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Helmut Sies - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH COMMUNICATION Attenuation of oxidation and nitration reactions of peroxynitrite by selenomethionine, selenocystine and ebselen
2016Co-Authors: Karlis Briviba, Victor S Sharov, Ivan Roussyn, Helmut SiesAbstract:The effect of the selenium-containing compounds seleno-methionine, selenocystine and ebselen [2-phenyl-1,2-benziso-selenazol-3(2H)-one] on the oxidation of Dihydrorhodamine 123 caused by peroxynitrite and on the nitration of 4-hydroxy-phenylacetate by peroxynitrite was studied in comparison with their sulphur analogues methionine, cystine and ebsulfur [2-phenyl-1,2-benzisothiazol-3(2H)-one]. The selenocompounds protected Dihydrorhodamine 123 from oxidation and 4
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Reactions of Peroxynitrite with Cocoa Procyanidin Oligomers
The Journal of Nutrition, 2000Co-Authors: Gavin E. Arteel, Peter Schroeder, Helmut SiesAbstract:Peroxynitrite is a mediator molecule in inflammation, and its biological properties are being studied extensively. Flavonoids, which are natural plant constituents, protect against peroxynitrite and thereby could play an anti-inflammatory role. Procyanidin oligomers of different sizes (monomer through nonamer), isolated from the seeds of Theobroma cacao, were recently examined for their ability to protect against peroxynitrite-dependent oxidation of Dihydrorhodamine 123 and nitration of tyrosine and were found to be effective in attenuating these reactions. The tetramer was particularly efficient at protecting against oxidation and nitration reactions. Epicatechin oligomers found in cocoa powder and chocolate may be a potent dietary source for defense against peroxynitrite.
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Interaction of Peroxynitrite with Carotenoids in Human Low Density Lipoproteins
Archives of biochemistry and biophysics, 2000Co-Authors: Oleg M. Panasenko, Victor S Sharov, Karlis Briviba, Helmut SiesAbstract:Interaction of peroxynitrite, the product of the reaction between nitric oxide and superoxide, with carotenes (lycopene, alpha-carotene, and beta-carotene) and oxocarotenoids (beta-cryptoxanthin, zeaxanthin, and lutein) was studied both in homogeneous solution and in human low-density lipoproteins (LDL). All carotenoids prevented the formation of rhodamine 123 from Dihydrorhodamine 123 caused by peroxynitrite, suggesting that the carotenoids react with peroxynitrite. Oxocarotenoids were as effective as biothiols, known scavengers of peroxynitrite, whereas lycopene, alpha-carotene, and beta-carotene exhibited a considerably more pronounced effect. Moreover, peroxynitrite caused a loss of carotenoids in LDL as was revealed by HPLC. The concentration of peroxynitrite causing half-maximal loss of carotenoids in LDL ranged from 13 +/- 3 to 68 +/- 3 microM for lycopene and lutein, respectively. Again, oxocarotenoids were less reactive in this system. A correlation between efficiency of carotenoids in the competitive assay with Dihydrorhodamine 123 and the concentration of peroxynitrite causing half-maximal loss of carotenoids in LDL was observed (r(2) = 0.91). These findings suggest that carotenoids can efficiently react with peroxynitrite and perform the role of scavengers of peroxynitrite in vivo.
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Water-soluble organotellurium compounds: catalytic protection against peroxynitrite and release of zinc from metallothionein.
Chemical research in toxicology, 2000Co-Authors: Claus Jacob, Gavin E. Arteel, Takahiro Kanda, Lars Engman, Helmut SiesAbstract:The antioxidant properties of a number of water-soluble diorganyl tellurides have been investigated. These organotellurium compounds efficiently protect against peroxynitrite-mediated oxidation of Dihydrorhodamine 123, hydroxylation of benzoate, and nitration of 4-hydroxyphenyl acetate. The peroxidation of the zinc storage protein, metallothionein, by tert-butyl hydroperoxide is also catalyzed by the water-soluble organotellurium compounds. As compared to selenium-containing compounds (e.g., ebselen and selenocystamine), some of the tellurides that were tested {e.g., 3-[4-(N,N-dimethylamino)benzenetellurenyl]propanesulfonic acid, sodium salt} exhibit a significantly higher reactivity in these assays, making them some of the most effective compounds tested thus far. The catalysis of destruction of zinc−sulfur clusters by water-soluble organotellurium compounds could have implications for the bioavailability of zinc in vivo. These compounds might be lead compounds for the development of a new class of water...
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Protection against peroxynitrite by cocoa polyphenol oligomers
FEBS Letters, 1999Co-Authors: Gavin E. Arteel, Helmut SiesAbstract:Flavonoids, natural plant constituents, protect against peroxynitrite and can thereby play a role in defense against this mediator of inflammation. Procyanidin oligomers of different size (monomer through nonamer), isolated from the seeds of Theobroma cacao, were examined for their ability to protect against peroxynitrite-dependent oxidation of Dihydrorhodamine 123 and nitration of tyrosine. By molarity, oligomers were more effective than the monomeric epicatechin; the tetramer was particularly efficient at protecting against oxidation and nitration reactions. These results suggest that epicatechin oligomers found in cocoa powder and chocolate may be a potent dietary source for defense against peroxynitrite.
C Szabó - One of the best experts on this subject based on the ideXlab platform.
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MELATONIN IS A SCAVENGER OF PEROXYNITRITE
Life sciences, 1997Co-Authors: Eli Gilad, A L Salzman, Salvatore Cuzzocrea, Basilia Zingarelli, C SzabóAbstract:Abstract Peroxynitrite is a toxic oxidant formed from the reaction of Superoxide and nitric oxide under conditions of inflammation and oxidant stress. Here we demonstrate that the pineal neurohormone melatonin inhibits peroxynitrite-mediated oxidant processes. Melatonin caused a dose-dependent inhibition of the oxidation of Dihydrorhodamine 123 to rhodamine in vitro . Moreover, in cultured J774 macrophages, melatonin inhibited the development of DNA single strand breakage in response to peroxynitrite and reduced the suppression of mitochondrial respiration. Thus, melatonin appears to be a scavenger of peroxynitrite. This action may contribute to the antioxidant and antiinflammatory effects of melatonin in various pathophysiological conditions.
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Evaluation of the relative contribution of nitric oxide and peroxynitrite to the suppression of mitochondrial respiration in immunostimulated macrophages using a manganese mesoporphyrin superoxide dismutase mimetic and peroxynitrite scavenger
FEBS Letters, 1996Co-Authors: C Szabó, Brian J. Day, A L SalzmanAbstract:Abstract Here we report that the cell-permeable superoxide dismutase mimetic Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP) inhibits the oxidation of Dihydrorhodamine-123 by peroxynitrite, but does not scavenge nitric oxide (NO). MnTBAP protects against the suppression of mitochondrial respiration in J774 cells exposed to peroxynitrite or to NO donors. MnTBAP and N G - methyl - l - arginine provide additive protective effect against the suppression of respiration in immunostimulated cells. Our data suggest separate contributions of NO and peroxynitrite to the suppression of mitochondrial respiration and support the role of oxidative stress in the expression of the inducible isoform of NO synthase.
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Peroxynitrite-mediated oxidation of Dihydrorhodamine 123 occurs in early stages of endotoxic and hemorrhagic shock and ischemia-reperfusion injury.
FEBS letters, 1995Co-Authors: C Szabó, A L Salzman, H IschiropoulosAbstract:To quantify peroxynitrite production during shock, we measured oxidation of Dihydrorhodamine 123 in rats. In endotoxic and hemorrhagic shock and splanchic ischemia-reperfusion, Dihydrorhodamine oxidation rapidly increased, which was prevented by inhibition of endothelial nitric oxide (.NO) synthase (ecNOS). Thus, peroxynitrite is already formed at early stages of shock from ecNOS-derived .NO. Overproduction of .NO by the inducible NOS at late shock was not associated with additional increases in Dihydrorhodamine oxidation. ecNOS inhibition enhanced Dihydrorhodamine oxidation in control rats. These latter findings may be explained by .NO-mediated inhibition of peroxynitrite-induced Dihydrorhodamine oxidation, a phenomenon also observed in vitro.
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Peroxynitrite‐mediated oxidation of Dihydrorhodamine 123 occurs in early stages of endotoxic and hemorrhagic shock and ischemia‐reperfusion injury
FEBS Letters, 1995Co-Authors: C Szabó, A L Salzman, Harry IschiropoulosAbstract:To quantify peroxynitrite production during shock, we measured oxidation of Dihydrorhodamine 123 in rats. In endotoxic and hemorrhagic shock and splanchic ischemia-reperfusion, Dihydrorhodamine oxidation rapidly increased, which was prevented by inhibition of endothelial nitric oxide (·NO) synthase (ecNOS). Thus, peroxynitrite is already formed at early stages of shock from ecNOS-derived ·NO. Overproduction of ·NO by the inducible NOS at late shock was not associated with additional increases in Dihydrorhodamine oxidation. ecNOS inhibition enhanced Dihydrorhodamine oxidation in control rats. These latter findings may be explained by ·NO-mediated inhibition of peroxynitrite-induced Dihydrorhodamine oxidation, a phenomenon also observed in vitro.
Walter Fiers - One of the best experts on this subject based on the ideXlab platform.
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Direct evidence for tumor necrosis factor-induced mitochondrial reactive oxygen intermediates and their involvement in cytotoxicity.
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: V. Goossens, J. Grooten, K De Vos, Walter FiersAbstract:Abstract Tumor necrosis factor (TNF) is selectively cytotoxic to some types of tumor cells in vitro and exerts antitumor activity in vivo. Reactive oxygen intermediates (ROIs) have been implicated in the direct cytotoxic activity of TNF. By using confocal microscopy, flow cytometry, and the ROI-specific probe Dihydrorhodamine 123, we directly demonstrate that intracellular ROIs are formed after TNF stimulation. These ROIs are observed exclusively under conditions where cells are sensitive to the cytotoxic activity of TNF, suggesting a direct link between both phenomena. ROI scavengers, such as butylated hydroxyanisole, effectively blocked the formation of free radicals and arrested the cytotoxic response, confirming that the observed ROIs are cytocidal. The mitochondrial glutathione system scavenges the major part of the produced ROIs, an activity that could be blocked by diethyl maleate; under these conditions, TNF-induced ROIs detectable by Dihydrorhodamine 123 oxidation were 5- to 20-fold higher.
Harry Ischiropoulos - One of the best experts on this subject based on the ideXlab platform.
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Peroxynitrite‐mediated oxidation of Dihydrorhodamine 123 occurs in early stages of endotoxic and hemorrhagic shock and ischemia‐reperfusion injury
FEBS Letters, 1995Co-Authors: C Szabó, A L Salzman, Harry IschiropoulosAbstract:To quantify peroxynitrite production during shock, we measured oxidation of Dihydrorhodamine 123 in rats. In endotoxic and hemorrhagic shock and splanchic ischemia-reperfusion, Dihydrorhodamine oxidation rapidly increased, which was prevented by inhibition of endothelial nitric oxide (·NO) synthase (ecNOS). Thus, peroxynitrite is already formed at early stages of shock from ecNOS-derived ·NO. Overproduction of ·NO by the inducible NOS at late shock was not associated with additional increases in Dihydrorhodamine oxidation. ecNOS inhibition enhanced Dihydrorhodamine oxidation in control rats. These latter findings may be explained by ·NO-mediated inhibition of peroxynitrite-induced Dihydrorhodamine oxidation, a phenomenon also observed in vitro.
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peroxynitrite mediated oxidation of Dihydrorhodamine 123
Free Radical Biology and Medicine, 1994Co-Authors: Neil W Kooy, James A Royall, Harry Ischiropoulos, Joseph S BeckmanAbstract:Nitric oxide reacts with superoxide to form peroxynitrite, which may be an important mediator of free radical-induced cellular injury. Oxidation of Dihydrorhodamine to fluorescent rhodamine is a marker of cellular oxidant production. We investigated the mechanisms of peroxynitrite-mediated formation of rhodamine from Dihydrorhodamine. Peroxynitrite at low levels (0–1000 nM) induced a linear, concentration-dependent, oxidation of Dihydrorhodamine. Hydroxyl radical scavengers mannitol and dimethylsulfoxide had minimal effect (< 10%) on rhodamine production. Peroxynitrite-mediated formation of rhodamine was not dependent on metal ion catalyzed reactions because studies were performed in metal ion-free buffer and rhodamine formation was not enhanced in the presence of Fe3+ ethylenediaminetetraacetic acid (EDTA). Thus, rhodamine formation appears to be mediated directly by peroxynitrite. Superoxide dismutase slightly enhanced rhodamine production. L-cysteine was an efficient inhibitor (KI ∼ 25 μM) of Dihydrorhodamine oxidation through competetive oxidation of free sulfhydryls. Urate was also an efficient inhibitor (KI ∼ 2.5 μM), possibly by reduction of an intermediate Dihydrorhodamine radical and recycling of Dihydrorhodamine. Under anaerobic conditions, nitric oxide did not oxidize Dihydrorhodamine and inhibited spontaneous oxidation of Dihydrorhodamine. In the presence of oxygen, nitric oxide induces a relatively slow oxidation of Dihydrorhodamine due to the formation of nitrogen dioxide. We conclude that Dihydrorhodamine is a sensitive and efficient trap for peroxynitrite and may serve as a probe for peroxynitrite production.
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Evaluation of 2',7'-dichlorofluorescin and Dihydrorhodamine 123 as fluorescent probes for intracellular H2O2 in cultured endothelial cells.
Archives of biochemistry and biophysics, 1993Co-Authors: James A Royall, Harry IschiropoulosAbstract:2',7'-Dichlorofluorescein and Dihydrorhodamine 123 were evaluated as probes for detecting changes in intracellular H2O2 in cultured endothelial cells. Stable intracellular levels of these probes were established within 15 min of exposure to the probe in culture medium. With continued presence of the probe in the medium, intracellular levels were unchanged for 1 h. However, if medium without the probes was used after intracellular loading had occurred, there was a greater than 90% loss of intracellular dichlorofluorescin, dichlorofluorescein, and Dihydrorhodamine 123 while intracellular rhodamine 123 decreased by only 15%. Exposure of endothelial cells to exogenous 100 microM H2O2 for 1 h increased intracellular rhodamine 123 by 83%, but there was a reproducible decrease of 53% in intracellular dichlorofluorescein. Exposure to 0.05 mM BCNU plus 10 mM aminotriazole for 2 h increased intracellular rhodamine 123 by 111%. In vitro studies of Dihydrorhodamine 123 oxidation were similar to previous reports of dichlorofluorescin oxidation. Oxidation of Dihydrorhodamine 123 does not occur with H2O2 alone, but is mediated by a variety of secondary H2O2-dependent intracellular reactions including H2O2-cytochrome c and H2O2-Fe2+. Our results suggest that detection of increased oxidation of these probes in endothelial cells is most useful as a marker of a change in general cellular oxidant production.
A L Salzman - One of the best experts on this subject based on the ideXlab platform.
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MELATONIN IS A SCAVENGER OF PEROXYNITRITE
Life sciences, 1997Co-Authors: Eli Gilad, A L Salzman, Salvatore Cuzzocrea, Basilia Zingarelli, C SzabóAbstract:Abstract Peroxynitrite is a toxic oxidant formed from the reaction of Superoxide and nitric oxide under conditions of inflammation and oxidant stress. Here we demonstrate that the pineal neurohormone melatonin inhibits peroxynitrite-mediated oxidant processes. Melatonin caused a dose-dependent inhibition of the oxidation of Dihydrorhodamine 123 to rhodamine in vitro . Moreover, in cultured J774 macrophages, melatonin inhibited the development of DNA single strand breakage in response to peroxynitrite and reduced the suppression of mitochondrial respiration. Thus, melatonin appears to be a scavenger of peroxynitrite. This action may contribute to the antioxidant and antiinflammatory effects of melatonin in various pathophysiological conditions.
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Evaluation of the relative contribution of nitric oxide and peroxynitrite to the suppression of mitochondrial respiration in immunostimulated macrophages using a manganese mesoporphyrin superoxide dismutase mimetic and peroxynitrite scavenger
FEBS Letters, 1996Co-Authors: C Szabó, Brian J. Day, A L SalzmanAbstract:Abstract Here we report that the cell-permeable superoxide dismutase mimetic Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP) inhibits the oxidation of Dihydrorhodamine-123 by peroxynitrite, but does not scavenge nitric oxide (NO). MnTBAP protects against the suppression of mitochondrial respiration in J774 cells exposed to peroxynitrite or to NO donors. MnTBAP and N G - methyl - l - arginine provide additive protective effect against the suppression of respiration in immunostimulated cells. Our data suggest separate contributions of NO and peroxynitrite to the suppression of mitochondrial respiration and support the role of oxidative stress in the expression of the inducible isoform of NO synthase.
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Peroxynitrite-mediated oxidation of Dihydrorhodamine 123 occurs in early stages of endotoxic and hemorrhagic shock and ischemia-reperfusion injury.
FEBS letters, 1995Co-Authors: C Szabó, A L Salzman, H IschiropoulosAbstract:To quantify peroxynitrite production during shock, we measured oxidation of Dihydrorhodamine 123 in rats. In endotoxic and hemorrhagic shock and splanchic ischemia-reperfusion, Dihydrorhodamine oxidation rapidly increased, which was prevented by inhibition of endothelial nitric oxide (.NO) synthase (ecNOS). Thus, peroxynitrite is already formed at early stages of shock from ecNOS-derived .NO. Overproduction of .NO by the inducible NOS at late shock was not associated with additional increases in Dihydrorhodamine oxidation. ecNOS inhibition enhanced Dihydrorhodamine oxidation in control rats. These latter findings may be explained by .NO-mediated inhibition of peroxynitrite-induced Dihydrorhodamine oxidation, a phenomenon also observed in vitro.
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Peroxynitrite‐mediated oxidation of Dihydrorhodamine 123 occurs in early stages of endotoxic and hemorrhagic shock and ischemia‐reperfusion injury
FEBS Letters, 1995Co-Authors: C Szabó, A L Salzman, Harry IschiropoulosAbstract:To quantify peroxynitrite production during shock, we measured oxidation of Dihydrorhodamine 123 in rats. In endotoxic and hemorrhagic shock and splanchic ischemia-reperfusion, Dihydrorhodamine oxidation rapidly increased, which was prevented by inhibition of endothelial nitric oxide (·NO) synthase (ecNOS). Thus, peroxynitrite is already formed at early stages of shock from ecNOS-derived ·NO. Overproduction of ·NO by the inducible NOS at late shock was not associated with additional increases in Dihydrorhodamine oxidation. ecNOS inhibition enhanced Dihydrorhodamine oxidation in control rats. These latter findings may be explained by ·NO-mediated inhibition of peroxynitrite-induced Dihydrorhodamine oxidation, a phenomenon also observed in vitro.