ascorbic-acid and thiobarbituric-acid

Considering the pathologic importance of oxidative stress and altered lipid metabolism in osteoarthritis (OA), this study aimed to investigate the effect of l-carnitine supplementation on oxidative stress, lipid profile, and clinical status in women with knee OA. We hypothesized that l-carnitine would improve clinical status by modulating serum oxidative stress and lipid profile. In this randomized double-blind, placebo-controlled trial, 72 overweight or obese women with mild to moderate knee OA were randomly allocated into 2 groups to receive 750 mg/d l-carnitine or placebo for 8 weeks. Dietary intake was evaluated using 24-hour recall for 3 days. Serum malondialdehyde (MDA), total antioxidant capacity (TAC) and lipid profile, visual analog scale for pain intensity, and patient global assessment of severity of disease were assessed before and after supplementation. Only 69 patients (33 in the l-carnitine group and 36 in the placebo group) completed the study. l-Carnitine supplementation resulted in significant reductions in serum MDA (2.46 ± 1.13 vs 2.16 ± 0.94 nmol/mL), total cholesterol (216.09 ± 34.54 vs 206.12 ± 39.74 mg/dL), and low-density lipoprotein cholesterol (129.45 ± 28.69 vs 122.05 ± 32.76 mg/dL) levels compared with baseline (P < .05), whereas these parameters increased in the placebo group. Serum triglyceride, high-density lipoprotein cholesterol, and TAC levels did not change significantly in both groups (P > .05). No significant differences were observed in dietary intake, serum lipid profile, MDA, and TAC levels between groups after adjusting for baseline values and covariates (P > .05). There were significant intragroup and intergroup differences in pain intensity and patient global assessment of disease status after supplementation (P < .05). Collectively, l-carnitine improved clinical status without changing oxidative stress and lipid profile significantly in women with knee OA.

Topics: Ascorbic Acid; Benzothiazoles; Body Mass Index; Carnitine; Cholesterol, HDL; Cholesterol, LDL; Dietary Fats; Dietary Proteins; Dietary Supplements; Double-Blind Method; Energy Intake; Female; Humans; Lipid Metabolism; Malondialdehyde; Middle Aged; Motor Activity; Nutrition Assessment; Obesity; Osteoarthritis, Knee; Overweight; Oxidative Stress; Selenium; Sulfonic Acids; Thiobarbiturates; Triglycerides; Vitamin A; Vitamin E; Zinc

To test the effect of supplementation of diet with ascorbic acid, selenium, alpha-tocopherol and beta-carotene on the oxidation resistance of very low (VLDL) + low density lipoprotein (LDL).. A randomized placebo-controlled double-masked clinical trial.. In healthy men aged 30-58 years smoking regularly 15-40 cigarettes/day.. Forty subjects recruited from the general population, who all completed the study.. 400 mg of slow release ascorbic acid, 100 micrograms of organic selenium, 200 mg of D-alpha-tocopheryl acetate and 30 mg of beta-carotene daily or placebo, 20 men in each group for 3 months.. The oxidation resistance of VLDL + LDL measured by inducing oxidation with copper chloride and, separately, with a combination of haemin and H2O2.. In plasma, alpha-tocopherol increased by 72%, beta-carotene by 209%, ascorbate by 45% and selenium by 20% in the supplemented men. The lag time to oxidation increased by 27% [95% confidence interval (CI) 18-35%, P < 0.001] after copper and by 29% (95% CI 12-46%, P = 0.002) after haemin plus H2O2 in the supplemented group as compared to the placebo group by t-tests. The respective net changes in the maximal oxidation velocity were a reduction of 10% (95% CI 1-21%, P = 0.037) after copper and a reduction of 15% (95% CI-1 to 30%, P = 0.070) after haemin and H2O2.. These findings provide further confirmation for the notion that the supplementation of diet with antioxidative vitamins and selenium increases the oxidation resistance of atherogenic lipoproteins in human plasma.

Topics: Adult; Antioxidants; Ascorbic Acid; Carotenoids; Double-Blind Method; Food, Fortified; Humans; Lipid Peroxidation; Lipoproteins, LDL; Lipoproteins, VLDL; Male; Middle Aged; Selenium; Smoking; Thiobarbiturates; Vitamin E

The development of UV-B protective mechanisms in aquacultural species is essential for the sustainable production of healthy aqua crop. Freshwater carp Catla catla larvae (13.5 ± 1.12 mg) were fed with a diet containing 0.5% vitamin C (D1) and a control diet (D2) for 40 days. Each group was exposed to two doses of UV-B irradiation: 360 (5 min, D1

Topics: Animals; Antioxidants; Ascorbic Acid; Carps; Dietary Supplements; DNA Fragmentation; HSP70 Heat-Shock Proteins; Larva; Models, Animal; Nitric Oxide Synthase; Radiation Protection; Sunscreening Agents; Thiobarbiturates; Ultraviolet Rays

The toxicity of Roundup Original® (GLY), a glyphosate-based herbicide widely used in crops in Mato Grosso state, was determined in hybrid fish jundiara or pintado da Amazônia. The 96 h-LC

Topics: Acetylcholinesterase; Animals; Ascorbic Acid; Biomarkers; Brain; Catalase; Catfishes; Glycine; Glyphosate; Herbicides; Liver; Muscles; Oxidative Stress; Protein Carbonylation; Superoxide Dismutase; Thiobarbiturates; Thiobarbituric Acid Reactive Substances

Little is known about how vitamins can affect the peroxidation and stability of polyunsaturated fatty acids in cooked foods. Thus the effects of 15 vitamins on toxic malondialdehyde (MDA) formation in cooked beef patties were examined with the application of solid phase extraction and thiobarbituric acid (TBA) analysis by HPLC-DAD. The polyunsaturated fatty acid profiles in cooked beef patties treated with some vitamins were further compared with that of control sample (no vitamin addition) by GC-MS analysis.. Pyridoxamine, pyridoxine, retinoic acid, α-tocopherol and L-ascorbic acid exhibited significant effects lowering the amount of MDA. It was further discovered that retinoic acid, α-tocopherol and l-ascorbic acid could help preserve polyunsaturated fatty acids, while pyridoxamine addition actually showed no effect upon the retention of most of the tested polyunsaturated fatty acids, even lowering the content of arachidonic acid. Further LC-MS analysis demonstrated that pyridoxamine could directly react with MDA via an addition reaction. The reaction involves a nucleophilic attack of pyridoxamine's free amine group on one of the aldehyde functional groups of MDA to form a new adduct, and may accelerate lipid peroxidation with the loss of more polyunsaturated fatty acids.. Some vitamins may directly participate in lipid peroxidation and affect food quality. © 2015 Society of Chemical Industry.

Topics: alpha-Tocopherol; Animals; Ascorbic Acid; Cattle; Drug Stability; Fatty Acids, Unsaturated; Lipid Peroxidation; Malondialdehyde; Pyridoxamine; Pyridoxine; Red Meat; Thiobarbiturates; Tretinoin; Vitamins

The objective of this study was to show the effects of probiotic supplementation on systemic and intestinal oxidant-antioxidant events in splenectomized rats.. Male rats were divided into control (group 1) and splenectomized (group 2) groups, and after splenectomy, some rats were given Lactobacillus delbruckii subsp. bulgaricus (highest amount of extracellular polysaccharides, 211 mg/l) for 7 days (group 3) or were given the treatment for 7 days before and 7 days after splenectomy (group 4). The plasma and small intestine tissue thiobarbituric acid reactive substances (TBARS), sulfhydryl group, glutathione, ascorbic acid, and nitric oxide metabolites (NO x ) levels were determined by a spectrophotometer.. We found increased TBARS levels in both the plasma and small intestine in the splenectomized rats compared to controls. L. delbruckii subsp. bulgaricus supplementation decreased the TBARS levels in the plasma in the splenectomized rats. In this study, the plasma TBARS and NO x levels were decreased by L. delbruckii subsp. bulgaricus supplementation after or both after and before splenectomy (groups 3 and 4).. Together, these data suggest that. L. delbruckii subsp. bulgaricus supplementation is beneficial for decreasing lipid peroxidation and enhancing the antioxidant capacity of systemic and intestinal tissue in splenectomized rats.

Topics: Animals; Antioxidants; Ascorbic Acid; Dietary Supplements; Female; Glutathione; Intestine, Small; Lactobacillus delbrueckii; Lipid Peroxidation; Male; Nitric Oxide; Probiotics; Rats, Sprague-Dawley; Spectrophotometry; Splenectomy; Sulfhydryl Compounds; Thiobarbiturates; Thiobarbituric Acid Reactive Substances

The source and quantity of nutrients available to plants can affect the quality of leafy herbs. A study was conducted to compare quality of Cosmos caudatus in response to rates of organic and mineral-based fertilizers. Organic based fertilizer GOBI (8% N:8% P₂O₅:8% K₂O) and inorganic fertilizer (15% N, 15% P₂O₅, 15% K₂O) were evaluated based on N element rates at 0, 30, 60, 90, 120 kg h⁻¹. Application of organic based fertilizer reduced nitrate, improved vitamin C, antioxidant activity as well as nitrogen and calcium nutrients content. Antioxidant activity and chlorophyll content were significantly higher with increased fertilizer application. Fertilization appeared to enhance vitamin C content, however for the maximum ascorbic acid content, regardless of fertilizer sources, plants did not require high amounts of fertilizer.

Topics: Antioxidants; Ascorbic Acid; Asteraceae; Chlorophyll; Fertilizers; Iron; Minerals; Nitrates; Organic Chemicals; Plant Leaves; Thiobarbiturates; Thiocyanates

Antioxidant enzymes and oxidative stress indicators were evaluated in fish exposed to different concentrations of the herbicide Roundup 48% (Monsanto, St. Louis, MO): control (none), 0.45, or 0.95 mg/l. After exposure for 8 days to herbicide, fish were transferred to clean water for a recovery response period (also 8 days). Herbicide increased thiobarbituric acid reactive species in liver and muscle at the higher concentration and in the brain at both concentrations. Protein carbonyl in liver increased after exposure. Catalase (CAT) and superoxide dismutase (SOD) activities and ascorbic acid levels in liver did not change in fish exposed to both concentrations. Glutathione S-transferase (GST) levels decreased at both concentrations. The nonprotein thiol levels decreased at the 0.95 mg/l concentration. During the recovery period, some of the parameters that had altered, such as protein carbonyl content, later recovered. However, some enzymes reacted during this period, e.g., GST increased its activity, possibly indicating a compensatory response against the toxic conditions. In contrast, CAT and SOD activities decreased during the recovery period, indicating herbicide toxicity. Oxidative stress that occurred during the exposure period was likely due to the increased lipid peroxidation and protein carbonyl content. The results concerning oxidative and antioxidant profiles indicate that short-term exposure to herbicide is capable of causing oxidative stress in fish tissues.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Catalase; Catfishes; Glutathione Transferase; Glycine; Glyphosate; Lipid Peroxidation; Liver; Muscles; Oxidative Stress; Protein Carbonylation; Superoxide Dismutase; Thiobarbiturates; Time Factors; Water Pollutants, Chemical

Design and synthesis of organoselenium compounds with high thiol peroxidase (TPx) and low thiol oxidase (TOx) activities have been a difficult task and remains a synthetic-activity relationship dilemma. In this regard we are reporting for the first time a detail experimental data (both in vitro and in vivo) about the anti-oxidant and toxicological profile of an Imine (-N) containing organoselenium compound (Compound A). The TPx activity of Compound A was significantly higher than diphenyl diselenide (DPDS). Both Compound A and DPDS protected sodium nitropruside (SNP) induced thiobarbituric acid reactive species (TBARS) production in rats tissue homogenate with significantly higher activity observed for Compound A than DPDS (p<0.05). The Compound A also exhibited strong antioxidant activity in the DPPH and ABTS radical scavenging assays. This study reveals that an imine group close to selenium atom drastically enhances the catalytic activities in the aromatic thiol (PhSH) assay systems. The oxidation of biologically significant thiols reflects the toxicity of the compounds. However, the present data showed that treatment with Compound A at 0, 10, 25 or 50mg/kg was not associated with mortality or body weight loss. Similarly it did not inhibit α-ALA-D and Na(+1)/K(+1) ATPase (sulfhydryl group containing enzymes) activities after acute oral treatment; rather it enhanced non-protein thiols (NPSH) concentration. The Compound A did not cause any oxidative stress as measured by TBARS production in rat's tissue preparation. Our data also indicate that exposure to Compound A did not affect plasma transaminase activities or levels of urea and creatinine in rats. Ascorbic acid is always considered a marker of oxidative stress and the reduction of its content may indicate an increase in oxidative stress. Treatment with Compound A did not alter Ascorbic acid levels in rats. The conducted in vitro and in vivo tests show the versatile therapeutic potential of this compound in the area of free radical induced damages, will undoubtedly enhance our understanding of the mechanism of model compounds and may ultimately yield insights that result in improved GPx mimics.

Topics: Animals; Ascorbic Acid; Brain; Creatinine; Free Radicals; Hydroxides; Imines; Kidney; Liver; Organoselenium Compounds; Porphobilinogen Synthase; Rats; Sodium-Potassium-Exchanging ATPase; Thiobarbiturates; Urea

Vitamin C is a water-soluble chain-breaking antioxidant that has beneficial effects on lipid-metabolizing enzymes. In the present study, the level of thiobarbituric acid (TBA) substances and antioxidant enzymes such as catalase, superoxide dismutase (SOD), glutathione peroxidase and glutathione-S-transferase were assayed.. The level of TBA substances and antioxidant enzymes was determined in plasma and RBC hemolysates, respectively, in 60 postmenopausal women with breast cancer.. The data obtained from the study revealed that the levels of TBA and the antioxidant enzymes catalase, SOD, glutathine peroxidase and glutathine-S-transferse were significantly normalized by vitamin C treatment in the RBC hemolysate.. The results compared vitamin C-treated breast cancer patients with normal individuals and showed that co-administration of vitamin C is more beneficial in breast cancer patients treated with tamoxifen.

Topics: Antineoplastic Agents, Hormonal; Antioxidants; Ascorbic Acid; Breast Neoplasms; Catalase; Erythrocytes; Female; Glutathione; Glutathione Peroxidase; Glutathione Transferase; Humans; Lipid Peroxidation; Oxidative Stress; Superoxide Dismutase; Tamoxifen; Thiobarbiturates; Vitamin E; Vitamins

This study examined whether two genotypes of hybrid poplar (Populus deltoides x Populus trichocarpa), previously classified as ozone tolerant and ozone sensitive, had differing physiological and biochemical responses when fumigated with 120 nL L(-1) ozone for 6 h per day for eight consecutive days. Isoprene emission rate, ozone uptake and a number of physiological and biochemical parameters were investigated before, during and after fumigation with ozone. Previous studies have shown that isoprene protects plants against oxidative stress. Therefore, it was hypothesized that these two genotypes would differ in either their basal isoprene emission rates or in the response of isoprene to fumigation by ozone. Our results showed that the basal emission rates of isoprene, physiological responses and ozone uptake rates were all similar. However, significant differences were found in visible damage, carotenoids, hydrogen peroxide (H(2)O(2)), thiobarbituric acid reactions (TBARS) and post-fumigation isoprene emission rates. It is shown that, although the classification of ozone tolerance or sensitivity had been previously clearly and carefully defined using one particular set of parameters, assessment of other key variables does not necessarily lead to the same conclusions. Thus, it may be necessary to reconsider the way in which plants are classified as ozone tolerant or sensitive.

Topics: Ascorbic Acid; Butadienes; Carotenoids; Chlorophyll; Chlorophyll A; Genotype; Hemiterpenes; Hydrogen Peroxide; Lipid Peroxidation; Oxidative Stress; Ozone; Pentanes; Plant Leaves; Populus; Thiobarbiturates

This study was designed to examine if diphenyl diselenide (PhSe)(2), an organoselenium compound, attenuates oxidative stress caused by acute physical exercise in skeletal muscle and lungs of mice. Swiss mice were pre-treated with (PhSe)(2) (5 mg kg(-1) day(-1)) for 7 days. At the 7th day, the animals were submitted to acute physical exercise which consisted of continuous swimming for 20 min. The animals were euthanized 1 and 24 h after the exercise test. The levels of thiobarbituric acid reactive species (TBARS), non-protein thiols (NPSH) and ascorbic acid and the activity of catalase (CAT) were measured in the lungs and skeletal muscle of mice. Glycogen content was determined in the skeletal muscle of mice. Parameters in plasma (urea and creatinine) were determined. The results demonstrated an increase in TBARS levels induced by acute physical exercise in the skeletal muscle and lungs of mice. Animals submitted to exercise showed an increase in non-enzymatic antioxidant defenses (NPSH and ascorbic acid) in the skeletal muscle. In lungs of mice, activity of CAT was increased. (PhSe)(2) protected against the increase in TBARS levels and ameliorated antioxidant defenses in the skeletal muscle and lungs of mice submitted to physical exercise. These results indicate that acute physical exercise caused a tissue-specific oxidative stress in the skeletal muscle and lungs of mice. (PhSe)(2) protected against oxidative damage induced by acute physical exercise in mice.

Topics: Animals; Antioxidants; Ascorbic Acid; Benzene Derivatives; Catalase; Creatinine; Glycogen; Lung; Male; Mice; Muscle, Skeletal; Organoselenium Compounds; Oxidative Stress; Physical Conditioning, Animal; Thiobarbiturates; Urea

Since raised oxidative stress (OS) or weak antioxidant defence or both are considered to be important players in multimechanistic pathogenesis of cancer, the present study was undertaken to evaluate their possible involvement in the pathogenesis of this disease in the local population. Levels of plasma vitamin C, vitamin E, total antioxidant activity (TAA) and thiobarbituric acid reacting substances (TBARS) as a marker of OS were measured in 20 cancer patients (Mean age 63.1 + 9.3 yr.) and 20 age, sex and socioeconomically matched healthy subjects (Mean age 63.7+7.8 yr.). Significantly low level of vitamin C (p <0.001), vitamin E (p <0.001) and TAA (p <0.003) were observed in cancer patients, whereas OS was significantly increased in patients as compared to control (p <0.003). Smokers had significantly lowered TAA and significantly raised OS than non-smokers, in both case and control groups. Tobacco chewer patients had raised OS as compared to control. This study supports the thesis that OS is a risk factor in carcinogenesis and that smoking, an established risk factor in cancer, at least partly appears through it.

Topics: Aged; Ascorbic Acid; Case-Control Studies; Female; Humans; Male; Middle Aged; Neoplasms; Oxidative Stress; Risk Assessment; Risk Factors; Thiobarbiturates; Vitamin E

Green leafy vegetables (GLV) offer a cheap but rich source of a number of micronutrients and other phytochemicals having antioxidant properties. The potential of 30 GLV in the raw and cooked form as natural antioxidant supplements for vegetarian diets was assessed. There was a large variability in the values of antioxidant activity of various GLV extracts in the lipid micelles (1.5-5.6 mM vitamin E/100 g for raw samples and 1.6-3.8 mM vitamin E/100 g for cooked samples). Similar to thiobarbituric acid reactive substances values, the super oxide scavenging ability values also exibited large variation (10.6-55.9), with significantly higher values in the raw state than the cooked state (P<0.001). Omum leaves, radish leaves and lettuce had high values for this index. The range of values for ferrous iron chelating activity was from 9.3 to 65.7 mM EDTA/100 g food material, indicating again a large variability in this assay. Leaves of coriander, amaranthus viridis, colcasia green and drumstick showed high values, while Amaranthus p. Colocasia black and amaranthus red exibited low values. Differences between raw and cooked values were highly significant for all the three indices (P<0.001).

Topics: Antioxidants; Ascorbic Acid; Cooking; Diet, Vegetarian; Iron Chelating Agents; Lipid Peroxidation; Micronutrients; Plant Extracts; Plant Leaves; Thiobarbiturates; Vegetables

We used factorial design to ascertain the influence of dietary fat source (linseed, sunflower and oxidized sunflower oils, and beef tallow) and the dietary supplementation with alpha-tocopheryl acetate (alpha-TA) (225 mg/kg of feed) and ascorbic acid (AA) (110 mg/kg) on dark chicken meat oxidation (lipid hydroperoxide and TBA values and cholesterol oxidation product content). alpha-TA greatly protected ground and vacuum-packaged raw or cooked meat from fatty acid and cholesterol oxidation after 0, 3.5, or 7 mo of storage at -20 C. In contrast, AA provided no protection, and no synergism between alpha-TA and AA was observed. Polyunsaturated fatty acid-enriched diets (those containing linseed, sunflower, or oxidized sunflower oils) increased meat susceptibility to oxidation. Cooking always involved more oxidation, especially in samples from linseed oil diets. The values of all the oxidative parameters showed a highly significant negative correlation with the alpha-tocopherol content of meat.

Topics: alpha-Tocopherol; Animal Feed; Animals; Ascorbic Acid; Cattle; Chickens; Cholesterol; Dietary Fats; Drug Interactions; Fats; Fatty Acids; Female; Food Packaging; Food Preservation; Freezing; Hot Temperature; Linseed Oil; Lipid Peroxides; Oxidation-Reduction; Plant Oils; Poultry Products; Sunflower Oil; Thiobarbiturates; Time Factors; Tocopherols

Topics: Animals; Antioxidants; Ascorbic Acid; Cells, Cultured; Liver; Male; Oxidative Stress; Rats; Rats, Sprague-Dawley; Thiobarbiturates; Vitamin E

Topics: Animals; Anti-Ulcer Agents; Antioxidants; Ascorbic Acid; Carcinogens; Catalase; Diethylnitrosamine; Drug Interactions; Free Radicals; Glutathione; Glutathione Peroxidase; Glutathione Reductase; Glutathione Transferase; Lipid Peroxidation; Male; Malondialdehyde; Mitochondria, Liver; Rats; Rats, Wistar; Succinic Acid; Superoxide Dismutase; Thiobarbiturates; Vitamin E

The generation of free radicals during the lipid peroxidation of liposomes composed of 1-palmitoyl-2-arachidonoylphosphatidylcholine (PAPC-liposome) in Fe2+/ascorbic acid (AsA) solution was studied by the ESR spin trapping technique. A carbon-centered radical adduct was observed using alpha-(4-pyridyl-1-oxide)-N-tert-butyl-nitorone (4-POBN) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), but no oxygen-centered radicals such as .OH, LO., and LOO. were observed. The lipid peroxidation evaluated as 2-thiobarbituric acid reactive substances was inhibited by the addition of 4-POBN. The intensity of this inhibitory effect was dependent on the time when 4-POBN was added to the mixture of PAPC-liposomes and Fe2+/AsA solution, and no inhibitory effect could be observed after 4 min. The signal intensity of the carbon-centered radical adduct was dependent on the lipid concentration of PAPC-liposomes. These results suggest that the alkyl radicals generated from PAPC-liposome peroxidation induced by Fe2+/AsA were trapped by DMPO or 4-POBN at an earlier stage of lipid peroxidation.

Topics: Ascorbic Acid; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Ferrous Compounds; Free Radicals; Kinetics; Lipid Peroxidation; Liposomes; Nitrogen Oxides; Phospholipid Ethers; Pyridines; Solutions; Spin Labels; Thiobarbiturates

In vitro generation of thiobarbituric acid reactive substances (TBARS) is frequently used to assess organ susceptibility to lipid peroxidation. The yield of TBARS is severalfold enhanced by an addition of iron ions with reductors or chelators such as ascorbate, NADPH, ADP or pyrophosphate. The process cannot be interpreted in a simple way, since it involves several enzymatic and nonenzymatic reactions. There are no clear interpretations of the ambiguous effects of denaturating factors and chelating agents on TBARS generation. Also controversy arises from the curvilinear relationship between the homogenate concentration and the yield of TBARS. This has been modelled in the present work by combining two functions describing the sequential reaction with two limiting steps. One of them is related to catalytic action of iron and ascorbate, while the other to an enzyme, possibly phospholipase A2, as has been suggested by some investigators. Two models should be considered since it is impossible to decide which kinetic equation should predominate in the model. Nevertheless, the model reflects kinetic properties of the process. The effects of catalyst concentration and some other modification upon the yield of TBARS were also investigated experimentally. The results of experiments and modelling showed that the analytical procedures used by investigators need standardisation as the results obtained under a variety of procedures may reflect quite different properties of the living systems.

Topics: Acetates; Animals; Ascorbic Acid; Brain; Cadmium; In Vitro Techniques; Iron; Kidney; Kinetics; Lipid Peroxidation; Liver; Models, Biological; Rats; Sodium Selenite; Thiobarbiturates; Thiobarbituric Acid Reactive Substances; Vitamin E

Feeding a high fish oil diet (25 wt%) to rats for 14 days increased the content of docosahexaenoic acid (DHA) in liver lipids, and diminished the liver antioxidant defenses as measured by the contents of alpha-tocopherol, ascorbic acid and non-protein SH, the last of which is consisting mostly of glutathione, and the activity of selenium-dependent glutathione peroxidase (GSHPx). These changes in antioxidant defenses are suggested to be associated with an increased susceptibility of the liver to lipid peroxidation as assessed by thiobarbituric acid (TBA) reaction and chemiluminescence intensity. Serum TBA value was also high in the rats given high fish oil diet. The present results demonstrate that a high fish oil diet potentiates susceptibility of rats to lipid peroxidation and augments requirement for antioxidants to provide adequate protection.

Topics: Animals; Antioxidants; Ascorbic Acid; Dietary Fats, Unsaturated; Docosahexaenoic Acids; Fish Oils; Glutathione; Glutathione Peroxidase; Lipid Peroxidation; Liver; Luminescent Measurements; Male; Rats; Rats, Sprague-Dawley; Sulfhydryl Compounds; Thiobarbiturates; Vitamin E

Relationships between serum thiobarbituric acid (TBA) level and smoking, alcohol drinking, differences in food intake with alcohol drinking, serum vitamin C (VC) and E (VE) were studied in 283 non-treated men (aged 20-69 years) who visited a human dock conducted in an urban area of Hyogo prefecture in 1989-1991 (annually May-July). The results were as follows: 1. An effect of smoking on serum TBA level was not observed. 2. The subjects were divided into three groups according to weekly sake intake levels, i.e., non-drinkers including ex-drinkers (ND), mild drinkers (MD, weekly sake intake: < or = 1260 ml), and heavy drinkers (HD, > 1260 ml). The serum TBA level of HD, but not of MD, was significantly higher than that of ND. 3. Serum TBA level had significant positive correlations with age, GPT, gamma-GTP, TC (total cholesterol), TG (triglycerides), PL (phospholipids), total serum lipids (TLP, i.e., TC+TG+PL), VE, eicosapentaenoic acid (EPA, C20:5) and docosahexaenoic acid (DHA, C22:6), but had no significant correlations with VC and VE/TLP. 4. The subjects (N+M) D, which included ND and MD, and those of HD were divided respectively into three groups according to weekly food intake levels, i.e., non-intake group (NF), low frequent intake group (LF, 1-3 days/week), and high frequent intake group (HF, > or = 4 days/week). The fish intake level of HD was significantly higher than that of (N+M) D, while the intake levels of vegetables, fruits and soft drinks of HD were significantly lower than those of (N+M) D. 5. Serum TBA level, GOT, GPT, gamma-GTP, TG, PL, TLP, VE, EPA and DHA of HD were significantly higher than those of (N+M) D. On the other hand, VC of HD was significantly lower than that of (N+M) D. 6. When the subjects of (N+M) D were divided into three groups according to weekly fish intake levels as mentioned above, serum TBA level, EPA and DHA of HF in (N+M) D were significantly higher than those of NF in (N+M) D. 7. Serum TBA level of HD in non-fish intake group was significantly higher than that of (N+M) D in the same group. These results suggest that increased serum TBA level in HD is closely related to the increased intake frequency of fish in addition to the effect of alcohol drinking.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Aged; Alcohol Drinking; Ascorbic Acid; Diet; Humans; Lipid Peroxides; Male; Middle Aged; Multiphasic Screening; Smoking; Thiobarbiturates; Vitamin E

The objective of this work is to reexamine the competitive degradation of deoxyribose by hydroxyl radicals (.OH) produced by the reaction between H2O2 and Fe(2+)-EDTA. The .OH radicals produced attack deoxyribose (D, rate constant kD) and eventually an .OH scavenger (S, rate constant kS). First, we examined the effect of [D], [H2O2], [Fe(2+)-EDTA], [EDTA]/[Fe2+] ratio and reaction time on the rate of D degradation, measured as the absorbance of the chromogen formed between the product of the reaction D + .OH (malondialdehyde) and thiobarbituric acid. In particular, it was showed that under our experimental conditions ([D] = 3 mM, [H2O2] = 0.85 mM, [Fe2+] = 0.13 mM), the rate of overall process is first order in Fe2+, zero order in H2O2 and is maximal for a ratio [EDTA]/[Fe2+] = 1.1. Second, the kinetics of .OH radical reaction in competition experiments between D and S (mannitol) was investigated. The results show that the ratio of the rates of D degradation in the absence (VD) and in the presence (VDS) of S should be represented by VD/VDS = 1 + ks[S]/(kD[D] + kx) where kx accounts for the rate of .OH reactions with other reagents such as Fe(2+)-EDTA, H2O2 etc . . . After having determined kx for each set of experimental conditions, we obtained the values of kS/kD by determining the variations of VD/VDS as a function of [S] and [D]. By taking kD = 1.9 x 10(9) M-1s-1 a value of kS = 1.9 x 10(9) M-1s-1 was obtained, very close to that obtained by pulse radiolysis. Finally, the validity of the established relation was confirmed for other biomolecules (methionine, k = 5.6 x 10(9)M-1s-1 and alanine, k = 3.3 x 10(8) M-1s-1). By contrast, it was not applicable to cysteine, thiourea and mercaptoethanol which was attributed to an interaction of the latter scavengers with Fe2+ and/or H2O2.

Topics: Amino Acids; Ascorbic Acid; Chromogenic Compounds; Deoxyribose; Edetic Acid; Ferrous Compounds; Hydrogen Peroxide; Hydroxyl Radical; Kinetics; Malondialdehyde; Mannitol; Sulfur; Thiobarbiturates

Iron-ascorbate stimulated lipid peroxidation in rat liver microsomes can be inhibited by glutathione (GSH). The role of protein thiols and vitamin E in this process was studied in liver microsomes isolated from rats fed diets either sufficient or deficient in vitamin E and incubated at 37 degrees C under 100% O2. Lipid peroxidation was induced by adding 400 microM adenosine 5'-triphosphate, 2.5 to 20 microM FeCl3, and 450 microM ascorbic acid. One mL of the incubation mixture was removed at defined intervals for the measurement of thiobarbituric acid reactive substances (TBARS), protein thiols and vitamin E. In vitamin E sufficient microsomes, the addition of GSH enhanced the lag time prior to the onset of maximal TBARS accumulation and inhibited the loss of vitamin E. Treatment of these microsomes with the protein thiol oxidant diamide resulted in a 56% loss of protein thiols, but did not significantly change vitamin E levels. However, diamide treatment abolished the GSH-mediated protection against TBARS formation and loss of vitamin E during ascorbate-induced peroxidation. Liver microsomes isolated from rats fed a vitamin E deficient diet contained 40-fold less vitamin E and generated levels of TBARS similar to vitamin E sufficient microsomes at a 4-fold lower concentration of iron. GSH did not affect the lag time prior to the onset of maximal TBARS formation in vitamin E deficient microsomes although total TBARS accumulation was inhibited. Similar to what was previously found in vitamin E sufficient microsomes [Palamanda and Kehrer, (1992) Arch. Biochem. Biophys. 293, 103-109], GSH prevented the loss of protein thiols in vitamin E deficient microsomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Triphosphate; Animals; Ascorbic Acid; Chlorides; Ferric Compounds; Glutathione; Kinetics; Lipid Peroxidation; Microsomes, Liver; Rats; Sulfhydryl Compounds; Thiobarbiturates; Vitamin E

The irreversible loss of activity of the sarcolemma-localized beta-receptor-adenylyl cyclase system (beta-RAS) in myocardial ischemia is a well documented phenomenon. Alterations in the sarcolemma (SL) induced by reactive O2 species could be responsible for this loss. Therefore the influence of oxidation of SH-groups and lipid peroxidation induced by Fe2+/Vit. C on the beta-RAS activity was studied. During incubation of SL with Fe2+/Vit. C a transient enhancement followed by a continuous loss of the beta-RAS activity (isoprenaline-, NaF-, Gpp(NH)p-, forskolin-stimulated and basal activity) was observed. In contrast there occurred a continuous loss of SH-groups and lipid peroxidation, beginning immediately after the start of incubation. Loss of SH-groups and lipid peroxidation as well as changes in the beta-RAS did not take place in the presence of the antioxidant t-Butyl-4-hydroxyanisole (BHA) or the Fe(2+)-chelator EGTA. In view of the known ischemia-induced formation of reactive O2 species our results show that these powerful oxidants could contribute to the modulation of the beta-RAS during myocardial ischemia.

Topics: Adenylyl Cyclases; Animals; Ascorbic Acid; Ferrous Compounds; In Vitro Techniques; Lipid Peroxidation; Oxidation-Reduction; Oxygen; Receptors, Adrenergic, beta; Sarcolemma; Sulfhydryl Compounds; Swine; Thiobarbiturates

The possible role of lipid peroxidation in the nephrotoxicity of the antitumour drug cisplatin was studied in vitro. In contrast to Adriamycin, cisplatin did not induce lipid peroxidation in rat kidney microsomes containing a NADPH-generating system. Pretreatment of rat kidney microsomes with cisplatin did not reduce the activity of a microsomal glutathione (GSH)-dependent protective factor against lipid peroxidation induced by Fe(2+)-ascorbate. However, pretreatment of rat kidney microsomes with 0.1 mM N-ethyl maleimide (NEM) did reduce this GSH-dependent protection. Cisplatin also did not reduce the activity of a cytosolic GSH-dependent protective factor against Fe(2+)-ascorbate-induced lipid peroxidation. The results of our experiments indicate that, in contrast to Adriamycin, cisplatin does not induce lipid peroxidation in vitro in various test systems. It also does not destroy microsomal and cytosolic GSH-dependent protective factors against lipid peroxidation.

Topics: Animals; Ascorbic Acid; Cisplatin; Cytosol; Doxorubicin; Ferric Compounds; Hot Temperature; Kidney; Lipid Peroxidation; Male; Microsomes; NADP; Rats; Rats, Wistar; Thiobarbiturates

Lipid peroxidation is known to be a mechanism for Adriamycin-induced toxicity. In the present study, two methods which detect fluorescent substances and high molecular weight protein aggregates in peroxidized membranes were applied to Adriamycin-induced lipid peroxidation in liver microsomes. A rat liver microsomal suspension containing an NADPH-generating system was incubated with Adriamycin. Thiobarbituric acid reactive substances (TBA-RS), formed during this incubation, were transferred from the microsomes to the medium. Fluorescent substances determined by the fluorescence emitted from both the microsomes themselves and the chloroform/methanol extracts of the microsomes, were found to be formed during this incubation. High molecular weight protein aggregates determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, were also formed. Fluorescent substances and high molecular weight protein aggregates were found in microsomal membranes themselves and increased time dependently. These substances retained in membranes can be of great use to delineate the site of Adriamycin-induced lipid peroxidation in vitro and in vivo and to determine how this lipid peroxidation affects the membrane.

Topics: Animals; Ascorbic Acid; Doxorubicin; Fluorescence; Iron; Lipid Peroxidation; Male; Microsomes, Liver; Molecular Weight; NADP; Protein Biosynthesis; Rats; Rats, Inbred Strains; Thiobarbiturates

The effects of dietary ascorbic acid on plasma lipoprotein and liver lipid peroxide concentrations were examined using ODS od/od rats with a genetic defect in the ability to synthesize ascorbic acid. ODS od/od rats were fed purified diets supplemented with 0 to 300 mg ascorbic acid/kg diet for 21 d. An ascorbic acid-free diet induced body weight loss, depleted ascorbic acid in the plasma and increased thiobarbituric acid-reactive substances in the plasma and liver as compared with rats fed ascorbic acid supplemented diets and with normal ODS +/+ rats fed the ascorbic acid-free diet. Increasing ascorbic acid concentration in the diet inhibited the development of these ascorbic acid deficiency symptoms in a dose-dependent manner. The dietary requirement of ascorbic acid to maintain normal body weight gain and plasma lipid peroxide concentrations was approximately 150 mg ascorbic acid/kg diet. On the other hand, even 300 mg ascorbic acid/kg diet was insufficient to maintain a hepatic concentration of ascorbic acid comparable to that in the liver of ODS +/+ rats. The lipid peroxide concentration in plasma LDL and liver was significantly elevated in ODS od/od rats fed the ascorbic acid-free diet. Supplementing the diet with 300 mg ascorbic acid/kg kept those concentrations within the normal ranges seen in the ODS +/+ rats.

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Cholesterol; Diet; Lipid Peroxidation; Lipid Peroxides; Lipoproteins, LDL; Liver; Male; Rats; Rats, Mutant Strains; Thiobarbiturates; Triglycerides; Weight Gain

The effect of an exchange transfusion on antioxidants in the plasma of newborns with rhesus hemolytic disease was studied. The antioxidant concentrations in donor blood were similar to normal adult values except for the lower vitamin C concentrations. Exchange transfusion decreased the newborns' iron and ferritin levels and increased their ceruloplasmin and transferrin (primary antioxidants) concentrations and latent iron-binding capacity. The changes in secondary antioxidant concentrations were variable; uric acid and thiols were stable, vitamin C and bilirubin fell, and vitamin E rose. The total peroxyl-radical trapping capacity of the secondary antioxidants did not change significantly. The fall in levels of thiobarbituric acid reactive substances, an index of lipid peroxidation, was related to the lower levels present in the donor blood. Exchange transfusion rapidly produced variable changes in the concentrations of prooxidant and antioxidant substances in plasma and may thus influence free radical metabolism in the newborn.

Topics: Adult; Antioxidants; Ascorbic Acid; Bilirubin; Blood Chemical Analysis; Blood Proteins; Ceruloplasmin; Erythroblastosis, Fetal; Exchange Transfusion, Whole Blood; Female; Ferritins; Humans; Infant, Newborn; Iron; Middle Aged; Serum Albumin; Sulfhydryl Compounds; Thiobarbiturates; Transferrin; Uric Acid; Vitamin E

Topics: Animals; Ascorbic Acid; Cell Membrane; Dihydroalprenolol; Ferrous Compounds; Lipid Peroxidation; Myocardium; Receptors, Adrenergic, beta; Sarcolemma; Swine; Thiobarbiturates

1. Blood antioxidants were measured in venous blood samples from 20 runners and six sedentary individuals. All subjects were male, between 20 and 40 years old, and in steady state with respect to body weight and physical activity patterns. Dietary analysis was undertaken using a 7-day weighed food intake. Correlations were sought between antioxidants in blood and (1) weekly training distance and (2) maximum oxygen uptake. In addition, 12 runners could be classified into two groups undertaking either low (range 16-43 km, n = 6) or high (80-147 km, n = 6) weekly training. 2. Body weight (range 55.3-90.0 kg) and percentage body fat (range 7-19%) both showed negative correlations with the weekly training distance (both P less than 0.001). Energy intake and maximum oxygen uptake were both correlated with the weekly training distance (both P less than 0.001). 3. Plasma creatine kinase activity, an indicator of muscle damage, was significantly correlated with the weekly training distance (P less than 0.01), whereas the plasma concentration of thiobarbituric acid-reactive substances, an indicator of free-radical-mediated lipid peroxidation, decreased with increased maximum oxygen uptake (P less than 0.01). 4. Erythrocyte alpha-tocopherol content was greater in the two running groups (P less than 0.05) compared with the sedentary group, and lymphocyte ascorbic acid concentration was significantly elevated in the high-training group (P less than 0.01) compared with the low-training group. 5. Erythrocyte activities of the antioxidant enzymes, glutathione peroxidase and catalase, were significantly and positively correlated with the weekly training distance (P less than 0.01 and P less than 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Antioxidants; Ascorbic Acid; Body Mass Index; Body Weight; Catalase; Creatine Kinase; Energy Intake; Erythrocytes; Glutathione; Glutathione Peroxidase; Humans; Lymphocytes; Male; Muscles; Oxygen Consumption; Physical Endurance; Running; Thiobarbiturates; Vitamin E

Fluorescence and non-enzymatic browning were observed in reactions between ascorbic acid (AH2) and amino acids (AA) as well as in reactions involving AH2 autoxidation and/or polymerization in the presence of trace amounts of adventitious iron (less than or equal to 10 microM). These reaction products exhibited fluorescent spectra (400-490 nm) akin to those of extracts from lipofuscin-rich tissues. Lengthy incubation of AH2 at 37 degrees C in phosphate buffer (pH 7.0) caused a concentration- and time-dependent increase in absorbance at 412 nm, paralleling increase in 377/440 nm fluorescence, due to formation of autoxidation/polymerization products. The fluorescences of these substances were increased by acidity and quenched at alkaline conditions but restored by neutralization. The reactions between AH2 (0.1-2.0 mM) and a number of AA (1.0-4.0 mM) were also found to result in products with blue fluorescence. Following TBA test, the AH2 autoxidation/polymerization products and AH2/AA reaction products showed only moderate and slight absorbance at 535 nm, respectively, indicating a little or minute formation of aldehydes with MDA-like reactivity. The findings in this study, nevertheless, suggest possible misinterpretations of results in previous studies dealing with AH2-dependent, oxygen free radical induced, 'lipofuscin-related fluorescence'. Thus, similar to nonenzymatic glycosylation (Maillard) reactions, AH2 autoxidation as well as reactions between AH2 and AA may result in 'lipofuscin-like material', as judged from their fluorescence spectral patterns.

Topics: Aging; Amino Acids; Ascorbic Acid; Free Radicals; Hydrogen-Ion Concentration; In Vitro Techniques; Lipofuscin; Oxidation-Reduction; Oxygen; Pigments, Biological; Spectrometry, Fluorescence; Thiobarbiturates

Young, adult, and old rats were used to study the effect of age on the integrity and functioning of brain synaptosomes. An evaluation was made of the differences in lipid composition, membrane fluidity, Na+, K(+)-ATPase activity, and susceptibility to in vitro lipid peroxidation. There was an age-related increase in synaptosomal free fatty acids, with no modification in acyl chain composition, and a decrease in membrane phospholipids which increased the cholesterol/phospholipid mole ratio. With altered lipid composition, there was a corresponding age-dependent decrease in membrane fluidity, a reduction of Na+, K(+)-ATPase activity, and an overall greater susceptibility to in vitro lipid peroxidation. Furthermore, lipid peroxidation promoted strong modifications of the membrane fluidity, lipid composition, and Na+,K(+)-ATPase activity just as aging did, thus indicating a possible contribution of oxidative damage to ageing processes. The cases studied revealed that the greater responsiveness of old membranes to in vitro lipid peroxidation resulted in the highest degree of membrane alteration, indicating that all pathological states known to promote a peroxidative injury can have even more dramatic consequences when they take place in old brain.

Topics: Aging; Animals; Ascorbic Acid; Brain; Cell Membrane; Cholesterol; Diphenylhexatriene; Fatty Acids, Nonesterified; Iron; Kinetics; Lipid Peroxidation; Malondialdehyde; Membrane Fluidity; Membrane Lipids; Phospholipids; Rats; Rats, Inbred Strains; Sodium-Potassium-Exchanging ATPase; Synaptosomes; Thiobarbiturates

To investigate molecular responses to lipid peroxidative stimuli in neoplastic cells, lipid peroxidation was induced in liver of rats bearing 3'-methyl-4-dimethylaminoazobenzene-induced hepatocellular carcinoma by injecting a high dose of carbon tetrachloride (CCl4), a strong lipoperoxidative reagent. Normal rat livers with or without CCl4 treatment served as controls. CCl4 administration markedly provoked fatty metamorphosis, visualized by oil red O staining, in normal livers while minimal fatty changes were seen in hepatocellular carcinomas, where necrosis was often observed instead. After CCl4 treatment, the thiobarbituric acid values (representing levels of lipid peroxides in the tissue) were increased two-fold in the untreated normal liver, but were unchanged in the cancer tissue. Levels of vitamin C, an acutely reactive antioxidant, measured by high-performance liquid chromatography were not influenced by the CCl4 injection in the cancer tissue whereas a significant decrease was evident in normal livers. The total fatty acid content, measured by gas chromatography, was significantly lower in the cancer tissue than in the normal liver while the ratio of polyunsaturated fatty acids (PUFAs) in total fatty acids was little changed. Resistance of hepatocellular cancer cells to fatty metamorphosis and their susceptibility to necrosis induced by free radicals may be due to the paucity of the target PUFAs in their cell membrane fraction, resulting in low levels of lipid peroxides. Peroxidation of PUFAs might act as a "shock absorber" against free radical-induced toxic cell death in normal cells.

Topics: Animals; Ascorbic Acid; Azo Compounds; Carbon Tetrachloride; Fatty Acids; Fatty Liver; Lipid Peroxidation; Liver; Liver Neoplasms, Experimental; Male; Methyldimethylaminoazobenzene; Necrosis; Rats; Thiobarbiturates

A method for a simultaneous separation of malondialdehyde (MDA), ascorbic acid and adenine nucleotide derivatives in biological samples by ion-pairing high-performance liquid chromatography is presented. The separation is obtained by an LC-18-T 15 cm x 4.6 mm 3 microns particle size column using tetrabutylammonium as the pairing ion. The starting buffer consists of 10 mM tetrabutylammonium hydroxide, 10 mM KH2PO4 plus 1% methanol, pH 7.00. A step gradient is formed using a second buffer consisting of 2.8 mM tetrabutylammonium hydroxide, 100 mM KH2PO4 plus 30% methanol, pH 5.5. Under these chromatographic conditions a highly resolved separation of MDA, ATP, ADP, AMP, adenosine, ascorbic acid, GTP, GDP, IMP, inosine, Hypoxanthine, Xanthine, uric acid, NAD, and NADP can be performed in about 36 min. In addition, the separation of NADH and NADPH can also be obtained; this renders the present method suitable for the detection of these reduced coenzymes in alkaline extracts from tissue samples. Data referring to PCA extracts from ischemic and reperfused isolated rat hearts and from human erythrocytes peroxidized in vitro by a challenge with 1 mM NaN3 and various concentrations of H2O2 are reported. The relevance of this chromatographic method lies in the possibility to determine directly MDA concentrations avoiding the unspecific thiobarbituric acid colorimetric test, any other manipulation of the sample out of the PCA extraction, and any possible coelution of other acid soluble compounds. The simultaneous determination of MDA, ascorbic acid, and of ATP and its degradation products gives the opportunity to correlate, by a single chromatographic run, peroxidative damages with the energy state of the cell which is of great importance in studies of ischemic and reperfused tissues.

Topics: Adenine Nucleotides; Animals; Ascorbic Acid; Chromatography, High Pressure Liquid; Erythrocytes; Evaluation Studies as Topic; Humans; Hydrogen Peroxide; In Vitro Techniques; Male; Malondialdehyde; Myocardial Reperfusion Injury; Rats; Rats, Inbred Strains; Thiobarbiturates

Treatment of the porcine intestinal brush-border membranes with 100 microM ascorbic acid and 10 microM Fe2+ in the presence of various concentrations of tert-butyl hydroperoxide (t-BuOOH) resulted in a marked fluorescence development at 430 nm, depending on the hydroperoxide concentration. This fluorescence formation was closely related to lipid peroxidation of the membranes as assessed by formation of conjugated diene. However there is no linear relation between thiobarbituric acid-reactive substances (TBARS) and fluorescence formation. On the other hand, fluorescence formation in the membranes by treatment with ascorbic acid/Fe2+ or t-BuOOH alone was negligible. The results with antioxidants and radical scavengers suggest that ascorbic acid/Fe2+/t-BuOOH-induced lipid peroxidation of the membranes is mainly due to t-butoxyl and/or t-butyl peroxy radicals. Most TBARS produced during the peroxidation reaction were released from the membranes, but fluorescent products remained in the membrane components. The fluorescence properties of products formed by lipid peroxidation of the membranes were compared with those of products derived from the interaction of malondialdehyde (MDA) or acetaldehyde with the membranes. The fluorescence products in the acetaldehyde-modified membranes also exhibited the emission maximum at 430 nm, while the emission maximum of MDA-modified membranes was 470 nm. The fluorescence intensity of MDA-modified membranes was markedly decreased by treatment with 10 mM NaBH4 but that of the peroxidized or acetaldehyde-modified membranes was enhanced by about two-fold with the treatment. In addition, a pH dependence profile revealed that the fluorescence intensity of the peroxidized or acetaldehyde-modified membranes decreases with increasing pH of the medium, whereas that of MDA-modified ones did not change over the pH range from 5.4 to 8.0. On the basis of these results, the fluorescence properties of products formed in the intestinal brush-border membranes by lipid peroxidation are discussed.

Topics: Animals; Ascorbic Acid; Borohydrides; Hydrogen-Ion Concentration; Intestinal Mucosa; Intestines; Lipid Peroxidation; Malondialdehyde; Microvilli; Peroxides; Spectrometry, Fluorescence; Swine; tert-Butylhydroperoxide; Thiobarbiturates

Incubation of rat-liver microsomes, previously azide-treated to inhibit catalase, with H2O2 caused a loss of cytochrome P-450 but not of cytochrome b5. This loss of P-450 was not prevented by scavengers of hydroxyl radical, chain-breaking antioxidants or metal ion-chelating agents. Application of the thiobarbituric acid (TBA) assay to the reaction mixture suggested that H2O2 induces lipid peroxidation, but this was found to be due largely or completely to an effect of H2O2 on the TBA assay. By contrast, addition of ascorbic acid and Fe(III) to the microsomes led to lipid peroxidation and P-450 degradation: both processes were inhibited by chelating agents and chain-breaking antioxidants, but not by hydroxyl radical scavengers. H2O2 inhibited ascorbate/Fe(III)-induced microsomal lipid peroxidation, but part of this effect was dues to an action of H2O2 in the TBA test itself. H2O2 also decreased the colour measured after carrying out the TBA test upon authentic malondialdehyde, tetraethoxypropane, a DNA-Cu2+/o-phenanthroline system in the presence of a reducing agent, ox-brain phospholipid liposomes in the presence of Fe(III) and ascorbate, or a bleomycin-ion iron/DNA/ascorbate system. Caution must be used in interpreting the results of TBA tests upon systems containing H2O2.

Topics: Animals; Ascorbic Acid; Bleomycin; Chlorides; Cytochrome P-450 Enzyme Inhibitors; Deferoxamine; DNA; DNA Damage; Edetic Acid; Ferric Compounds; Hydrogen Peroxide; Lipid Peroxidation; Liposomes; Male; Microsomes, Liver; Phenanthrolines; Rats; Thiobarbiturates

Rats were given a 0.05% polychlorinated biphenyls (PCB) diet supplemented with adequate nutrients for 10 days and not only PCB-induced lipid peroxidation as measured by thiobarbituric acid (TBA)-reactive substances but also variations of lipid peroxides scavengers in liver and its subcellular fractions (nuclei and cell debris, mitochondrial, microsomal and cytosolic fractions) were investigated. The lipid peroxidation in liver and subcellular fractions in the PCB-treated group increased significantly except in the nuclei and cell debris fraction. The increase in lipid peroxidation in the microsomal fraction appeared to be associated in part with the decrease in vitamin E (alpha-tocopherol) content and induction of drug-metabolizing enzymes. In the cytosolic fraction, the total lipid content increased, glutathione peroxidase (GSHPx) activity decreased and the quantity of free radical-reactive substances suppressing lipid peroxidation was low as measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) value. From these results, the increase in lipid peroxidation in the cytosolic fraction in the PCB-treated group was ascribed to the abundance and availability of oxidizable substrate attended with fatty liver, to the decline in GSHPx activity, and to the insufficiency in antioxygenic activity as observed by the decrease in the DPPH value.

Topics: Animals; Ascorbic Acid; Copper; Free Radicals; Lipid Peroxidation; Lipid Peroxides; Male; Microsomes, Liver; Polychlorinated Biphenyls; Rats; Rats, Inbred Strains; Subcellular Fractions; Thiobarbiturates; Vitamin E

Alloxan-diabetic rats and age-matched controls were killed after 6 weeks of diabetes; heart and kidneys were removed and assayed for thiobarbituric acid-reactive substances (TBARS), lipid hydroperoxides, lipid phosphorus, total fatty acid composition and glutathione. Tissue homogenates from a second group of diabetic and control rats were incubated in oxygen-saturated buffer with and without the free radical generating system Fe2+/ascorbate (0.1/1.0 mM) and were assayed for lipid peroxidation. Diabetic hearts contained markedly lower levels of TBARS and lipid hydroperoxides (40% and 18%, respectively) than control hearts, whereas differences in TBARS were less pronounced in kidneys (9%). Incubation of homogenates of both organs in the presence or absence of Fe2+/ascorbate for up to 2 h yielded significantly lower levels of TBARS and lipid hydroperoxides with diabetic tissue. Diabetic hearts and kidneys contained higher levels of glutathione (28% and 13% over controls) and both diabetic tissues showed much higher linoleate/arachidonate ratios than did the controls (9.86 vs. 2.56 for heart, 2.01 vs. 0.86 for kidney). We conclude that diabetic tissues develop enhanced defense systems against oxidative stress and we assume tha the lower levels of arachidonate contribute to their resistance to lipid peroxidation as well.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Ascorbic Acid; Diabetes Mellitus, Experimental; Fatty Acids; Ferrous Compounds; Free Radicals; Glutathione; Kidney; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Lipid Peroxides; Male; Myocardium; Phosphorus; Rats; Rats, Inbred Strains; Thiobarbiturates

In the presence of H2O2, solutions of Fe2+ were applied to brain homogenate and isolated myelin from adult SWV control mice and the shiverer dysmyelinating mutant mouse as a source of a reactive oxygen species (Fenton reaction). Under these conditions, lipid peroxidation was initiated and measured as thiobarbituric acid-reactive oxidation products (TBAR). This was accompanied by 85% inhibition of myelin-associated Na+,K(+)-ATPase and 25% inhibition of 5'-nucleotidase. In contrast, CNPase activity was not altered. Studies on the shiverer mutant brain revealed that in spite of hypomyelination and prevalence of premature, myelin-like membranes in the homogenate, the myelin-related enzymes reacted as normal enzymes to peroxidation. Differences in the resistance of Na+,K(+)-ATPase to peroxidation in the brain homogenate and myelin suggest that the myelin enzyme is extremely sensitive to reactive oxygen toxicity.

Topics: 2',3'-Cyclic-Nucleotide Phosphodiesterases; 5'-Nucleotidase; Animals; Ascorbic Acid; Brain; Female; Ferric Compounds; Ferrous Compounds; Hydrogen Peroxide; Lipid Peroxidation; Male; Mice; Mice, Neurologic Mutants; Myelin Sheath; Sodium-Potassium-Exchanging ATPase; Thiobarbiturates

The effect of acute smoking on plasma lipoproteins was studied in seventeen smokers. In study 1, 7 subjects were examined prior to and 2 weeks after supplementation with vitamin C. In study 2, the effect of acute smoking was first determined in 10 additional subjects and subsequently they were divided into 3 groups, 3 and 4 subjects were supplemented with vitamin C or E, respectively, for 4 weeks, and 3 remained untreated. Plasma and LDL TBARS were examined at time zero (i.e., 40-48 h after total abstention from smoking) and at 90 min after acute smoking (5-7 cigarettes). In all 17 subjects examined prior to vitamin supplementation, significantly higher TBARS values were found in plasma, native LDL and LDL conditioned with smooth muscle cells (SMC) when the 90 min values were compared to 0 time. The LDL isolated after 90 min and conditioned with SMC was metabolized more extensively by mouse peritoneal macrophages than its zero time counterpart. The differences between the 0 time and 90 min values were not seen after the subjects had been supplemented with vitamin C for 2 or 4 weeks or with vitamin E for 4 weeks. The present results indicate that acute smoking exerts an oxidative stress on plasma lipoproteins and that higher plasma levels of natural antioxidants, such as vitamins C and E have a protective role.

Topics: Adult; Ascorbic Acid; Female; Humans; Lipid Peroxidation; Lipoproteins; Lipoproteins, LDL; Male; Smoking; Thiobarbiturates; Vitamin E

Ebselen, 2-phenyl-1,2-benzisoselenazol-3(2H)one, and its derivatives were compared for their ability to protect microsomal membranes against iron/ADP/ascorbate-induced lipid peroxidation, measured as low-level chemiluminescence and accumulation of thiobarbituric acid-reactive substances (TBARS). The concentrations of the compounds required to double the lag time of the control with no added antioxidants were 0.13 microM for ebselen, 0.5 microM for the N-pyridyl analog, 0.3-0.7 microM for the selenylsulfides, about 1.0 microM for the selenoxide derivative and 2.0 microM for the sulfur analog of ebselen. The open-chain seleno- and thioether derivatives, on the other hand, exhibited comparatively low abilities to protect the membrane, the lag doubling concentrations for these compounds being 100-1,000 fold higher than that for ebselen. The rate of loss of alpha-tocopherol in the microsomal membrane during peroxidation was significantly diminished in the presence of 0.1-0.5 microM ebselen, while the glutathione adduct of ebselen was equally effective in protecting the loss of alpha-tocopherol. The sulphur analogue and, the benzylated and methylated derivatives of ebselen did not afford protection. Ebselen was without effect in microsomes from vitamin E-deficient rats up to 20 microM, indicative of the dependence of its protective ability upon alpha-tocopherol.

Topics: Adenosine Diphosphate; Animals; Antioxidants; Ascorbic Acid; Azoles; Intracellular Membranes; Iron; Isoindoles; Kinetics; Lipid Peroxidation; Luminescent Measurements; Male; Microsomes; Organoselenium Compounds; Rats; Rats, Inbred Strains; Selenium; Thiobarbiturates; Vitamin E

The effect of lipid peroxidation on the Mg2(+)-independent and Mg2(+)-dependent activity of brain cell membrane 5'-nucleotidase was determined and the affinity of the active sites of Mg2(+)-dependent enzyme for 5'-AMP (substrate) and Mg2+ (activator) was examined. Brain cell membranes were peroxidized at 37 degrees C in the presence of 100 microM ascorbate and 25 microM FeCl2 (resultant) for 10 min. The activity of 5'-nucleotidase and lipid peroxidation products (thiobarbituric acid reactive substances) were determined. At 10 min, the level of lipid peroxidation products increased from 0.20 +/- 0.10 to 17.5 +/- 1.5 nmoles malonaldehyde/mg membrane protein. The activity of Mg2(+)-independent 5'-nucleotidase increased from 0.201 +/- 0.020 in controls to 0.305 +/- 0.028 mumol Pi/mg protein/hr in peroxidized membranes. In the presence of 10 mM Mg2+, the activity increased by 5.8-fold in the peroxidized membrane preparation in comparison to 14-fold in control. In peroxidized preparation, the affinity of active site of Mg2(+)-dependent 5'-nucleotidase for 5'-AMP tripled, as indicated by a significant decrease in Km (Km = 95 +/- 2 microM AMP for control; Km = 32 +/- 2 microM AMP for peroxidized). Vmax was significantly reduced from 3.35 +/- 0.16 in control to 1.70 +/- 0.9 mumoles Pi/mg protein in peroxidized membranes. The affinity of the active site for Mg2+ significantly increased (Km = 6.17 +/- 0.37 mM Mg2+ for control; Km = 4.0 +/- 0.31 peroxidized).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 5'-Nucleotidase; Adenosine Monophosphate; Animals; Ascorbic Acid; Binding Sites; Brain; Cell Membrane; Ferrous Compounds; Lipid Peroxidation; Magnesium; Malondialdehyde; Swine; Thiobarbiturates

The influence of deciduoma-induced differentiation on the lipid peroxidation in the rat uterus was investigated. The wet weight of uterus and its protein content increased during deciduoma progression. Content of the thiobarbituric acid reactive substances (TBARS) as well as lipid peroxidation induced by ascorbate and cumene hydroperoxide showed significant decreases during deciduoma growth. Restoration of normalcy was observed during regression. The activity of superoxide dismutase, an inhibitor of lipid peroxidation showed an opposite pattern namely increase during deciduoma development and decline during the regressive phase. We conclude that cell differentiation during deciduoma induction is accompanied by a temporary and reversible decrease in the peroxidative potential of the rat uterus.

Topics: Animals; Ascorbic Acid; Benzene Derivatives; Cell Differentiation; Decidua; Female; Lipid Peroxidation; Organ Size; Pregnancy; Rats; Rats, Inbred Strains; Thiobarbiturates; Uterus

Previous studies have suggested that free radicals and related species play a role in lens damage. The molecules involved may include proteins, lipids and DNA. Focal cortical changes and cortical liquefaction have been reported in patients with Down's syndrome over the age of 15 years. There is evidence supporting the hypothesis that trisomy 21 patients have an increase in free radical reactions and lipoperoxidation susceptibility. This could be due to an increase in the H2O2 generation catalysed by CuZn SOD although the activity of other gene products coded for on chromosome 21 cannot be excluded. Thiobarbituric acid reactive products were measured in human erythrocytes of nine DS patients and nine age-matched controls. There was a significant increase in the first group (21.0 +/- 2.3 nmol MDA/g Hb vs 16.4 +/- 2.9 nmol MDA/g Hb; p less than or equal to 0.01). In plasma, however, TBA products and antioxidant levels (ascorbic acid, tocopherol and uric acid) were not significantly different. Further studies should be carried out, namely through the use of more specific and sensitive methods, to assess the possible association between oxidative stress and cortical lens damage in DS patients.

Topics: Adolescent; Adult; Ascorbic Acid; Cataract; Child; Child, Preschool; Down Syndrome; Erythrocytes; Free Radicals; Humans; Infant; Lipid Peroxidation; Oxygen; Superoxide Dismutase; Thiobarbiturates; Uric Acid; Vitamin E

1. t-Butylhydroperoxide (tBuOOH) a lipoperoxide analog, causes rapid and considerable sulphydryl (SH) oxidation but almost no lipid peroxidation in red blood cell membranes (ghosts) containing no detectable haemoglobin. 2. tBuOOH, in the presence of ascorbate, produces significant lipid peroxidation the level of which is proportional to the ascorbate concentration. The initiation of lipid peroxidation is thought to occur by the reactive tBuO (butoxyl) species via the reductive decomposition of tBuOOH by ascorbate. 3. Ascorbate protects ghost membranes from the tBuOOH-induced SH oxidation in a dose-dependent fashion. 4. There is no parallelism between lipid peroxidation and SH oxidation in these systems. This suggests that the two processes occur independently of each other. 5. These findings indicate that, simultaneously, ascorbate can have both a protective and a prooxidant action in different membrane components under the same oxidative stress.

Topics: Antioxidants; Ascorbic Acid; Deferoxamine; Erythrocyte Membrane; Ethylmaleimide; Humans; In Vitro Techniques; Kinetics; Lipid Peroxidation; Oxidation-Reduction; Peroxides; Sulfhydryl Compounds; tert-Butylhydroperoxide; Thiobarbiturates

Comparative effects of hexavalent (K2Cr2O7:Cr(VI)) and trivalent chromium (Cr(NO3)3:Cr(III)) on the development of lipid peroxidation, and the relationship between the lipid peroxidation and damage to tissues were studied using male ddY strain mice. The animals were administered with either of two chemicals at a dose of 20 mg Cr/kg by a single intraperitoneal injection. The results obtained were as follows: (1) Lipid peroxidation in the liver, as measured by the synthesis of thiobarbituric acid reactive substances (TBARS), showed a significant increase at 24 and 48 hr after Cr(VI) injection, while in the kidney it was observed only at 48 hr. In the mice administered with Cr(III), TBARS formation in the liver went down below the control levels, while no change was observed in the kidney. (2) Chromium contents in the liver and kidney showed a maximum level at 6 hr after injection of Cr(VI) and then those declined to the half of the maximum level at 48 hr, respectively. Chromium contents in the liver and kidney of the mice injected with Cr(III) were lower than those injected with Cr(VI) during the experimental period. (3) Increases of TBARS formation in the liver, chromium content in the liver and kidney, and ornithine carbamyl transferase (OCT) activity indicative of the liver cell damage, and urea nitrogen content in the serum, indicative of the kidney damage, observed at 24 hr after injection of Cr(VI) were inhibited by simultaneous injection of 100 mg/kg of L-ascorbic acid, as antichrome agent, respectively. These observations might suggest a possible causative role of lipid peroxidation in Cr(VI) toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Ascorbic Acid; Chromates; Chromium; Chromium Compounds; Kidney; Lipid Peroxidation; Liver; Male; Mice; Nitrates; Nitrogen; Phenylenediamines; Potassium Dichromate; Thiobarbiturates

Investigations of aqueous humor in primary open-angle glaucoma have shown a change in its normal contents: decreased ascorbic acid in it and increased secondary products of lipid peroxidation. In patients with glaucoma of stages III and IV, a correlative relationship between them is recorded (r = -0.78). It is suggested that in the pathomechanism of increased intraocular pressure in primary glaucoma activation of the process of lipid peroxidation plays a role due to decreased concentration of ascorbic acid in the aqueous humor, being one of the most important components of antioxidative system of the eye.

Topics: Aged; Aqueous Humor; Ascorbic Acid; Cataract; Female; Glaucoma, Open-Angle; Humans; Lipid Peroxidation; Male; Middle Aged; Spectrophotometry; Thiobarbiturates

Polyunsaturated fatty acid (PUFA) levels (an index of the amount of substrate available for lipid peroxidation) were measured in several brain regions from patients who died with Parkinson's disease and age-matched control human postmortem brains. PUFA levels were reduced in parkinsonian substantia nigra compared to other brain regions and to control tissue. However, basal malondialdehyde (MDA; an intermediate in the lipid peroxidation process) levels were increased in parkinsonian nigra compared with other parkinsonian brain regions and control tissue. Expressing basal MDA levels in terms of PUFA content, the difference between parkinsonian and control substantia nigra was even more pronounced. Stimulating MDA production by incubating tissue with FeSO4 plus ascorbic acid, FeSO4 plus H2O2, or air alone produced lower MDA levels in the parkinsonian substantia nigra, probably reflecting the lower PUFA content. These results may indicate that an increased level of lipid peroxidation continues to occur in the parkinsonian nigra up to the time of death, perhaps because of continued exposure to excess free radicals derived from some endogenous or exogenous neurotoxic species.

Topics: Aged; Animals; Ascorbic Acid; Brain; Fatty Acids, Unsaturated; Female; Ferrous Compounds; Free Radicals; Humans; Hydrogen Peroxide; Lipid Peroxidation; Male; Malondialdehyde; Parkinson Disease; Postmortem Changes; Rats; Rats, Inbred Strains; Substantia Nigra; Thiobarbiturates

The reaction of iron (II) with H2O2 is believed to generate highly reactive species (e.g. .OH) capable of initiating biological damage. This study investigates the possibility that the severity of oxidative damage induced by iron in hepatic mitochondria is determined by the level of mitochondrial-H2O2 generation, which is believed to be particularly prominent in state-4 respiration. Iron-induced damage is found to be greater in state-4 than in state-3 respiration. Experiments using uncoupling agents and Ca++ to mimic state-3 conditions indicate that this effect reflects differences in the steady-state oxidation-level of the electron carriers of the respiratory chain (and hence the level of H2O2-generation), rather than changes in redox potential or transportation of the metal-ion. Evidence is also presented for a mechanism in which Fe(II) and H2O2 react inside the mitochondrial matrix. Ascorbate (vitamin C) is shown to be pro-oxidant in this system, except when present at very high concentration when it becomes antioxidant in nature.

Topics: Adenine Nucleotides; Animals; Ascorbic Acid; Calcium; Catalase; Dose-Response Relationship, Drug; Ethylmaleimide; In Vitro Techniques; Iron; Lipid Peroxides; Mitochondria, Liver; Oxidation-Reduction; Rats; Superoxide Dismutase; Thiobarbiturates; Time Factors; Uncoupling Agents

Hemorrhage within the central nervous system (CNS) may be associated with subsequent development of seizure states or paralysis. Prior investigations indicate that hemoglobin, released from extravasated erythrocytes, may be toxic to the CNS by promoting peroxidation of lipids and inhibition of Na,K-ATPase. These deleterious effects are blocked both in vitro and in vivo by the Fe3+ chelator, desferrioxamine, indicating the involvement of free iron derived from hemoglobin. We now report that the Fe2+ chelator, ferene, also inhibits methemoglobin- and ferric iron-mediated CNS lipid oxidation, reflecting the reduction of Fe3+ by some component of the CNS. This reduction is apparent in the accumulation of the highly chromophoric ferene: Fe2+ chelate after the addition of Fe3+ salts to supernatants of murine brain homogenates. Because large amounts of ascorbic acid occur in mammalian CNS, we suspected that this reducing substance might be responsible. Indeed, the peroxidative effects of hemoglobin and iron on murine brain are blocked by washing of CNS membranes or by preincubation of crude homogenates with ascorbate oxidase. Furthermore, the addition of ascorbate to washed CNS membranes fully restores hemoglobin/iron-driven peroxidation. We conclude that posthemorrhagic CNS dysfunction may stem from damaging redox reactions between hemoglobin iron, ascorbic acid, and oxidizable components of the nervous system.

Topics: Animals; Ascorbic Acid; Brain; Cerebrovascular Circulation; Deferoxamine; Hemoglobins; Hemorrhage; Lipid Peroxides; Male; Mice; Oxidation-Reduction; Sodium-Potassium-Exchanging ATPase; Thiobarbiturates

Non-enzymatic and enzymatically-driven lipid peroxidation processes were studied in rat liver nuclei and isolated nuclear membranes, by evaluating the formation of thiobarbituric acid-chromophore, free malondialdehyde, lipofuscin-like pigments, and the degradation of polyunsaturated fatty acids of the nuclear membrane lipids. The results obtained show that: (1) both non-enzymatic and enzymatically driven lipid peroxidation processes are operative in cell nuclei and isolated nuclear membranes; (2) only for isolated nuclear membranes, a good qualitative and up to a great extent quantitative correlation between malondialdehyde and lipofuscin-like pigment formation was obtained; (3) there is a qualitative but not quantitative correlation between malondialdehyde formation and polyunsaturated fatty acid degradation; (4) lipid peroxidation processes in isolated nuclear membranes and intact nuclei have an essentially identical kinetic behaviour. No statistical differences in the relative increases in the concentrations of malondialdehyde and lipofuscin-like pigments or in the degradation of polyunsaturated fatty acids were obtained, when the two systems were compared, except in the presence of NADPH-ADP-Fe3+, which induced a significantly larger degradation of polyunsaturated fatty acids in isolated nuclear membranes than in intact nuclei, and (5) no malondialdehyde-DNA fluorescent adduct formation was observed in any of the experimental groups studied, as inferred from the characteristics of the fluorescent spectra of lipofuscin-like pigments extracted from incubated nuclear preparations.

Topics: Adenosine Diphosphate; Animals; Ascorbic Acid; Cell Nucleus; Chlorides; Chromatography, High Pressure Liquid; Fatty Acids; Fatty Acids, Unsaturated; Ferric Compounds; Ferrous Compounds; Kinetics; Lipid Peroxides; Lipids; Lipofuscin; Liver; Male; Malondialdehyde; NADP; Nuclear Envelope; Rats; Rats, Inbred Strains; Thiobarbiturates

Weanling male Sprague Dawley rats were fed a vitamin E and C-free basal diet with or without supplementation of 100 IU vitamin E per kg diet. After 20 weeks, the vitamin E-deficient rats were divided into four groups, six in each group, and received supplemental ascorbic acid and/or vitamin E by tube feeding daily for 7 days: Group I, 30 mg ascorbic acid/100 g body wt.; Group II, 0.03 mg RRR-alpha-tocopheryl acetate/100 g body wt.; Group III, 30 mg ascorbic acid and 0.03 mg RRR-alpha-tocopheryl acetate/100 g body wt.; and Group IV, placebo. The six control rats (Group V) received placebo. The rats were sacrificed, blood and liver samples were collected for biochemical determinations. Vitamin E deficiency significantly increased erythrocyte (RBC) spontaneous hemolysis, liver thiobarbituric acid (TBA) value, activities of glutamateoxaloacetate transaminase (GOT), pyruvate kinase (PK), and creatine phosphokinase (CPK) in plasma, and significantly lowered plasma vitamin E levels and glutathione peroxidase (GPX) activities. Tube-feeding ascorbic acid for 7 days produced partial reversal effect on liver TBA values, activities of plasma PK, GOT, CPK, and plasma vitamin E levels but not on RBC hemolysis and plasma GPX activity. Tube feeding both ascorbic acid and vitamin E showed similar partial reversal effect as feeding vitamin E alone on all the parameters stated above. The results suggest that ascorbic acid may spare the metabolism of vitamin E and partially reverse the changes in some of the biochemical parameters characteristic of vitamin E deficiency.

Topics: alpha-Tocopherol; Animals; Ascorbic Acid; Aspartate Aminotransferases; Creatine Kinase; Drug Therapy, Combination; Glutathione Peroxidase; Hemolysis; Lipid Peroxides; Liver; Male; Pyruvate Kinase; Rats; Rats, Inbred Strains; Thiobarbiturates; Tocopherols; Vitamin E; Vitamin E Deficiency

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

The sensitivity of the bleomycin assay for loosely-bound iron depends on the concentration of bleomycin and ascorbic acid and the pH of the reaction. The non-haem-iron proteins transferrin, conalbumin and ferritin release iron at an acid pH value, whereas the haem-iron proteins release iron more readily at an alkaline pH. In addition, haem proteins are liable to release iron when peroxides are present. Organic peroxides and hydrogen peroxide can be produced during the bleomycin reaction leading to iron release from haem proteins. However, this can be prevented from reacting with bleomycin by adding zinc ions to the reaction following addition of the sample. Iron already bound to bleomycin is not displaced by zinc whereas zinc bound to bleomycin is not displaced by iron allowing 'free' and 'released' iron to be discriminated.

Topics: Ascorbic Acid; Bleomycin; Chemical Phenomena; Chemistry; DNA; DNA Damage; Free Radicals; Hemoglobins; Hydrogen-Ion Concentration; In Vitro Techniques; Iron; Thiobarbiturates; Zinc

Intense lipid peroxidation of brain synaptosomes initiated with Fenton's reagent (H2O2 + Fe2+) began instantly upon addition of Fe2+ and preceded detectable OH. formation. Although mannitol or Tris partially blocked peroxidation, concentrations required were 10(3)-fold in excess of OH. actually formed, and inhibition by Tris was pH dependent. Lipid peroxidation also was initiated by either Fe2+ or Fe3+ alone, although significant lag phases (minutes) and slowed reaction rates were observed. Lag phases were dramatically reduced or nearly eliminated, and reaction rates were increased by a combination of Fe3+ and Fe2+. In this instance, lipid peroxidation initiated by optimal concentrations of H2O2 and Fe2+ could be mimicked or even surpassed by providing optimal ratios of Fe3+ to Fe2+. Peroxidation observed with Fe3+ alone was dependent upon trace amounts of contaminating Fe2+ in Fe3+ preparations. Optimal ratios of Fe3+:Fe2+ for the rapid initiation of lipid peroxidation were on order of 1:1 to 7:1. No OH. formation could be detected with this system. Although low concentrations of H2O2 or ascorbate increased lipid peroxidation by Fe2+ or Fe3+, respectively, high concentrations of H2O2 or ascorbate (in excess of iron) inhibited lipid peroxidation due to oxidative or reductive maintenance of iron exclusively in Fe2+ or Fe3+ form. Stimulation of lipid peroxidation by low concentrations of H2O2 or ascorbate was due to the oxidative or reductive creation of Fe3+:Fe2+ ratios. The data suggest that the absolute ratio of Fe3+ to Fe2+ was the primary determining factor for the initiation of lipid peroxidation reactions.

Topics: Animals; Ascorbic Acid; Brain; Ferric Compounds; Ferrous Compounds; Hydrogen Peroxide; Hydroxides; Hydroxyl Radical; Iron; Kinetics; Lipid Peroxides; Oxidation-Reduction; Oxygen Consumption; Rats; Spectrophotometry, Ultraviolet; Synaptosomes; Thiobarbiturates

The effect of the addition of dietary ascorbic acid and/or vitamin E (all-rac-alpha-tocopheryl acetate) in rats and guinea pigs exposed to PCB (polychlorinated biphenyls) was studied. Rats were fed diets containing one of three levels of vitamin E (30, 500 or 1000 mg/kg diet) with or without PCB (200 mg/kg diet). Guinea pigs were fed diets containing PCB (40 mg/kg diet) with 200 or 1000 mg ascorbic acid/kg diet and/or 70 or 2000 mg vitamin E/kg diet. For rats fed PCB, ascorbic acid in urine was 40-fold higher and in liver, 2-fold higher than for rats fed no PCB, and thiobarbituric acid-reactive substances (TBA-RS, indicators of lipid peroxidation) in liver was 1.5-fold higher. In rats fed PCB, high dietary vitamin E significantly lowered the urinary ascorbic acid and TBA-RS. Liver ascorbic acid was lowered by high dietary vitamin E only in control rats. In guinea pigs, feeding PCB caused severe growth retardation and the liver TBA-RS was 1.8-fold higher than in guinea pigs not fed PCB. Feeding high levels of both ascorbic acid and vitamin E was more effective in reversing the growth depression and in lowering TBA-RS level (due to PCB) than feeding the vitamins separately. Ascorbic acid metabolism in rats was affected by high dietary vitamin E. The possibility of a higher requirement for ascorbic acid and vitamin E in guinea pigs exposed to PCB was indicated. Interaction of ascorbic acid and vitamin E in animals exposed to PCB was suggested.

Topics: Animals; Ascorbic Acid; Cholesterol; Cholesterol, HDL; Diet; Growth; Guinea Pigs; Lipid Metabolism; Lipid Peroxides; Liver; Metabolism; Organ Size; Polychlorinated Biphenyls; Rats; Rats, Inbred Strains; Thiobarbiturates; Triglycerides; Vitamin E

Rat brain homogenate was incubated with various concentrations of ascorbate in a Tris-HC1 buffer. Thiobarbituric acid-reactive substances (TBARS) were measured and 3H-QNB (quinuclidinyl benzilate) binding was also assayed on the same homogenate. Good parallelism between TBARS formation and loss of 3H-QNB binding activity confirmed that loss of 3H-QNB binding resulted from ascorbate-induced lipid peroxidation. However, neither formation of TBARS nor loss of 3H-QNB binding occurred in phosphate buffer or in the Tris-HC1 system in the presence of metal-chelating reagents. This indicates that phosphate addition prevents the ascorbate effects due to complete chelation of intrinsic metal ions.

Topics: Animals; Ascorbic Acid; Brain; Buffers; Edetic Acid; Kinetics; Lipid Peroxides; Male; Phosphates; Quinuclidines; Quinuclidinyl Benzilate; Rats; Rats, Inbred Strains; Receptors, Muscarinic; Thiobarbiturates; Tromethamine

Topics: Animals; Antioxidants; Ascorbic Acid; Glutathione; In Vitro Techniques; Lipid Peroxides; Liver; Male; Rats; Rats, Inbred Strains; Thiobarbiturates; Vitamin E

Topics: Animals; Ascorbic Acid; Catalase; Cattle; Copper; Erythrocytes; Free Radicals; Hydroxides; Hydroxyl Radical; Liver; Spectrophotometry; Superoxide Dismutase; Thiobarbiturates

Topics: Ascorbic Acid; Barbiturates; Thiobarbiturates

Topics: Administration, Intravenous; Animals; Ascorbic Acid; Rabbits; Sodium; Thiobarbiturates; Thiopental; Vitamins

Topics: Animals; Ascorbic Acid; Brain; Neurochemistry; Rabbits; Sodium; Stupor; Thiobarbiturates; Thiopental; Vitamins