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Nitroxyl Radical

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https://www.readbyqxmd.com/read/30080991/don-t-just-say-no-differential-pathways-and-pharmacological-responses-to-diverse-nitric-oxide-donors
#1
REVIEW
Juan J Chiesa, Fernando M Baidanoff, Diego A Golombek
Nitric oxide (NO•) is a gaseous free radical molecule with a short half-life (∼1 sec), which can gain or lose an electron into three interchangeable redox-dependent forms, the radical (NO•), the nitrosonium cation (NO+ ), and nitroxyl anion (HNO). NO• acts as an intra and extracellular signaling molecule regulating a wide range of functions in the cardiovascular, immune, and nervous system. NO• donors are collectively known by their ability to release NO• in vitro and in vivo, being proposed as therapeutic pharmacological tools for the treatment of several pathologies, such as cardiovascular disease...
August 3, 2018: Biochemical Pharmacology
https://www.readbyqxmd.com/read/29771534/nitroxyl-modified-tobacco-mosaic-virus-as-a-metal-free-high-relaxivity-mri-and-epr-active-superoxide-sensor
#2
Madushani Dharmarwardana, André F Martins, Zhuo Chen, Philip M Palacios, Chance M Nowak, Raymond P Welch, Shaobo Li, Michael A Luzuriaga, Leonidas Bleris, Brad S Pierce, A Dean Sherry, Jeremiah J Gassensmith
Superoxide overproduction is known to occur in multiple disease states requiring critical care; yet, noninvasive detection of superoxide in deep tissue remains a challenge. Herein, we report a metal-free magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR) active contrast agent prepared by "click conjugating" paramagnetic organic radical contrast agents (ORCAs) to the surface of tobacco mosaic virus (TMV). While ORCAs are known to be reduced in vivo to an MRI/EPR silent state, their oxidation is facilitated specifically by reactive oxygen species-in particular, superoxide-and are largely unaffected by peroxides and molecular oxygen...
May 29, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29608853/nitrogen-dioxide-reaction-with-nitroxide-radical-derived-from-hydroxamic-acids-the-intermediacy-of-acyl-nitroso-and-nitroxyl-hno
#3
Eric Maimon, Amram Samuni, Sara Goldstein
Hydroxamic acids (RC(O)NHOH) form a class of compounds that display interesting chemical and biological properties The chemistry of RC(O)NHOH) is associated with one- and two-electron oxidations forming the respective nitroxide radical (RC(O)NHO• ) and acyl nitroso (RC(O)N═O), respectively, which are relatively unstable species. In the present study, the kinetics and mechanism of the • NO2 reaction with nitroxide radicals derived from acetohydroxamic acid, suberohydroxamic acid, benzohydroxamic acid, and suberoylanilide hydroxamic acid have been studied in alkaline solutions...
April 19, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29573493/magnetic-interactions-through-a-nonconjugated-framework-observed-in-back-to-back-connected-triazinyl-nitroxyl-biradical-derivatives
#4
Yusuke Takahashi, Ryo Matsuhashi, Youhei Miura, Naoki Yoshioka
Three hetero-biradical derivatives, with the structure of a back-to-back connected benzotriazinyl and tetramethyl or tetraethylisoindoline N-oxyl sharing a common benzo ring, 3-tert-butyl-1-phenyl-1,4,6,8-tetrahydro-6,6,8,8-tetramethyl-pyrrolo[4,5-g]-1,2,4-benzotriazin-4-yl-7-oxyl (1-tBu), 1,3-diphenyl-1,4,6,8-tetrahydro-6,6,8,8-tetramethyl-pyrrolo[4,5-g]-1,2,4-benzotriazin-4-yl-7-oxyl (1-Ph), and 3-tert-butyl-1-phenyl-1,4,6,8-tetrahydro-6,6,8,8-tetraethyl-pyrrolo[4,5-g]-1,2,4-benzotriazin-4-yl-7-oxyl (2-tBu), were synthesized and characterized by single-crystal X-ray analyses, variable-temperature magnetic susceptibility studies, and DFT calculations...
June 4, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29517233/when-do-strongly-coupled-diradicals-show-strongly-coupled-reactivity-thermodynamics-and-kinetics-of-hydrogen-atom-transfer-reactions-of-palladium-and-platinum-bis-iminosemiquinone-complexes
#5
Kyle M Conner, AnnaMaria C Arostegui, Daniel D Swanson, Seth N Brown
The 2,2'-biphenylene-bridged bis(iminosemiquinone) complexes ( t BuClip)M [ t BuClipH4 = 4,4'-di- tert-butyl- N, N'-bis(3,5-di- tert-butyl-2-hydroxyphenyl)-2,2'-diaminobiphenyl; M = Pd, Pt] can be reduced to the bis(aminophenoxide) complexes ( t BuClipH2 )M by reaction with hydrazobenzene (M = Pd) or by catalytic hydrogenation (M = Pt). The palladium complex with one aminophenoxide ligand and one iminosemiquinone ligand, ( t BuClipH)Pd, is generated by comproportionation of ( t BuClip)Pd with ( t BuClipH2 )Pd in a process that is both slow (0...
March 8, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29476040/hemodynamic-effects-of-glutathione-liganded-binuclear-dinitrosyl-iron-complex-evidence-for-nitroxyl-generation-and-modulation-by-plasma-albumin
#6
Taiming Liu, Meijuan Zhang, Michael H Terry, Hobe Schroeder, Sean M Wilson, Gordon G Power, Qian Li, Trent E Tipple, Dan Borchardt, Arlin B Blood
Glutathione-liganded binuclear dinitrosyl iron complex (glut-BDNIC) has been proposed to be a donor of nitric oxide (NO). This study was undertaken to investigate the mechanisms of vasoactivity, systemic hemodynamic effects, and pharmacokinetics of glut-BDNIC. To test the hypothesis that glut-BDNICs vasodilate by releasing NO in its reduced [nitroxyl (HNO)] state, a bioassay method of isolated, preconstricted ovine mesenteric arterial rings was used in the presence of selective scavengers of HNO or NO free radical (NO• ); the vasodilatory effects of glut-BDNIC were found to have characteristics similar to those of an HNO donor and markedly different than an NO• donor...
May 2018: Molecular Pharmacology
https://www.readbyqxmd.com/read/29469215/dinitrosyl-iron-complexes-formation-and-antiradical-action-in-heart-mitochondria
#7
Konstantin B Shumaev, Arina L Dudylina, Marina V Ivanova, Igor S Pugachenko, Enno K Ruuge
Mitochondria are widely known as a major source of reactive oxygen and nitrogen species for the cardiovascular system. Numerous studies established that superoxide anion radical production by heart mitochondria is only slightly suppressed under conditions of deep hypoxia, but is completely blocked under anoxia. It was found also that dinitrosyl iron complexes (DNIC) compare favourably with other physiologically active derivatives of nitric oxide (NO). DNIC with glutathione effectively scavenge superoxide radicals generated by mitochondria at different partial pressures of oxygen...
May 2018: BioFactors
https://www.readbyqxmd.com/read/29432006/enantioselective-synthesis-of-pyrroloindolines-via-noncovalent-stabilization-of-indole-radical-cations-and-applications-to-the-synthesis-of-alkaloid-natural-products
#8
Emily C Gentry, Lydia J Rono, Martina E Hale, Rei Matsuura, Robert R Knowles
While interest in the synthetic chemistry of radical cations continues to grow, controlling enantioselectivity in the reactions of these intermediates remains a challenge. Based on recent insights into the oxidation of tryptophan in enzymatic systems, we report a photocatalytic method for the generation of indole radical cations as hydrogen-bonded adducts with chiral phosphate anions. These noncovalent open-shell complexes can be intercepted by the stable nitroxyl radical TEMPO· to form alkoxyamine-substituted pyrroloindolines with high levels of enantioselectivity...
March 7, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29385348/electrochemically-controlled-cationic-polymerization-of-vinyl-ethers
#9
Brian M Peterson, Song Lin, Brett P Fors
Control of polymer initiation, propagation and termination is important in the development of complex polymer structures and advanced materials. Typically, this has been achieved chemically, electrochemically, photochemically or mechanochemically. Electrochemical control has been demonstrated in radical polymerizations; however, regulation of a cationic polymerization has yet to be achieved. Through the reversible oxidation of a polymer chain end with an electrochemical mediator, temporal control over polymer chain growth in cationic polymerizations was realized...
February 14, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29379338/synthesis-structure-antioxidant-activity-and-water-solubility-of-trolox-ion-conjugates
#10
Yuliya V Yushkova, Elena I Chernyak, Yuriy V Gatilov, Vladimir G Vasil'ev, Sergey V Morozov, Igor A Grigor'ev
The interaction of trolox with ammonia, alkylamines of different classes, and amino derivatives of heterocyclic compounds, including nitroxyl radicals and alkaloids, led to the production of ammonium salts called ion conjugates (ICs). Five ICs were characterised by X-ray diffraction. This is the first time a wide range of ICs were made from trolox with amines, and ESI-MS data demonstrated they have the potential to generate pseudomolecular [(A- B+ ) + H]+ ions. For all obtained trolox ICs, a significant increase (1-3 orders of magnitude) in water solubility was achieved while retaining high antioxidant activity...
January 2018: Saudi Pharmaceutical Journal: SPJ: the Official Publication of the Saudi Pharmaceutical Society
https://www.readbyqxmd.com/read/29320888/comparative-studies-with-epr-and-mri-on-the-in-vivo-tissue-redox-status-estimation-using-redox-sensitive-nitroxyl-probes-influence-of-the-choice-of-the-region-of-interest
#11
Ken-Ichiro Matsumoto, James B Mitchell, Murali C Krishna
In vivo decay rates of a nitroxyl contrast agent were estimated by a MR redox imaging (MRRI) technique and compared with the decay rates obtained by the electron paramagnetic resonance spectroscopy (EPRS) and imaging (EPRI). MRRI is a dynamic imaging technique employing T1 -weighted pulse sequence, which can visualise a nitroxyl-induced enhancement of signal intensity by T1 -weighted contrast. EPR techniques can directly measure the paramagnetic nitroxyl radical. Both the squamous cell carcinoma (SCC) tumour-bearing and normal legs of a female C3H mouse were scanned by T1 -weighted SPGR sequence at 4...
February 2018: Free Radical Research
https://www.readbyqxmd.com/read/29205482/low-frequency-esr-studies-on-permeable-and-impermeable-deuterated-nitroxyl-radicals-in-corn-oil-solution
#12
D David Jebaraj, Hideo Utsumi, A Milton Franklin Benial
Low-frequency electron spin resonance studies were performed for 2 mM concentration of deuterated permeable and impermeable nitroxyl spin probes, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and 3-carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy in pure water and various concentrations of corn oil solution. The electron spin resonance parameters such as the line width, hyperfine coupling constant, g factor, rotational correlation time, permeability, and partition parameter were estimated. The broadening of line width was observed for nitroxyl radicals in corn oil mixture...
April 2018: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29165366/nitroxides-as-antioxidants-and-anticancer-drugs
#13
REVIEW
Marcin Lewandowski, Krzysztof Gwozdzinski
Nitroxides are stable free radicals that contain a nitroxyl group with an unpaired electron. In this paper, we present the properties and application of nitroxides as antioxidants and anticancer drugs. The mostly used nitroxides in biology and medicine are a group of heterocyclic nitroxide derivatives of piperidine, pyrroline and pyrrolidine. The antioxidant action of nitroxides is associated with their redox cycle. Nitroxides, unlike other antioxidants, are characterized by a catalytic mechanism of action associated with a single electron oxidation and reduction reaction...
November 22, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29130334/pulsed-electron-paramagnetic-resonance-imaging-applications-in-the-studies-of-tumor-physiology
#14
Shun Kishimoto, Ken-Ichiro Matsumoto, Keita Saito, Ayano Enomoto, Shingo Matsumoto, James B Mitchell, Nallathamby Devasahayam, Murali C Krishna
SIGNIFICANCE: Electron paramagnetic resonance imaging (EPRI) is capable of generating images of tissue oxygenation using exogenous paramagnetic probes such as trityl radicals or nitroxyl radicals. The spatial distribution of the paramagnetic probe can be generated using magnetic field gradients as in magnetic resonance imaging and, from its spectral features, spatial maps of oxygen can be obtained from live objects. In this review, two methods of signal acquisition and image formation/reconstruction are described...
May 20, 2018: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/29127716/conformational-properties-membrane-interaction-and-antibacterial-activity-of-the-peptaibiotic-chalciporin-a-multitechnique-spectroscopic-and-biophysical-investigations-on-the-natural-compound-and-labeled-analogs
#15
Barbara Biondi, Cristina Peggion, Marta De Zotti, Chiara Pignaffo, Annalisa Dalzini, Marco Bortolus, Simona Oancea, Geta Hilma, Annalisa Bortolotti, Lorenzo Stella, Jens Z Pedersen, Victoria N Syryamina, Yuri D Tsvetkov, Sergei A Dzuba, Claudio Toniolo, Fernando Formaggio
In this work, an extensive set of spectroscopic and biophysical techniques (including FT-IR absorption, CD, 2D-NMR, fluorescence, and CW/PELDOR EPR) was used to study the conformational preferences, membrane interaction, and bioactivity properties of the naturally occurring synthetic 14-mer peptaibiotic chalciporin A, characterized by a relatively low (≈20%), uncommon proportion of the strongly helicogenic Aib residue. In addition to the unlabeled peptide, we gained in-depth information from the study of two labeled analogs, characterized by one or two residues of the helicogenic, nitroxyl radical-containing TOAC...
November 11, 2017: Biopolymers
https://www.readbyqxmd.com/read/29118910/feasibility-of-magnetic-resonance-redox-imaging-at-low-magnetic-field-comparison-at-1-t-and-7-t
#16
Mizuki Nakamura, Sayaka Shibata, Toshihide Yamasaki, Megumi Ueno, Ikuo Nakanishi, Ken-Ichiro Matsumoto, Tadashi Kamada, Ken-Ichi Yamada, Ichio Aoki
The effect of different static magnetic field strengths, 1 T or 7 T, on the quality of nitroxyl radical-based magnetic resonance redox imaging (MRRI) was examined. A stable nitroxyl radical, 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine- N -oxyl (MC-PROXYL), was used as a T1 contrast agent. Phantoms and animals were scanned at 1 T and 7 T using a similar gradient echo sequence. The quality of T1 -weighted images and susceptibility of T1 -weighted signals were compared. The nitroxyl radical-based T1 -weighted signal enhancement ratio was higher at 1 T compared with at 7 T when the identical phantom was scanned using a similar gradient echo sequence...
2017: American Journal of Translational Research
https://www.readbyqxmd.com/read/29101507/novel-synthesized-radical-containing-nanoparticles-limit-infarct-size-following-ischemia-and-reperfusion-in-canine-hearts
#17
Hiroshi Asanuma, Shoji Sanada, Toru Yoshitomi, Hideyuki Sasaki, Hiroyuki Takahama, Madoka Ihara, Hiroko Takahama, Yoshiro Shinozaki, Hidezo Mori, Masanori Asakura, Atsushi Nakano, Masaru Sugimachi, Yoshihiro Asano, Tetsuo Minamino, Seiji Takashima, Yukio Nagasaki, Masafumi Kitakaze
PURPOSE: Although nitroxyl radicals such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) scavenge free radicals, their short half-life and considerable side effects such as systemic hypotension and bradycardia have limited their clinical application. Since a radical-containing nanoparticle (RNP) delivers nitroxyl radicals with a prolonged half-life specific to ischemic hearts, we investigated whether RNPs reduce infarct size without the occurrence of substantial side effects and whether nitric oxide (NO) contributes to the cardioprotective effects of RNPs...
December 2017: Cardiovascular Drugs and Therapy
https://www.readbyqxmd.com/read/29095519/no-and-hno-donors-nitrones-and-nitroxides-past-present-and-future
#18
REVIEW
Catarina Oliveira, Sofia Benfeito, Carlos Fernandes, Fernando Cagide, Tiago Silva, Fernanda Borges
The biological effects attributed to nitric oxide (• NO) and nitroxyl (HNO) have been extensively studied, propelling their array of putative clinical applications beyond cardiovascular disorders toward other age-related diseases, like cancer and neurodegenerative diseases. In this context, the unique properties and reactivity of the N-O bond enabled the development of several classes of compounds with potential clinical interest, among which • NO and HNO donors, nitrones, and nitroxides are of particular importance...
July 2018: Medicinal Research Reviews
https://www.readbyqxmd.com/read/28961477/design-and-testing-of-a-750mhz-cw-epr-digital-console-for-small-animal-imaging
#19
Hideo Sato-Akaba, Miho C Emoto, Hiroshi Hirata, Hirotada G Fujii
This paper describes the development of a digital console for three-dimensional (3D) continuous wave electron paramagnetic resonance (CW-EPR) imaging of a small animal to improve the signal-to-noise ratio and lower the cost of the EPR imaging system. A RF generation board, an RF acquisition board and a digital signal processing (DSP) & control board were built for the digital EPR detection. Direct sampling of the reflected RF signal from a resonator (approximately 750MHz), which contains the EPR signal, was carried out using a band-pass subsampling method...
September 20, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28926245/hno-is-produced-by-the-reaction-of-no-with-thiols
#20
Sebastian A Suarez, Martina Muñoz, Lucia Alvarez, Mateus F Venâncio, Willian R Rocha, Damian E Bikiel, Marcelo A Marti, Fabio Doctorovich
Azanone (nitroxyl, HNO) is a highly reactive compound whose biological role is still a matter of debate. One possible route for its formation is NO reduction by biological reductants. These reactions have been historically discarded due to the negative redox potential for the NO,H+/HNO couple. However, the NO to HNO conversion mediated by vitamins C, E, and aromatic alcohols has been recently shown to be feasible from a chemical standpoint. Based on these precedents, we decided to study the reaction of NO with thiols as potential sources of HNO...
October 18, 2017: Journal of the American Chemical Society
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