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Abstract
Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R1R2N-O•. The spin distribution over the nitroxide N and O atoms contributes to the thermodynamic stability of these radicals. The presence of bulky N-substituents R1 and R2 prevents nitroxide radical dimerization, ensuring their kinetic stability. Despite their reactivity toward various transient C radicals, some nitroxides can be easily stored under air at room temperature. Furthermore, nitroxides can be oxidized to oxoammonium salts (R1R2N═O+) or reduced to anions (R1R2N-O-), enabling them to act as valuable oxidants or reductants depending on their oxidation state. Therefore, they exhibit interesting reactivity across all three oxidation states. Due to these fascinating properties, nitroxides find extensive applications in diverse fields such as biochemistry, medicinal chemistry, materials science, and organic synthesis. This review focuses on the versatile applications of nitroxides in organic synthesis. For their use in other important fields, we will refer to several review articles. The introductory part provides a brief overview of the history of nitroxide chemistry. Subsequently, the key methods for preparing nitroxides are discussed, followed by an examination of their structural diversity and physical properties. The main portion of this review is dedicated to oxidation reactions, wherein parent nitroxides or their corresponding oxoammonium salts serve as active species. It will be demonstrated that various functional groups (such as alcohols, amines, enolates, and alkanes among others) can be efficiently oxidized. These oxidations can be carried out using nitroxides as catalysts in combination with various stoichiometric terminal oxidants. By reducing nitroxides to their corresponding anions, they become effective reducing reagents with intriguing applications in organic synthesis. Nitroxides possess the ability to selectively react with transient radicals, making them useful for terminating radical cascade reactions by forming alkoxyamines. Depending on their structure, alkoxyamines exhibit weak C-O bonds, allowing for the thermal generation of C radicals through reversible C-O bond cleavage. Such thermally generated C radicals can participate in various radical transformations, as discussed toward the end of this review. Furthermore, the application of this strategy in natural product synthesis will be presented.
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Affiliation(s)
- Dirk Leifert
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
| | - Armido Studer
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
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2
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Konopko A, Litwinienko G. Mutual Activation of Two Radical Trapping Agents: Unusual "Win-Win Synergy" of Resveratrol and TEMPO during Scavenging of dpph • Radical in Methanol. J Org Chem 2022; 87:15530-15538. [PMID: 36321638 PMCID: PMC9680031 DOI: 10.1021/acs.joc.2c02080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The reaction of the 2,2'-diphenyl-1-picrylhydrazyl radical (dpph•) with resveratrol in methanol (kMeOH = 192 M-1 s-1) is greatly accelerated in the presence of stable nitroxyl radical TEMPO• (kmixMeOH = 1.4 × 103 M-1 s-1). This synergistic effect is surprising because TEMPO• alone reacts with dpph• relatively slowly (kS = 31 M-1 s-1 in methanol and 0.03 M-1 s-1 in nonpolar ethyl acetate). We propose a putative mechanism in which a mutual activation occurs within the acid-base pair TEMPO•/RSV to the resveratrol (RSV) anion and TEMPOH•+ radical cation, both being extremely fast scavengers of the dpph• radical. The fast initial reaction is followed by a much slower but continuous decay of dpph• because a nitroxyl radical is recovered from the TEMPOnium cation, which is reduced directly by RSV/RSV- to TEMPO• or recovered indirectly via a reaction with methanol, producing TEMPOH subsequently oxidized by dpph• to TEMPO•.
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Affiliation(s)
- Adrian Konopko
- Faculty
of Chemistry, University of Warsaw, Pasteura 1, Warsaw02-093, Poland,Polish
Academy of Sciences, Nencki Institute of
Experimental Biology, Pasteura 3, Warsaw02-093, Poland
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3
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Naguib M, Feldman N, Zarodkiewicz P, Shropshire H, Biamis C, El-Halfawy OM, McCain J, Dezanet C, Décout JL, Chen Y, Cosa G, Valvano MA. An evolutionary conserved detoxification system for membrane lipid-derived peroxyl radicals in Gram-negative bacteria. PLoS Biol 2022; 20:e3001610. [PMID: 35580139 PMCID: PMC9113575 DOI: 10.1371/journal.pbio.3001610] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/18/2022] [Indexed: 11/30/2022] Open
Abstract
How double-membraned Gram-negative bacteria overcome lipid peroxidation is virtually unknown. Bactericidal antibiotics and superoxide ion stress stimulate the transcription of the Burkholderia cenocepacia bcnA gene that encodes a secreted lipocalin. bcnA gene orthologs are conserved in bacteria and generally linked to a conserved upstream gene encoding a cytochrome b561 membrane protein (herein named lcoA, lipocalin-associated cytochrome oxidase gene). Mutants in bcnA, lcoA, and in a gene encoding a conserved cytoplasmic aldehyde reductase (peroxidative stress-associated aldehyde reductase gene, psrA) display enhanced membrane lipid peroxidation. Compared to wild type, the levels of the peroxidation biomarker malondialdehyde (MDA) increase in the mutants upon exposure to sublethal concentrations of the bactericidal antibiotics polymyxin B and norfloxacin. Microscopy with lipid peroxidation-sensitive fluorescent probes shows that lipid peroxyl radicals accumulate at the bacterial cell poles and septum and peroxidation is associated with a redistribution of anionic phospholipids and reduced antimicrobial resistance in the mutants. We conclude that BcnA, LcoA, and PsrA are components of an evolutionary conserved, hitherto unrecognized peroxidation detoxification system that protects the bacterial cell envelope from lipid peroxyl radicals.
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Affiliation(s)
- Marwa Naguib
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast, United Kingdom
- Department of Microbiology and Immunology, Faculty of Pharmacy, Damanhour University, Damanhour, Egypt
| | - Nicolás Feldman
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast, United Kingdom
| | - Paulina Zarodkiewicz
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast, United Kingdom
| | - Holly Shropshire
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Christina Biamis
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast, United Kingdom
| | - Omar M. El-Halfawy
- Department of Chemistry and Biochemistry, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
- Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Julia McCain
- Department of Chemistry and Quebec Center for Advanced Materials, McGill University, Montreal, Québec, Canada
| | - Clément Dezanet
- Department of Molecular Pharmacochemistry, Université Grenoble Alpes/CNRS, Grenoble, France
| | - Jean-Luc Décout
- Department of Molecular Pharmacochemistry, Université Grenoble Alpes/CNRS, Grenoble, France
| | - Yin Chen
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Gonzalo Cosa
- Department of Chemistry and Quebec Center for Advanced Materials, McGill University, Montreal, Québec, Canada
| | - Miguel A. Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast, United Kingdom
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4
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Rao MS, Hussain S. TEMPO-mediated aerobic oxidative synthesis of 2-aryl benzoxazoles via ring-opening of benzoxazoles with benzylamines. SYNTHETIC COMMUN 2021. [DOI: 10.1080/00397911.2021.1949476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
| | - Sahid Hussain
- Department of Chemistry, Indian Institute of Technology Patna, Patna, India
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5
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Akari AS, Hodgson GK, Golian KP, Impellizzeri S. Photochemical Insights on Intramolecular Dye‐Sensitized Free‐Radical Processes with a Quinoline Antenna. ChemistrySelect 2021. [DOI: 10.1002/slct.202100027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Aviya S. Akari
- Laboratory for Nanomaterials and Molecular Plasmonics Department of Chemistry and Biology Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
| | - Gregory K. Hodgson
- Laboratory for Nanomaterials and Molecular Plasmonics Department of Chemistry and Biology Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
| | - Karol P. Golian
- Laboratory for Nanomaterials and Molecular Plasmonics Department of Chemistry and Biology Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
| | - Stefania Impellizzeri
- Laboratory for Nanomaterials and Molecular Plasmonics Department of Chemistry and Biology Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
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6
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Xiao Y, Yi Z, Yu X, Xiao F. Copper-catalyzed synthesis of α-ketoamides using water and dioxygen as the oxygen source. RSC Adv 2020; 10:29114-29118. [PMID: 35521140 PMCID: PMC9055944 DOI: 10.1039/d0ra05921h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 07/27/2020] [Indexed: 01/22/2023] Open
Abstract
The reaction employing H2O and O2 as the co-oxygen source in the catalytic synthesis of α-ketoamides is described. This copper-catalyzed reaction is carried out in a tandem manner constituted by the hydroamination of alkyne, hydration of vinyl–Cu complex and subsequent oxidation. Isotope labeling and radical capture experiments reveal that the oxygen atom of α-ketone at α-ketoamides derives from O2 and the oxygen atom of amide group originates from H2O. The reaction employing H2O and O2 as the co-oxygen source in the catalytic synthesis of α-ketoamides is described. This Cu-catalyzed reaction is carried out in a tandem manner constituted by hydroamination of alkyne, hydration of vinyl–Cu complex and subsequent oxidation.![]()
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Affiliation(s)
- Yuanyuan Xiao
- Department of Health Toxicology
- Xiangya School of Public Health
- Central South University
- Changsha 410078
- PR China
| | - Zijuan Yi
- School of Chemistry and Chemical Engineering
- Hunan University of Science and Technology
- Xiangtan 411201
- China
| | - Xianyong Yu
- School of Chemistry and Chemical Engineering
- Hunan University of Science and Technology
- Xiangtan 411201
- China
| | - Fang Xiao
- Department of Health Toxicology
- Xiangya School of Public Health
- Central South University
- Changsha 410078
- PR China
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7
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Hu Q, Yue YH, Chai LQ, Tang LJ. Synthesis, characterization, spectral property, Hirshfeld surface analysis and TD/DFT calculations of 2, 6-disubstituted benzobisoxazoles. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.07.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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8
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Wylie L, Seeger ZL, Hancock AN, Izgorodina EI. Increased stability of nitroxide radicals in ionic liquids: more than a viscosity effect. Phys Chem Chem Phys 2019; 21:2882-2888. [DOI: 10.1039/c8cp04854a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Experimental EPR and quantum chemical analyses show that ionic liquid solvents can stabilise radical through intermolecular interactions.
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Affiliation(s)
- Luke Wylie
- School of Chemistry
- Monash University
- Wellington Rd
- Clayton
- Australia
| | - Zoe L. Seeger
- School of Chemistry
- Monash University
- Wellington Rd
- Clayton
- Australia
| | - Amber N. Hancock
- Division of Natural Sciences & Mathematics
- Bennington College
- Bennington
- USA
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9
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Smulik-Izydorczyk R, Dębowska K, Pięta J, Michalski R, Marcinek A, Sikora A. Fluorescent probes for the detection of nitroxyl (HNO). Free Radic Biol Med 2018; 128:69-83. [PMID: 29704623 DOI: 10.1016/j.freeradbiomed.2018.04.564] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 04/19/2018] [Accepted: 04/20/2018] [Indexed: 11/19/2022]
Abstract
Nitroxyl (HNO), which according to the IUPAC recommended nomenclature should be named azanone, is the protonated one-electron reduction product of nitric oxide. Recently, it has gained a considerable attention due to the interesting pharmacological effects of its donors. Although there has been great progress in the understanding of HNO chemistry and chemical biology, it still remains the most elusive reactive nitrogen species, and its selective detection is a real challenge. The development of reliable methodologies for the direct detection of azanone is essential for the understanding of important signaling properties of this reactive intermediate and its pharmacological potential. Over the last decade, there has been considerable progress in the development of low-molecular-weight fluorogenic probes for the detection of HNO, and therefore, in this review, we have focused on the challenges and limitations of and perspectives on nitroxyl detection based on the use of such probes.
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Affiliation(s)
- Renata Smulik-Izydorczyk
- Institute of Applied Radiation Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
| | - Karolina Dębowska
- Institute of Applied Radiation Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
| | - Jakub Pięta
- Institute of Applied Radiation Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
| | - Radosław Michalski
- Institute of Applied Radiation Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
| | - Andrzej Marcinek
- Institute of Applied Radiation Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
| | - Adam Sikora
- Institute of Applied Radiation Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland.
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10
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Greene LE, Lincoln R, Cosa G. Spatio-temporal monitoring of lipid peroxyl radicals in live cell studies combining fluorogenic antioxidants and fluorescence microscopy methods. Free Radic Biol Med 2018; 128:124-136. [PMID: 29649566 DOI: 10.1016/j.freeradbiomed.2018.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/05/2018] [Accepted: 04/06/2018] [Indexed: 12/28/2022]
Abstract
Lipid peroxidation of polyunsaturated fatty acids in cells may occur via their catalytic autoxidation through peroxyl radicals under oxidative stress conditions. Lipid peroxidation is related to a number of pathologies, and may be invoked in new forms of regulated cell death, yet it may also have beneficial roles in cell signaling cascades. Antioxidants are a natural line of defense against lipid peroxidation, and may accordingly impact the biological outcome associated with the redox chemistry of lipid peroxidation. Critical to unraveling the physiological and pathological role of lipid peroxidation is the development of novel probes with the partition, chemical sensitivity and more importantly, molecular specificity, enabling the spatial and temporal imaging of peroxyl radicals in the lipid membranes of live cells, reporting on the redox status of the cell membrane. This review describes our recent progress to visualize lipid peroxidation in model membrane systems and in live cell studies. Our work portrays the mechanistic insight leading to the development of a highly sensitive probe to monitor lipid peroxyl radicals (LOO•). It also describes technical aspects including reagents and fluorescence microscopy methodologies to consider in order to achieve the much sought after monitoring of rates of lipid peroxyl radical production in live cell studies, be it under oxidative stress but also under cell homeostasis. This review seeks to bring attention to the study of lipid redox reactions and to lay the groundwork for the adoption of fluorogenic antioxidant probeshancement and maximum intensity recorded in turn provide a benchmark to estimate, when compared to the control BODIPY dye lacking the intramolecular PeT based switch, the overall exte and related fluorescence microscopy methods toward gaining rich spatiotemporal information on lipid peroxidation in live cells.
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Affiliation(s)
- Lana E Greene
- Department of Chemistry and Quebec Center for Advanced Materials (QCAM/CQMF), McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada H3A 0B8
| | - Richard Lincoln
- Department of Chemistry and Quebec Center for Advanced Materials (QCAM/CQMF), McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada H3A 0B8
| | - Gonzalo Cosa
- Department of Chemistry and Quebec Center for Advanced Materials (QCAM/CQMF), McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada H3A 0B8.
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11
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Aliaga C, López de Arbina A, Pastenes C, Rezende MC. Antioxidant-spotting in micelles and emulsions. Food Chem 2018; 245:240-245. [DOI: 10.1016/j.foodchem.2017.10.094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/05/2017] [Accepted: 10/18/2017] [Indexed: 10/18/2022]
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12
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Liras M, Simoncelli S, Rivas-Aravena A, García O, Scaiano JC, Alarcon EI, Aspée A. Nitroxide amide-BODIPY probe behavior in fibroblasts analyzed by advanced fluorescence microscopy. Org Biomol Chem 2018; 14:4023-6. [PMID: 27065020 DOI: 10.1039/c6ob00533k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A novel synthesized nitroxide amide-BODIPY prefluorescent probe was used to study cellular redox balance that modulates nitroxide/hydroxylamine ratio in cultured human fibroblasts. FLIM quantitatively differentiated between nitroxide states of the cytoplasm-localized probe imaged by TIRF, monitoring nitroxide depletion by hydrogen peroxide; eluding incorrect interpretation if only fluorescence intensity is considered.
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Affiliation(s)
- M Liras
- Instituto de Ciencia y Tecnología de Polímeros, Consejo Superior de Investigaciones Científicas (ICTP-CSIC), Juan de la Cierva 3, 28006, Madrid, España and Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N6N5, Canada
| | - S Simoncelli
- Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N6N5, Canada and INQUIMAE and Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina
| | - A Rivas-Aravena
- Laboratorio de Radiobiología Molecular y Celular, Departamento de Aplicaciones Nucleares, Comisión Chilena de Energía Nuclear, Santiago, Chile
| | - O García
- Instituto de Ciencia y Tecnología de Polímeros, Consejo Superior de Investigaciones Científicas (ICTP-CSIC), Juan de la Cierva 3, 28006, Madrid, España
| | - J C Scaiano
- Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N6N5, Canada
| | - E I Alarcon
- Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N6N5, Canada and Bio-nanomaterials Chemistry and Engineering Laboratory, Division of Cardiac Surgery, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, Ontario K1Y 4W7, Canada.
| | - A Aspée
- Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile.
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13
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Aspée A, Aliaga C, Maretti L, Zúñiga-Núñez D, Godoy J, Pino E, Cárdenas-Jirón G, Lopez-Alarcon C, Scaiano JC, Alarcon EI. Reaction Kinetics of Phenolic Antioxidants toward Photoinduced Pyranine Free Radicals in Biological Models. J Phys Chem B 2017; 121:6331-6340. [DOI: 10.1021/acs.jpcb.7b02779] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexis Aspée
- Facultad
de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Christian Aliaga
- Facultad
de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Luca Maretti
- Department
of Chemistry and Biomolecular Sciences and Centre for Catalysis Research
and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N6N5, Canada
| | - Daniel Zúñiga-Núñez
- Facultad
de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Jessica Godoy
- Facultad
de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Eduardo Pino
- Facultad
de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Gloria Cárdenas-Jirón
- Facultad
de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Camilo Lopez-Alarcon
- Departamento
de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile, C.P. 782 0436, Santiago, Chile
| | - Juan C. Scaiano
- Department
of Chemistry and Biomolecular Sciences and Centre for Catalysis Research
and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N6N5, Canada
| | - Emilio I. Alarcon
- Department
of Chemistry and Biomolecular Sciences and Centre for Catalysis Research
and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N6N5, Canada
- Bio-nanomaterials
Chemistry and Engineering Laboratory, Division of Cardiac Surgery, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada
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14
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Matsuoka Y, Ohkubo K, Yamasaki T, Yamato M, Ohtabu H, Shirouzu T, Fukuzumi S, Yamada KI. A profluorescent nitroxide probe for ascorbic acid detection and its application to quantitative analysis of diabetic rat plasma. RSC Adv 2016. [DOI: 10.1039/c6ra07693a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
15-((9-(Ethylimino)-10-methyl-9Hbenzo[a]phenoxazin-5-yl)amino)-3,11-dioxa-7-azadispiro[5.1.58.36]hexadecan-7-yloxyl, (Nile-DiPy) has been synthesized and examined as an off–on profluorescent nitroxide probe for measuring ascorbic acid in plasma.
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Affiliation(s)
- Yuta Matsuoka
- Department of Bio-functional Science
- Faculty of Pharmaceutical Sciences
- Kyushu University
- Fukuoka 812-8582
- Japan
| | - Kei Ohkubo
- Department of Material and Life Science
- Graduate School of Engineering
- Osaka University
- ALCA and SENTAN
- Japan Science and Technology Agency (JST)
| | - Toshihide Yamasaki
- Department of Bio-functional Science
- Faculty of Pharmaceutical Sciences
- Kyushu University
- Fukuoka 812-8582
- Japan
| | - Mayumi Yamato
- Innovation Center for Medical Redox Navigation
- Kyushu University
- Fukuoka 812-8582
- Japan
| | - Hiroshi Ohtabu
- Department of Bio-functional Science
- Faculty of Pharmaceutical Sciences
- Kyushu University
- Fukuoka 812-8582
- Japan
| | - Tomonori Shirouzu
- Department of Bio-functional Science
- Faculty of Pharmaceutical Sciences
- Kyushu University
- Fukuoka 812-8582
- Japan
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 120-750
- Korea
- Faculty of Science and Technology
| | - Ken-ichi Yamada
- Department of Bio-functional Science
- Faculty of Pharmaceutical Sciences
- Kyushu University
- Fukuoka 812-8582
- Japan
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15
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Novel Coumarin Substituted Water Soluble Cyclophosphazenes as “Turn-Off” Type Fluorescence Chemosensors for Detection of Fe3+ ions in Aqueous Media. J Fluoresc 2015; 25:1819-30. [DOI: 10.1007/s10895-015-1672-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 09/15/2015] [Indexed: 10/23/2022]
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16
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Yadav N, Singh S, Mangawa SK, Dixit SK, Gupta U, Khajuria Y, Awasthi SK. Fluorescent probe 7-(prop-2-yn-1-yloxy)-2H-chromen-2-one: Experimental and DFT based approach to photophysical properties. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 148:311-317. [PMID: 25909905 DOI: 10.1016/j.saa.2015.03.113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 03/12/2015] [Accepted: 03/27/2015] [Indexed: 06/04/2023]
Abstract
Compound 7-(prop-2-yn-1-yloxy)-2H-chromen-2-one was synthesized by Pechmann condensation reaction and characterized by various spectroscopic techniques. The structure of title compound was confirmed by single crystal X-ray diffraction. The compound crystallized in the orthorhombic system with P 21 21 21 space group and the corresponding lattice parameters were found to be a=4.0138 (11) Å, α=90°; b=23.536 (6) Å, β=90°; c=10.93 (2) Å, γ=90°. The crystal packing of molecule showed that intermolecular hydrogen bonds C3-H3⋯O3 [D=3.53 Å], C-13-H13⋯O2 [D=3.67 Å] and intermolecular short interaction between C1-H1⋯C1-H1 [2.68 Å] forms a dimeric unit which finally stabilizes the crystal packing in three dimensional network in the molecule. Absorption and emission spectra shows that compound is fluorescent with good Stoke shift values ranging between 57 and 62 nm. Thermal analysis further supports by TGA, DTA. The photophysical results show that the compound exhibits change in fluorescence quantum yield with change in solvent polarity. The structural parameters and the vibrational wave numbers obtained from the optimized geometry of the compound from DFT-B3LYP calculations employing 6-311G (d,p) basis set are in good agreement with the experimental data. UV-Vis spectrum calculated by employing time dependent density functional theory (TD-DFT) is also in very good agreement with the experiment for all solvents.
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Affiliation(s)
- Neesha Yadav
- Chemical Biology Laboratory, Department of Chemistry, University of Delhi, 110007, India
| | - Shailja Singh
- Chemical Biology Laboratory, Department of Chemistry, University of Delhi, 110007, India
| | - Shrawan Kumar Mangawa
- Chemical Biology Laboratory, Department of Chemistry, University of Delhi, 110007, India
| | - Sandeep K Dixit
- Chemical Biology Laboratory, Department of Chemistry, University of Delhi, 110007, India
| | - Ujval Gupta
- School of Physics, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir 182320, India
| | - Yugal Khajuria
- School of Physics, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir 182320, India
| | - Satish Kumar Awasthi
- Chemical Biology Laboratory, Department of Chemistry, University of Delhi, 110007, India.
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17
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Aliaga C, Rezende MC. EPR spectrum of a radical from a nontypical antioxidant. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:409-411. [PMID: 24706586 DOI: 10.1002/mrc.4070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 03/05/2014] [Accepted: 03/11/2014] [Indexed: 06/03/2023]
Affiliation(s)
- Carolina Aliaga
- Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago, Chile; Centro para el Desarrollo de la Nanociencia y la Nanotecnología (CEDENNA), Universidad de Santiago de Chile, Santiago, Chile
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18
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Moghanian H, Mobinikhaledi A, Monjezi R. Synthesis, spectroscopy (vibrational, NMR and UV–vis) studies, HOMO–LUMO and NBO analysis of 8-formyl-7-hydroxy-4-methylcoumarin by ab initio calculations. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.08.043] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Sleiman M, Destaillats H, Gundel LA. Solid-phase supported profluorescent nitroxide probe for the determination of aerosol-borne reactive oxygen species. Talanta 2013; 116:1033-9. [DOI: 10.1016/j.talanta.2013.08.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/15/2013] [Accepted: 08/16/2013] [Indexed: 11/25/2022]
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20
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Mravljak J, Ojsteršek T, Pajk S, Sollner Dolenc M. Coumarin-based dual fluorescent spin-probes. Tetrahedron Lett 2013. [DOI: 10.1016/j.tetlet.2013.07.084] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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21
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Chat OA, Najar MH, Dar AA. Evaluation of reduction kinetics of 2,2-diphenyl-1-picrylhydrazyl radical by flavonoid glycoside Rutin in mixed solvent based micellar media. Colloids Surf A Physicochem Eng Asp 2013. [DOI: 10.1016/j.colsurfa.2013.06.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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Impellizzeri S, Stamplecoskie KG, Scaiano JC. Sensitized excited free-radical processes as read–write tools: impact on non-linear lithographic processes. Phys Chem Chem Phys 2013; 15:14873-8. [DOI: 10.1039/c3cp51723c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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23
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Aliaga C, Torres P, Silva F. A simple method for the determination of the partitioning of nitroxide probes in microheterogeneous media. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:779-783. [PMID: 23008158 DOI: 10.1002/mrc.3871] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 07/04/2012] [Accepted: 08/15/2012] [Indexed: 06/01/2023]
Abstract
The use of the ESR g-factor of spin labels for the easy and clean assessment of their partitioning in microheterogeneous media is described. The method constitutes a valuable alternative in those cases where the classical Benesi-Hildebrand treatment, based on UV-visible measurements, is difficult or not feasible.
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Affiliation(s)
- Carolina Aliaga
- Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago de Chile, Chile.
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24
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Braslau R, Rivera F, Lilie E, Cottman M. Urushiol Detection using a Profluorescent Nitroxide. J Org Chem 2012; 78:238-45. [DOI: 10.1021/jo301135m] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Rebecca Braslau
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, 95064
| | - Frank Rivera
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, 95064
| | - Erin Lilie
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, 95064
| | - MariEllen Cottman
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, 95064
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25
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Reaction of several resveratrol glycoside derivatives with hypochlorites in various media. Chem Nat Compd 2012. [DOI: 10.1007/s10600-012-0146-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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26
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Kertész J, Bognár B, Kormos A, Móczár I, Baranyai P, Kubinyi M, Kálai T, Hideg K, Huszthy P. Synthesis and metal ion complexation of spin labeled 18-crown-6 ethers containing an acridone or an acridine fluorophore unit. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.09.092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Abstract
Stable nitroxyl radicals are important tools in chemistry, biophysics, biology, and materials science. Their stability and the sensitivity of their EPR spectra to the local environment make them valuable molecular probes. This review seeks to give an overview of the developments in the field of nitroxide spin probes and their various applications, with the main focus on the pH-sensitive imidazoline nitroxide family.
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Affiliation(s)
- Evelyn Zottler
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Georg Gescheidt
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
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28
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Tebben L, Studer A. Nitroxides: applications in synthesis and in polymer chemistry. Angew Chem Int Ed Engl 2011; 50:5034-68. [PMID: 21538729 DOI: 10.1002/anie.201002547] [Citation(s) in RCA: 505] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Indexed: 01/23/2023]
Abstract
This Review describes the application of nitroxides to synthesis and polymer chemistry. The synthesis and physical properties of nitroxides are discussed first. The largest section focuses on their application as stoichiometric and catalytic oxidants in organic synthesis. The oxidation of alcohols and carbanions, as well as oxidative C-C bond-forming reactions are presented along with other typical oxidative transformations. A section is also dedicated to the extensive use of nitroxides as trapping reagents for C-centered radicals in radical chemistry. Alkoxyamines derived from nitroxides are shown to be highly useful precursors of C-centered radicals in synthesis and also in polymer chemistry. The last section discusses the basics of nitroxide-mediated radical polymerization (NMP) and also highlights new developments in the synthesis of complex polymer architectures.
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Affiliation(s)
- Ludger Tebben
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
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29
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Pajk S, Garvas M, Štrancar J, Pečar S. Nitroxide–fluorophore double probes: a potential tool for studying membrane heterogeneity by ESR and fluorescence. Org Biomol Chem 2011; 9:4150-9. [DOI: 10.1039/c0ob01173h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Blinco JP, Fairfull-Smith KE, Morrow BJ, Bottle SE. Profluorescent Nitroxides as Sensitive Probes of Oxidative Change and Free Radical Reactions. Aust J Chem 2011. [DOI: 10.1071/ch10442] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This paper presents a review on the use of tethered nitroxide–fluorophore molecules as probes of oxidative change and free radical generation and reaction. The proximity of the nitroxide free radical to the fluorophore suppresses the normal fluorescence emission process. Nitroxide free radical scavenging, metabolism or redox chemistry return the system to its natural fluorescent state and so these tethered nitroxide–fluorophore molecules are described as being profluorescent. A survey of profluorescent nitroxides found in the literature is provided as well as background on the mechanism of action and applications of these compounds as fluorometric probes within the fields of biological, materials and environmental sciences.
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31
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Tansakul C, Lilie E, Walter ED, Rivera F, Wolcott A, Zhang JZ, Millhauser GL, Braslau R. Distance-dependent Fluorescence Quenching and Binding of CdSe Quantum Dots by Functionalized Nitroxide Radicals. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2010; 114:7793-7805. [PMID: 20473339 PMCID: PMC2867053 DOI: 10.1021/jp1005023] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Quantum dot (QD) fluorescence is effectively quenched at low concentration by nitroxides bearing amine or carboxylic acid ligands. The association constants and fluorescence quenching of CdSe QDs with these derivatized nitroxides have been examined using electron paramagnetic resonance (EPR) and fluorescence spectroscopy. The EPR spectra in the non-protic solvent toluene are extremely sensitive to intermolecular and intramolecular hydrogen bonding of the functionalized nitroxides. Fluorescence measurements show that quenching of QD luminescence is nonlinear, with a strong dependence on the distance between the radical and the QD. The quenched fluorescence is restored when the surface-bound nitroxides are converted to hydroxylamines by mild reducing agents, or trapped by carbon radicals to form alkoxyamines. EPR studies indicate that photoreduction of the nitroxide occurs in toluene solution upon photoexcitation at 365 nm. However, photolysis in benzene solution gives no photoreduction, suggesting that photoreduction in toluene is independent of the quenching mechanism. The fluorescence quenching of QDs by nitroxide binding is a reversible process.
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Affiliation(s)
- Chittreeya Tansakul
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064 USA
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32
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Aspée A, Orrego A, Alarcón E, López-Alarcón C, Poblete H, González-Nilo D. Antioxidant reactivity toward nitroxide probes anchored into human serum albumin. A new model for studying antioxidant repairing capacity of protein radicals. Bioorg Med Chem Lett 2009; 19:6382-5. [DOI: 10.1016/j.bmcl.2009.09.070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 09/15/2009] [Accepted: 09/17/2009] [Indexed: 11/24/2022]
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33
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Jia M, Tang Y, Lam YF, Green SA, Blough NV. Prefluorescent Nitroxide Probe for the Highly Sensitive Determination of Peroxyl and Other Radical Oxidants. Anal Chem 2009; 81:8033-40. [DOI: 10.1021/ac901374m] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Min Jia
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, and Chemistry Department, Michigan Technological University, Houghton, Michigan 49931
| | - Yu Tang
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, and Chemistry Department, Michigan Technological University, Houghton, Michigan 49931
| | - Yiu-Fai Lam
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, and Chemistry Department, Michigan Technological University, Houghton, Michigan 49931
| | - Sarah A. Green
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, and Chemistry Department, Michigan Technological University, Houghton, Michigan 49931
| | - Neil V. Blough
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, and Chemistry Department, Michigan Technological University, Houghton, Michigan 49931
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34
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35
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Liu Y, Liu S, Wang Y. TEMPO-based Redox-sensitive Fluorescent Probes and Their Applications to Evaluating Intracellular Redox Status in Living Cells. CHEM LETT 2009. [DOI: 10.1246/cl.2009.588] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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36
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Oliveira CM, Ferreira ACS, de Pinho PG, Silva AMS. New qualitative approach in the characterization of antioxidants in white wines by antioxidant free radical scavenging and NMR techniques. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2008; 56:10326-10331. [PMID: 18828596 DOI: 10.1021/jf8013662] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The aim of this study was to obtain new information on antioxidant compounds in white wines. For this purpose, white wine degradation was promoted by a forced aged protocol, and six normally aged white wines from different vintages were analyzed. Both normal and forced aged wines were sequentially extracted using hexane and ethyl acetate. Apolar antioxidants were removed using hexane, and polar antioxidants were extracted with ethyl acetate. This last residue was subject to partial re-extraction with hexane and acetone. The antioxidant capacity of the wines and of each fraction was evaluated by two free radical methods, ABTS and DPPH. Normal aging provides a decrease in the total antioxidant capacity of wines. The antioxidant activity of ethyl acetate/acetone extracts was approximately 95% higher than that found for the hexane extracts. Concerning the forced aged wines, results showed that the wine submitted to a temperature of 60 degrees C for 21 days had higher antioxidant activity than that submitted to a temperature of 20 degrees C. With regard to the ethyl acetate/acetone extracts, oxygen and temperature treatment leads to a decrease in their antioxidant activity. NMR analysis was performed in the highest antioxidant capacity organic fractions (ethyl acetate/acetone extracts) and in the aqueous fraction of the control wine (T = 20 degrees C), in order to attempt the characterization of species involved in oxygen protection. Possible structures of antioxidant compounds in white wines were proposed. Two of these are tyrosol-like structures. This molecule is a well-known phenolic compound in wine, and it is reported to have antioxidative effects.
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Affiliation(s)
- Carla M Oliveira
- Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. Bernardino de Almeida, 4200-072 Porto, Portugal.
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37
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Chen Y, Qian L, Zhang W, Han B. Efficient Aerobic Oxidative Synthesis of 2‐Substituted Benzoxazoles, Benzothiazoles, and Benzimidazoles Catalyzed by 4‐Methoxy‐TEMPO. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200803381] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Yong‐Xing Chen
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou 730000 (P. R. China), Fax: (+86) 931‐891‐2582
| | - Ling‐Feng Qian
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou 730000 (P. R. China), Fax: (+86) 931‐891‐2582
| | - Wei Zhang
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou 730000 (P. R. China), Fax: (+86) 931‐891‐2582
| | - Bing Han
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou 730000 (P. R. China), Fax: (+86) 931‐891‐2582
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38
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Chen Y, Qian L, Zhang W, Han B. Efficient Aerobic Oxidative Synthesis of 2‐Substituted Benzoxazoles, Benzothiazoles, and Benzimidazoles Catalyzed by 4‐Methoxy‐TEMPO. Angew Chem Int Ed Engl 2008; 47:9330-3. [DOI: 10.1002/anie.200803381] [Citation(s) in RCA: 284] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Yong‐Xing Chen
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou 730000 (P. R. China), Fax: (+86) 931‐891‐2582
| | - Ling‐Feng Qian
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou 730000 (P. R. China), Fax: (+86) 931‐891‐2582
| | - Wei Zhang
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou 730000 (P. R. China), Fax: (+86) 931‐891‐2582
| | - Bing Han
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, 222 Tianshui Street S., Lanzhou 730000 (P. R. China), Fax: (+86) 931‐891‐2582
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