Antioxidative properties of nitroxyl radicals and hydroxyamines in reactions with triplet and deaminated kynurenine

Yanshole, Vadim V.; Kirilyuk, Igor A.; Григорьев, И. А.; Морозов, С. В.; Tsentalovich, Yu. P.

doi:10.1007/s11172-010-0046-y

Cited by 14 publications

(14 citation statements)

References 49 publications

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“…The rate constants of the reactions of TMT-H and DCP-H with O 2 ÅÀ are similar, 4.9 and 3.2 Â 10 3 M À1 s À1 , respectively [13]. Taking Illumination of thylakoid suspension containing either DCP-H or TMT-H leads to a gradual accumulation of nitroxide radicals (Fig.…”

Section: Resultsmentioning

confidence: 74%

Production of superoxide in chloroplast thylakoid membranes

et al. 2011

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a b s t r a c tAccumulation of nitroxide radicals, DCP Å or TMT Å , under illumination of a thylakoid suspension containing either hydrophilic, DCP-H, or lipophilic, TMT-H, cyclic hydroxylamines that have high rate constants of the reaction with superoxide radicals, was measured using ESR. A slower accumulation of TMT Å in contrast with DCP Å accumulation was explained by re-reduction of TMT Å by the carriers of the photosynthetic electron transport chain within the membrane. Superoxide dismutase suppressed TMT Å accumulation to a lesser extent than DCP Å accumulation. The data are interpreted as evidencing the production of intramembrane superoxide in thylakoids.

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Section: Resultsmentioning

confidence: 74%

Production of superoxide in chloroplast thylakoid membranes

et al. 2011

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“…The compound was prepared from nitroxide DCP-AM using previously described procedure [22], in brief, the catalyst (Pd/C, 1%, 20 mg per mmol of nitroxide) was added to a 0.2 M solution of DCP-AM in methanol and the mixture vigorously stirred in hydrogen atmosphere. After the calculated volume of hydrogen was absorbed the catalyst was filtered off and the methanol was distilled off in a vacuum.…”

Section: Methodsmentioning

confidence: 99%

Cellular accumulation and antioxidant activity of acetoxymethoxycarbonyl pyrrolidine nitroxides

Dikalov

Dikalova

Morozov

et al. 2017

Free Radical Research

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Nitroxides are widely used in biology as antioxidants, spin labels, functional spin probes for pH, oxygen and thiol levels, and tissue redox status imaging using electron paramagnetic resonance (EPR); however, biological applications of nitroxides is hindered by fast bioreduction to EPR-silent hydroxylamines and rapid clearance. In this work, we have studied pyrrolidine nitroxides with acetoxymethoxycarbonyl groups which can undergo hydrolysis by cellular esterases to hydrophilic carboxylate derivatives resistant to bioreduction. Nitroxides containing acetoxymethoxycarbonyl groups were rapidly absorbed by cells from the media, 3,4-bis-(acetoxymethoxycarbonyl)-proxyl (DCP-AM2) and 3-(2-(bis(2-(acetoxymethoxy)-2-oxoethyl)amino)acetamido)-proxyl (DCAP-AM2) showing the strongest EPR signal of the cellular fraction. Remarkably, the EPR parameters of 3,4-dicarboxy-proxyl (DCP) and its mono- and di-acetoxymethyl esters are different, and consequent intracellular hydrolysis of acetoxymethoxycarbonyl groups in DCP-AM2 can be followed by EPR. To elucidate intracellular location of the resultant DCP, the mitochondrial fraction has been isolated. EPR measurements showed that mitochondria were the main place where DCP was finally accumulated. TEMPO derivatives showed expectedly much faster decay of EPR signal in the cellular fraction, compared to pyrrolidine nitroxides. It was found that supplementation of endothelial cells with 50 nM of DCP-AM2 completely normalised the mitochondrial superoxide level. Moreover, administration of DCP-AM2 to mice (1.4 mg/kg/day) resulted in substantial nitroxide accumulation in the tissues and significantly reduced hypertension. We found that hydroxylamine derivatives of dicarboxyproxyl nitroxide DCP-AM-H can be used for the detection of superoxide in vivo in angiotensin II model of hypertension. Infusion of DCP-AM-H in mice leads to accumulation of persistent EPR signal of nitroxide in the blood and vascular tissue in angiotensin II-infused wild-type but not in SOD2 overexpressing mice. Our data demonstrate that acetoxymethoxycarbonyl group containing nitroxides accumulate in mitochondria and demonstrate site-specific antioxidant activity.

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“…Nitroxyl radicals 1a , 1c , 1d , 1f , 1g , 1i , 1j , 1o , 1p , 1q , 1r were synthesized according to; radicals 1b , 1e , 1k , 1m , 1s were synthesized as described in, respectively. The purity of compounds was checked by TLC and HPLC [Milikhrom chromatograph equipped with a 2 × 64‐mm column (Separon C18, 5 µm) and a UV detector (λ 220 nm), eluent 40% aqueous MeCN].…”

Section: Methodsmentioning

confidence: 99%

Effect of the structure of nitroxyl radicals on the kinetics of their acid-catalyzed disproportionation

Тихонов

Sen

Borodin

et al. 2013

J. Phys. Org. Chem.

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Acid‐catalyzed disproportionation of cyclic nitroxyl radicals R2NO• includes the half‐reactions of their oxidation to oxoammonium cations R2NO+ and reduction to hydroxylamines R2NOH. For many nitroxyl radicals, this reaction is characterized by its ~100% reversibility. Quantitative characteristics of acid–base and redox properties of the whole redox triad may be obtained from research of kinetics and equilibrium of this reaction. Here, we have examined the kinetics for the disproportionation of twenty piperidine‐, pyrroline‐, pyrrolidine‐, and imidazoline nitroxyl radicals in aqueous H2SO4, and interpreted it in terms of the excess acidity function X. The rate‐limiting step of this reaction is R2NO• oxidation by its protonated counterpart R2NOH+•. Kinetic stability of R2NO• in acidic media depends on the basicity of nitroxyl group. This basicity is influenced predominantly by protonation of another, more basic group in radical structure, and its proximity to nitroxyl group. The discovered estimates of pK values for radical cations R2NOH+• (from −5.8 to −12.0) indicate a very low basicity of nitroxyl groups in all commonly used R2NO•. For the first time, a linear correlation is obtained between the one‐electron reduction potentials of oxoammonium cations and the basicity of nitroxyl groups of related radicals. Copyright © 2013 John Wiley & Sons, Ltd.

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Antioxidative properties of nitroxyl radicals and hydroxyamines in reactions with triplet and deaminated kynurenine

Cited by 14 publications

References 49 publications

Production of superoxide in chloroplast thylakoid membranes

Production of superoxide in chloroplast thylakoid membranes

Cellular accumulation and antioxidant activity of acetoxymethoxycarbonyl pyrrolidine nitroxides

Effect of the structure of nitroxyl radicals on the kinetics of their acid-catalyzed disproportionation

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