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At least 19 recordsLinked to original sources
PubMed2005

[Application of slightly acidic hypochlorous acid water to the dental field--setting expansion and compressive strength of dental gypsum mixed with slightly acidic hypochlorous acid water].

PURPOSE: This study investigated both the setting expansion and compressive strength of dental gypsum mixed with slightly acidic hypochlorous acid water for the prevention of hospital infection. METHODS: Slightly acidic hypochlorous acid water (PURESTER Mp-240B, Morinaga Milk Industry) was used to mix each of three types of gypsum (model plaster, dental stone and high strength dental stone), and both the setting expansion and compressive strength of these gypsum products were analyzed in comparison with those mixed with tap water. RESULTS: 1. With regard to the setting expansion, a significant difference was not observed between gypsum products mixed with the two types of water, except for both the model plaster and dental stone 30 minutes after the start of mixing. 2. Regarding the compressive strength, a significant difference was not observed between gypsum products mixed with the two types of water, except for the model plaster 90 minutes after the start of mixing. CONCLUSIONS: From the results of the study, it was revealed that both the setting expansion and compressive strength of gypsum products using the slightly acidic hypochlorous acid water showed almost the same characteristics as those using tap water.

Calcium Sulfate↗
PubMed2000

Biomarkers of myeloperoxidase-derived hypochlorous acid.

Hypochlorous acid is the major strong oxidant generated by neutrophils. The heme enzyme myeloperoxidase catalyzes the production of hypochlorous acid from hydrogen peroxide and chloride. Although myeloperoxidase has been implicated in the tissue damage that occurs in numerous diseases that involve inflammatory cells, it has proven difficult to categorically demonstrate that it plays a crucial role in any pathology. This situation should soon be rectified with the advent of sensitive biomarkers for hypochlorous acid. In this review, we outline the advantages and limitations of chlorinated tyrosines, chlorohydrins, 5-chlorocytosine, protein carbonyls, antibodies that recognize HOCl-treated proteins, and glutathione sulfonamide as potential biomarkers of hypochlorous acid. Levels of 3-chlorotyrosine and 3,5-dichlorotyrosine are increased in proteins after exposure to low concentrations of hypochlorous acid and we conclude that their analysis by gas chromatography and mass spectrometry is currently the best method available for probing the involvement of oxidation by myeloperoxidase in the pathology of particular diseases. The appropriate use of other biomarkers should provide complementary information.Keywords-Free radicals, Myeloperoxidase, Neutrophil oxidant, Hypochlorous acid, Chlorotyrosine, Chlorohydrin, Oxidant biomarker

Animals↗
PubMed1991

Role of functional groups of human plasma and luminol in scavenging of NaOCl and neutrophil-derived hypochlorous acid.

Hypochlorous acid HOCl/OCl- and other oxidants derived from stimulated polymorphonuclear leukocytes are involved in tissue damage during a number of pathological processes. In order to obtain more detailed information on possible reactions of HOCl/OCl- the effects of both NaOCl and PMN-derived hypochlorous acid on functional groups of amino acid solutions and human plasma are studied. In valine and lysine solutions NaOCl diminishes the number of amino groups in a molar ratio of 1:1 between NaOCl and amino groups. In cysteine and methionine samples the decrease of amino groups starts only after all sulfhydryl or thioether groups are oxidized by NaOCl. If freshly prepared human plasma is treated with increasing amounts of NaOCl all plasma SH groups are oxidized first, then probably the thioether groups and only after this the amino groups are affected. Furthermore, it was found, that the reactivity of luminol against NaOCl is similar to that of amino groups. Increasing amounts of SH groups of components of human plasma are oxidized by incubation with PMA-stimulated polymorphonuclear leukocytes dependent on the incubation time. Plasma amino groups are not affected under the same experimental conditions. The addition of plasma to FMLP-stimulated PMN in the presence of luminol decreases that part of chemiluminescence caused by extracellularly generated hypochlorous acid. Plasma samples pretreated with NaOCl cause a lower inhibition of light generation in FMLP-stimulated PMN only when more than 4.10(-8) mol NaOCl per mg protein are used to pretreat plasma. It is assumed that in the development of tissue injuries caused by infiltrated PMN the following sequence of damage occurs in accessible tissue regions. First, the sulfhydryl groups are oxidized, then the thioether groups, and only after this amino and other target groups are affected.

Amino Acids↗
PubMed2005

Mechanism of interaction of betanin and indicaxanthin with human myeloperoxidase and hypochlorous acid.

Hypochlorous acid (HOCl) is the most powerful oxidant produced by human neutrophils and contributes to the damage caused by these inflammatory cells. It is produced from H2O2 and chloride by the heme enzyme myeloperoxidase (MPO). Based on findings that betalains provide antioxidant and anti-inflammatory effects, we performed the present kinetic study on the interaction between the betalains, betanin and indicaxanthin, with the redox intermediates, compound I and compound II of MPO, and its major cytotoxic product HOCl. It is shown that both betalains are good peroxidase substrates for MPO and function as one-electron reductants of its redox intermediates, compound I and compound II. Compound I is reduced to compound II with a second-order rate constant of (1.5+/-0.1) x 10(6) M(-1) s(-1) (betanin) and (1.1+/-0.2) x 10(6) M(-1) s(-1) (indicaxanthin), respectively, at pH 7.0 and 25 degrees C. Formation of ferric (native) MPO from compound II occurs with a second-order rate constant of (1.1+/-0.1) x 10(5) M(-1) s(-1) (betanin) and (2.9+/-0.1) x 10(5) M(-1) s(-1) (indicaxanthin), respectively. In addition, both betalains can effectively scavenge hypochlorous acid with determined rates of (1.8+/-0.2) x 10(4) M(-1) s(-1) (betanin) and (7.7+/-0.1) x 10(4) M(-1) s(-1) (indicaxanthin) at pH 7.0 and 25 degrees C. At neutral pH and depending on their concentration, both betalains can exhibit a stimulating and inhibitory effect on the chlorination activity of MPO, whereas at pH 5.0 only inhibitory effects were observed even at micromolar concentrations. These findings are discussed with respect to our knowledge of the enzymatic mechanisms of MPO.

Antioxidants↗
PubMed2003

Characterization of non-covalent oligomers of proteins treated with hypochlorous acid.

Hypochlorous acid (HOCl) is a potent oxidant produced by myeloperoxidase that causes aggregation of many proteins. Treatment of apohaemoglobin and apomyoglobin with HOCl produced a regular series of oligomer bands when the proteins were separated by SDS/PAGE under reducing conditions. Aggregation was detectable at a HOCl/protein molar ratio of 0.5:1 and was maximal at ratios of 10:1-20:1. Dimers formed within 1 min of adding HOCl, and further aggregation occurred over the next 30 min. No convincing evidence for covalent cross-linking was obtained by amino acid analysis, peptide analysis or electrospray ionization-MS of HOCl-modified apomyoglobin. The latter showed an increase in mass consistent with conversion of the two methionine residues into sulphoxides. A 5-fold excess of HOCl generated approximately three chloramines on the apomyoglobin. These underwent slow decay. Protein carbonyls were formed and were almost entirely located only on the polymer bands. Conversion of positively into negatively charged groups on the protein by succinylation caused preformed aggregates to dissociate. Treatment of apomyoglobin with taurine chloramine generated methionine sulphoxides but few protein carbonyls, and did not result in aggregation. We conclude that aggregation was due to strong, non-covalent interactions between protein chains. We propose that formation of protein carbonyls and possibly chloramines, along with methionine oxidation, alters protein folding to expose hydrophobic areas on neighbouring molecules that associate to form dimers and higher-molecular-mass aggregates. This process could lead to the formation of aggregated proteins at sites of myeloperoxidase activity and contribute to inflammatory tissue injury.

Amino Acids↗
PubMed2005

Indole ring oxidation by activated leukocytes prevents the production of hypochlorous acid.

Hypochlorous acid (HOCl) released by activated leukocytes has been implicated in the tissue damage that characterizes chronic inflammatory diseases. In this investigation, 14 indole derivatives, including metabolites such as melatonin, tryptophan and indole-3-acetic acid, were screened for their ability to inhibit the generation of this endogenous oxidant by stimulated leukocytes. The release of HOCl was measured by the production of taurine-chloramine when the leukocytes (2 x 10(6) cells/mL) were incubated at 37 degrees C in 10 mM phosphate-buffered saline, pH 7.4, for 30 min with 5 mM taurine and stimulated with 100 nM phorbol-12-myristate acetate. Irrespective of the group substituted in the indole ring, all the compounds tested including indole, 2-methylindole, 3-methylindole, 2,3-dimethylindole, 2,5-dimethylindole, 2-phenylindole, 5-methoxyindole, 6-methoxyindole, 5-methoxy-2-methylindole, melatonin, tryptophan, indole-3-acetic acid, 5-methoxy-2-methyl-3-indole-acetic acid, and indomethacin (10 microM) inhibited the chlorinating activity of myeloperoxidase (MPO) in the 23-72% range. The compounds 3-methylindole and indole-3-acetic acid were chosen as representative of indole derivatives in a dose-response study using purified MPO. The IC50 obtained were 0.10 +/- 0.03 and 5.0 +/- 1.0 microM (N = 13), respectively. These compounds did not affect the peroxidation activity of MPO or the production of superoxide anion by stimulated leukocytes. By following the spectral change of MPO during the enzyme turnover, the inhibition of HOCl production can be explained on the basis of the accumulation of the redox form compound-II (MPO-II), which is an inactive chlorinating species. These results show that indole derivatives are effective and selective inhibitors of MPO-chlorinating activity.

Dose-Response Relationship, Drug↗
PubMed1999

Reactive oxygen species are partially involved in the bacteriocidal action of hypochlorous acid.

Hypochlorous acid (HOCl) is probably the most widely used disinfectant worldwide and has an important role in inflammatory reaction and in human resistance to infection. However, the nature and mechanisms of its bactericidal activity are still poorly understood. Bacteria challenged aerobically with HOCl concentrations ranging from 9.5 to 76 microM exhibit higher ability to form colonies anaerobically than aerobically. Conversely, aerobic plating greatly increased lethality after an anaerobic HOCl challenge, although anaerobic survival did not depend on whether HOCl exposure was aerobic or anaerobic. Even a short transient exposure to air after anaerobic HOCl challenge reduced anaerobic survival, indicative of immediate deleterious effects of oxygen. Exposure to HOCl can cause lethal DNA damage as judged by the fact that recA sensitivity to HOCl was oxygen dependent. Antioxidant defenses such as reduced glutathione and glucose-6-phosphate dehydrogenase were depleted or inactivated at 10 microM HOCl, while other activities, such as superoxide dismutase, dropped only above 57 microM HOCl. Cumulative deficiencies in superoxide dismutase and glucose-6-phosphate dehydrogenase rendered strains hypersensitive to HOCl. This indicates that part of HOCl toxicity on Escherichia coli is mediated by reactive oxygen species during recovery.

DNA Damage↗
PubMed1996

Free radicals produced during the oxidation of hydrazines by hypochlorous acid.

Hypochlorous acid (HOCl) derived from activated neutrophils and monocytes has been implicated in the activation of hydrazine-containing drugs to toxic intermediates. However, reactive intermediates formed during the reaction between HOCl and these drugs have not been identified. We investigated the oxidation of the hydrazine derivatives isoniazid, iproniazid, and hydralazine by HOCl. The reaction between HOCl and all three hydrazines resulted in O2 consumption, indicating that free radicals were produced, but the rate and extent of O2 consumption were different for each hydrazine. Moreover, reduction of nitroblue tetrazolium (NBT) was observed only during the reaction between HOCl and isoniazid, suggesting that different radical species may be produced from HOCl reaction with each hydrazine. The oxidation of iproniazid by HOCl in the presence of the radical trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) resulted in the formation of a carbon-centered radical adduct. In contrast, the reaction between HOCl and hydralazine resulted in the formation of a nitrogen-centered DMPO radical adduct. The oxidation of isoniazid by HOCl resulted in the formation of two oxygen-centered radical adducts, DMPO-OOH and DMPO-OH. Myeloperoxidase-catalyzed oxidation of these hydrazines in the presence of Cl- and H2O2 produced radical species that were identical to those observed with HOCl. Thus, some of the toxic side effects of these drugs may be the result of the production of free-radical intermediates from reaction with neutrophil-derived oxidants, such as HOCl. The types of radicals produced and the consequences of generating these reactive species are discussed.

Electron Spin Resonance Spectroscopy↗
PubMed1993

Structural analysis of oxidation products of urofuran acid by hypochlorous acid.

The oxidation of urofuran acid derivatives (1-2) by hypochlorous acid (HOCl) was investigated with the goal to possibly simplify the detection of their metabolites in biological materials. The oxidation products of 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (1) were obtained as an isomeric mixture and confirmed to exist as cis (3a) and trans (3b) isomers, based on their 13C nuclear magnetic resonance (NMR) spectra. Similarly, the products of 5-H substituted acid 2 obtained by oxidation with HOCl were identified as 4a and 4b by 13C and 1H NMR which indicated the presence of cis and trans hemiacetal hydrogens at C-5 in a ratio of 2.11:1. The oxidation was found to proceed in a manner different from that of the F-acid, because of the presence of the electron withdrawing COOCH3 group at C-3 which favored the nucleophilic attack on the carbonyl group to afford cis- and trans-2,5-dihydroxy-2,5-dihydrofurans (3a-b, 4a-b).

Chromatography, Gel↗
PubMed1994

Free fatty acids enhance hypochlorous acid production by activated neutrophils.

Activated polymorphonuclear neutrophils (PMNs) may contribute to the genesis of chronic obstructive lung disease in long-term cigarette smokers. However, it is not presently known which elements in smoke are important in triggering this progressive pulmonary damage or in affecting the activities of inflammatory cells such as PMNS. We earlier found substances in organic concentrates of cigarette smoke that bound ferrous iron and transferred the metal into organic phases. These substances were later identified as saturated free fatty acids, predominantly palmitic and stearic acids (16:0 and 18:0). We now report investigations of the effects of fatty acids on the oxidative metabolism of PMNs. In accord with most earlier reports, we find that saturated fatty acids have little direct effect on PMN oxidative metabolism. However, micromolar amounts of free fatty acids will more than double production of hypochlorous acid (HOCl) by PMNs stimulated with small amounts of phorbol myristate acetate. Similar fatty acid-mediated increases in HOCl production also occur when PMNs are stimulated with 1,2-dioctanoyl-sn-glycerol and 1-oleoyl-2-acetyl-sn-glycerol (also thought to be agonists of protein kinase C) but not when cells are stimulated with the calcium ionophore A23187, the formylated tripeptide f-met-leu-phe, or opsonized zymosan. Fatty acid-mediated enhancement of PMN HOCl production evidently arises from increased release of myeloperoxidase from stimulated PMNs. Furthermore, in the presence of free fatty acids, stimulated PMNs are much more cytotoxic toward cultured mink lung epithelial cells, a toxicity that is blocked by scavengers of HOCl. These results suggest that the relatively large amounts of free fatty acids present in tobacco smoke may act to amplify PMN-mediated oxidative damage to the lungs of smokers.

Adult↗
PubMed1995

Oxidation of 5-aminosalicylic acid by hypochlorous acid to a reactive iminoquinone. Possible role in the treatment of inflammatory bowel diseases.

5-Aminosalicylic acid (5-ASA) is an agent widely used in the treatment of inflammatory bowel disease. 5-ASA has been shown to be a potential scavenger of the oxidants, such as hypochlorous acid (HOCl), that are released by neutrophils present in inflammatory bowel disease. We studied the oxidation of 5-ASA by HOCl and characterized the reaction pathway involving reactive intermediates. The reactive intermediates in the reaction of 5-ASA with HOCl were identified by use of a flow system interfaced with a Sciex API III mass spectrometer. The mass spectral analysis revealed the formation of iminoquinone and quinone reactive intermediates. The major stable product formed was identified as gentisic acid. The iminoquinone and quinone intermediates were trapped by glutathione (GSH) and the products analyzed by LC/MS. The major conjugate was formed from the quinone with one dominant isomer. In contrast, three isomers of the iminoquinone-GSH conjugates were observed in almost equal proportion. Covalent binding of the reactive intermediates to the alpha-chain of human hemoglobin was also observed. We propose that the iminoquinone is the major intermediate formed in the scavenging of neutrophil-generated HOCl by 5-ASA. Although this reaction may inactivate HOCl and be responsible for the antiinflammatory effects of the drug, it also forms reactive intermediates that covalently bind to protein and may be responsible for adverse reactions that are associated with the use of the drug.

Amino Acids↗
PubMed1992

Chlorohydrin formation from unsaturated fatty acids reacted with hypochlorous acid.

Stimulated neutrophils produce hypochlorous acid (HOCl) via the myeloperoxidase-catalyzed reaction of hydrogen peroxide with chloride. The reactions of HOCl with oleic, linoleic, and arachidonic acids both as free fatty acids or bound in phosphatidylcholine have been studied. The products were identified by gas chromatography-mass spectrometry of the methylated and trimethylsilylated derivatives. Oleic acid was converted to the two 9,10-chlorohydrin isomers in near stoichiometric yield. Linoleic acid, at low HOCl:fatty acid ratios, yielded predominantly a mixture of the four possible monochlorohydrin isomers. Bischlorohydrins were also formed, in increasing amounts at higher HOCl concentrations. Arachidonic acid gave a complex mixture of mono- and bischlorohydrins, the relative proportions depending on the amount of HOCl added. Linoleic acid appears to be slightly more reactive than oleic acid with HOCl. Reactions of oleic and linoleic acids with myeloperoxidase, hydrogen peroxide, and chloride gave chlorohydrin products identical to those with HOCl. Lipid chlorohydrins have received little attention as products of reactions of neutrophil oxidants. They are more polar than the parent fatty acids, and if formed in cell membranes could cause disruption to membrane structure. Since cellular targets for HOCl appear to be membrane constituents, chlorohydrin formation from unsaturated lipids could be significant in neutrophil-mediated cytotoxicity.

Arachidonic Acid↗
PubMed2000

Hypochlorous acid and human blood low density lipoproteins modified by hypochlorous acid increase erythrocyte adhesion to endothelial cells.

The ability of hypochlorous acid (HOCl) (anion form - hypochlorite, OCl-) and HOCl/OCl- -modified human blood low density lipoproteins (HOCl-LDLs) to stimulate erythrocyte adhesion to endothelial cell monolayers was studied. LDLs were modified by incubating at different HOCl/OC- concentrations. This led to a damage of proteins and lipids. We found (1) a more than 20-fold decrease of LDL fluorescence intensity (extinction at 285 nm, emission at 340 nm), (2) accumulation of secondary (TBA-reactive substances) and final (Schiff bases) products of lipid peroxidation, and (3) increase in the electrophoretic mobility of LDLs. Preincubation of endothelial cells (ECs) with HOCI/OCl- (up to 50 microM) enhanced erythrocyte adhesion to the EC monolayer. Preincubation of ECs with HOCl-LDLs (up to 250 microM of HOCI//OCl- during LDL modification) (1) caused an increase in the cholesterol/phospholipid molar ratio in EC and (2) enhanced adhesion of erythrocytes to endothelium. Application of HOCl/OCl- at concentrations above 50 microM or treatment of LDLs with 500 microM HOCl resulted in the cytotoxic effect on ECs and led to a decrease in the molar cholesterol/phospholipid ratio in ECs and adhesion of erythrocytes to endothelium. The results suggest that HOCl/OCl- at physiological concentrations stimulates the adhesion of blood cells to the endothelium and cholesterol accumulation in the vessel wall ECs either directly or due to LDL modification. Both effects could be important in the development of many vascular diseases.

Arteriosclerosis↗
PubMed1995

Kinetics and mechanisms of hypochlorous acid reactions.

Hypochlorous acid (HOCl) is a strong oxidant formed in neutrophils by the myeloperoxidase-catalyzed oxidation of chloride. Using stopped-flow with spectrophotometric detection, HOCl was found to react very rapidly with glutathione and ascorbate and less rapidly with taurine. No evidence could be found for the formation of reactive free-radical intermediates in these reactions, in support of an electrophilic mechanism. In contrast, the reaction with iron(II) aquo or citrate complexes (k approximately 10(4) dm3 mol-1 s-1 in acidic solution) yielded reactive intermediates distinguishable from hydroxyl radicals. The reaction between HOCl and ferrous ions, which is analogous to but faster than the Fenton reaction, is a potential source of free radicals in activated neutrophils.

Ascorbic Acid↗
PubMed2000

Comparison of mono- and dichlorinated tyrosines with carbonyls for detection of hypochlorous acid modified proteins.

Hypochlorous acid is a potent oxidant capable of oxidizing and chlorinating proteins. Based on its indiscriminant reactivity, it is proposed to play a major role in tissue damage associated with a range of inflammatory diseases. We have determined the relative tendencies for formation of protein carbonyls, chlorinated tyrosine residues, and epitopes recognized by an antibody raised against hypochlorous acid oxidized protein (HOP-1) when albumin is treated with hypochlorous acid. We have also tested the specificity of the HOP-1 antibody by measuring how effectively it recognizes proteins oxidized by hypobromous acid. 3-Chlorotyrosine, along with a new marker of hypochlorous acid dependent protein modification, 3, 5-dichlorotyrosine, was formed at the lowest doses of hypochlorous acid that were capable of generating protein carbonyls. Comparatively high doses of hypochlorous acid were needed to generate epitopes recognized by HOP-1, which were also produced by hypobromous acid. Our study demonstrates that it is advantageous to measure protein carbonyls and HOP-1 epitopes in conjunction with chlorinated tyrosines when attempting to identify the oxidants responsible for inflammatory tissue damage.

Animals↗
PubMed2002

Nicotine-modulated formation of spiroiminodihydantoin nucleoside via 8-oxo-7,8-dihydro-2'-deoxyguanosine in 2'-deoxyguanosine-hypochlorous acid reaction.

Hypochlorous acid (HOCl) is generated by myeloperoxidase of activated neutrophils which kill invading microorganisms, but also cause DNA damage in inflamed tissues. We report here that spiroiminodihydantoin nucleoside (dS), a further oxidized product of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), is formed, in addition to 8-chloro-2'-deoxyguanosine and 8-oxo-dG, by reaction of 2'-deoxyguanosine with HOCl. Presence of low concentrations of nicotine significantly enhanced the yields of these HOCl-modified nucleosides. Our results imply that nicotine may enhance genotoxicity and tissue damage caused by neutrophil activation. dS may also serve as a new biomarker for oxidative DNA damage induced by oxidants such as HOCl.

8-Hydroxy-2'-Deoxyguanosine↗
PubMedDate not supplied

Chemiluminescence associated with amino acid oxidation mediated by hypochlorous acid.

Although most amino acids readily react with hypochlorous acid (HOCl), only the reaction involving tryptophan (Trp) produces a measurable chemiluminescence (CL). Most of this luminescence takes place after total consumption of HOCI when the process is carried out in an excess of Trp. The quantum yield of the process is relatively low (2 x 10(-8) Einstein/mol HOCl reacted). The luminescence is attributed to free radical-mediated secondary reactions of the initially produced chloramines. This is supported by experiments showing that the chloramines produced when HOCl reacts with alanine are able to induce Trp chemiluminescence, and that this luminescence is partially quenched by free radical scavengers. The spectral changes and the effect of pH upon the observed luminescence are compatible with light emission from products produced in the free radical oxidation of Trp.

Amino Acids↗
PubMed2005

Linoleic acid hydroperoxide reacts with hypochlorous acid, generating peroxyl radical intermediates and singlet molecular oxygen.

The reaction of hypochlorous acid (HOCl) with hydrogen peroxide is known to generate stoichiometric amounts of singlet molecular oxygen [O2 (1Deltag)]. This study shows that HOCl can also react with linoleic acid hydroperoxide (LAOOH), generating O2 (1Deltag) with a yield of 13 +/- 2% at physiological pH. Characteristic light emission at 1,270 nm, corresponding to O2 (1Deltag) monomolecular decay, was observed when HOCl was reacted with LAOOH or with liposomes containing phosphatidylcholine hydroperoxides, but not with cumene hydroperoxide or tert-butyl hydroperoxide. The generation of O2 (1Deltag) was confirmed by the acquisition of the spectrum of the light emitted in the near-infrared region showing a band with maximum intensity at 1,270 nm and by the observation of the enhancing effect of deuterium oxide and the quenching effect of sodium azide. Mechanistic studies using 18O-labeled linoleic acid hydroperoxide (LA18O18OH) showed that its reaction with HOCl yields 18O-labeled O2 (1Deltag) [18O2 (1Deltag)], demonstrating that the oxygen atoms in O2 (1Deltag) are derived from the hydroperoxide group. Direct analysis of radical intermediates in the reaction of LAOOH with HOCl by continuous-flow electron paramagnetic resonance spectroscopy showed a doublet signal with a g-value of 2.014 and a hyperfine coupling constant from the alpha-hydrogen of a(H) = 4.3 G, indicating the formation of peroxyl radicals. Taken together, our results clearly demonstrate that HOCl reacts with biologically relevant lipid hydroperoxides, generating O2 (1Deltag). In addition, the detection of 18O2 (1Deltag) and peroxyl radicals strongly supports the involvement of a Russell mechanism in the generation of O2 (1Deltag).

Hydrogen Peroxide↗