6-nitronorepinephrine has been researched along with 6-nitrodopamine* in 2 studies
2 other study(ies) available for 6-nitronorepinephrine and 6-nitrodopamine
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Oxidative conversion of 6-nitrocatecholamines to nitrosating products: a possible contributory factor in nitric oxide and catecholamine neurotoxicity associated with oxidative stress and acidosis.
Oxidation of 6-nitrodopamine (1) and 6-nitronorepinephrine (2), as well as of the model compounds 4-nitrocatechol and 4-methyl-5-nitrocatechol, with horseradish peroxidase (HRP)/H(2)O(2), lactoperoxidase (LPO)/H(2)O(2), Fe(2+)/H(2)O(2), Fe(2+)-EDTA/H(2)O(2) (Fenton reagent), HRP or Fe(2+)/EDTA in combination with D-glucose-glucose oxidase, or Fe(2+)/O(2), resulted in the smooth formation of yellowish-brown pigments positive to the Griess assay. In the case of 1, formation of the Griess positive pigment (GPP-1) promoted by HRP/H(2)O(2) proceeded through the intermediacy of two main dimeric species that could be isolated and identified as 3 and the isomer 4, featuring the 4-nitro-6,7-dihydroxyindole system linked to a unit of 1 through ether bonds. Spectroscopic (FAB-MS, (1)H NMR) and chemical analysis of GPP-1 indicated a mixture of oligomeric species related to 3 and 4 in which oxidative modification of the nitrocatechol moiety of 1 led to the generation of reactive nitro groups supposedly linked to sp(3) hybridized carbons. In the pH range 3-6, GPP-1 induced concentration- and pH-dependent nitrosation of 2,3-diaminonaphthalene, but very poor (up to 2%) nitration of 600 microM tyrosine. At pH 7.4, 1 exerted significant toxicity to PC12 cells, while GPP-1 proved virtually innocuous. By contrast, when assayed on Lactobacillus bulgaricus cells at pH 3.5, 1 was inactive whereas GGP-1 caused about 70% inhibition of cell growth. Overall, these results hint at novel pH-dependent mechanisms of nitrocatecholamine-induced cytotoxicity of possible relevance to ischemia- or inflammation-induced catecholaminergic neuron damage. Topics: Acidosis; Catecholamines; Cell Division; Dopamine; Ethylenediamines; Free Radical Scavengers; Hydrogen Peroxide; Hydrogen-Ion Concentration; Kinetics; Lactobacillus; Magnetic Resonance Spectroscopy; Mass Spectrometry; Nitric Oxide; Norepinephrine; Oxidants; Oxidation-Reduction; Oxidative Stress; Signal Transduction; Structure-Activity Relationship; Sulfanilamides | 2001 |
Inhibition of neuronal nitric oxide synthase by 6-nitrocatecholamines, putative reaction products of nitric oxide with catecholamines under oxidative stress conditions.
6-Nitrodopamine and 6-nitronoradrenaline (6-nitronorepinephrine), putative products of the nitric oxide (NO)-dependent nitration of dopamine and noradrenaline, are reported to be reversible, competitive inhibitors of neuronal nitric oxide synthase (nNOS) with K(i) values of 45 and 52 microM respectively. The nitrocatecholamines inhibited H(2)O(2) production in the absence of L-arginine and tetrahydrobiopterin (BH(4)) (the IC(50) values for 6-nitrodopamine and 6-nitronoradrenaline were 85 and 55 microM respectively) but without affecting cytochrome c reduction. The apparent K(i) values for nitrocatecholamine inhibition of enzyme activation by BH(4) were 18 microM for 6-nitrodopamine and 40 microM for 6-nitronoradrenaline. Both nitrocatecholamines antagonized the dimerization of nNOS induced by BH(4) and by L-arginine, the effect being reversed by BH(4) (more than 10 microM) and L-arginine (e.g. 100 microM). Overall, these results suggest that nitrocatecholamines interfere with nNOS activity by binding to the enzyme in the proximity of the substrate and BH(4)-binding sites near the haem group. Topics: Animals; Arginine; Biopterins; Dopamine; Hydrogen Peroxide; Mice; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Norepinephrine; Oxidative Stress; Recombinant Proteins | 2001 |