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Gong X, Chen S, Zhang S. JOM-4S Overhauser Magnetometer and Sensitivity Estimation. SENSORS (BASEL, SWITZERLAND) 2021; 21:7698. [PMID: 34833789 PMCID: PMC8624099 DOI: 10.3390/s21227698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/17/2021] [Accepted: 11/17/2021] [Indexed: 11/29/2022]
Abstract
The Overhauser magnetometer is a scalar quantum magnetometer based on the dynamic nuclear polarization (DNP) effect in the Earth's magnetic field. Sensitivity is a key technical specification reflecting the ability of instruments to sense small variations of the Earth's magnetic field and is closely related to the signal-to-noise ratio (SNR) of the free induction decay (FID) signal. In this study, deuterated 15N TEMPONE radical is used in our sensor to obtain high DNP enhancement. The measured SNR of the FID signal is approximately 63/1, and the transverse relaxation time T2 is 2.68 s. The direct measurement method with a single instrument and the synchronous measurement method with two instruments are discussed for sensitivity estimation in time and frequency domains under different electromagnetic interference (EMI) environments and different time periods. For the first time, the correlation coefficient of the magnetic field measured by the two instruments is used to judge the degree of the influence of the environmental noise on the sensitivity estimation. The sensitivity evaluation in the field environment is successfully realized without electrical and magnetic shields. The direct measurement method is susceptible to EMI and cannot work in general electromagnetic environments, except it is sufficiently quiet. The synchronous measurement method has an excellent ability to remove most natural and artificial EMIs and can be used under noisy environments. Direct and synchronous experimental results show that the estimated sensitivity of the JOM-4S magnetometer is approximately 0.01 nT in time domain and approximately 0.01 nT/Hz in frequency domain at a 3 s cycling time. This study provides a low-cost, simple, and effective sensitivity estimation method, which is especially suitable for developers and users to estimate the performance of the instrument.
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Affiliation(s)
| | | | - Shuang Zhang
- College of Electronic Science and Engineering, Jilin University, Changchun 130012, China; (X.G.); (S.C.)
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2
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Fehling P, Buckenmaier K, Dobrynin SA, Morozov DA, Polienko YF, Khoroshunova YV, Borozdina Y, Mayer P, Engelmann J, Scheffler K, Angelovski G, Kirilyuk IA. The effects of nitroxide structure upon 1H Overhauser dynamic nuclear polarization efficacy at ultralow-field. J Chem Phys 2021; 155:144203. [PMID: 34654311 DOI: 10.1063/5.0064342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The efficacy in 1H Overhauser dynamic nuclear polarization in liquids at ultralow magnetic field (ULF, B0 = 92 ± 0.8 µT) and polarization field (Bp = 1-10 mT) was studied for a broad variety of 26 different spin probes. Among others, piperidine, pyrrolidine, and pyrroline radicals specifically synthesized for this study, along with some well-established commercially available nitroxides, were investigated. Isotope-substituted variants, some sterically shielded reduction-resistant nitroxides, and some biradicals were included in the measurements. The maximal achievable enhancement, Emax, and the radio frequency power, P1/2, needed for reaching Emax/2 were measured. Physico-chemical features such as molecular weight, spectral linewidth, heterocyclic structure, different types of substituents, deuteration, and 15N-labeling as well as the difference between monoradicals and biradicals were investigated. For the unmodified nitroxide radicals, the Emax values correlate with the molecular weight. The P1/2 values correlate with the spectral linewidth and are additionally influenced by the type of substituents neighboring the nitroxide group. The nitroxide biradicals with high intramolecular spin-spin coupling show low performance. Nitroxides enriched with 15N and/or 2H afford significantly higher |Emax| and require lower power to do so, compared to their unmodified counterparts containing at natural abundance predominantly 14N and 1H. The results allow for a correlation of chemical features with physical hyperpolarization-related properties and indicate that small nitroxides with narrow spectral lines have clear advantages for the use in Overhauser dynamic nuclear polarization experiments. Perdeuteration and 15N-labeling can be used to additionally boost the spin probe performance.
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Affiliation(s)
- Paul Fehling
- Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Kai Buckenmaier
- Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Sergey A Dobrynin
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - Denis A Morozov
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - Yuliya F Polienko
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - Yulia V Khoroshunova
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - Yulia Borozdina
- Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Philipp Mayer
- Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Jörn Engelmann
- Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Klaus Scheffler
- Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Goran Angelovski
- Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany
| | - Igor A Kirilyuk
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
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David Jebaraj D, Utsumi H, Milton Franklin Benial A. Low-frequency ESR studies on permeable and impermeable deuterated nitroxyl radicals in corn oil solution. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:257-264. [PMID: 29205482 DOI: 10.1002/mrc.4686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/13/2017] [Accepted: 11/16/2017] [Indexed: 06/07/2023]
Abstract
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. The rotational correlation time increases with increasing concentration of corn oil, which indicates the less mobile nature of spin probe in corn oil mixture. The membrane permeability and partition parameter values were estimated as a function of corn oil concentration, which reveals that the nitroxyl radicals permeate equally into the aqueous phase and oil phase at the corn oil concentration of 50%. The electron spin resonance spectra demonstrate the permeable and impermeable nature of nitroxyl spin probes. From these results, the corn oil concentration was optimized as 50% for phantom studies. In this work, the corn oil and pure water mixture phantom models with various viscosities correspond to plasma membrane, and whole blood membrane with different hematocrit levels was studied for monitoring the biological characteristics and their interactions with permeable nitroxyl spin probe. These results will be useful for the development of electron spin resonance and Overhauser-enhanced magnetic resonance imaging modalities in biomedical applications.
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Affiliation(s)
- D David Jebaraj
- Department of Physics, The American College, Madurai, Tamil Nadu, 625 002, India
| | - Hideo Utsumi
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, 812-8582, Japan
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4
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Wessig M, Spitzbarth M, Klaiber A, Drescher M, Polarz S. Negative and Positive Confinement Effects in Chiral Separation Chromatography Monitored with Molecular-Scale Precision by In-Situ Electron Paramagnetic Resonance Techniques. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11968-11976. [PMID: 28990785 DOI: 10.1021/acs.langmuir.7b02713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Separation of compounds using liquid chromatography is a process of enormous technological importance. This is true in particular for chiral substances, when one enantiomer has the desired set of properties and the other one may be harmful. The degree of development in liquid chromatography is extremely high, but still there is a lack in understanding based on experimental data how selectivity works on a molecular level directly at the surfaces of a porous host material. We have prepared amino-acid containing organosilica as such host materials. Watching the rotational dynamics of chiral spin probes using electron paramagnetic resonance spectroscopy allows us to differentiate between surface adsorbed and free guest species. Diastereotopic selectivity factors were determined, and the influence of chiral surface group density, chemical character of the surface groups, pore-size, and temperature was investigated. We found higher selectivity values in macroporous solids with a rather rigid organosilica network and at lower temperature, indicating the significant effect of confinement effects. In mesoporous materials features are opposed with regards to the T-dependent behavior. From EPR imaging techniques and the resulting (macroscopic) diffusion coefficients, we could confirm that the correlations found on the microscopic level transform also to the macroscopic behavior. Thus, our study is of value for the development of future chromatography materials by design.
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Affiliation(s)
- Martin Wessig
- University of Konstanz , Department of Chemistry, D-78457 Konstanz, Germany
| | - Martin Spitzbarth
- University of Konstanz , Department of Chemistry, D-78457 Konstanz, Germany
| | - Alexander Klaiber
- University of Konstanz , Department of Chemistry, D-78457 Konstanz, Germany
| | - Malte Drescher
- University of Konstanz , Department of Chemistry, D-78457 Konstanz, Germany
| | - Sebastian Polarz
- University of Konstanz , Department of Chemistry, D-78457 Konstanz, Germany
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David Jebaraj D, Utsumi H, Milton Franklin Benial A. Dynamic nuclear polarization studies on deuterated nitroxyl spin probes. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:909-916. [PMID: 28444914 DOI: 10.1002/mrc.4602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/22/2017] [Accepted: 04/24/2017] [Indexed: 06/07/2023]
Abstract
Detailed dynamic nuclear polarization and electron spin resonance studies were carried out for 3-carbamoyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-carboxy-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl,3-methoxycarbonyl-2,2,5,5-tetramethy pyrolidine-1-oxyl nitroxyl radicals and their corresponding deuterated nitroxyl radicals, used in Overhauser-enhanced magnetic resonance imaging for the first time. The dynamic nuclear polarization parameters such as dynamic nuclear polarization (DNP) factor, longitudinal relaxivity, saturation parameter, leakage factor and coupling factor were estimated for deuterated nitroxyl radicals. DNP enhancement increases with agent concentration up to 3 mm and decreases above 3 mm. The proton spin-lattice relaxation time and the longitudinal relaxivity parameters were estimated. The leakage factor increases with increasing agent concentration up to 3 mm and reaches plateau in the region 3-5 mm. The coupling parameter shows the interaction between the electron and nuclear spins to be mainly dipolar in origin. DNP spectrum exhibits that the full width at half maximum values are higher for undeuterated nitroxyl radicals compared with deuterated nitroxyl radicals, which leads to the increase in DNP enhancement. The ESR parameters such as, the line width, line shape, signal intensity ratio, rotational correlation time, hyperfine coupling constant and g-factor were calculated. The narrow line width was observed for deuterated nitroxyl radicals compared with undeuterated nitroxyl radicals, which leads to the higher saturation parameter value and DNP enhancement. The novelty of the work permits clear understanding of the DNP parameters determining the higher DNP enhancement compared with the undeuterated nitroxyl radicals. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- D David Jebaraj
- Department of Physics, The American College, Madurai, 625 002, Tamil Nadu, India
| | - Hideo Utsumi
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, 812-8582, Japan
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6
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David Jebaraj D, Utsumi H, Milton Franklin Benial A. Electron spin resonance studies on deuterated nitroxyl spin probes used in Overhauser-enhanced magnetic resonance imaging. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:700-705. [PMID: 28052402 DOI: 10.1002/mrc.4576] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 12/30/2016] [Indexed: 06/06/2023]
Abstract
The electron spin resonance studies were carried out for 2 mm concentration of 14 N-labeled and 15 N-labeled 3-carbamoyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-carboxy-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and their deuterated nitroxyl radicals using X-band electron spin resonance spectrometer. The electron spin resonance line shape analysis was carried out. The electron spin resonance parameters such as linewidth, Lorentzian component, signal intensity ratio, rotational correlation time, hyperfine coupling constant and g-factor were estimated. The deuterated nitroxyl radicals have narrow linewidth and an increase in Lorentzian component, compared with undeuterated nitroxyl radicals. The dynamic nuclear polarization factor was observed for all nitroxyl radicals. Upon 2 H labeling, about 70% and 40% increase in dynamic nuclear polarization factor were observed for 14 N-labeled and 15 N-labeled nitroxyl radicals, respectively. The signal intensity ratio and g-value indicate the isotropic nature of the nitroxyl radicals in pure water. Therefore, the deuterated nitroxyl radicals are suitable spin probes for in vivo/in vitro electron spin resonance and Overhauser-enhanced magnetic resonance imaging modalities. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- D David Jebaraj
- Department of Physics, The American College, Madurai, 625 002, Tamilnadu, India
| | - Hideo Utsumi
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, 812 8582, Japan
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7
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Meenakumari V, Utsumi H, Jawahar A, Milton Franklin Benial A. ESR line width and line shape dependence of Overhauser-enhanced magnetic resonance imaging. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:874-879. [PMID: 27432403 DOI: 10.1002/mrc.4489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 07/10/2016] [Accepted: 07/13/2016] [Indexed: 06/06/2023]
Abstract
Electron spin resonance and Overhauser-enhanced magnetic resonance imaging studies were carried out for various concentrations of 14 N-labeled 3-carbamoyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl in pure water. Overhauser-enhancement factor attains maxima in the range of 2.5-3 mm concentration. The leakage factor showed an asymptotic increase with increasing agent concentration. The coupling parameter showed the interaction between the electron and nuclear spins to be mainly dipolar in origin. The electron spin resonance parameters, such as the line width, line shape and g-factor, were determined. The line width analysis confirms that the line broadening is proportional to the agent concentration, and also the agent concentration is optimized in the range of 2.5-3 mm. The line shape analysis shows that the observed electron spin resonance line shape is a Voigt line shape, in which the Lorentzian component is dominant. The contribution of Lorentzian component was estimated using the winsim package. The Lorentzian component of the resonance line attains maxima in the range of 2.5-3 mm concentration. Therefore, this study reveals that the agent concentration, line width and Lorentzian component are the important factors in determining the Overhauser-enhancement factor. Hence, the agent concentration was optimized as 2.5-3 mm for in vivo/in vitro electron spin resonance imaging and Overhauser-enhanced magnetic resonance imaging phantom studies. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- V Meenakumari
- Department of Physics, NMSSVN College, Madurai, Tamil Nadu, India
| | - Hideo Utsumi
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan
| | - A Jawahar
- Department of Chemistry, NMSSVN College, Madurai, Tamil Nadu, India
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8
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Ito S, Hyodo F. Dynamic nuclear polarization-magnetic resonance imaging at low ESR irradiation frequency for ascorbyl free radicals. Sci Rep 2016; 6:21407. [PMID: 26892591 PMCID: PMC4759784 DOI: 10.1038/srep21407] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/22/2016] [Indexed: 11/14/2022] Open
Abstract
Highly water-soluble ubiquinone-0 (CoQ0) reacts with ascorbate monoanion (Asc) to mediate the production of ascorbyl free radicals (AFR). Using aqueous reaction mixture of CoQ0 and Asc, we obtained positively enhanced dynamic nuclear polarization (DNP)-magnetic resonance (MR) images of the AFR at low frequency (ranging from 515 to 530 MHz) of electron spin resonance (ESR) irradiation. The shape of the determined DNP spectrum was similar to ESR absorption spectra with doublet spectral peaks. The relative locational relationship of spectral peaks in the DNP spectra between the AFR (520 and 525 MHz), 14N-labeled carbamoyl-PROXYL (14N-CmP) (526.5 MHz), and Oxo63 (522 MHz) was different from that in the X-band ESR spectra, but were similar to that in the 300-MHz ESR spectra. The ratio of DNP enhancement to radical concentration for the AFR was higher than those for 14N-CmP, Oxo63, and flavin semiquinone radicals. The spectroscopic DNP properties observed for the AFR were essentially the same as those for AFR mediated by pyrroloquinoline quinone. Moreover, we made a success of in vivo DNP-MR imaging of the CoQ0-mediated AFR which was administered by the subcutaneous and oral injections as an imaging probe.
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Affiliation(s)
- Shinji Ito
- Innovation Center for Medical Redox Navigation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Fuminori Hyodo
- Innovation Center for Medical Redox Navigation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Kirilyuk IA, Bobko AA, Semenov SV, Komarov DA, Irtegova IG, Grigor'ev IA, Bagryanskaya E. Effect of Sterical Shielding on the Redox Properties of Imidazoline and Imidazolidine Nitroxides. J Org Chem 2015; 80:9118-25. [PMID: 26302173 DOI: 10.1021/acs.joc.5b01494] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The oxidant properties of the series of 2,2,5,5-tetraalkyl imidazoline and imidazolidine nitroxides were investigated. An increase in the number of bulky alkyl substituents leads to a decrease in the rate of reduction with ascorbate, which makes the electrochemical reduction potential more negative and shifts the equilibrium in the mixture of nitroxide and reference hydroxylamine (3-carboxy-1-hydroxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl-1-(15)N) toward the starting compounds. The effect of structural factors on these reactions was analyzed by means of multiple regression using the Fujita steric constant Es and the inductive Hammett constant σI. Satisfactory statistical outputs were obtained in all of the biparameter correlations, denoting that the oxidant properties of the nitroxides are determined by steric and electronic effects of the substituents. The data imply that bulky substituents can stabilize nitroxide and/or destabilize hydroxylamine.
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Affiliation(s)
- Igor A Kirilyuk
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS , Academician Lavrentjev Avenue 9, Novosibirsk, 630090, Russia.,Novosibirsk State University , Pirogova str. 2, Novosibirsk 630090, Russia
| | - Andrey A Bobko
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Ohio State University , Columbus, Ohio 43210, United States
| | - Sergey V Semenov
- Novosibirsk State University , Pirogova str. 2, Novosibirsk 630090, Russia
| | - Denis A Komarov
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS , Academician Lavrentjev Avenue 9, Novosibirsk, 630090, Russia.,Novosibirsk State University , Pirogova str. 2, Novosibirsk 630090, Russia
| | - Irina G Irtegova
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS , Academician Lavrentjev Avenue 9, Novosibirsk, 630090, Russia.,Novosibirsk State University , Pirogova str. 2, Novosibirsk 630090, Russia
| | - Igor A Grigor'ev
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS , Academician Lavrentjev Avenue 9, Novosibirsk, 630090, Russia
| | - Elena Bagryanskaya
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS , Academician Lavrentjev Avenue 9, Novosibirsk, 630090, Russia.,Novosibirsk State University , Pirogova str. 2, Novosibirsk 630090, Russia
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10
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Soikkeli M, Sievänen K, Peltonen J, Kaasalainen T, Timonen M, Heinonen P, Rönkkö S, Lehto VP, Kavakka JS, Heikkinen S. Synthesis and in vitro phantom NMR and MRI studies of fully organic free radicals, TEEPO-glucose and TEMPO-glucose, potential contrast agents for MRI. RSC Adv 2015. [DOI: 10.1039/c4ra11455h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Two organic radical contrast agents, TEMPO-Glc and TEEPO-Glc, were synthesized and their stabilities and contrast enhancing properties were tested with in vitro NMR and MRI experiments.
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Affiliation(s)
- M. Soikkeli
- Laboratory of Organic Chemistry
- Department of Chemistry
- University of Helsinki
- Finland
| | - K. Sievänen
- Laboratory of Organic Chemistry
- Department of Chemistry
- University of Helsinki
- Finland
| | - J. Peltonen
- HUS Helsinki Medical Imaging Center
- Helsinki
- Finland
| | | | - M. Timonen
- HUS Helsinki Medical Imaging Center
- Helsinki
- Finland
| | - P. Heinonen
- Laboratory of Organic Chemistry
- Department of Chemistry
- University of Helsinki
- Finland
| | - S. Rönkkö
- Department of Applied Physics
- University of Eastern Finland
- FIN-70211 Kuopio
- Finland
| | - V.-P. Lehto
- Department of Applied Physics
- University of Eastern Finland
- FIN-70211 Kuopio
- Finland
| | - J. S. Kavakka
- Laboratory of Organic Chemistry
- Department of Chemistry
- University of Helsinki
- Finland
| | - S. Heikkinen
- Laboratory of Organic Chemistry
- Department of Chemistry
- University of Helsinki
- Finland
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Romainczyk O, Elduque X, Engels JW. Attachment of Nitroxide Spin Labels to Nucleic Acids for EPR. ACTA ACUST UNITED AC 2012; Chapter 7:Unit7.17. [DOI: 10.1002/0471142700.nc0717s49] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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12
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Deguchi H, Yasukawa K, Yamasaki T, Mito F, Kinoshita Y, Naganuma T, Sato S, Yamato M, Ichikawa K, Sakai K, Utsumi H, Yamada KI. Nitroxides prevent exacerbation of indomethacin-induced gastric damage in adjuvant arthritis rats. Free Radic Biol Med 2011; 51:1799-805. [PMID: 21906674 DOI: 10.1016/j.freeradbiomed.2011.08.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 08/11/2011] [Accepted: 08/12/2011] [Indexed: 02/02/2023]
Abstract
Nonsteroidal anti-inflammatory drugs are the drugs of choice in the treatment of rheumatoid arthritis (RA) because of their rapid analgesic effect. However, they induce severe gastric damage in RA patients and animals by a process mediated by reactive oxygen species (ROS). Nitroxides (nitroxyl radicals) are widely used as imaging agents and antioxidants to explore the role of ROS generation in the pathogenesis of disease. In this study, the effectiveness of the newly synthesized nitroxides 8-aza-7,7,9,9-tetramethyl-1,4-dioxaspiro[4.5]undecan-8-oxyl (compound 1) and 4-oxo-2,2,6,6-tetraethylpiperidine-1-oxyl (compound 2) in the prevention of gastric ulcers in adjuvant arthritis rats treated with indomethacin was evaluated by monitoring the reaction of reactive oxygen species in gastric tissue with Overhauser-enhanced magnetic resonance imaging (OMRI). Pretreatment with all tested nitroxides suppressed the ulcers induced by indomethacin treatment in arthritic rats. OMRI using compounds 1 and 2 as well as 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) demonstrated a redox imbalance in the stomach of these rats. Lipid peroxide and interleukin (IL)-1β levels in the gastric mucosa were significantly suppressed by compound 1 and TEMPOL, whereas CINC/gro, a member of the IL-8 family, was significantly suppressed by compound 1 only. These results suggest that the preventive effects of nitroxides on gastric ulcers may operate by different mechanisms.
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Affiliation(s)
- Hisato Deguchi
- Department of Bio-Functional Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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Burks SR, Bakhshai J, Makowsky MA, Muralidharan S, Tsai P, Rosen GM, Kao JPY. (2)H,(15)N-substituted nitroxides as sensitive probes for electron paramagnetic resonance imaging. J Org Chem 2011; 75:6463-7. [PMID: 20828113 DOI: 10.1021/jo1011619] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electron paramagnetic resonance imaging (EPRI) using nitroxides is an emergent imaging method for studying in vivo physiology, including O(2) distribution in various tissues. Such imaging capabilities would allow O(2) mapping in tumors and in different brain regions following hypoxia or drug abuse. We have recently demonstrated that the anion of 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxyl (2) can be entrapped in brain tissue to quantitate O(2) concentration in vivo. To increase the sensitivity of O(2) measurement by EPR imaging, we synthesized 3-carboxy-2,2,5,5-tetra((2)H(3))methyl-1-(3,4,4-(2)H(3),1-(15)N)pyrrolidinyloxyl (7). EPR spectroscopic measurements demonstrate that this fully isotopically substituted nitroxide markedly improves signal-to-noise ratio and, therefore, the sensitivity of EPR imaging. The new isotopically substituted nitroxide shows increased sensitivity to changes in O(2) concentration, which will enable more accurate O(2) measurement in tissues using EPRI.
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Affiliation(s)
- Scott R Burks
- Center for Biomedical Engineering and Technology, and Center for EPR Imaging In Vivo Physiology, University of Maryland, Baltimore, Maryland 21201, USA
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14
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Kinoshita Y, Yamada KI, Yamasaki T, Mito F, Yamato M, Kosem N, Deguchi H, Shirahama C, Ito Y, Kitagawa K, Okukado N, Sakai K, Utsumi H. In vivo evaluation of novel nitroxyl radicals with reduction stability. Free Radic Biol Med 2010; 49:1703-9. [PMID: 20828609 DOI: 10.1016/j.freeradbiomed.2010.08.027] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 08/25/2010] [Accepted: 08/30/2010] [Indexed: 10/19/2022]
Abstract
Nitroxyl radicals (nitroxide) have great potential advantages as spin probes, antioxidants, contrast agents, and radiation-protecting agents. However, they are readily reduced by reductants in cells and lose their paramagnetic nature. Recently, tetraethyl-substituted nitroxyl radicals have been reported to have high stability toward reduction by ascorbic acid (AsA). We report the general considerations of tetraethyl nitroxyl radicals for in vivo application. The reason for the low reactivity to AsA reduction was the positive value of Gibbs energy between the tetraethyl nitroxyl radical and AsA. Further, these compounds had an inhibitory effect on lipid peroxidation despite having AsA resistance. They had low antiproliferative effects in HepG2 cells and HUVECs and did not have a lowering effect on blood pressure in animals. Further, after intravenous injection, the ESR signal intensities of tetraethyl-substituted piperidine nitroxyl radicals were very stable in mice over 20 min. These results suggest that tetraethyl-substituted nitroxyl radicals have stability against bioreduction with reductants such as AsA and confer onto them features as antioxidants and paramagnetic tracers/contrast agents. Hence, they will be useful in identifying the foci of oxidative stress in vivo using redox-based imaging approaches.
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Affiliation(s)
- Yuichi Kinoshita
- Department of Bio-functional Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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Sakai K, Yamada KI, Yamasaki T, Kinoshita Y, Mito F, Utsumi H. Effective 2,6-substitution of piperidine nitroxyl radical by carbonyl compound. Tetrahedron 2010. [DOI: 10.1016/j.tet.2010.02.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Hatano B, Araya H, Yoshimura Y, Sato H, Ito T, Ogata T, Kijima T. Facile Synthesis of 3-Methoxycarbonyl-2,2,5,5-tetra-methylpyrrolidine-1-oxyl and Derivatives. HETEROCYCLES 2010. [DOI: 10.3987/com-09-11861] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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