Sensitization of Peroxynitrite Chemiluminescence by the Triplet Carbonyl Sensitizer Coumarin-525. Effect of CO2

Sharov, Victor S.; Driomina, Elena S.; Briviba, Karlis; Sies, Helmut

doi:10.1562/0031-8655(1998)068<0797:sopcbt>2.3.co;2

Cited by 2 publications

(1 citation statement)

References 4 publications

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“…Only a 10% protective effect on the disappearance of spectrin bands could be observed (data not shown). This result shows that hydroxyl radicals are not the main reactive species in this system (11,12,28,29). However, nitrogen dioxide formed by the decomposition of ONOO -may also be involved in this damage (30).…”

Section: Resultsmentioning

confidence: 99%

Ghost protein damage by peroxynitrite and its protection by melatonin

Mascio

Dewez

Garcia

2000

Braz J Med Biol Res

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We have studied the effect of peroxynitrite (ONOO -) on the membrane cytoskeleton of red blood cells and its protection by melatonin. Analysis of the protein fraction of the preparation by SDS-PAGE revealed a dose-dependent (0-600 µM ONOO -) disappearance at pH 7.4 of the main proteins: spectrin, band 3, and actin, with the concomitant formation of high-molecular weight aggregates resistant to reduction by ß-mercaptoethanol (2%) at room temperature for 20 min. These aggregates were not solubilized by 8 M urea. Incubation of the membrane cytoskeleton with ONOO -was characterized by a marked depletion of free sulfhydryl groups (50% at 250 µM ONOO -). However, a lack of effect of ß-mercaptoethanol suggests that, under our conditions, aggregate formation is not mediated only by sulfhydryl oxidation. The lack of a protective effect of the metal chelator diethylenetriaminepentaacetic acid confirmed that ONOO --induced oxidative damage does not occur only by a transition metal-dependent mechanism. However, we demonstrated a strong protection against cytoskeletal alterations by desferrioxamine, which has been described as a direct scavenger of the protonated form of peroxynitrite. Desferrioxamine (0.5 mM) also inhibited the loss of tryptophan fluorescence observed when the ghosts were treated with ONOO -. Glutathione, cysteine, and Trolox ® (1 mM), but not mannitol (100 mM), were able to protect the proteins against the effect of ONOO -in a dose-dependent manner. Melatonin (0-1 mM) was especially efficient in reducing the loss of spectrin proteins when treated with ONOO -(90% at 500 µM melatonin). Our findings show that the cytoskeleton, and in particular spectrin, is a sensitive target for ONOO -. Specific antioxidants can protect against such alterations, which could seriously impair cell dynamics and generate morphological changes.

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Section: Resultsmentioning

confidence: 99%

Ghost protein damage by peroxynitrite and its protection by melatonin

Mascio

Dewez

Garcia

2000

Braz J Med Biol Res

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Solid-Phase Synthesis and Spectral Properties of 2-Alkylthio-6H-pyrano[2,3-f]benzimidazole-6-ones: A Combinatorial Approach for 2-Alkylthioimidazocoumarins

et al. 2004

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The solid-phase synthesis of 2-alkylthio-6H-pyrano[2,3-f]benzimidazole-6-ones (2-alkylthioimidazocoumarins) is described. 7-Fluoro-4-methyl-6-nitro-2-oxo-2H-1-benzopyran-3-carboxylic acid was coupled to Rink amide resin via its carboxyl group. The resin-bound scaffold then underwent aromatic nucleophilic substitution with primary amines, followed by reduction of the nitro group with tin (II) chloride. Subsequent cyclization of the o-dianilino intermediates with thiocarbonyldiimidazole (TCD) afforded resin-bound 1,3-dihydro-2-thioxo-6H-pyrano[2,3-f]benzimidazole-6-ones, which were then S-alkylated with alkyl halides in the presence of N,N-diisopropylethylamine (DIEA). The desired products were obtained in good yield with high purity after trifluoroacetic acid cleavage. The unique spectral properties of 2-alkylthioimidazocoumarins indicate that they may be useful in photodynamic therapy.

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Sensitization of Peroxynitrite Chemiluminescence by the Triplet Carbonyl Sensitizer Coumarin-525. Effect of CO2

Cited by 2 publications

References 4 publications

Ghost protein damage by peroxynitrite and its protection by melatonin

Ghost protein damage by peroxynitrite and its protection by melatonin

Solid-Phase Synthesis and Spectral Properties of 2-Alkylthio-6H-pyrano[2,3-f]benzimidazole-6-ones: A Combinatorial Approach for 2-Alkylthioimidazocoumarins

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