ascorbic-acid and pentane

Exercise appears to increase reactive oxygen species, which can result in damage to cells. Exercise results in increased amounts of malondialdehyde in blood and pentane in breath; both serve as indirect indicators of lipid peroxidation. However, not all studies report increases; these equivocal results may be due to the large intersubject variability in response or the nonspecificity of the assays. Some studies have reported that supplementation with vitamins C and E, other antioxidants, or antioxidant mixtures can reduce symptoms or indicators of oxidative stress as a result of exercise. However, these supplements appear to have no beneficial effect on performance. Exercise training seems to reduce the oxidative stress of exercise, such that trained athletes show less evidence of lipid peroxidation for a given bout of exercise and an enhanced defense system in relation to untrained subjects. Whether the body's natural antioxidant defense system is sufficient to counteract the increase in reactive oxygen species with exercise or whether additional exogenous supplements are needed is not known, although trained athletes who received antioxidant supplements show evidence of reduced oxidative stress. Until research fully substantiates that the long-term use of antioxidants is safe and effective, the prudent recommendation for physically active individuals is to ingest a diet rich in antioxidants.

Topics: Antioxidants; Ascorbic Acid; Dietary Supplements; Estrogens; Exercise; Female; Glutathione; Humans; Male; Malondialdehyde; Oxidative Stress; Pentanes; Physical Endurance; Reactive Oxygen Species; Selenium; Vitamin E

Increased oxidative stress has been associated with work at high altitude; however, it is not known whether oxidative stress is a significant problem at moderate altitudes. The oxidative stress indicators, breath pentane (BP), 8-hydroxydeoxyguanosine (8-OHdG), oxygen radical absorption capacity (ORAC), 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), and lipid peroxides (LPO) were measured in breath, blood and urine samples of U.S. Marines engaged in moderate altitude ( approximately 3000 m) cold weather field training. The test subjects were divided into a placebo and four antioxidant supplement groups (n = 15/group) and received the following supplements for 28 d: 1) vitamin E, 440 alpha-tocopherol equivalents (alpha-TE); 2) vitamin A, 2000 retinol equivalents (RE) of beta-carotene; 3) vitamin C, 500 mg ascorbic acid; 4) a mixture of 440 alpha-TE, 2000 RE of beta-carotene, 500 mg ascorbic acid, 100 microg selenium and 30 mg zinc daily. Strenuous work ( approximately 23 MJ/d) in cold weather at moderate altitude was accompanied by increases in several indicators of oxidative stress that were not effectively controlled by conventional antioxidant supplements. The group receiving the antioxidant mixture exhibited lower BP (P < 0. 05) compared with those receiving single antioxidant supplements; however, not all markers of oxidative stress responded like BP. Because these markers did not respond in the same manner, it is important to include markers from more than one source to assess the effect of supplemental dietary antioxidants.

Topics: Adult; Altitude; Antioxidants; Ascorbic Acid; Breath Tests; Cold Temperature; Double-Blind Method; Energy Metabolism; Humans; Lipid Peroxides; Male; Malondialdehyde; Oxidative Stress; Pentanes; Physical Exertion; Vitamin A; Vitamin E

Previous studies have shown that cigarette smoke enhances lipid peroxidation. This study examined the effect of daily consumption of a tomato-based juice supplemented with vitamin C (600 mg), vitamin E (400 IU, or 400 mg), and beta-carotene (30 mg) on various indexes of lipid peroxidation (breath pentane excretion and susceptibility of LDL to copper-mediated oxidation) in smokers. In addition, plasma lycopene and vitamin concentrations and total peroxyl radical trapping potential, a measure of antioxidant defenses, were assessed. Relative to the placebo juice, the vitamin-supplemented juice resulted in a significant decrease in breath-pentane excretion as well as a significant improvement in the resistance of LDL to oxidation. The lag phase of conjugated diene formation lengthened and the propagation rate decreased, indicating a decreased susceptibility of LDL to oxidative modification. Increased concentrations of plasma vitamin C, beta-carotene, and lycopene were found to be significantly correlated with the conjugated diene lag phase and rate of formation. Vitamin E was highly correlated with beta-carotene. Plasma total peroxyl radical trapping potential values did not change in response to supplementation. This study thus indicates that an antioxidant-supplemented drink can reduce lipid peroxidation and susceptibility of LDL to oxidation in smokers and may ameliorate the oxidative stress of cigarette smoke.

Topics: Adult; Antioxidants; Ascorbic Acid; beta Carotene; Dietary Supplements; Humans; Lipid Peroxidation; Lipoproteins, LDL; Pentanes; Regression Analysis; Smoking; Vitamin E

We studied the effects of ingesting an antioxidant vitamin mixture for 6 wk on breath pentane and serum malondialdehyde (MDA) levels before and after exercise. Twenty young (mean age 25.0 +/- 2.9 yr) healthy males were randomly assigned to either an antioxidant vitamin group (daily doses of 592 mg of alpha-tocopherol equivalents, 1,000 mg of ascorbic acid, and 30 mg of beta-carotene) or a placebo group. Exercise consisted of 30 min of treadmill running at 60% of maximal O2 consumption (VO2max) followed by 5 min of running at a pace that elicited approximately 90% of VO2max. Blood and breath samples were collected immediately after the two exercise bouts. The antioxidant supplement did not prevent the exercise-induced increase in lipid peroxidation, as reflected by the rate of pentane production and the increase in serum MDA concentration. However, ingestion of the antioxidant vitamins did result in significantly lower resting and postexercise levels of expired pentane and serum MDA. We conclude that taking ascorbate, alpha-tocopherol, and beta-carotene in the amounts used in this study serves to lower markers of lipid peroxidation at rest and after exercise but does not prevent the exercise-induced increase in oxidative stress.

Topics: Adult; Antioxidants; Ascorbic Acid; Carotenoids; Diet; Drug Combinations; Exercise; Humans; Lipid Peroxidation; Male; Malondialdehyde; Oxygen Consumption; Pentanes; Rest; Vitamin E; Vitamins

Reversed micelles can be used to concentrate water-soluble materials in the water pool. In this study, the extraction of water-soluble vitamins into reversed micelles was attempted, and a flow system was used to determine the time-course of the vitamin extraction. The efficiency of extraction was strongly affected by the extraction temperature and the concentration of reversed micelles, and the selectivity depended on the size of micelles. Water-soluble vitamins could be efficiently and rapidly extracted. The selective extraction of a model mixture of vitamins from pharmaceutical preparations was also attempted. Moreover, the usefulness of the proposed method for the determination of vitamins in various commercial tablets was also demonstrated. Using of this method, the surfactant remains mixed with the extracted compounds, and so we attempted to remove the surfactant from the extract by supercritical fluid extraction. Supercritical carbon dioxide containing 7.5% ethanol as entrainer was found to be the most efficient solvent for removing residual surfactant from the extract.

Topics: Ascorbic Acid; Chromatography, High Pressure Liquid; Dioctyl Sulfosuccinic Acid; Micelles; Pentanes; Reproducibility of Results; Solubility; Spectrophotometry, Ultraviolet; Vitamin B Complex

The alkanes, ethane and pentane, are often used as indices of lipid peroxidation. Because it has been indicated that O2 tension can affect the yield of these compounds, a systematic study of this was carried out. Rat liver microsomes were peroxidized using an iron-ascorbate system. The incubations were carried out in sealed flasks at 37 degrees under N2 and various concentrations of O2 up to 100%. Ethane and pentane production were measured by gas chromatography, and malondialdehyde was measured by the thiobarbituric acid reaction. Microsomal fatty acids were measured by gas chromatography. Polyunsaturated fatty acids were lost during lipid peroxidation. There was no loss of saturated or monounsaturated fatty acids. Loss of polyunsaturated fatty acids correlated with O2 tension in the flask. Half-maximal losses of docosahexaenoic acid, arachidonic acid, and linoleic acid occurred at 3, 5, and 35% O2 respectively. Malondialdehyde formation reflected polyunsaturated fatty acid loss at all O2 concentrations. Alkane formation reflected polyunsaturated fatty acid loss below 5% O2 but not above it. The ratio of alkane formed to precursor polyunsaturated fatty acid lost decreased progressively as O2 concentration was increased above 5%. For example, the molar yield of pentane formed per precursor polyunsaturated fatty acid lost was 0.3% at 5% O2 but only 0.003% at 100% O2. This indicates that quantitation of lipid peroxidation using alkane formation requires consideration of O2 tension at the site of alkane formation.

Topics: Animals; Ascorbic Acid; Carbon Tetrachloride; Ethane; Fatty Acids, Unsaturated; Iron; Lipid Peroxides; Male; Malonates; Malondialdehyde; Microsomes, Liver; Oxygen; Pentanes; Rats; Rats, Inbred Strains

The antioxidant properties of alpha-tocopherol and alpha-tocopheryl acetate in lung tissue were quantitated in vitro by measurement of thiobarbituric acid (TBA) reactants, pentane production and lipid peroxides following either an iron/ascorbate or a xanthine/xanthine oxidase oxidant stress. Lung homogenates were obtained from newborn rabbits treated intravenously with either 10 or 100 mg/kg of either alpha-tocopherol or alpha-tocopheryl acetate. The animals were killed 5 min after dosing to minimize the conversion of alpha-tocopheryl acetate to alpha-tocopherol. Lung homogenates from animals treated with alpha-tocopherol had decreased concentrations of TBA reactants and pentane production after incubation with either oxidant stress compared to lung homogenate from animals treated with alpha-tocopheryl acetate or vehicle alone. Lipid peroxide concentrations were no different in homogenates from alpha-tocopherol or alpha-tocopheryl acetate treated animals. Correlations between antioxidant activity and tissue concentrations of alpha-tocopherol indicate 50% inhibition is achieved with 30-100 micrograms/g lung tissue. In vitro addition of alpha-tocopherol required concentrations between 100 and 200 micrograms/g to reduce lipid peroxidation by 50%.

Topics: alpha-Tocopherol; Animals; Animals, Newborn; Antioxidants; Ascorbic Acid; Iron; Lipid Peroxides; Lung; Pentanes; Rabbits; Thiobarbiturates; Tocopherols; Vitamin E; Xanthine; Xanthine Oxidase; Xanthines

Lipid peroxidation activity was determined in liver microsomes, hepatocytes and cultured granuloma cells by measuring ethane and pentane production with an improved capillary gas chromatographic method. Lipid peroxidation initiated by ferrous ions and NADPH produced significantly more hydrocarbons at 4% O2 than under atmospheric (21% O2), hyperoxic or hypoxic conditions. In liver microsomes ferrous ions and ascorbic acid stimulated the non-enzymatic lipid peroxidation and concomitantly the epoxidation of aldrin. The results demonstrate that epoxidation of aldrin can be triggered by the iron initiated lipid peroxidation.

Topics: Aldrin; Animals; Ascorbic Acid; Chromatography, Gas; Dieldrin; Epoxy Compounds; Ethane; Ferrous Compounds; Granuloma; Lipid Peroxides; Liver; Male; Microsomes, Liver; NADP; Pentanes; Rats; Rats, Inbred Strains

The present study investigates the effect of ascorbate on red cell lipid peroxidation. At a concentration between 0.2 mmol - 20 mmol/1 ascorbic acid reduces hydrogen peroxide-induced red blood cell lipid peroxidation resulting in a marked decrease in ethane and pentane production as well as in haemolysis. Ascorbic acid also shows an antioxidant effect on chelated iron-catalyzed hydrogen peroxide-induced peroxidation of erythrocyte membranes. At a concentration of 10 mmol/1 ascorbic acid totally inhibits oxidative break-down of polyunsaturated fatty acids by radicals originating from hydrogen peroxide. Our results indicate that ascorbate at the chosen concentration has an antioxidant effect on red blood cell lipid peroxidation.

Topics: Ascorbic Acid; Erythrocyte Membrane; Ethane; Fatty Acids; Hemolysis; Humans; Hydrogen Peroxide; In Vitro Techniques; Lipid Peroxides; Oxidation-Reduction; Pentanes

Measurements of pentane and ethane as indices of in vivo lipid peroxidation were made on samples of breath from vitamin C-sufficient and vitamin C-deficient guinea pigs injected with 23 microliters carbon tetrachloride (CCl4)/100 g body wt. Vitamin C-deficient animals produced significantly more pentane and ethane after CCl4 treatment than did vitamin C-sufficient guinea pigs. Pretreatment of vitamin C-deficient animals with 75 mg ascorbic acid/100 g body wt significantly lowered both pentane and ethane evolution. Protection against in vivo lipid peroxidation similar to that provided by ascorbic acid was also found when vitamin C-deficient guinea pigs were pretreated with isoascorbic acid, reduced glutathione, alpha-tocopherol or beta-carotene. When animals were pretreated with the radical scavenger mannitol, a protective effect was also observed as measured by pentane evolution.

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Carbon Tetrachloride Poisoning; Ethane; Guinea Pigs; Lipid Peroxides; Male; Pentanes; Time Factors