scholarly journals The antioxidant action of taurine, hypotaurine and their metabolic precursors

1988 ◽  
Vol 256 (1) ◽  
pp. 251-255 ◽  
Author(s):  
O I Aruoma ◽  
B Halliwell ◽  
B M Hoey ◽  
J Butler
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Radical ◽  
Hypochlorous Acid ◽  
Cysteic Acid ◽  
Iron Ions ◽  
Antioxidant Action ◽  
Iron Ion ◽  
Metabolic Precursors ◽  
Sufficient Concentration

It has been suggested that taurine, hypotaurine and their metabolic precursors (cysteic acid, cysteamine and cysteinesulphinic acid) might act as antioxidants in vivo. The rates of their reactions with the biologically important oxidants hydroxyl radical (.OH), superoxide radical (O2.-), hydrogen peroxide (H2O2) and hypochlorous acid (HOCl) were studied. Their ability to inhibit iron-ion-dependent formation of .OH from H2O2 by chelating iron ions was also tested. Taurine does not react rapidly with O2.-, H2O2 or .OH, and the product of its reaction with HOCl is still sufficiently oxidizing to inactivate alpha 1-antiproteinase. Thus it seems unlikely that taurine functions as an antioxidant in vivo. Cysteic acid is also poorly reactive to the above oxidizing species. By contrast, hypotaurine is an excellent scavenger of .OH and HOCl and can interfere with iron-ion-dependent formation of .OH, although no reaction with O2.- or H2O2 could be detected within the limits of our assay techniques. Cysteamine is an excellent scavenger of .OH and HOCl; it also reacts with H2O2, but no reaction with O2.- could be measured within the limits of our assay techniques. It is concluded that cysteamine and hypotaurine are far more likely to act as antioxidants in vivo than is taurine, provided that they are present in sufficient concentration at sites of oxidant generation.

scholarly journals Peroxidase activity of hemoglobin and heme destruction in the presence of hydrogen peroxide and CT-DNA

2020 ◽  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Peroxidase Activity ◽  
Hypochlorous Acid ◽  
Iron Ion ◽  
Acid Effect ◽  
High Concentrations ◽  
Ct Dna ◽  
Heme Destruction ◽  
Protein Environment

The aim of this study was to investigate the peroxidase activity of Hb with different concentrations of hydrogen peroxide and compare it with hypochlorous acid effect on Hb. Hypochlorous acid at higher concentrations decomposed Hb and heme, releasing fee iron ion from the metal center. High concentrations of hydrogen peroxide switched the peroxidase activity of Hb towards the partial Hb and heme destruction. Heme alone was degraded showing that the Hb conformation and protein environment protects Hb from the distraction in the presence of highly increased hydrogen peroxide concentration that occurs as a result of oxidative stress. In the presence of CT-DNA acted inhibition of the peroxidase activity of Hb was observed signaling inhibited hydrogen peroxide consumption.

scholarly journals Carnosine, homocarnosine and anserine: could they act as antioxidants in vivo?

1989 ◽  
Vol 264 (3) ◽  
pp. 863-869 ◽  
Author(s):  
O I Aruoma ◽  
M J Laughton ◽  
B Halliwell
Keyword(s):  
Lipid Peroxidation ◽  
Hypochlorous Acid ◽  
Thiobarbituric Acid ◽  
Structural Similarity ◽  
Iron Ion ◽  
Inhibitory Effects ◽  
Inhibit Lipid Peroxidation ◽  
High Concentrations ◽  
Radical Damage

Carnosine, homocarnosine and anserine have been proposed to act as antioxidants in vivo. Our studies show that all three compounds are good scavengers of the hydroxyl radical (.OH) but that none of them can react with superoxide radical, hydrogen peroxide or hypochlorous acid at biologically significant rates. None of them can bind iron ions in ways that interfere with ‘site-specific’ iron-dependent radical damage to the sugar deoxyribose, nor can they restrict the availability of Cu2+ to phenanthroline. Homocarnosine has no effect on iron ion-dependent lipid peroxidation; carnosine and anserine have weak inhibitory effects when used at high concentrations in some (but not all) assay systems. However, the ability of these compounds to interfere with a commonly used version of the thiobarbituric acid (TBA) test may have led to an overestimate of their ability to inhibit lipid peroxidation in some previous studies. By contrast, histidine stimulated iron ion-dependent lipid peroxidation. It is concluded that, because of the high concentrations present in vivo, carnosine and anserine could conceivably act as physiological antioxidants by scavenging .OH, but that they do not have a broad spectrum of antioxidant activity, and their ability to inhibit lipid peroxidation is not well established. It may be that they have a function other than antioxidant protection (e.g. buffering), but that they are safer to accumulate than histidine, which has a marked pro-oxidant action upon iron ion-dependent lipid peroxidation. The inability of homocarnosine to react with HOCl, interfere with the TBA test or affect lipid peroxidation systems in the same way as carnosine is surprising in view of the apparent structural similarity between these two molecules.

scholarly journals Theoretical investigations on hydrogen peroxide decomposition in aquo

2018 ◽  
Vol 20 (38) ◽  
pp. 24992-24999 ◽  
Author(s):  
Takao Tsuneda ◽  
Tetsuya Taketsugu
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Oh Radical ◽  
Iron Ions ◽  
Hydrogen Bond Network ◽  
Iron Ion ◽  
Hydrogen Peroxide Decomposition ◽  
Peroxide Decomposition ◽  
Theoretical Investigations ◽  
Bond Network

Hydrogen peroxide (H2O2) decomposition mechanisms in the absence and presence of iron ions in aqueous solution, which contain no OH radical formation, are theoretically determined. H2O2 decomposition in the presence of iron ions is driven by electron transfer to the iron ion and proceeds by hydrogen transfers in the hydrogen bond network around H2O2.

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.

scholarly journals Protective Role of d-Amino Acid Oxidase against Staphylococcus aureus Infection

2012 ◽  
Vol 80 (4) ◽  
pp. 1546-1553 ◽  
Author(s):  
Hideaki Nakamura ◽  
Jun Fang ◽  
Hiroshi Maeda
Keyword(s):  
Hydrogen Peroxide ◽  
Staphylococcus Aureus ◽  
Amino Acid ◽  
Bactericidal Activity ◽  
Hypochlorous Acid ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Content Type

ABSTRACTd-Amino acid oxidase (DAO) is a hydrogen peroxide-generating enzyme that uses ad-amino acid as a substrate. We hypothesized that DAO may protect against bacterial infection, because hydrogen peroxide is one of the most important molecules in the antibacterial defense systems in mammals. We show here that DAO suppressed the growth ofStaphylococcus aureusin a manner that depended on the concentration of DAO andd-amino acidin vitro. Addition of catalase abolished the bacteriostatic activity of DAO. Although DAO plusd-Ala showed less bactericidal activity, addition of myeloperoxidase (MPO) greatly enhanced the bactericidal activity of DAO. Furthermore, DAO was able to utilize bacterial lysate, which containsd-Ala derived from peptidoglycan; this could produce hydrogen peroxide with, in the presence of myeloperoxidase, formation of hypochlorous acid. This concerted reaction of DAO and MPO led to the bactericidal action.In vivoexperiments showed that DAO−/−(mutant) mice were more susceptible toS. aureusinfection than were DAO+/+(wild-type) mice. These results suggest that DAO, together with myeloperoxidase, may play an important role in antibacterial systems in mammals.

scholarly journals The antioxidant action of human extracellular fluids. Effect of human serum and its protein components on the inactivation of α1-antiproteinase by hypochlorous acid and by hydrogen peroxide

1987 ◽  
Vol 243 (1) ◽  
pp. 219-223 ◽  
Author(s):  
M Wasil ◽  
B Halliwell ◽  
D C S Hutchison ◽  
H Baum
Keyword(s):  
Hydrogen Peroxide ◽  
Protective Effect ◽  
Hydroxyl Radicals ◽  
Hypochlorous Acid ◽  
Antioxidant Action ◽  
Serum Samples ◽  
Inhibitory Capacity ◽  
Low Concentrations ◽  
High Concentrations ◽  
Protein Components

The elastase-inhibitory capacity of purified human alpha 1-antiproteinase is inactivated by low concentrations of the myeloperoxidase-derived oxidant hypochlorous acid, but much higher concentrations are required to inhibit the elastase-inhibitory capacity of serum samples. The protective effect of serum appears to be largely due to albumin. High concentrations of H2O2 also inactivate the elastase-inhibitory capacity of alpha 1-antiproteinase, by a mechanism not involving formation of hydroxyl radicals. Serum offers protection against H2O2 inactivation of alpha 1-antiproteinase. The relevance of these results to the tissue damage produced by activated phagocytes is discussed.

scholarly journals OXIDATION OF FERRIC XYLENOL ORANGE CHELATES BY HYDROGEN PEROXIDE IN AQUEOUS SOLUTION: CONCEPTION OF OXYGEN SINGLET ATOMS GENERATION FROM HYDROGEN PEROXIDE

2018 ◽  
Vol 61 (2) ◽  
pp. 15
Author(s):  
Anton A. Chumakov ◽  
Oleg A. Kotelnikov ◽  
Yuriy G. Slizhov
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Ferric Iron ◽  
Xylenol Orange ◽  
Oxygen Species ◽  
Iron Ions ◽  
Iron Ion ◽  
Radical Chain ◽  
Mechanism Of Interaction ◽  
Peroxide Molecule

We observed for the first time the reaction of oxidation of ferric xylenol orange chelates by hydrogen peroxide in aqueous solution. The reaction is accompanied with decoloration of the violet aqueous solution. Based on generally accepted conception, there is a process of free radical chain oxidation of indicator molecule in the solution. However, after investigating the final colorless solution by 1H NMR-spectroscopy we found the modified but not broken structure in which the initial hydrocarbon core remained mainly unchanged. We concluded that kind of reaction was an oxyfunctionalization by hydrogen peroxide versus free radical chain destruction. We argued steps of the reaction such as N-oxidation, Cope’s elimination, and certain rearrangements with possible products oligomerization. There was a need to explain the mechanism of interaction between the ferric iron ion and the hydrogen peroxide molecule and to argue the nature of intermediate reactive oxygen species. There is similarity between the ferric-catalyzed hydroperoxide xylenol orange oxidation and the peroxygenase-catalyzed biochemical oxyfunctionalization reactions. However, based on literature data and molecular orbital modeling, we proposed another mechanism of interaction between the ferric iron ion and the hydrogen peroxide molecule instead the tetravalent iron generation. Concretely, we proposed the hydrogen peroxide zwitter-ionization (isomerization to oxywater molecule) and subsequent intramolecular disproportionation with generation of a water molecule and a singlet oxygen atom as a reactive oxygen species. In this view, the iron ion oxidation state is unchanged during the reaction and remains ferric. An oxyfunctionalization of any organic substrate by hydrogen peroxide in the presence of ferric iron ions is promising approach in organic synthesis. However, the usage of organic ligands for ferric iron ions as components of catalysts is limited and requires only non-oxidizable compounds. On the other hand, one can choose an oxidation substrate as a ligand for ferric iron ions that is the formation of chelate complex of ferric catalyst with an organic substrate.Forcitation:Chumakov A.A., Kotelnikov O.A., Slizhov Yu.G. Oxidation of ferric xylenol orange chelates by hydrogen peroxide in aqueous solution: conception of oxygen singlet atoms generation from hydrogen peroxide. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 15-22

Fluorescent proteins for in vivo imaging, where's the biliverdin?

2020 ◽  
Vol 48 (6) ◽  
pp. 2657-2667
Author(s):  
Felipe Montecinos-Franjola ◽  
John Y. Lin ◽  
Erik A. Rodriguez
Keyword(s):  
Hydrogen Peroxide ◽  
In Vivo Imaging ◽  
Near Infrared ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescent Imaging ◽  
Infrared Light ◽  
Red Fluorescent Protein ◽  
Color Palette

Noninvasive fluorescent imaging requires far-red and near-infrared fluorescent proteins for deeper imaging. Near-infrared light penetrates biological tissue with blood vessels due to low absorbance, scattering, and reflection of light and has a greater signal-to-noise due to less autofluorescence. Far-red and near-infrared fluorescent proteins absorb light >600 nm to expand the color palette for imaging multiple biosensors and noninvasive in vivo imaging. The ideal fluorescent proteins are bright, photobleach minimally, express well in the desired cells, do not oligomerize, and generate or incorporate exogenous fluorophores efficiently. Coral-derived red fluorescent proteins require oxygen for fluorophore formation and release two hydrogen peroxide molecules. New fluorescent proteins based on phytochrome and phycobiliproteins use biliverdin IXα as fluorophores, do not require oxygen for maturation to image anaerobic organisms and tumor core, and do not generate hydrogen peroxide. The small Ultra-Red Fluorescent Protein (smURFP) was evolved from a cyanobacterial phycobiliprotein to covalently attach biliverdin as an exogenous fluorophore. The small Ultra-Red Fluorescent Protein is biophysically as bright as the enhanced green fluorescent protein, is exceptionally photostable, used for biosensor development, and visible in living mice. Novel applications of smURFP include in vitro protein diagnostics with attomolar (10−18 M) sensitivity, encapsulation in viral particles, and fluorescent protein nanoparticles. However, the availability of biliverdin limits the fluorescence of biliverdin-attaching fluorescent proteins; hence, extra biliverdin is needed to enhance brightness. New methods for improved biliverdin bioavailability are necessary to develop improved bright far-red and near-infrared fluorescent proteins for noninvasive imaging in vivo.

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