Formation of Hydroxyl Radicals from Hydrogen Peroxide and Iron Salts by Superoxide- and Ascorbate-Dependent Mechanisms: Relevance to the Pathology of Rheumatoid Disease

1983 ◽  
Vol 64 (6) ◽  
pp. 649-653 ◽  
Author(s):  
D. A. Rowley ◽  
B. Halliwell
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Oxygen Radicals ◽  
Rheumatoid Disease ◽  
Iron Salts ◽  
Low Concentrations ◽  
Short Period ◽  
Generating System

1. Superoxide and hydrogen peroxide are formed by activated phagocytes and react together in the presence of iron salts to form the hydroxyl radical, which attacks hyaluronic acid. Ascorbic acid also interacts with hydrogen peroxide and iron salts to form hydroxyl radical in a reaction independent of superoxide. Since iron salts, ascorbate and activated phagocytes are present in the rheumatoid joint, experiments were designed to see whether ascorbate-dependent or superoxide-dependent formation of hydroxyl radicals would be more important in vivo. 2. in the present study, addition of ascorbate to a superoxide-generating system at concentrations of 100 μmol/l provoked a superoxide-independent formation of hydroxyl radicals for a short period. Lower concentrations of ascorbate did not do this. It is therefore suggested that the superoxide-dependent reaction is probably more important. 3. It is further suggested that destruction of ascorbate by oxygen radicals formed by activated phagocytes accounts for the previously reported low concentrations of this compound in the serum and synovial fluid of rheumatoid patients.

How to characterize an antioxidant: an update

1995 ◽  
Vol 61 ◽  
pp. 73-101 ◽  
Author(s):  
Barry Halliwell
Keyword(s):  
Hydrogen Peroxide ◽  
Antioxidant Activity ◽  
Hydroxyl Radical ◽  
Hypochlorous Acid ◽  
Water Soluble ◽  
Peroxyl Radicals ◽  
Low Concentrations ◽  
Ferryl Species ◽  
Do So

The term antioxidant is widely used but rarely defined. One suggested definition is that an antioxidant is 'a substance that, when present at low concentrations compared with those of an oxidizable substrate, significantly delays or prevents oxidation of that substrate'. Many substances have been suggested to act as antioxidants in vivo, but few have been proved to do so. This chapter addresses the criteria necessary to evaluate a proposed antioxidant activity. Simple methods for assessing the possibility of physiologically feasible scavenging of important biological oxygen-derived species (superoxide, hydrogen peroxide, hydroxyl radical, hypochlorous acid, haem-associated ferryl species, radicals derived from activated phagocytes and peroxyl radicals, both lipid-soluble and water-soluble) are presented. Methods that may be used to gain evidence that a compound actually does function as an antioxidant in vivo are discussed.

Ischemia-induced vascular changes: role of xanthine oxidase and hydroxyl radicals

1983 ◽  
Vol 245 (2) ◽  
pp. G285-G289 ◽  
Author(s):  
D. A. Parks ◽  
D. N. Granger
Keyword(s):  
Hydroxyl Radical ◽  
Dimethyl Sulfoxide ◽  
Xanthine Oxidase ◽  
Vascular Permeability ◽  
Hydroxyl Radicals ◽  
Vascular Injury ◽  
Oxygen Radicals ◽  
Intestinal Ischemia ◽  
Xanthine Oxidase Inhibitor

The results of previous studies indicate that oxygen-derived free radicals are responsible for the increased vascular permeability produced by 1 h of intestinal ischemia. The aims of this study were 1) to test the hypothesis that the enzyme xanthine oxidase is the source of oxygen radicals in the ischemic bowel and 2) to assess the role of the hydroxyl radical in the ischemia-induced vascular injury. The capillary osmotic reflection coefficient was estimated from lymphatic protein flux data in the cat ileum for the following conditions: ischemia, ischemia plus pretreatment with allopurinol (a xanthine oxidase inhibitor), and ischemia plus pretreatment with dimethyl sulfoxide (a hydroxyl radical scavenger). The increased vascular permeability produced by ischemia was largely prevented by pretreatment with either allopurinol or dimethyl sulfoxide. These findings support the hypothesis that xanthine oxidase is the source of oxygen radicals produced during ischemia. The results also indicate that hydroxyl radicals, derived from the superoxide anion, are primarily responsible for the vascular injury associated with intestinal ischemia.

scholarly journals Production of the Hydroxyl Radical and Removal of Formaldehyde by Calcined Green Tuff Powder and Tile

2019 ◽  
Vol 11 (12) ◽  
pp. 3390 ◽  
Author(s):  
Toyohisa Fujita ◽  
Lanyin Zhang ◽  
Gjergj Dodbiba ◽  
Ji-Whan Anh ◽  
Yuezhou Wei ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Uv Light ◽  
Adsorption Rate ◽  
Optimum Temperature ◽  
High Adsorption ◽  
Alkaline Conditions ◽  
Formaldehyde Adsorption ◽  
High Decomposition Rate

Waste green tuff powder produced by cutting Towada stone has been utilized to eliminate formaldehyde related to greenhouse gases. The green tuff contains TiO2 on zeolite as observed by scanning electron microscope (SEM)t. The green tuff is a natural catalyst that can produce hydrogen peroxide with moisture and oxygen with light. The optimum temperature for calcination of the green tuff powder has been investigated in order to produce hydroxyl radicals from the decomposition of hydrogen peroxide using ultraviolet light (UV) and no light. The green tuff calcined at 800 °C showed a high decomposition rate of hydrogen peroxide with no UV light under high alkaline conditions when measured by using ESR. With UV light, the optimum temperature for calcination of green tuff powder in order to reduce the hydroxyl radical was also 800 °C. Next, the powder calcined at 800 °C was used to produce the tile by compression and heating, and then the formaldehyde adsorption rate was measured. The green tuff powder calcined at 800 °C showed a high adsorption rate, similar to that of the activated carbon. The tiles formed at 40 MPa and heated at 1100 °C were the strongest and also showed adsorption with respect to formaldehyde. The adsorbed formaldehyde on the green tuff tile and powder was possibility decomposed by the hydroxyl radical produced by photocatalysis.

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 Ferrous ion-EDTA-stimulated phospholipid peroxidation. A reaction changing from alkoxyl-radical- to hydroxyl-radical-dependent initiation

1984 ◽  
Vol 224 (3) ◽  
pp. 697-701 ◽  
Author(s):  
J M C Gutteridge
Keyword(s):  
Hydrogen Peroxide ◽  
Lipid Peroxidation ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Superoxide Radicals ◽  
Ferrous Ion ◽  
Radical Scavengers ◽  
Alkoxyl Radical ◽  
Phospholipid Peroxidation ◽  
Hydroxyl Radical Scavengers

The stimulatory effect of ferrous salts on the peroxidation of phospholipids can be enhanced by EDTA when the concentration of Fe2+ in the reaction is greater than that of EDTA. Hydroxyl-radical scavengers do not inhibit peroxidation until the concentrations of Fe2+ and EDTA in the reaction are equal. Lipid peroxidation is then substantially initiated by hydroxyl radicals derived from a Fenton-type reaction requiring hydrogen peroxide. Superoxide radicals appear to play some role in the formation of initiating species.

scholarly journals Metal Complexes Containing Redox-Active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1046 ◽  
Author(s):  
Georgiy B. Shul’pin ◽  
Yuriy N. Kozlov ◽  
Lidia S. Shul’pina
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Oxidation States ◽  
Acetonitrile Molecule ◽  
Oxidation Of Hydrocarbons ◽  
Alkyl Hydroperoxides ◽  
Redox Active ◽  
Tert Butyl Hydroperoxide ◽  
Saturated And Aromatic Hydrocarbons

Ligands are innocent when they allow oxidation states of the central atoms to be defined. A noninnocent (or redox) ligand is a ligand in a metal complex where the oxidation state is not clear. Dioxygen can be a noninnocent species, since it exists in two oxidation states, i.e., superoxide (O2−) and peroxide (O22−). This review is devoted to oxidations of C–H compounds (saturated and aromatic hydrocarbons) and alcohols with peroxides (hydrogen peroxide, tert-butyl hydroperoxide) catalyzed by complexes of transition and nontransition metals containing innocent and noninnocent ligands. In many cases, the oxidation is induced by hydroxyl radicals. The mechanisms of the formation of hydroxyl radicals from H2O2 under the action of transition (iron, copper, vanadium, rhenium, etc.) and nontransition (aluminum, gallium, bismuth, etc.) metal ions are discussed. It has been demonstrated that the participation of the second hydrogen peroxide molecule leads to the rapture of O–O bond, and, as a result, to the facilitation of hydroxyl radical generation. The oxidation of alkanes induced by hydroxyl radicals leads to the formation of relatively unstable alkyl hydroperoxides. The data on regioselectivity in alkane oxidation allowed us to identify an oxidizing species generated in the decomposition of hydrogen peroxide: (hydroxyl radical or another species). The values of the ratio-of-rate constants of the interaction between an oxidizing species and solvent acetonitrile or alkane gives either the kinetic support for the nature of the oxidizing species or establishes the mechanism of the induction of oxidation catalyzed by a concrete compound. In the case of a bulky catalyst molecule, the ratio of hydroxyl radical attack rates upon the acetonitrile molecule and alkane becomes higher. This can be expanded if we assume that the reactions of hydroxyl radicals occur in a cavity inside a voluminous catalyst molecule, where the ratio of the local concentrations of acetonitrile and alkane is higher than in the whole reaction volume. The works of the authors of this review in this field are described in more detail herein.

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