Role of hydrogen peroxide and hydroxyl radical in pyrite oxidation by molecular oxygen

2010 ◽  
Vol 74 (17) ◽  
pp. 4971-4987 ◽  
Author(s):  
Martin A.A. Schoonen ◽  
Andrea D. Harrington ◽  
Richard Laffers ◽  
Daniel R. Strongin
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Molecular Oxygen ◽  
Pyrite Oxidation ◽  
Oxidation By Molecular Oxygen

The Role of Hydrogen Peroxide in Dioxygen Induced Hydroxylation of Salicylic Acid

1994 ◽  
Vol 59 (11) ◽  
pp. 2447-2453 ◽  
Author(s):  
Kamil Lang ◽  
Dana M. Wagnerová ◽  
Jiřina Brodilová
Keyword(s):  
Hydrogen Peroxide ◽  
Salicylic Acid ◽  
Molecular Oxygen ◽  
Fenton Reaction ◽  
Radical Scavengers

The photochemically initiated oxidation of salicylic acid by molecular oxygen in the presence of [Fe(C2O4)3]3- leads to a mixture of 2,3- and 2,5-dihydroxybenzoic acids. Iron(II) generated by the photoreduction is reoxidized by dioxygen. Hydrogen peroxide formed in this reaction takes part in the Fenton reaction in the presence of Fe(II). Experiments with OH. radical scavengers document the role of the radicals in the photochemical and thermal hydroxylation of salicylic acid.

scholarly journals Photochemistry of the Cloud Aqueous Phase: A Review

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 423
Author(s):  
Angelica Bianco ◽  
Monica Passananti ◽  
Marcello Brigante ◽  
Gilles Mailhot
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Aqueous Phase ◽  
Review Paper ◽  
Formation Rate ◽  
Nitrate Radical ◽  
Steady State Concentration ◽  
Potential Impact ◽  
State Concentration

This review paper describes briefly the cloud aqueous phase composition and deeply its reactivity in the dark and mainly under solar radiation. The role of the main oxidants (hydrogen peroxide, nitrate radical, and hydroxyl radical) is presented with a focus on the hydroxyl radical, which drives the oxidation capacity during the day. Its sources in the aqueous phase, mainly through photochemical mechanisms with H2O2, iron complexes, or nitrate/nitrite ions, are presented in detail. The formation rate of hydroxyl radical and its steady state concentration evaluated by different authors are listed and compared. Finally, a paragraph is also dedicated to the sinks and the reactivity of the HO• radical with the main compounds found in the cloud aqueous phase. This review presents an assessment of the reactivity in the cloud aqueous phase and shows the significant potential impact that this medium can have on the chemistry of the atmosphere and more generally on the climate.

scholarly journals Superoxide dismutase enhances the formation of hydroxyl radicals in the reaction of 3-hydroxyanthranilic acid with molecular oxygen

1988 ◽  
Vol 251 (3) ◽  
pp. 893-899 ◽  
Author(s):  
H Iwahashi ◽  
T Ishii ◽  
R Sugata ◽  
R Kido
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Hydroxyl Radical ◽  
Molecular Oxygen ◽  
Hydroxyl Radicals ◽  
Fenton Reaction ◽  
Potassium Phosphate ◽  
Radical Formation ◽  
Superoxide Anions ◽  
Hydroxyanthranilic Acid

Superoxide dismutase (SOD) enhanced the formation of hydroxyl radicals, which were detected by using the e.s.r. spin-trapping technique, in a reaction mixture containing 3-hydroxyanthranilic acid (or p-aminophenol), Fe3+ ions, EDTA and potassium phosphate buffer, pH 7.4. The hydroxyl-radical formation enhanced by SOD was inhibited by catalase and desferrioxamine, and stimulated by EDTA and diethylenetriaminepenta-acetic acid, suggesting that both hydrogen peroxide and iron ions participate in the reaction. The hydroxyl-radical formation enhanced by SOD may be considered to proceed via the following steps. First, 3-hydroxyanthranilic acid is spontaneously auto-oxidized in a process that requires molecular oxygen and yields superoxide anions and anthranilyl radicals. This reaction seems to be reversible. Secondly, the superoxide anions formed in the first step are dismuted by SOD to generate hydrogen peroxide and molecular oxygen, and hence the equilibrium in the first step is displaced in favour of the formation of superoxide anions. Thirdly, hydroxyl radicals are generated from hydrogen peroxide through the Fenton reaction. In this Fenton reaction Fe2+ ions are available since Fe3+ ions are readily reduced by 3-hydroxyanthranilic acid. The superoxide anions do not seem to participate in the reduction of Fe3+ ions, since superoxide anions are rapidly dismuted by SOD present in the reaction mixture.

scholarly journals Dual Role of ROS as Signal and Stress Agents: Iron Tips the Balance in favor of Toxic Effects

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Elena Gammella ◽  
Stefania Recalcati ◽  
Gaetano Cairo
Keyword(s):  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Oxidative Damage ◽  
Cell Signaling ◽  
Hydroxyl Radical ◽  
Iron Homeostasis ◽  
Storage Proteins ◽  
Oxygen Species ◽  
Physiologic Role

Iron is essential for life, while also being potentially harmful. Therefore, its level is strictly monitored and complex pathways have evolved to keep iron safely bound to transport or storage proteins, thereby maintaining homeostasis at the cellular and systemic levels. These sequestration mechanisms ensure that mildly reactive oxygen species like anion superoxide and hydrogen peroxide, which are continuously generated in cells living under aerobic conditions, keep their physiologic role in cell signaling while escaping iron-catalyzed transformation in the highly toxic hydroxyl radical. In this review, we describe the multifaceted systems regulating cellular and body iron homeostasis and discuss how altered iron balance may lead to oxidative damage in some pathophysiological settings.

Reactive forms of oxygen and chemiluminescence in phagocytizing rabbit alveolar macrophages

1978 ◽  
Vol 235 (3) ◽  
pp. C103-C108 ◽  
Author(s):  
P. R. Miles ◽  
V. Castranova ◽  
P. Lee
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Hydroxyl Radical ◽  
Alveolar Macrophages ◽  
Superoxide Anion ◽  
Extracellular Fluid ◽  
Particle Uptake ◽  
O2 Production

Chemiluminescence (CL), superoxide anion (O2-) production, and particle uptake were measured to determine the role of antibacterial substances in the chemiluminescent response associated with phagocytosis in rabbit alveolar macrophages (AM). Exposure of AM to zymosan particles induced both CL and the production of extracellular O2-. CL is inhibited by superoxide dismutase, an enzyme which catalyzes the conversion of O2- to hydrogen peroxide (H2O2), by catalase, an enzyme which destroys H2O2, and by the hydroxyl radical (.OH) scavengers, benzoate and ethanol. Superoxide dismutase and catalase probably exert their effects in the extracellular fluid. CL can also be produced by the addition of NaO2 or H2O2 to zymosan in a noncellular system. The chemiluminescent response occurs before particle uptake is complete, which also indicates that CL occurs in the extracellular fluid. These results suggest that CL induced by zymosan in AM is due to the extracellular reaction between various reactive forms of oxygen and zymosan.

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