Showing papers on "Hydrogen peroxide published in 1999"
TL;DR: It is shown that human A beta directly produces hydrogen peroxide (H2O2) by a mechanism that involves the reduction of metal ions, Fe(III) or Cu(II), setting up conditions for Fenton-type chemistry.
Abstract: Oxidative stress markers characterize the neuropathology both of Alzheimer's disease and of amyloid-bearing transgenic mice. The neurotoxicity of amyloid Aβ peptides has been linked to peroxide gen...
1,065 citations
TL;DR: With superoxide, the results are consistent with each thiol reacting via a short chain that consumes oxygen and regenerates superoxide and the consumed oxygen recovered as hydrogen peroxide.
728 citations
05 Nov 1999
TL;DR: An introduction to the preparation and properties of hydrogen peroxide can be found in this article, along with a discussion of the application of hydrogen Peroxide for the synthesis of fine chemicals.
Abstract: An introduction to the preparation and properties of hydrogen peroxide The activation of hydrogen peroxide using inorganic and organic species The application of hydrogen peroxide for the synthesis of fine chemicals The heterogeneous activation and application of hydrogen peroxide The environmental application of hydrogen peroxide Miscellaneous uses for hydrogen peroxide technology
584 citations
TL;DR: Monitoring the presence of the OxyR disulfide bond after exposure to hydrogen peroxide in vivo and in vitro shows that the kinetics of OxyR oxidation by low concentrations of Hydrogen peroxide is significantly faster than the kinetic process of oxyR reduction, allowing for transient activation in an overall reducing environment.
Abstract: The Escherichia coli transcription factor OxyR is activated by the formation of an intramolecular disulfide bond and subsequently is deactivated by enzymatic reduction of the disulfide bond. Here we show that OxyR can be activated by two possible pathways. In mutants defective in the cellular disulfide-reducing systems, OxyR is constitutively activated by a change in the thiol—disulfide redox status in the absence of added oxidants. In wild-type cells, OxyR is activated by hydrogen peroxide. By monitoring the presence of the OxyR disulfide bond after exposure to hydrogen peroxide in vivo and in vitro, we also show that the kinetics of OxyR oxidation by low concentrations of hydrogen peroxide is significantly faster than the kinetics of OxyR reduction, allowing for transient activation in an overall reducing environment. We propose that the activity of OxyR in vivo is determined by the balance between hydrogen peroxide levels and the cellular redox environment.
533 citations
TL;DR: In this paper, the characteristics of the Fenton oxidation of p-chlorophenol were investigated experimentally to develop a mechanistic model that appropriately represented the mechanism, and the results showed that an initially fast decomposition rate was significantly reduced within a few minutes.
414 citations
TL;DR: It is found that regulators of the Escherichia coli responses to oxidative stress, OxyR and SoxRS, activate the expression of Fur, the global repressor of ferric ion uptake, which demonstrates that iron metabolism is coordinately regulated with the oxidative stress defenses.
Abstract: The cytotoxic effects of reactive oxygen species are largely mediated by iron. Hydrogen peroxide reacts with iron to form the extremely reactive and damaging hydroxyl radical via the Fenton reaction. Superoxide anion accelerates this reaction because the dismutation of superoxide leads to increased levels of hydrogen peroxide and because superoxide elevates the intracellular concentration of iron by attacking iron-sulfur proteins. We found that regulators of the Escherichia coli responses to oxidative stress, OxyR and SoxRS, activate the expression of Fur, the global repressor of ferric ion uptake. A transcript encoding Fur was induced by hydrogen peroxide in a wild-type strain but not in a DeltaoxyR strain, and DNase I footprinting assays showed that OxyR binds to the fur promoter. In cells treated with the superoxide-generating compound paraquat, we observed the induction of a longer transcript encompassing both fur and its immediate upstream gene fldA, which encodes a flavodoxin. This polycistronic mRNA is induced by paraquat in a wild-type strain but not in a DeltasoxRS strain, and SoxS was shown to bind to the fldA promoter. These results demonstrate that iron metabolism is coordinately regulated with the oxidative stress defenses.
396 citations
TL;DR: Evidence of QS control of genes essential for relieving oxidative stress is provided, as PAI mutant biofilm sensitivity appeared not to be incrementally correlated to catalase levels.
Abstract: Quorum sensing (QS) governs the production of virulence factors and the architecture and sodium dodecyl sulphate (SDS) resistance of biofilm-grown Pseudomonas aeruginosa. P. aeruginosa QS requires two transcriptional activator proteins known as LasR and RhlR and their cognate autoinducers PAI-1 (N-(3-oxododecanoyl)-L-homoserine lactone) and PAI-2 (N-butyryl-L-homoserine lactone) respectively. This study provides evidence of QS control of genes essential for relieving oxidative stress. Mutants devoid of one or both autoinducers were more sensitive to hydrogen peroxide and phenazine methosulphate, and some PAI mutant strains also demonstrated decreased expression of two superoxide dismutases (SODs), Mn-SOD and Fe-SOD, and the major catalase, KatA. The expression of sodA (encoding Mn-SOD) was particularly dependent on PAI-1, whereas the influence of autoinducers on Fe-SOD and KatA levels was also apparent but not to the degree observed with Mn-SOD. beta-Galactosidase reporter fusion results were in agreement with these findings. Also, the addition of both PAIs to suspensions of the PAI-1/2-deficient double mutant partially restored KatA activity, while the addition of PAI-1 only was sufficient for full restoration of Mn-SOD activity. In biofilm studies, catalase activity in wild-type bacteria was significantly reduced relative to planktonic bacteria; catalase activity in the PAI mutants was reduced even further and consistent with relative differences observed between each strain grown planktonically. While wild-type and mutant biofilms contained less catalase activity, they were more resistant to hydrogen peroxide treatment than their respective planktonic counterparts. Also, while catalase was implicated as an important factor in biofilm resistance to hydrogen peroxide insult, other unknown factors seemed potentially important, as PAI mutant biofilm sensitivity appeared not to be incrementally correlated to catalase levels.
387 citations
TL;DR: Unlike superoxide dismutase, the enzyme that protects aerobes from the toxic effects of oxygen, SOR does not catalyze the production of oxygen from superoxide and therefore confers a selective advantage on anaerobes.
Abstract: Superoxide reductase from the hyperthermophilic anaerobe Pyrococcus furiosus uses electrons from reduced nicotinamide adenine dinucleotide phosphate, by way of rubredoxin and an oxidoreductase, to reduce superoxide to hydrogen peroxide, which is then reduced to water by peroxidases. Unlike superoxide dismutase, the enzyme that protects aerobes from the toxic effects of oxygen, SOR does not catalyze the production of oxygen from superoxide and therefore confers a selective advantage on anaerobes. Superoxide reductase and associated proteins are catalytically active 80°C below the optimum growth temperature (100°C) of P. furiosus , conditions under which the organism is likely to be exposed to oxygen.
361 citations
TL;DR: This study shows that hydrogen peroxide-induced apoptosis in T-cells did not require tyrosine kinase p56lck, phosphatase CD45, the CD95 receptor and its associated Caspase-8, and that pharmacological and genetic inhibition of transcription factor NF-κB protected cells from hydrogenperoxide-elicited cell death.
Abstract: Hydrogen peroxide-induced apoptosis is CD95-independent, requires the release of mitochondria-derived reactive oxygen species and the activation of NF-κB
320 citations
TL;DR: Spatially resolved infrared and ultraviolet wavelength spectra of Europa's leading, anti-jovian quadrant observed from the Galileo spacecraft show absorption features resulting from hydrogen peroxide, demonstrating that Europa's surface chemistry is dominated by radiolysis.
Abstract: Spatially resolved infrared and ultraviolet wavelength spectra of Europa's leading, anti-jovian quadrant observed from the Galileo spacecraft show absorption features resulting from hydrogen peroxide. Comparisons with laboratory measurements indicate surface hydrogen peroxide concentrations of about 0.13 percent, by number, relative to water ice. The inferred abundance is consistent with radiolytic production of hydrogen peroxide by intense energetic particle bombardment and demonstrates that Europa's surface chemistry is dominated by radiolysis.
278 citations
TL;DR: In this article, the effects of pH, amounts of ferrous sulfate (FeSO4) and hydrogen peroxide (H2O2) and temperature on the surfactant removal were investigated.
TL;DR: Borage meal exerted a concentration-dependent antioxidant activity in a meat model system, and the resulting extract inhibited 2-thiobarbituric acid-reactive substances (TBARS), hexanal and total volatile formation in meat by 26.5, 30.5 and 18.6%, respectively.
TL;DR: In this paper, a correlation equation was proposed to correct quantitatively the effect of the concentration of hydrogen peroxide on the chemical oxygen demand, which showed that the ratio of the chemical dioxide demand to the concentration is affected by its concentration and is increased up to 0.4706.
TL;DR: Results suggest that cytochrome c, a well known electron transfer, and mediator of apoptotic cell death may be involved in the oxidative stress-induced aggregation of α-synuclein in Parkinson’s disease and related disorders.
TL;DR: In this article, the authors investigated the efficiency of using soybean peroxidase (SBP) to remove several different phenolic compounds from unbuffered synthetic wastewater, including parent phenol, chlorinated phenols, cresols, 2,4-dichlorophenol and 4,4′-isopropylidenediphenol (commonly known as bisphenol A).
TL;DR: It is found that enhanced Mn-SOD activity, via an unbalanced H2O2overproduction and detoxification, induces MMP-1 mRNA levels, and this effect is at least partly mediated by the DNA recognition sequence AP-1.
TL;DR: Impairment of α-oxoaldehyde detoxification is cytotoxic, and this may contribute to toxicity associated with GSH oxidation and S conjugation in oxidative stress and chemical toxicity, and to chronic pathogenesis associated with diabetes mellitus where there is oxidative stressand the formation of glyoxal, MG, and 3-DG is increased.
TL;DR: It is shown that arachidonic acid causes an uncoupling effect under state 4 respiration of intact mitochondria as well as a marked inhibition of uncoupled respiration, and that the inhibition is stronger for unsaturated acids.
TL;DR: In this article, it is demonstrated that hydrogen peroxide, electrogenerated at a reticulated vitreous carbon cathode by the reduction of oxygen in the presence of Fe(II) is a powerful oxidant for organic compounds.
TL;DR: In this article, the degradation of 2-chlorobiphenyl (2-CB) with oxidant concentration of 10 −3 and 10 −2 M and TiO 2 concentration of 25 µm/l was investigated.
TL;DR: There is evidence to suggest that studies may have broader implication in being relevant to other aminoglycosides including streptomycin and being applicable to other major toxicity of am inoglycoside such as ototoxicity.
Abstract: Acute renal failure is a major complication of aminoglycoside antibiotics, which are widely used in the treatment of gram-negative infections. Sequential reduction of oxygen along the univalent pathway leads to the generation of superoxide anion, hydrogen peroxide, hydroxyl radical, and water. A large body of in vitro and in vivo evidence indicates that these partially reduced oxygen metabolites are important mediators of gentamicin nephrotoxicity. Gentamicin has been shown to enhance the generation of superoxide anion and hydrogen peroxide by renal cortical mitochondria. The interaction between superoxide anion and hydrogen peroxide in the presence of metal catalyst can lead to the generation of hydroxyl radical. Gentamicin has been shown to lead to release of iron from renal cortical mitochondria and to enhance generation of hydroxyl radical. These in vitro observations have been supported by in vivo studies in which scavengers of reactive oxygen metabolites and iron chelators have shown to be protective in gentamicin induced acute renal failure. There is evidence to suggest that studies may have broader implication in being relevant to other aminoglycosides including streptomycin and being applicable to other major toxicity of aminoglycoside such as ototoxicity.
TL;DR: Hydrogen peroxide treatment of retinal pigment epithelial cells resulted in significantly increased mitochondrial DNA damage, and mitochondrial DNA appears susceptible to hydrogen peroxide mediated damage in vitro, and thus, may serve as a catalyst in the initial events leading to retinal pigmentation epithelial cell dysfunction in vivo.
TL;DR: It is concluded that urine contains autooxidizable molecules that, upon exposure to 21% O(2), undergo rapid superoxide-dependent autooxidation reactions to generate H(2)O(2).
TL;DR: It is found that sodC, the gene that encodes the periplasmic SOD of Escherichia coli, is repressed anaerobically by Fnr and is among the many antioxidant genes that are induced in stationary phase by RpoS.
Abstract: The discovery of superoxide dismutase (CuZnSOD) within the periplasms of several Gram-negative pathogens suggested that this enzyme evolved to protect cells from exogenous sources of superoxide, such as the oxidative burst of phagocytes. However, its presence in some non-pathogenic bacteria implies that there may be a role for this SOD during normal growth conditions. We found that sodC, the gene that encodes the periplasmic SOD of Escherichia coli, is repressed anaerobically by Fnr and is among the many antioxidant genes that are induced in stationary phase by RpoS. Surprisingly, the entry of wild-type E. coli into stationary phase is accompanied by a several-hour-long period of acute sensitivity to hydrogen peroxide. Induction of the RpoS regulon helps to diminish that sensitivity. While mutants of E. coli and Salmonella typhimurium that lacked CuZnSOD were not detectably sensitive to exogenous superoxide, both were killed more rapidly than their parent strains by exogenous hydrogen peroxide in early stationary phase. This sensitivity required prior growth in air. Evidently, periplasmic superoxide is generated during stationary phase by endogenous metabolism and, if it is not scavenged by CuZnSOD, it causes an unknown lesion that augments or accelerates the damage done by peroxide. The molecular details await elucidation.
TL;DR: The mechanism for enhanced desorption of chloroaliphatic compounds from a silty loam soil by modified Fenton's reagent was investigated using a series of probe compounds of varying hydrophobicities as discussed by the authors.
Abstract: The mechanism for enhanced desorption of chloroaliphatic compounds from a silty loam soil by modified Fenton's reagent was investigated using a series of probe compounds of varying hydrophobicities. Hexachloroethane, which has negligible reactivity with hydroxyl radicals, was transformed more rapidly in modified Fenton's reactions (≥0.3 M hydrogen peroxide) than it was lost by gas-purge desorption, suggesting the existence of a non-hydroxyl radical mechanism. The addition of excess 2-propanol to scavenge hydroxyl radicals slowed, but did not stop, the desorption and degradation of hexachloroethane. In the presence of the reductant scavenger chloroform, hexachloroethane did not desorb and was not degraded, indicating that a reductive pathway in vigorous Fenton-like reactions is responsible for enhanced contaminant desorption. Fenton-like degradation of hexachloroethane yielded the reduced product pentachloroethane, confirming the presence of a reductive mechanism. In the presence of excess 2-propanol, tolu...
TL;DR: In this paper, a reaction mechanism for the photochemical generation of hydroxyl radicals by ultraviolet or visible irradiation of oxalato iron(III) complexes (ferrioxalate) in the presence of hydrogen peroxide and 2-propanol as a model substrate was validated.
Abstract: A reaction mechanism has been validated for the photochemical generation of hydroxyl radicals by ultraviolet or visible irradiation of oxalato iron(III) complexes (ferrioxalate) in the presence of hydrogen peroxide and 2-propanol as a model substrate. A kinetic simulation program incorporating the set of reactions was written to predict the behavior of this photochemical system. The program calculates the quantum yield of oxidation of 2-propanol used as a hydroxyl radical scavenger. The scavenger's oxidation product, 2-propanone, was analyzed by gas chromatog raphy after controlled exposure of the solution to a calibrated light source. The theoretical quantum yields of 2-propanol oxidation, ΦRH, agreed reasonably well with experimentally determined ΦRH values under a variety of initial reaction conditions. The value of ΦRH, which under appropriate conditions is directly proportional to the quantum yield for the generation of hydroxyl radicals, ΦOH, was considerably greater than unity in most cases (often ...
TL;DR: When stabilized hydrogen peroxide is injected into the subsurface during in situ bioremediation, naturally occurring minerals such as goethite may initiate Fenton-like reactions, which have the potential to chemically oxidize contaminants in soils and groundwater.
Journal Article•
TL;DR: The control of inflammation in arthritic patients by natural as well as synthetic antioxidants could become a relevant component of antirheumatic prevention and therapy.
Abstract: Rheumatoid arthritis (RA) is a chronic disease affecting up to 3% of the population in most countries The causes of RA have not been completely elucidated This paper aims to review the role of reactive oxygen and nitrogen species in the etiopathogenesis of RA Reactive oxygen species (ROS), such as superoxide radical, hydrogen peroxide, hydroxyl radical and hypochlorous acid, as well as reactive nitrogen species (RNS), such as nitric oxide and peroxynitrite, contribute significantly to tissue injury in RA Several mechanisms are involved in the generation and action of ROS and RNS Superoxide radical, hydrogen peroxide and nitric oxide do not directly damage the majority of biological molecules They are however converted into the highly reactive hydroxyl radical, which reacts with almost all molecules in living cells The resulting chronic inflammation process can be reduced with antioxidant therapy To date, scavenging, preventive, and enzyme antioxidants are available The most important mode is scavenging of the hydroxyl radical and of hypochlorous acid Another important way is to inhibit production of RNS and ROS by neutrophils, monocytes, and macrophages The control of inflammation in arthritic patients by natural as well as synthetic antioxidants could become a relevant component of antirheumatic prevention and therapy
TL;DR: Bcl-2 appears to allow cells to adapt to an increased state of oxidative stress, fortifying the cellular anti-oxidant defenses and counteracting the radical overproduction imposed by different cell death stimuli.
TL;DR: The reported data suggest that the low H2O2 levels originating as a by‐product during GGT activity are able to act as sort of a ‘life signal’ in U937 cells, insofar as they can maintain cell proliferation and protect against apoptosis, possibly through an up‐regulation of PARP activity.
Abstract: It has been reported in several cell lines that exposure to low levels of reactive oxygen species can exert a stimulatory effect on their proliferation. We have previously shown that mild oxidative conditions can also counteract apoptotic stimuli. A constitutive cellular production of low levels of superoxide and hydrogen peroxide originates from various sources; among these, γ-glutamyl transpeptidase (GGT), the plasma membrane-bound activity in charge of metabolizing extracellular reduced glutathione, has recently been included. Since the inhibition of GGT is a sufficient stimulus for the induction of apoptosis in selected cell lines, we investigated whether this effect might result from the suppression of the mentioned GGT-dependent prooxidant reactions, on the theory that the latter may represent a basal antiapoptotic and proliferative signal for the cell. Experiments showed that: 1) GGT activity in U937 monoblastoid cells is associated with the production of low levels of hydrogen peroxide, and two in...