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Yamauchi K, Matsuoka Y, Takahashi M, Izumi Y, Naka H, Taniguchi Y, Kawai K, Bamba T, Yamada KI. Detection and structural analysis of pyrimidine-derived radicals generated on DNA using a profluorescent nitroxide probe. Chem Commun (Camb) 2021; 58:56-59. [PMID: 34897335 DOI: 10.1039/d1cc04998d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The oxidative damage of DNA is associated with aging and the development of various diseases. Although nucleoside-derived radicals play an important role in DNA oxidation, their analysis methods are limited. Herein, we propose a fluorometric detection and structural analysis of radicals on the surface of oxidatively damaged DNA using a profluorescent nitroxide probe combined with liquid chromatography-fluorometry and high-resolution tandem mass spectrometry.
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Affiliation(s)
- Kosho Yamauchi
- Physical Chemistry for Life Science Laboratory, Faculty of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan.
| | - Yuta Matsuoka
- Physical Chemistry for Life Science Laboratory, Faculty of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan.
| | - Masatomo Takahashi
- Metabolomics Laboratory, Research Center for Transomics Medicine, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan
| | - Yoshihiro Izumi
- Metabolomics Laboratory, Research Center for Transomics Medicine, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan
| | - Hideto Naka
- Physical Chemistry for Life Science Laboratory, Faculty of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan.
| | - Yosuke Taniguchi
- Frontier in Biofunction of Nucleic Acid and Organic Chemistry, Faculty of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan
| | - Kazuaki Kawai
- Department of Environmental Oncology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Takeshi Bamba
- Metabolomics Laboratory, Research Center for Transomics Medicine, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan
| | - Ken-Ichi Yamada
- Physical Chemistry for Life Science Laboratory, Faculty of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan.
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2
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Chang Z, Huang J, Wang S, Chen G, Zhao H, Wang R, Zhao D. Copper catalyzed late-stage C(sp 3)-H functionalization of nitrogen heterocycles. Nat Commun 2021; 12:4342. [PMID: 34267229 PMCID: PMC8282657 DOI: 10.1038/s41467-021-24671-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 06/21/2021] [Indexed: 11/15/2022] Open
Abstract
Nitrogen heterocycle represents a ubiquitous skeleton in natural products and drugs. Late-stage C(sp3)-H bond functionalization of N-heterocycles with broad substrate scope remains a challenge and of particular significance to modern chemical synthesis and pharmaceutical chemistry. Here, we demonstrate copper-catalysed late-stage C(sp3)-H functionalizaion of N-heterocycles using commercially available catalysts under mild reaction conditions. We have investigated 8 types of N-heterocycles which are usually found as medicinally important skeletons. The scope and utility of this approach are demonstrated by late-stage C(sp3)-H modification of these heterocycles including a number of pharmaceuticals with a broad range of nucleophiles, e.g. methylation, arylation, azidination, mono-deuteration and glycoconjugation etc. Preliminary mechanistic studies reveal that the reaction undergoes a C-H fluorination process which is followed by a nucleophilic substitution.
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Affiliation(s)
- Zhe Chang
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Jialin Huang
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Si Wang
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Geshuyi Chen
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China
| | - Heng Zhao
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Rui Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China.
| | - Depeng Zhao
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China.
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3
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Gomez-Mejiba SE, Ramirez DC. Trapping of DNA radicals with the nitrone spin trap 5,5-dimethyl-1-pyrroline N-oxide and genotoxic damage: Recent advances using the immuno-spin trapping technology. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2019; 782:108283. [DOI: 10.1016/j.mrrev.2019.108283] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 06/14/2019] [Accepted: 06/22/2019] [Indexed: 02/07/2023]
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4
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Lee VEY, Chin CF, Ang WH. Design and investigation of photoactivatable platinum(iv) prodrug complexes of cisplatin. Dalton Trans 2019; 48:7388-7393. [PMID: 30957798 DOI: 10.1039/c9dt00540d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Platinum(iv) carboxylate scaffolds have garnered considerable research interest because they can be engineered to function as prodrugs of clinical platinum(ii) anticancer drugs. These platinum(iv) prodrug complexes are stable and tunable, and activated by reduction to release their cytotoxic platinum(ii) cargo. Here we propose new platinum(iv) prodrug complexes designed to release cisplatin via photoreduction upon UV irradiation. The central strategy is to utilise aryl carboxylate ligands on the axial positions of that platinum(iv) scaffold that confer significant UV absorption and would stabilise carboxyl radical formation, thus favouring homolytic Pt-O bond cleavage. We isolated and identified aryl carboxyl radicals via spin-trapping and showed that the photoreduced platinum species mirror cisplatin reactivity toward DNA bases, thereby validating the efficacy of this approach.
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Affiliation(s)
- Violet Eng Yee Lee
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543. and NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, 21 Lower Kent Ridge Rd, Singapore 119077
| | - Chee Fei Chin
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543.
| | - Wee Han Ang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543. and NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, 21 Lower Kent Ridge Rd, Singapore 119077
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5
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Serrano MP, Vignoni M, Lorente C, Vicendo P, Oliveros E, Thomas AH. Thymidine radical formation via one-electron transfer oxidation photoinduced by pterin: Mechanism and products characterization. Free Radic Biol Med 2016; 96:418-31. [PMID: 27154982 DOI: 10.1016/j.freeradbiomed.2016.04.196] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 04/26/2016] [Accepted: 04/29/2016] [Indexed: 12/13/2022]
Abstract
UV-A radiation (320-400nm), recognized as a class I carcinogen, induces damage to the DNA molecule and its components through different mechanisms. Pterin derivatives are involved in various biological functions, including enzymatic processes, and it has been demonstrated that oxidized pterins may act as photosensitizers. In particular, they accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder. We have investigated the ability of pterin (Ptr), the parent compound of oxidized pterins, to photosensitize the degradation of the pyrimidine nucleotide thymidine 5'-monophosphate (dTMP) in aqueous solutions under UV-A irradiation. Although thymine is less reactive than purine nucleobases, our results showed that Ptr is able to photoinduce the degradation of dTMP and that the process is initiated by an electron transfer from the nucleotide to the triplet excited state of Ptr. In the presence of molecular oxygen, the photochemical process leads to the oxidation of dTMP, whereas Ptr is not consumed. In the absence of oxygen, both compounds are consumed to yield a product in which the pterin moiety is covalently linked to the thymine. This compound retains some of the spectroscopic properties of Ptr, such as absorbance in the UV-A region and fluorescence properties.
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Affiliation(s)
- Mariana P Serrano
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Diagonal 113 y 64, 1900 La Plata, Argentina
| | - Mariana Vignoni
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Diagonal 113 y 64, 1900 La Plata, Argentina
| | - Carolina Lorente
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Diagonal 113 y 64, 1900 La Plata, Argentina
| | - Patricia Vicendo
- Laboratoire des Interactions Moléculaires et Réactivité Chimique et Photochimique (IMRCP), UMR 5623-CNRS/UPS, Université Toulouse III (Paul Sabatier), 118, route de Narbonne, F-31062 Toulouse cédex 9, France
| | - Esther Oliveros
- Laboratoire des Interactions Moléculaires et Réactivité Chimique et Photochimique (IMRCP), UMR 5623-CNRS/UPS, Université Toulouse III (Paul Sabatier), 118, route de Narbonne, F-31062 Toulouse cédex 9, France
| | - Andrés H Thomas
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Diagonal 113 y 64, 1900 La Plata, Argentina.
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6
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Spiteller G, Afzal M. The action of peroxyl radicals, powerful deleterious reagents, explains why neither cholesterol nor saturated fatty acids cause atherogenesis and age-related diseases. Chemistry 2014; 20:14928-45. [PMID: 25318456 DOI: 10.1002/chem.201404383] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cells respond to alterations in their membrane structure by activating hydrolytic enzymes. Thus, polyunsaturated fatty acids (PUFAs) are liberated. Free PUFAs react with molecular oxygen to give lipid hydroperoxide molecules (LOOHs). In case of severe cell injury, this physiological reaction switches to the generation of lipid peroxide radicals (LOO(·)). These radicals can attack nearly all biomolecules such as lipids, carbohydrates, proteins, nucleic acids and enzymes, impairing their biological functions. Identical cell responses are triggered by manipulation of food, for example, heating/grilling and particularly homogenization, representing cell injury. Cholesterol as well as diets rich in saturated fat have been postulated to accelerate the risk of atherosclerosis while food rich in unsaturated fatty acids has been claimed to lower this risk. However, the fact is that LOO(·) radicals generated from PUFAs can oxidize cholesterol to toxic cholesterol oxides, simulating a reduction in cholesterol level. In this review it is shown how active LOO(·) radicals interact with biomolecules at a speed transcending usual molecule-molecule reactions by several orders of magnitude. Here, it is explained how functional groups are fundamentally transformed by an attack of LOO(·) with an obliteration of essential biomolecules leading to pathological conditions. A serious reconsideration of the health and diet guidelines is required.
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Affiliation(s)
- Gerhard Spiteller
- University of Bayreuth, Universitätsstr. 30, 95445 Bayreuth (Germany).
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7
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Ravanat JL, Breton J, Douki T, Gasparutto D, Grand A, Rachidi W, Sauvaigo S. Radiation-mediated formation of complex damage to DNA: a chemical aspect overview. Br J Radiol 2014; 87:20130715. [PMID: 24472775 DOI: 10.1259/bjr.20130715] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
During the last three decades, a considerable amount of work has been undertaken to determine the nature, the mechanism of formation and the biological consequences of radiation-induced DNA lesions. Most of the information was obtained via the development of chemical approaches, including theoretical, analytical and organic synthesis methods. Since it is not possible to present all the results obtained in this review article, we will focus on recent data dealing with the formation of complex DNA lesions produced by a single oxidation event, as these lesions may play a significant role in cellular responses to ionizing radiation and also to other sources of oxidative stress. Through the description of specific results, the contribution of different chemical disciplines in the assessment of the structure, the identification of the mechanism of formation and the biological impacts in terms of repair and mutagenicity of these complex radiation-induced DNA lesions will be highlighted.
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Affiliation(s)
- J-L Ravanat
- Laboratoire Lésions des Acides Nucléiques, Université Joseph Fourier/CEA/Institut Nanoscience et Cryogénie/SCIB, UMR-E3, Grenoble, France
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8
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Zhang X. Single electron transfer between selectfluor and chloride: A mass spectrometric and theoretical study. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.07.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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9
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Xiang Z. Hydrogen abstraction/nucleophilic addition: A novel reaction pathway between aromatic olefin radical cation and TEMPO. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2012.06.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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10
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Du QQ, Liu SY, Xu RF, Li M, Song FR, Liu ZQ. Studies on structures and activities of initial Maillard reaction products by electrospray ionisation mass spectrometry combined with liquid chromatography in processing of red ginseng. Food Chem 2012; 135:832-8. [DOI: 10.1016/j.foodchem.2012.04.126] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 02/15/2012] [Accepted: 04/23/2012] [Indexed: 12/21/2022]
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12
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13
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Bhattacharjee S, Deterding LJ, Chatterjee S, Jiang J, Ehrenshaft M, Lardinois O, Ramirez DC, Tomer KB, Mason RP. Site-specific radical formation in DNA induced by Cu(II)-H₂O₂ oxidizing system, using ESR, immuno-spin trapping, LC-MS, and MS/MS. Free Radic Biol Med 2011; 50:1536-45. [PMID: 21382477 PMCID: PMC3100166 DOI: 10.1016/j.freeradbiomed.2011.02.034] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 02/23/2011] [Accepted: 02/25/2011] [Indexed: 11/29/2022]
Abstract
Oxidative stress-related damage to the DNA macromolecule produces a multitude of lesions that are implicated in mutagenesis, carcinogenesis, reproductive cell death, and aging. Many of these lesions have been studied and characterized by various techniques. Of the techniques that are available, the comet assay, HPLC-EC, GC-MS, HPLC-MS, and especially HPLC-MS/MS remain the most widely used and have provided invaluable information on these lesions. However, accurate measurement of DNA damage has been a matter of debate. In particular, there have been reports of artifactual oxidation leading to erroneously high damage estimates. Further, most of these techniques measure the end product of a sequence of events and thus provide only limited information on the initial radical mechanism. We report here a qualitative measurement of DNA damage induced by a Cu(II)-H₂O₂ oxidizing system using immuno-spin trapping (IST) with electron paramagnetic resonance (EPR), MS, and MS/MS. The radical generated is trapped by DMPO immediately upon formation. The DMPO adduct formed is initially EPR active but subsequently is oxidized to the stable nitrone, which can then be detected by IST and further characterized by MS and MS/MS.
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Affiliation(s)
- Suchandra Bhattacharjee
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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14
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Koszytkowska-Stawińska M, Mironiuk-Puchalska E, Sas W. Synthesis of 1-pyrroline 1-oxides analogous to pseudouridine. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.02.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Domingues P, Fonseca C, Reis A, Domingues MRM. Identification of isomeric spin adducts of Leu-Tyr and Tyr-Leu free radicals using liquid chromatography-tandem mass spectrometry. Biomed Chromatogr 2011; 26:51-60. [DOI: 10.1002/bmc.1624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Revised: 01/22/2011] [Accepted: 01/24/2011] [Indexed: 01/08/2023]
Affiliation(s)
- Pedro Domingues
- Mass Spectrometry Centre; Department of Chemistry; University of Aveiro; 3810-193; Aveiro; Portugal
| | - Conceição Fonseca
- Mass Spectrometry Centre; Department of Chemistry; University of Aveiro; 3810-193; Aveiro; Portugal
| | - Ana Reis
- Mass Spectrometry Centre; Department of Chemistry; University of Aveiro; 3810-193; Aveiro; Portugal
| | - M. Rosário M. Domingues
- Mass Spectrometry Centre; Department of Chemistry; University of Aveiro; 3810-193; Aveiro; Portugal
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16
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Metal-independent decomposition of hydroperoxides by halogenated quinones: detection and identification of a quinone ketoxy radical. Proc Natl Acad Sci U S A 2009; 106:11466-71. [PMID: 19556549 DOI: 10.1073/pnas.0900065106] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have shown recently that halogenated quinones could enhance the decomposition of hydroperoxides and formation of alkoxyl/hydroxyl radicals through a metal-independent mechanism. However, neither the proposed quinone enoxy radical intermediate, nor the major reaction products were unambiguously identified. In the present study, one of the major reaction products between 2,5-dichloro-1,4-benzoquinone (DCBQ) and t-butylhydroperoxide (t-BuOOH) was isolated and purified by semipreparative HPLC, and identified as 2-hydroxy-3-t-butoxy-5-chloro-1,4-benzoquinone [CBQ(OH)-O-t-Bu], which is the rearranged isomer of the postulated quinone-peroxide reaction intermediate. The formation of CBQ(OH)-O-t-Bu was found to be inhibited by the spin trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and concurrently, a new DMPO adduct with 1-chlorine isotope peak clusters at m/z 268 was observed. Further electron spin resonance (ESR) spin-trapping, (1)H-NMR and HPLC/Fourier transform ion cyclotron resonance (FTICR) mass spectrometric studies with oxygen-17-labeled and unlabeled hydrogen peroxide strongly suggest that the radical trapped by DMPO is a carbon-centered quinone ketoxy radical, which is the spin isomer of the proposed oxygen-centered quinone enoxy radical. Analogous results were observed when DCBQ was substituted by other halogenated quinones. This study represents the first detection and identification of an unusual carbon-centered quinone ketoxy radical, which provides direct experimental evidence to further support and expand our previously proposed mechanism for metal-independent decomposition of hydroperoxides by halogenated quinones.
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Schäfer M, Drayß M, Springer A, Zacharias P, Meerholz K. Radical Cations in Electrospray Mass Spectrometry: Formation of Open‐Shell Species, Examination of the Fragmentation Behaviour in ESI‐MS
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and Reaction Mechanism Studies by Detection of Transient Radical Cations. European J Org Chem 2007. [DOI: 10.1002/ejoc.200700199] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Mathias Schäfer
- Institute for Organic Chemistry, University of Cologne, Greinstrasse 4, 50939 Köln, Germany, Fax: +49‐221‐4703064
| | - Miriam Drayß
- Institute for Organic Chemistry, University of Cologne, Greinstrasse 4, 50939 Köln, Germany, Fax: +49‐221‐4703064
| | - Andreas Springer
- Department of Chemistry, Free University Berlin, Berlin, Germany
| | - Philipp Zacharias
- Institute of Physical Chemistry, University of Cologne, Köln, Germany
| | - Klaus Meerholz
- Institute of Physical Chemistry, University of Cologne, Köln, Germany
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18
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:266-277. [PMID: 17262881 DOI: 10.1002/jms.1071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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Abstract
Immuno-spin trapping is a highly sensitive method for detecting DNA radicals in biological systems. This technique involves three main steps: (i) in situ and real-time trapping of DNA radicals with the nitrone spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), thus forming DMPO-DNA nitrone adducts (referred to here as nitrone adducts); (ii) purification of nitrone adducts; and (iii) analysis of nitrone adducts by heterogeneous immunoassays using Abs against DMPO. In experiments, DMPO is added prior to the formation of free radicals. It diffuses easily through all cell compartments and is present when DNA free radicals are formed as a result of oxidative damage. Due to its low toxicity, DMPO can be used in cells at high enough concentrations to out-compete the normal reactions of DNA radicals, thus ensuring a high yield of DNA nitrone adducts. Because both protein and DNA nitrone adducts are formed, it is important that the DNA be pure in order to avoid misinterpretations. Depending on the model under study, this protocol can be completed in as few as 6 h.
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Affiliation(s)
- Dario C Ramirez
- Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institutes of Health, 111 TW Alexander Drive, Building 101, MD F0-02, Research Triangle Park, North Carolina 27709, USA.
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