambs are born with low levels of the vitamin. Vitamin E has been shown to increase performance of feedlot cattle and to increase immune response for ruminant health, including being beneficial for mastitis control. Vitamin E given to finishing cattle at higher than National Research Council (NRC) requirements dramatically maintained the red color (oxymyoglobin) compared with the oxidized metmyoglobin of beef. It appears that supplementation of 500 IU vitamin E per head daily for 84–126 days yields tissue -tocopherol that would maintain a favorable level of oxymyoglobin in meat, thus increasing its value. Vitamin E nutritional status is commonly estimated from plasma concentration, with a high correlation between plasma and liver levels of -tocopherol. The NRC estimates for vitamin E requirements of beef cattle, dairy cattle and sheep to range from 15 to 40 mg kg⁻¹; however, higher levels will likely improve performance, and megadose levels will improve carcass quality.     

Antioxidant status (CoQ10 and Vit. E levels) and immunohistochemical analysis of soft tissues in periodontal diseases

Reactive oxygen species and antioxidant status in periodontal diseases and periodontal-related pathologies is an item of growing interest. Immunohistochemical approach may be usefully employed in the study of soft tissues affected by periodontal disease, giving valuable information on tissue morphology and vascular proliferation that depends directly on the inflammatory state. In order to study CoQ(10) and vitamin E content in healthy gingiva and in gingivitis a new adaptation to previously published methods for their determination was adopted. During gingivitis tissue displayed a large inflammatory infiltration in the lamina propria and a VEGF positive squamous epithelium. The inflammatory infiltration consisted mainly of lymphocytes, plasma cells and neutrophils. Vitamin E dramatically decreased and CoQ(10) remained unchanged despite the increased amount of cells present in the periodontally affected tissues, indicating that continuous oxidative stress which occurred in these structure affected the antioxidant pattern of the tissue.     

Augmented efficacy of tamoxifen in rat breast tumorigenesis when gavaged along with riboflavin, niacin, and CoQ10: effects on lipid peroxidation and antioxidants in mitochondria

Reactive oxygen species (ROS) play a major role in causing mitochondrial changes linked to cancer and metastasis. Uptake of antioxidants by tissue to reduce the ROS production could be instrumental in controlling cancer. Tamoxifen (TAM), a nonsteroidal anti-estrogen drug most used in the chemotherapy and chemoprevention of breast cancer. Riboflavin, niacin and coenzyme Q10 (CoQ10) are proved to be potent antioxidants and protective agents against many diseases including cancer. The objective of this research is to determine the therapeutic efficacy of combinatorial therapy on mammary carcinoma bearing rats in terms of the mitochondrial lipid peroxidation and antioxidant status especially MnSOD. Female albino rats of Sprague-Dawley strain were selected for the investigation. Mammary carcinoma was induced with 7,12-dimethyl benz(a)anthracene (DMBA: 25 mg), and the treatment was started by the oral administration of TAM (10 mg/kg body weight/day) along with riboflavin (45 mg/kg body weight/day), niacin (100 mg/kg body weight/day) and CoQ10 (40 mg/kg body weight/day) for 28 days. The levels of lipid peroxides, activities of enzymic and non-enzymic antioxidants were measured in the mitochondria isolated from the mammary gland and liver of control and experimental rats. Rats treated with DMBA showed an increase in mitochondrial lipid peroxidation (mammary gland 52.3%; liver 25.1%) accompanied by high malondialdehyde levels along with lowered activities of mitochondrial enzymic antioxidants [superoxide dismutase (mammary gland 19.9%; liver 24.8%), catalase (mammary gland 50%; liver 19.7%), glutathione peroxidase (mammary gland 47.8%; liver 31.1%)] and non-enzymic antioxidants [reduced glutathione (mammary gland 14.3%; liver 13.3%), Vitamin C (mammary gland 6.49%; liver 21.4%) and E (mammary gland 20.3%; liver 22.2%)]. Administration of combinatorial therapy restored lipid peroxide level and the activities of enzymic and non-enzymic antioxidants to near normalcy. In addition, antitumour activity was also found to be enhanced which is evident from the increased expression of tumour suppressor gene MnSOD thereby preventing cancer cell proliferation. These results suggested that TAM treatment is the most effective during co-administration of riboflavin, niacin and CoQ10 in terms of mitochondrial antioxidant and antitumour activity.     

Lipophilic antioxidants in human sebum and aging

Skin surface lipids (SSL), a very complex mixture of sebum mixed to small amounts of epidermal lipids, mantle the human epidermis, thus representing the outermost protection of the body against exogenous oxidative insults. The present work is a systematic and quantitative analysis of upper-chest SSL and their content in antioxidants in 100 healthy volunteers, divided into five age groups using TLC, HPLC, and GC-MS methods. Further, the effect of exposing SSL in vitro to increasing doses of UV irradiation was examined. Straight monounsaturated and diunsaturated as well as branched monounsaturated fatty acids of triglycerides and pooled fractions were found to be higher at maturity than in childhood and in advancing age. Diunsaturated fatty acids were below 3% of the total and constituted exclusively of C18:2 Δ5,8 , C20:2 Δ7,10 , C18:2 Δ9,12 . Squalene, vitamin E (vit. E) and Coenzyme Q 10 (CoQ 10 ) were found to increase from childhood to maturity to decrease again significantly in old age. Vitamin E and CoQ 10 were the only known lipophilic antioxidants present in SSL. In spite of their low levels they were found to synergically inhibit the UV induced depletion of squalene, cholesterol and of unsaturated fatty acids of SSL. In fact, exposure of SSL to increasing amounts of UV irradiation led preferentially to lowering of the levels of vit. E and CoQ 10 . Four minimal erythema dose (MED) (5.6 J/cm 2 ) were able to deplete 84% vit. E and 70% ubiquinone, and only 13% squalene. Diunsaturated and monounsaturated fatty acids as well as cholesterol were unaffected even following 10 MED UV exposures, which produced a 26% loss of squalene. The same UV dose when applied in the absence of vit. E and CoQ 10 produced a 90% decrease of squalene.     

Lipophilic Antioxidants in Human Sebum and Aging

Skin surface lipids (SSL), a very complex mixture of sebum mixed to small amounts of epidermal lipids, mantle the human epidermis, thus representing the outermost protection of the body against exogenous oxidative insults. The present work is a systematic and quantitative analysis of upper-chest SSL and their content in antioxidants in 100 healthy volunteers, divided into five age groups using TLC, HPLC, and GC-MS methods. Further, the effect of exposing SSL in vitro to increasing doses of UV irradiation was examined. Straight monounsaturated and diunsaturated as well as branched monounsaturated fatty acids of triglycerides and pooled fractions were found to be higher at maturity than in childhood and in advancing age. Diunsaturated fatty acids were below 3% of the total and constituted exclusively of C18:2 &#106 5,8 , C20:2 &#106 7,10 , C18:2 &#106 9,12 . Squalene, vitamin E (vit. E) and Coenzyme Q 10 (CoQ 10 ) were found to increase from childhood to maturity to decrease again significantly in old age. Vitamin E and CoQ 10 were the only known lipophilic antioxidants present in SSL. In spite of their low levels they were found to synergically inhibit the UV induced depletion of squalene, cholesterol and of unsaturated fatty acids of SSL. In fact, exposure of SSL to increasing amounts of UV irradiation led preferentially to lowering of the levels of vit. E and CoQ 10 . Four minimal erythema dose (MED) (5.6 J/cm 2 ) were able to deplete 84% vit. E and 70% ubiquinone, and only 13% squalene. Diunsaturated and monounsaturated fatty acids as well as cholesterol were unaffected even following 10 MED UV exposures, which produced a 26% loss of squalene. The same UV dose when applied in the absence of vit. E and CoQ 10 produced a 90% decrease of squalene.     

Serum and tissue coenzyme Q9 in rats with thyroid dysfunctions

Serum and tissue CoQ9 levels were determined in hypothyroid, euthyroid and hyperthyroid rats. A significant negative correlation was demonstrated between serum FT4 or T3 and CoQ9 in rats with various states of thyroid functions. Liver CoQ9 was significantly increased in rats rendered mildly hyperthyroid. There was a significant positive correlation between serum FT4 or T3 and liver CoQ9. While liver CoQ9 did not significantly change in severely hyperthyroid animals, liver mitochondrial CoQ9 showed a significant positive correlation with serum T3. Kidney and heart CoQ9 levels did not significantly change in hyperthyroid rats, but those in hypothyroid rats showed a tendency to increase. It was suggested that the synthesis of CoQ9 was increased in the liver in hyperthyroidism.     

Content of dolichol and retinol in isolated rat non-parenchymal liver cells

The liver sinusoids, that are considered as a functional unit, harbour four types of sinusoidal cells (Ito, Kupffer, endothelial and pit cells). Dolichol content has been determined in many tissues and subcellular compartments, alteration has been reported in many types of liver injury, but until now no data are available on its content in every type of sinusoidal non-parenchymal liver cells. Dolichol and retinol metabolism might intersect in their traffic in biological membranes. Intercellular as well as intracellular exchange of retinoids is an essential element of important processes occurring in liver cells. It has been suggested that the role of dolichol, besides being a carrier of oligosaccharides in the biosynthesis of N-linked glycoproteins, may be to modify membrane fluidity and permeability, and facilitate fusion of membranes. Dolichol in the membrane is intercalated between the two halves of the phospholipid bilayer, but its exact disposition is not known and the movement and distribution of retinoid in membranes may vary with the geometry of the membranes. Therefore the aim of this study is to obtain a global understanding of the sinusoidal system regarding dolichol and retinol content in each type of isolated rat liver sinusoidal cell, in normal conditions and after vitamin A administration. The information that can be drawn from the present results is that with normal vitamin A status of the animal, the dolichol content is almost uniform in all liver cells. After vitamin A supplementation, a great increase of dolichol, together with the known increase of retinol, can be measured only in a subpopulation of the Ito cells, the Ito-1 subfraction. Therefore in the cells that are present in the hepatic sinusoid, different pools of dolichol may have separate functions. Because retinol traffic among cells, membranes and plasma still remains to be fully understood, roles of dolichol in the exchange of vitamin A among sinusoidal liver cells are discussed. © 1998 John Wiley & Sons, Ltd.     

Evaluation of the dietary effects of coenzyme Q in vivo by the oxidative stress marker, hydroxyoctadecadienoic acid and its stereoisomer ratio

Coenzyme Q (CoQ) is an endogenous enzyme cofactor that may provide protective benefits as an antioxidant. In this study, in order to determine whether the concentrations of CoQ(9) are associated with the oxidative status in vivo, the effects of dietary supplements of CoQ(9) on mice were evaluated by using a new biomarker, total hydroxyoctadecadienoic acid (tHODE). Biological samples were first reduced and then saponified to convert the various oxidation products of linoleates to tHODE. Subsequently, by using GC-MS analyses, we simultaneously determined the absolute concentration of tHODE; its stereoisomer ratio, 9- and 13-(Z,E)-HODE/9- and 13-(E,E)-HODE, which is a measure of the hydrogen donor capacity of antioxidants; and the concentration of 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)). Remarkable decreases in tHODE and 8-iso-PGF(2alpha) levels were observed in the plasma, erythrocytes, liver, and brain of mice that were maintained for 1 month on an alpha-tocopherol (alphaT)-free (E-free) diet supplemented with ubiquinone-9 (Q(9); 0.04 wt.%) as compared to those of mice that were fed an E-free diet. The (Z,E/E,E) HODE ratio was increased in the plasma and erythrocytes of mice that were fed a Q(9)-fortified diet as compared to those that were fed an E-free diet. In particular, the (Z,E/E,E) HODE ratios in the plasma and brain were significantly correlated with the concentrations of ubiquinol-9 (Q(9)H(2)). Further, the liver and brain levels of tHODE and 8-iso-PGF(2alpha) were significantly correlated with the plasma and erythrocyte levels of tHODE and 8-iso-PGF(2alpha), respectively, and in some cases, also exhibited significant correlations with antioxidants. These results indicate that the plasma and erythrocyte levels of tHODE and its stereoisomeric ratio can be prominent biomarkers for the evaluation of the oxidative status and antioxidant capacity in vivo, including in the liver and brain, and that CoQ plays a major role in the in vivo antioxidant network.     

Interaction of epithelial cells and fibroblasts in culture: Effect on glycosaminoglycan levels

Twelve- to fifteen-day chick embryo liver cells (epithelial) were cultured on top of confluent chick embryo fibroblasts to produce an in vitro model of an epithelial-mesenchymal interacting system. This cocultivation resulted in a marked increase in hyaluronic acid (HA) levels and a decrease in chondroitin sulfate (CS) levels, either in total or in proportion to HA, compared with the two cell types cultured separately. The liver cells cultured alone produced little or no detectable glycosaminoglycans (GAGs). Cocultivation of increasing numbers of liver cells with fibroblasts resulted in a progressive increase and decrease of HA and CS levels, respectively, and the combined effect of these changes was a progressive increase in the HA/CS ratio. Fibroblasts cultured in liver-cell-conditioned growth medium also showed increased levels of HA, but in contrast to cocultivation, an increase in CS and no change in the HA/CS ratio. Liver cells cultured in fibroblast-conditioned growth medium showed no changes in GAG level. This suggests that under conditions of cocultivation the fibroblasts alone could be responsible for the increased HA levels and that the decreased CS levels are a result of conditions produced by the close proximity of the two cell types. In vivo most connective tissues immediately adjacent to epithelial tissues are also characterized by a matrix rich in HA and these results support the concept that some epithelial tissues are able to modulate the GAG composition of adjacent connective tissues and thereby affect their immediate extracellular environment.     

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.     

Involvement of retinoid X receptor alpha in coenzyme Q metabolism

The nuclear retinoid X receptor alpha (RXRalpha) is the heterodimer partner in several nuclear receptors, some of them regulating lipid biosynthesis. Since coenzyme Q (CoQ) levels are greatly modified in aging and a number of diseases, we have investigated the involvement of RXRalpha in the biosynthetic regulation of this lipid by using a hepatocyte-specific RXRalpha-deficient mouse strain (RXRalpha-def). In the receptor-deficient liver, the amount of CoQ decreased to half of the control, and it was demonstrated that this decrease was caused by a significantly lowered rate of biosynthesis. On the other hand, induction of CoQ was extensive in both control and RXRalpha-def liver using the peroxisomal inducer di(2-ethylhexyl)phthalate (DEHP). Since the RXRalpha deficiency was specific to liver, no change in CoQ content or biosynthesis was observed in kidney. The other mevalonate pathway lipids, cholesterol and dolichol, were unchanged in the RXRalpha-def liver. Upon treatment with DEHP, cholesterol decreased in the control but remained unchanged in the receptor-deficient mice. In control mice, cold exposure elevated CoQ levels by 60%, but this induction did not occur in the liver of RXRalpha-def mice. In contrast, PPARalpha-null mice, which lack induction upon treatment with peroxisomal inducers, respond to cold exposure and CoQ content is increased. The amount of cholesterol decreased in both control and RXRalpha-def liver upon cold treatment. The results demonstrate that RXRalpha is required for CoQ biosynthesis and for its induction upon cold treatment, but does not appear to be involved in the basic synthesis of cholesterol and dolichol. The receptor is not involved in the elevated CoQ biosynthesis during peroxisomal induction.     

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.     

Enrichment of rat hepatic organelles by vitamin E administered subcutaneously

Novel modes of administering antioxidants to improve delivery to targeted tissues or cells may be advantageous in preventing oxidant-induced pathologies. Vitamin E (alpha-tocopherol) has been shown to be protective in several models of liver injury. The objectives of this study were: (1) to determine if subcutaneously (s.q.) administered emulsified vitamin E enriched liver and hepatic subcellular fractions with the antioxidant and (2) to carry out a time-dependent analysis of serum and tissue vitamin E in rats receiving daily s.q. vitamin E. In the first experiment rats injected daily s.q. with emulsified vitamin E for 9 d increased serum, total liver, liver mitochondria, and liver microsomes by 8-, 16-, 30-, and 29-fold, respectively, compared with placebo injections. Similar enrichment was observed after intramuscular injections. In the second experiment, daily doses of s.q. vitamin E increased liver concentrations 40-fold by 9 d, which decreased to 22-fold by 18 d, whereas serum adjusted vitamin E levels maximized with a 24-fold increase by day 3 and plateaued thereafter. In conclusion, s.q. administration of emulsified vitamin E to rats resulted in substantially elevated serum and liver concentrations of alpha-tocopherol compared with levels achievable by dietary supplementation. The s.q. route of administration is a potentially effective parenteral mode of delivery of vitamin E for conditions in which hepatic oxidative stress is present.     

Coenzyme Q10, antioxidant status and ApoE isoforms

The aim of this study was to inquire the antioxidant status in plasma and lipoproteins isolated from normal subjects possessing different ApoE genotypes. For this purpose we investigated blood samples from 106 healthy blood donors: the distribution of ApoE alleles (E2/E2 = 0.9%, E2/E3 = 10.4%, E2/E4 = 2.8%, E3/E3 = 71.7%, E3/E4 = 12.3% and E4/E4 1.9% with 1, 11, 3, 76, 13, and 2 subjects respectively for each genotype) was in agreement with previous data. Almost no differences were found in the concentrations of both coenzyme Q10 (CoQ10) and vitamin E for the different genotypes. Concentration of CoQ10 in isolated lipoproteins was also similar, in the different genotypes, when referred to cholesterol; CoQ10 in LDL was higher for the E3/E3 subjects when referred to protein. Neither CoQ10 nor vitamin E correlated with paraoxonase (PON) activity or cholesteryl-ester hydroperoxides (CHP). Furthermore, there was no correlation between the same lipophilic antioxidants and CHP levels. The only E2 homozygous subject found had high levels of PON and low levels of CHP; the two E4/E4 subjects had low PON activity together with low levels of CHP.     

Coenzymes Q9 and Q10, vitamin E and peroxidation in rat synaptic and non-synaptic occipital cerebral cortex mitochondria during ageing

Great attention has been devoted both to ageing phenomena at the mitochondrial level and to the antioxidant status of membrane structures. These kinds of investigations are difficult to perform in the brain because of its heterogeneity. It is known that synaptic heavy mitochondria (HM) may represent an aged mitochondrial population characterized by a partial impairment of their typical mitochondrial function. We arranged a novel system requiring no extraction procedure, very limited handling of the samples and their direct injection into the HPLC apparatus, to carry out, for the first time, a systematic and concomitant determination of vitamin E, Coenzyme Q9 (CoQ9) and Coenzyme Q10 (CoQ10) contents in rat brain mitochondria. The trends found for CoQ9 and CoQ10 levels in synaptic and non-synaptic occipital cerebral cortex mitochondria during rat ageing are consistent with previous data. Hydroperoxides (HP) differed with age and it was confirmed that in the HM fraction the summation of contributions results in an oxidatively jeopardized subpopulation. We found that vitamin E seems to increase with age, at least in non-synaptic free (FM) and synaptic light (LM) mitochondria, while it was inclined to remain substantially constant in HM.     

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.