SciCombinator

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Concept: Superoxide

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BACKGROUND: This study examined the effects of bovine colostrum on exercise –induced modulation of antioxidant parameters in the skeletal muscles in mice. Adult male BALB/c mice were randomly divided into four groups (control, colostrum alone, exercise and exercise with colostrum) and each group had three subgroups (day 0, 21 and 42). Colostrum groups of mice were given a daily oral supplement of 50 mg/kg body weight of bovine colostrum and the exercise group of mice were made to exercise on the treadmill for 30 minutes per day. Total antioxidants, lipid hydroperoxides, xanthine oxidase and super oxide dismutase level was assayed from the homogenate of hind limb skeletal muscles. RESULTS: Exercise—induced a significant oxidative stress in skeletal muscles as evidenced by the elevated lipid hydroperoxides and xanthine oxidase levels. There was a significant decrease in skeletal muscle total antioxidants and superoxide dismutase levels. Daily colostrum supplement significantly reduced the lipid hydroperoxides and xanthine oxidase enzyme level and increased the total antioxidant levels in the leg muscle. CONCLUSION: Thus, the findings of this study showed that daily bovine colostrum supplementation was beneficial to the skeletal muscle to reduce the oxidant-induced damage during muscular exercise.

Concepts: Metabolism, Antioxidant, Oxidative stress, Reactive oxygen species, Superoxide dismutase, Glycogen, Muscular system, Superoxide

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Ample of evidence proved the gastroprotective effect of thymoquinone (TQ), the main constituent of Nigella sativa oil; however, the full mechanistic cassette on the gastric ulcer etiopathogenesis is not fully elucidated. The aim of the present work is to unveil some of the possible mechanisms. Animals were injected with vehicle, TQ (10 & 20mg/kg), omeprazole (10 & 20mg/kg) or their combination (10mg/kg). Thirty minutes later, pyloric ligation was carried out and followed consequently with ischemia for another 30min, abided by reperfusion for 120min. The ischemia/reperfusion insult increased the gastric acid secretion, acid output, and pepsin, as well as the gastric mucosal content/activity of lipid peroxide, proton pump and myeloperoxidase, along with ulcer index. However, content/activity of gastric mucin, reduced glutathione, total nitric oxide, and superoxide dismutase were decreased. TQ, especially the high dose level, corrected the altered parameters in a comparable manner to that of the reference drug used, omeprazole. In addition, when the low doses were combined they add to each other to reach the effect of the high dose of either drug. These results showed that apart from its known antioxidant properties, TQ has novel gastroprotective mechanisms via inhibiting proton pump, acid secretion and neutrophil infiltration, while enhancing mucin secretion, and nitric oxide production.

Concepts: Antioxidant, Reactive oxygen species, Stomach, Helicobacter pylori, Nitric oxide, Superoxide, Gastric acid, Nigella sativa

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Development of hepatic cirrhosis involves oxidative stress, inflammation, hepatic stellate cells (HSC)s activation and fibrosis. On the other hand, quercetin, a natural flavonoid is a potent antioxidant and activator of superoxide dismutase and catalase. The aim was to determinate the effect of quercetin on HSCs and development of hepatic fibrosis.

Concepts: Enzyme, Antioxidant, Oxidative stress, Superoxide dismutase, Cirrhosis, Vitamin C, Superoxide, Hepatic stellate cell

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Iron 2,6-diacetylpyridinebis(semioxamazide) (Fe(dapsox)) is a heptacoordinate pentagonal bipyramidal, functional mimic of iron-dependent superoxide dismutase that has been well-characterized on the basis of kinetics and mechanistic studies; however, prior to our studies, its electronic structure had yet to be examined. This paper details our initial characterization of Fe(dapsox) in both its reduced and oxidized states, by electronic absorption (Abs) and low-temperature magnetic circular dichroism spectroscopies. Density functional theory (DFT) geometry optimizations have yielded models in good agreement with the published crystal structures. Time-dependent DFT and INDO/S-CI calculations performed on these models successfully reproduce the experimental Abs spectra and identify intense, low-energy transitions in the reduced complex (Fe(II)(H(2)dapsox)) as metal-to-ligand charge transfer transitions, suggesting the presence of π-backbonding in this complex. This backbonding, along, with the proton uptake accompanying metal ion reduction, provides a compelling mechanism by which the metal-centered redox potential is correctly tuned for catalytic superoxide disproportionation.

Concepts: Iron, Hydrogen, Redox, Electrochemistry, Carbon, Aluminium, Superoxide, Manganese

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We investigated the prooxidant effects of bisphenol A (BPA) phenoxyl radicals in comparison with the phenoxyl radicals of 3-tert-butyl-4-hydroxyanisole (BHA), 2,6-di- tert-butyl-methylphenol (BHT), and 4-tert-butylphenol (TBP). The phenoxyl radicals, generated in situ by 1-electron oxidation of the corresponding phenol, were allowed to react with NADPH and rifampicin. The antioxidant activity of various phenols was examined based on reduction of 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH). It was found that the prooxidant activity of BPA phenoxyl radicals far exceeded those of BHA and BHT of phenoxyl radicals. Unlike Trolox, BPA showed minimal DPPH scavenging activity. The strong prooxidant properties of BPA phenoxyl radicals propelled us to study the markers of cellular oxidative stress in GT1-7 hypothalamic neurons exposed to BPA. It was observed that neuronal cells exposed to BPA had increased generation of intracellular peroxides and mitochondrial superoxide (O(2)(•)¯). The formation of peroxides and O(2)(•)¯ were time- and dose-dependent and that co-incubation with N-acetyl-L-cysteine or Trolox greatly lowered their levels. The results of the present study are consistent with emerging evidence that human populations (non-institutionalized) having higher levels of urinary BPA also have increased levels of oxidative stress markers and are prone to higher risk of cardiovascular diseases, diabetes, and abnormalities in hepatic enzymes.

Concepts: Photosynthesis, Antioxidant, Redox, Oxidative stress, Radical, Hydrogen peroxide, Bisphenol A, Superoxide

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AIMS: To determine the effects of Lactobacillus fermentum I5007 on the redox state of piglets oxidatively stressed with diquat. METHODS AND RESULTS: Twenty-four, 28-day old barrows were used in a 2 x 2 factorial design experiment with the main effects being L. fermentum supplementation and diquat challenge. Half of the pigs (n=12) were orally administered with 20 ml of a solution containing 10(8) CFU ml(-1) of L. fermentum each morning of the 21 day trial while the remainder received saline. On d 8, these two groups were further subdivided so that half of the pigs in each group (n=6) were intraperitoneally injected with 10 mg kg(-1) BW diquat while the remainder received saline. The diquat-injected pigs had significantly poorer performance and increased levels of plasma cortisol, adrenaline, carbonyl and malondialdehyde. L. fermentum supplementation significantly increased superoxide dismutase and glutathione and increased the ability to inhibit superoxide anion production in liver and muscle. CONCLUSIONS: L. fermentum improved the anti-oxidative defense system and alleviated damage caused by diquat. © 2013 The Authors Journal of Applied Microbiology © 2013 The Society for AppliedMicrobiology.

Concepts: Microbiology, Redox, Oxidative stress, Superoxide dismutase, Cortisol, Design of experiments, Superoxide, Lactobacillus fermentum

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The direct effect of the four catecholamines (adrenaline, noradrenaline, dopamine and isoproterenol) on superoxide anion radicals (O2-•) was investigated. The reaction between 18-crown-6-ether and potassium superoxide in dimethylsulfoxide was used as a source of O2-•. The reactivity of catecholamines with O2-• was examined using chemiluminescence, reduction of nitroblue tetrazolium and electron paramagnetic resonance spin-trapping techniques. 5,5-Dimethyl-1-pyrroline-N-oxide was included as the spin trap. The results showed that the four catecholamines were effective and efficient in inhibiting chemiluminescence accompanying the potassium superoxide/18-crown-6-ether system in a dose-dependent manner over the range 0.05-2 mm in the following order: adrenaline > noradrenaline > dopamine > isoproterenol, with, IC(50)  = 0.15 ± 0.02 mm 0.21 ± 0.03 mm, 0.27 ± 0.03 mm and 0.50 ± 0.04 mm, respectively. The catecholamines examined also exhibited a strong scavenging effect towards O2-• when evaluated this property by the inhibition of nitroblue tetrazolium reduction (56-73% at 1 m concentration). A very similar capacity of O2-• scavenging was monitored in the 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping assay. The results suggest that catecholamines tested may involve a direct effect on scavenging O2- radicals. Copyright © 2013 John Wiley & Sons, Ltd.

Concepts: Redox, NADPH oxidase, Epinephrine, Superoxide, Chronic granulomatous disease, Dopamine, Norepinephrine, Potassium superoxide

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It is currently accepted that superoxide anion (O2•-) is an important mediator in pain and inflammation. The role of superoxide anion in pain and inflammation has been mainly determined indirectly by modulating its production and inactivation. Direct evidence using potassium superoxide (KO2), a superoxide anion donor, demonstrated that it induced thermal hyperalgesia, as assessed by the Hargreaves method. However, it remains to be determined whether KO2 is capable of inducing other inflammatory and nociceptive responses attributed to superoxide anion. Therefore, in the present study, we investigated the nociceptive and inflammatory effects of KO2. The KO2-induced inflammatory responses evaluated in mice were: mechanical hyperalgesia (electronic version of von Frey filaments), thermal hyperalgesia (hot plate), edema (caliper rule), myeloperoxidase activity (colorimetric assay), overt pain-like behaviors (flinches, time spent licking and writhing score), leukocyte recruitment, oxidative stress, and cyclooxygenase-2 mRNA expression (quantitative PCR). Administration of KO2 induced mechanical hyperalgesia, thermal hyperalgesia, paw edema, leukocyte recruitment, the writhing response, paw flinching, and paw licking in a dose-dependent manner. KO2 also induced time-dependent cyclooxygenase-2 mRNA expression in the paw skin. The nociceptive, inflammatory, and oxidative stress components of KO2-induced responses were responsive to morphine (analgesic opioid), quercetin (antioxidant flavonoid), and/or celecoxib (anti-inflammatory cyclooxygenase-2 inhibitor) treatment. In conclusion, the well-established superoxide anion donor KO2 is a valuable tool for studying the mechanisms and pharmacological susceptibilities of superoxide anion-triggered nociceptive and inflammatory responses ranging from mechanical and thermal hyperalgesia to overt pain-like behaviors, edema, and leukocyte recruitment.

Concepts: Inflammation, Antioxidant, Oxidative stress, Oxidative phosphorylation, Superoxide dismutase, Superoxide, Potassium superoxide, Chemical oxygen generator

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Diabetic microvascular complications have been considered to be mediated by a glucose-driven increase in mitochondrial superoxide anion production. Here, we report that superoxide production was reduced in the kidneys of a steptozotocin-induced mouse model of type 1 diabetes, as assessed by in vivo real-time transcutaneous fluorescence, confocal microscopy, and electron paramagnetic resonance analysis. Reduction of mitochondrial biogenesis and phosphorylation of pyruvate dehydrogenase (PDH) were observed in kidneys from diabetic mice. These observations were consistent with an overall reduction of mitochondrial glucose oxidation. Activity of AMPK, the major energy-sensing enzyme, was reduced in kidneys from both diabetic mice and humans. Mitochondrial biogenesis, PDH activity, and mitochondrial complex activity were rescued by treatment with the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR). AICAR treatment induced superoxide production and was linked with glomerular matrix and albuminuria reduction in the diabetic kidney. Furthermore, diabetic heterozygous superoxide dismutase 2 (Sod2+/-) mice had no evidence of increased renal disease, and Ampka2-/- mice had increased albuminuria that was not reduced with AICAR treatment. Reduction of mitochondrial superoxide production with rotenone was sufficient to reduce AMPK phosphorylation in mouse kidneys. Taken together, these results demonstrate that diabetic kidneys have reduced superoxide and mitochondrial biogenesis and activation of AMPK enhances superoxide production and mitochondrial function while reducing disease activity.

Concepts: Kidney, Adenosine triphosphate, Enzyme, Redox, Cellular respiration, Nicotinamide adenine dinucleotide, Superoxide dismutase, Superoxide

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Most scientific studies are too long to be conducted in a single day or even in a few days. Thus, there is a need to store samples for subsequent investigations. There is sparse information about specific sample storage protocols that minimize analytical error and variability in evaluations of redox parameters. Therefore, the effects of storage temperature and freezing time on enzymatic activities, protein oxidative damage, and CAT (catalase) and SOD1 (superoxide dismutase) immunocontent of blood, liver, and brain from rats were determined for two different sample forms (frozen homogenized tissue or frozen intact tissue). Superoxide dismutase activity was drastically decreased in blood and liver with an increase in freezing time, but not in brain. Catalase activity showed a decrease only in intact liver at -20 and -80°C. In contrast, in blood it showed an increase in intact tissue at -20 and -80°C. Reduced thiol groups generally decreased with freezing time, but showed an increase in intact blood at -20 and -80°C, probably because of color interference. Carbonyl groups in homogenized liver and brain, and in intact blood (except at 80°C) drastically increased with freezing time. Freezing time did not modulate the immunocontent of CAT and SOD1 levels in any tissue. In conclusion, our results indicate that storage at -20°C affects redox parameters more than storage at -80°C. Storage for a long time may compromise the samples, leading to changing parameters due to oxidative stress. Thus, we suggest processing the samples as soon as possible. However, if this is not possible, then material can be aliquoted into different tubes to prevent the effect of refreezing of samples.

Concepts: Enzyme, Iron, Redox, Oxidative stress, Superoxide dismutase, Hydrogen peroxide, Superoxide, Catalase