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Bolton JL, Dunlap T. Formation and Biological Targets of Quinones: Cytotoxic versus Cytoprotective Effects. Chem Res Toxicol 2016; 30:13-37. [PMID: 27617882 PMCID: PMC5241708 DOI: 10.1021/acs.chemrestox.6b00256] [Citation(s) in RCA: 248] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Quinones represent a class of toxicological intermediates, which can create a variety of hazardous effects in vivo including, acute cytotoxicity, immunotoxicity, and carcinogenesis. In contrast, quinones can induce cytoprotection through the induction of detoxification enzymes, anti-inflammatory activities, and modification of redox status. The mechanisms by which quinones cause these effects can be quite complex. The various biological targets of quinones depend on their rate and site of formation and their reactivity. Quinones are formed through a variety of mechanisms from simple oxidation of catechols/hydroquinones catalyzed by a variety of oxidative enzymes and metal ions to more complex mechanisms involving initial P450-catalyzed hydroxylation reactions followed by two-electron oxidation. Quinones are Michael acceptors, and modification of cellular processes could occur through alkylation of crucial cellular proteins and/or DNA. Alternatively, quinones are highly redox active molecules which can redox cycle with their semiquinone radical anions leading to the formation of reactive oxygen species (ROS) including superoxide, hydrogen peroxide, and ultimately the hydroxyl radical. Production of ROS can alter redox balance within cells through the formation of oxidized cellular macromolecules including lipids, proteins, and DNA. This perspective explores the varied biological targets of quinones including GSH, NADPH, protein sulfhydryls [heat shock proteins, P450s, cyclooxygenase-2 (COX-2), glutathione S-transferase (GST), NAD(P)H:quinone oxidoreductase 1, (NQO1), kelch-like ECH-associated protein 1 (Keap1), IκB kinase (IKK), and arylhydrocarbon receptor (AhR)], and DNA. The evidence strongly suggests that the numerous mechanisms of quinone modulations (i.e., alkylation versus oxidative stress) can be correlated with the known pathology/cytoprotection of the parent compound(s) that is best described by an inverse U-shaped dose-response curve.
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Affiliation(s)
- Judy L Bolton
- Department of Medicinal Chemistry and Pharmacognosy (M/C 781), College of Pharmacy, University of Illinois at Chicago , 833 S. Wood Street, Chicago, Illinois 60612-7231, United States
| | - Tareisha Dunlap
- Department of Medicinal Chemistry and Pharmacognosy (M/C 781), College of Pharmacy, University of Illinois at Chicago , 833 S. Wood Street, Chicago, Illinois 60612-7231, United States
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Wangpradit O, Rahaman A, Mariappan SVS, Buettner GR, Robertson LW, Luthe G. Breaking the dogma: PCB-derived semiquinone free radicals do not form covalent adducts with DNA, GSH, and amino acids. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:2138-2147. [PMID: 26396011 PMCID: PMC4767158 DOI: 10.1007/s11356-015-5007-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 07/01/2015] [Indexed: 06/05/2023]
Abstract
Covalent bond formations of free radical metabolites with biomolecules like DNA and proteins are thought to constitute a major mechanism of toxicity and carcinogenesis. Glutathione (GSH) is generally accepted as a radical scavenger protecting the cell. In the present study, we investigated a semiquinone radical (SQ(●-)) metabolite of the semivolatile 4-chlorobiphenyl, using electron paramagnetic resonance spectroscopy, and oxygen consumption. Proton nuclear magnetic resonance ((1)H NMR) and liquid chromatography-mass spectrometry (LC-MS) were also employed to elucidate the radical interaction with DNA, amino acids, and GSH. We found that DNA and oligonucleotides stabilized SQ(●-) by electron delocalization in the π-stacking system, resulting in persistent radical intercalated, rather than forming a covalent bond with SQ(●-). This finding was strongly supported by the semiempirical calculation of the semioccupied molecular orbital and the linear combination of the atomic orbitals, indicating 9.8 kcal mol(-1) energy gain. The insertion of SQ(●-) into the DNA strand may result in DNA strand breaks and interruption of DNA replication process or even activate radical mediated secondary reactions. The presence of amino acids resulted in a decrease of the electron paramagnetic resonance (EPR) signal of SQ(●-) and correlated with their isoelectric points. The pH shifts the equilibrium of the dianions of hydroquinone and influenced indirectly the formation of SQ(●-). Similar findings were observed with GSH and Cys. GSH and Cys functioned as indirect radical scavengers; their activities depend on their chemical equilibria with the corresponding quinones, and their further reaction via Michael addition. The generally accepted role of GSH as radical scavenger in biological systems should be reconsidered based upon these findings, questioning the generally accepted view of radical interaction of semiquinones with biologically active compounds, like DNA, amino acids, proteins, and radical scavengers like GSH.
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Affiliation(s)
- Orarat Wangpradit
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
- Sirindhorn College of Public Health, BanSuan, Muang, Chonburi, 2000, Thailand
| | - Asif Rahaman
- Department of Chemistry, City College of New York, Convent Avenue at 138th St., New York, NY, 10031, USA
| | - S V Santhana Mariappan
- Central High-Field NMR Research Facility, Department of Chemistry, The University of Iowa, Iowa, IA, 52242, USA
| | - Garry R Buettner
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
- Free Radical and Radiation Biology Program, The University of Iowa, Iowa, IA, 52242, USA
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
| | - Gregor Luthe
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA.
- School of Life Science, Engineering & Design, Saxion University of Applied Sciences, Enschede, Netherlands.
- Luthe-Pharma, Fabrikstrasse 3, 48599, Gronau.
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Song Y, Ambati J, Parkin S, Rankin SE, Robertson LW, Lehmler HJ. Crystal structure and density functional theory studies of toxic quinone metabolites of polychlorinated biphenyls. CHEMOSPHERE 2011; 85:386-392. [PMID: 21824639 PMCID: PMC3206982 DOI: 10.1016/j.chemosphere.2011.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 06/29/2011] [Accepted: 07/06/2011] [Indexed: 05/31/2023]
Abstract
Lower chlorinated polychlorinated biphenyls (PCBs) are readily metabolized via hydroxylated metabolites to reactive PCB quinones. Although these PCB metabolites elicit biochemical changes by mechanisms involving cellular target molecules, such as the aryl hydrocarbon receptor, and toxicity by interacting with enzymes like topoisomerases, only few PCB quinones have been synthesized and their conformational properties investigated. Similar to the parent compounds, knowledge of the three-dimensional structure of PCB quinones may therefore be important to assess their fate and risk. To address this gap in our knowledge, the gas phase molecular structure of a series of PCB quinones was predicted using HF/3-21G, B3LYP/6-31G∗∗ and UB3LYP/6-311G∗∗ calculations and compared to the respective solid state structure. All three methods overestimated the Cl-C bond length, but otherwise provided a reasonable approximation of the solid state bond angles and bond lengths. Overall, the UB3LYP/6-311G∗∗ level of theory yielded the best approximation of the molecular structure of PCB quinones in the solid state. Chlorine addition at the ortho position of both rings was found to increase the dihedral angle of the resulting quinone compound, which may have important implications for their interaction with cellular targets and, thus, their toxicity.
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Affiliation(s)
- Yang Song
- Key Laboratory on Luminescence and Real-Time Analysis (Ministry of Education), College of Pharmaceutical Sciences, Southwest University, Chong Qing, 400716, P.R. China
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
| | - Jyothirmai Ambati
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-13 0046, USA
| | - Sean Parkin
- Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Stephen E. Rankin
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-13 0046, USA
| | - Larry W. Robertson
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA 52242-5000, USA
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA 52242-5000, USA
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Anderson DG, Mariappan SVS, Buettner GR, Doorn JA. Oxidation of 3,4-dihydroxyphenylacetaldehyde, a toxic dopaminergic metabolite, to a semiquinone radical and an ortho-quinone. J Biol Chem 2011; 286:26978-86. [PMID: 21642436 DOI: 10.1074/jbc.m111.249532] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The oxidation and toxicity of dopamine is believed to contribute to the selective neurodegeneration associated with Parkinson disease. The formation of reactive radicals and quinones greatly contributes to dopaminergic toxicity through a variety of mechanisms. The physiological metabolism of dopamine to 3,4-dihydroxyphenylacetaldehyde (DOPAL) via monoamine oxidase significantly increases its toxicity. To more adequately explain this enhanced toxicity, we hypothesized that DOPAL is capable of forming radical and quinone species upon oxidation. Here, two unique oxidation products of DOPAL are identified. Several different oxidation methods gave rise to a transient DOPAL semiquinone radical, which was characterized by electron paramagnetic resonance spectroscopy. NMR identified the second oxidation product of DOPAL as the ortho-quinone. Also, carbonyl hydration of DOPAL in aqueous media was evident via NMR. Interestingly, the DOPAL quinone exists exclusively in the hydrated form. Furthermore, the enzymatic and chemical oxidation of DOPAL greatly enhance protein cross-linking, whereas auto-oxidation results in the production of superoxide. Also, DOPAL was shown to be susceptible to oxidation by cyclooxygenase-2 (COX-2). The involvement of this physiologically relevant enzyme in both oxidative stress and Parkinson disease underscores the potential importance of DOPAL in the pathogenesis of this condition.
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Affiliation(s)
- David G Anderson
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City, Iowa 52242-1112, USA
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