Showing papers on "Hydrogen peroxide published in 2007"
TL;DR: The molecular mechanisms by which hydrogen peroxide is sensed and the increasing evidence that antioxidant enzymes play multiple, key roles as sensors and regulators of signal transduction in response to hydrogen peroxy are discussed.
1,464 citations
TL;DR: It is proposed that genes that control H2O2 production are selected determinants of lifespan and not simply the result of a genetic programme or the by-product of physiological processes.
Abstract: The reactive oxygen species that are generated by mitochondrial respiration, including hydrogen peroxide (H2O2), are potent inducers of oxidative damage and mediators of ageing. It is not clear, however, whether oxidative stress is the result of a genetic programme or the by-product of physiological processes. Recent findings demonstrate that a fraction of mitochondrial H2O2, produced by a specialized enzyme as a signalling molecule in the pathway of apoptosis, induces intracellular oxidative stress and accelerates ageing. We propose that genes that control H2O2 production are selected determinants of lifespan.
1,277 citations
TL;DR: Evidence that aquaporins can channel hydrogen peroxide (H2O2) through specific members of the aquaporin family is presented, the first molecular genetic evidence for the diffusion of H2 O2 through specificMembers of the Aquaporin Family is presented.
1,154 citations
TL;DR: Quadratic models using time, temperature, and concentration as continuous variables were developed to predict xylan and lignin reduction, respectively for sulfuric acid and sodium hydroxide pretreatments, and explained most of the variation in xylan or lign in reduction through simple linear regressions.
801 citations
TL;DR: It is demonstrated that nanoparticles formulated from peroxalate esters and fluorescent dyes can image hydrogen peroxide in vivo with high specificity and sensitivity and deep-tissue-imaging capability.
Abstract: The overproduction of hydrogen peroxide is implicated in the development of numerous diseases and there is currently great interest in developing contrast agents that can image hydrogen peroxide in vivo. In this report, we demonstrate that nanoparticles formulated from peroxalate esters and fluorescent dyes can image hydrogen peroxide in vivo with high specificity and sensitivity. The peroxalate nanoparticles image hydrogen peroxide by undergoing a three-component chemiluminescent reaction between hydrogen peroxide, peroxalate esters and fluorescent dyes. The peroxalate nanoparticles have several attractive properties for in vivo imaging, such as tunable wavelength emission (460-630 nm), nanomolar sensitivity for hydrogen peroxide and excellent specificity for hydrogen peroxide over other reactive oxygen species. The peroxalate nanoparticles were capable of imaging hydrogen peroxide in the peritoneal cavity of mice during a lipopolysaccharide-induced inflammatory response. We anticipate numerous applications of peroxalate nanoparticles for in vivo imaging of hydrogen peroxide, given their high specificity and sensitivity and deep-tissue-imaging capability.
461 citations
TL;DR: This mechanism underlies cGMP-independent vasorelaxation in response to oxidants in the cardiovascular system and provides a molecular explantion for how hydrogen peroxide can operate as an endothelium-derived hyperpolarizing factor.
Abstract: Changes in the concentration of oxidants in cells can regulate biochemical signaling mechanisms that control cell function. We have found that guanosine 3',5'-monophosphate (cGMP)-dependent protein kinase (PKG) functions directly as a redox sensor. The Ialpha isoform, PKGIalpha, formed an interprotein disulfide linking its two subunits in cells exposed to exogenous hydrogen peroxide. This oxidation directly activated the kinase in vitro, and in rat cells and tissues. The affinity of the kinase for substrates it phosphorylates was enhanced by disulfide formation. This oxidation-induced activation represents an alternate mechanism for regulation along with the classical activation involving nitric oxide and cGMP. This mechanism underlies cGMP-independent vasorelaxation in response to oxidants in the cardiovascular system and provides a molecular explantion for how hydrogen peroxide can operate as an endothelium-derived hyperpolarizing factor.
440 citations
TL;DR: The synthesis and application of Peroxy Green 1 (PG1) and Peroxy Crimson 1 (PC1) are reported, two new fluorescent probes that show high selectivity for H2O2 and are capable of visualizing endogenous H 2O2 produced in living cells by growth factor stimulation, including the first direct imaging of peroxide produced for brain cell signaling.
Abstract: Hydrogen peroxide (H2O2) is emerging as a newly recognized messenger in cellular signal transduction. However, a substantial challenge in elucidating its diverse roles in complex biological environments is the lack of methods for probing this reactive oxygen metabolite in living systems with molecular specificity. Here we report the synthesis and application of Peroxy Green 1 (PG1) and Peroxy Crimson 1 (PC1), two new fluorescent probes that show high selectivity for H2O2 and are capable of visualizing endogenous H2O2 produced in living cells by growth factor stimulation, including the first direct imaging of peroxide produced for brain cell signaling. The combined features of reactive oxygen species selectivity, sensitivity to signaling levels of H2O2, and live-cell compatibility presage many new opportunities for PG1, PC1 and related synthetic reagents for exploring the physiological roles of H2O2 in living systems with molecular imaging.
404 citations
TL;DR: Application of activated bleaching procedures should be critically assessed considering the physical, physiological and patho-physiological implications.
392 citations
TL;DR: Results demonstrate that peroxiredoxin 2 has a tertiary structure that facilitates reaction of the active site thiol with hydrogen peroxide while restricting its reactivity with other thiol reagents.
358 citations
TL;DR: In scavenger-deficient mutants, the H2O2 that was generated as an adventitious by-product of metabolism (<1 μm) was sufficient to damage these [4Fe-4S] enzymes, demonstrating that aerobic organisms must synthesize H 2O2 scavengers to avoid poisoning their own pathways.
313 citations
TL;DR: In this article, an efficient undivided electrochemical system using a graphite-polytetrafluoroethylene (PTFE) cathode with high production rate of hydrogen peroxide and current efficiency under wider pH ranges was applied to the electro-Fenton oxidation of a model azo dye, methyl red.
TL;DR: In the search for an efficient and economical method to treat a leachate generated from a controlled municipal solid waste landfill site (Jebel Chakir) in the region of greater Tunis in Tunisia, ozone alone and ozone combined with hydrogen peroxide were studied.
TL;DR: CP-Pt may be a SOD/catalase mimetic which is useful for medical treatment of oxidative stress diseases and quenched hydrogen peroxide and superoxide anion radical in dose-dependent manners.
Abstract: Bimetallic nanoparticles consisting of gold and platinum were prepared by a citrate reduction method and complementarily stabilized with pectin (CP-Au/Pt). The percent mole ratio of platinum was varied from 0 to 100%. The CP-Au/Pt were alloy-structured. They were well dispersed in water. The average diameter of platinum nanoparticles (CP-Pt) was 4.7 ± 1.5 nm. Hydrogen peroxide (H2O2) was quenched by CP-Au/Pt consisting of more than 50% platinum whereas superoxide anion radical () was quenched by any CP-Au/Pt. The CP-Au/Pt quenched these two reactive oxygen species in dose-dependent manners. The CP-Pt is the strongest quencher. The CP-Pt decomposed H2O2 and consequently generated O2 like catalase. The CP-Pt actually quenched which was verified by a superoxide dismutase (SOD) assay kit. This quenching activity against persisted like SOD. Taken together, CP-Pt may be a SOD/catalase mimetic which is useful for medical treatment of oxidative stress diseases.
TL;DR: In this paper, the photocatalytic degradation of maleic hydrazide (1), propham (2), tebuthiuron (3), propachlor (4), chlortoluron (5), thiram (6), phenoxyacetic acid (7), 2,4,5-trichlorophenoxy acetic acid(8), 4-chlorophenoxy acid (9), uracil (10), 5-bromouracil(11) and bromothymol blue (12) have been investigated
TL;DR: A new chiral Fe(salan) complex was synthesized, and it was found to serve as an efficient catalyst for asymmetric oxidation of sulfides using hydrogen peroxide in water without surfactant.
Abstract: A new chiral Fe(salan) complex was synthesized, and it was found to serve as an efficient catalyst for asymmetric oxidation of sulfides using hydrogen peroxide in water without surfactant. Not only alkyl aryl sulfides but also various methyl alkyl sulfides were oxidized to the corresponding sulfoxides with high enantioselectivities up to 96% ee. It should be noted that the turnover number of complex 4 amounts to 8000.
TL;DR: Methylamine (MA) was found to be a major amino product from NDMA oxidation initiated by (*)OH, and Bromate formation may be the limiting factor forNDMA oxidation during ozonation and ozone-based AOPs in bromide-containing waters.
TL;DR: The reaction system was modeled as a plug flow reactor in series with a continuous stirred tank reactor (CSTR), and the pseudo-first order rate constant of COD removal was determined from the model based on the experimental data.
TL;DR: The detection results of thiol compounds showed high sensitivity, good precision, and acceptable accuracy, suggesting the promising application of the proposed method for quick detection of both scavengers and generators of hydroxyl radical in different fields.
Abstract: This work elucidated the detailed electrochemiluminescence (ECL) process of the thioglycolic acid-capped CdSe quantum dots (QDs) film/peroxide aqueous system. The QDs were first electrochemically reduced to form electrons-injected QDs ∼ −1.1 V, which then reduced hydrogen peroxide to produce OH• radical. The intermediate OH• radical was a key species for producing holes-injected QDs. The ECL emission with a peak at −1.114 V was demonstrated to come from the 1Se−1Sh transition emission. Using thiol compounds as the model molecules to annihilate the OH• radical, their quenching effects on ECL emission were studied. This effect led to a novel strategy for ECL sensing of the scavengers of hydroxyl radical. The detection results of thiol compounds showed high sensitivity, good precision, and acceptable accuracy, suggesting the promising application of the proposed method for quick detection of both scavengers and generators of hydroxyl radical in different fields.
TL;DR: In this article, two polysaccharides, GAPS1 and SAPS-1, were isolated from the gel and the skin of Aloe barbadensis Miller irrigated with sea water for 3.5 years through a combination of anion-exchange column chromatography and repeated gel chromatography.
TL;DR: In this paper, the authors determined the dose-dependency of myofibrillar protein oxidation on oxidizing ferric ion and found that protein unfolding and loss of myosin heavy chain occurred continuously with increasing H 2 O 2 2 concentrations.
Journal Article•
TL;DR: In this article, the rate of SO2 oxidation in a wine-model system under aerial oxygen saturation conditions was investigated and it was shown that the SO2 consumption is dependent on the degree of catechol oxidation.
Abstract: The rate of oxidation of SO2 was studied in a wine-model system under aerial oxygen saturation conditions to gain further insight into its mechanism of action in wine. When SO2 was studied alone, no significant oxidation was observed unless iron and copper were introduced. When these metals were added a slow oxidation was observed and bound SO2 also increased to a small but significant extent. These results are consistent with a radical chain mechanism initiated by metal catalysis, in which powerful oxidizing radicals, capable of oxidizing ethanol to acetaldehyde, are produced. This increase in bound SO2 is prevented by 4-methylcatechol (4-MeC) in keeping with the known ability of polyphenols to scavenge these intermediate radicals and thus to inhibit SO2 autoxidation, which consequently should not occur in wine. When 4-MeC was introduced at a concentration that simulated the reducing capacity of red wine, again no significant SO2 oxidation was observed without addition of iron and copper. Had the catechol been oxidized, hydrogen peroxide would have been generated and reacted with the SO2. In the presence of both metals the rate of SO2 oxidation was markedly increased compared to SO2 alone and then was dependent on the concentration of the catechol. These results demonstrate the crucial importance of metals in allowing polyphenol oxidation and that the rate of SO2 consumption is dependent on the rate of catechol oxidation. When iron and copper were added separately, only a modest increase in rate of catechol oxidation resulted. However, when combined, marked synergism was observed and the rate then became very sensitive to copper concentration. It is proposed that copper, by interacting with oxygen, facilitates redox cycling of iron. Exposure of a red wine to the conditions used in this study produced similar results regarding SO2 oxidation to those observed.
TL;DR: In this article, gold particles supported on carbon and titania were explored as catalysts for oxidation of CO or glycerol by O2 at room temperature in liquid-phase water, and a turnover frequency of 5 s−1 could be achieved with comparable CO concentration in aqueous solution containing 1 M NaOH.
Abstract: Gold particles supported on carbon and titania were explored as catalysts for oxidation of CO or glycerol by O2 at room temperature in liquid-phase water. Although Au/carbon catalysts were not active for vapor phase CO oxidation at room temperature, a turnover frequency of 5 s−1 could be achieved with comparable CO concentration in aqueous solution containing 1 M NaOH. The turnover frequency on Au/carbon was a strong function of pH, decreasing by about a factor of 50 when the pH decreased from 14 to 0.3. Evidently, a catalytic oxidation route that was not available in the vapor phase is enabled by operation in the liquid water at high pH. Since Au/titania is active for vapor phase CO oxidation, the role of water, and therefore hydroxyl concentration, is not as significant as that for Au/carbon. Hydrogen peroxide is also produced during CO oxidation over Au in liquid water and increasing the hydroxyl concentration enhances its formation rate. For glycerol oxidation to glyceric acid (C3) and glycolic acid (C2) with O2 (1–10 atm) at 308–333 K over supported Au particles, high pH is required for catalysis to occur. Similar to CO oxidation in liquid water, H2O2 is also produced during glycerol oxidation at high pH. The formation of the C-C cleavage product glycolic acid is attributed to peroxide in the reaction.
TL;DR: Grape seed and bagasse extract obtained from Narince grape cultivar using different solvent mixtures were assayed for their antioxidant properties by the Folin-Ciocalteu method as mentioned in this paper.
TL;DR: In this paper, Boron-doped diamond (BDD) electrodes with respect to the formation of inorganic byproducts in water electrolysis were studied with experiments in non-divided cells with systems containing sulphate, chloride, chlorite, chlorate and nitrate ions.
TL;DR: In this paper, the authors used the Bronsted acid ionic liquid N-methyl-pyrrolidoniumtetrafluoroborate ([Hnmp]BF4) as the extractant and catalyst for extraction/oxidative desulfurization (ODS) of model oil and diesel fuel in the presence of H2O2 by a combination of both chemical oxidation and solvent extraction.
TL;DR: The results obtained in the present study indicate that C. rotundus rhizomes extract can be a potential source of natural antioxidant.
Abstract: In this study, Antioxidant activity of Cyperus rotundus rhizomes extract (CRRE) was evaluveted in a series of in vitro assay involving free radicals and reactive oxygen species and IC50 values were determined. CRRE exhibited its scavenging effect in concentration dependent manner on superoxide anion radicals, hydroxyl radicals, nitric oxide radical, hydrogen peroxide, and property of metal chelating and reducing power. The extract was also studied for lipid peroxidation assay by thiobarbituric acid–reactive substances (TBARS) using young and aged rat brain mitochondria. The extract was also effective in preventing mitochondrial lipid peroxidation induced by FeSO4/ ascorbate in concentration dependent manner. The results obtained in the present study indicate that C. rotundus rhizomes extract can be a potential source of natural antioxidant.
TL;DR: A competitive kinetic approach with horseradish peroxidase was developed to determine the second-order rate constant of the reaction of peroxiredoxins with peroxynitrite and hydrogen peroxide, and this method provided a useful method for studying thiol protein kinetics.
TL;DR: In this article, the photocatalysed degradation of two selected dyes, such as Acridine Orange (1) and Ethidium Bromide (2) has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view.
TL;DR: In this article, the conversion of rice hull cellulose and hemicellulose to simple sugars was investigated using enzymatic saccharification and a dilated H2O2 pretreatment.