1
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Matsui T, Yamada N, Kuno H, Kanaly RA. Characterization of N-(2,6-dimethylphenyl)hydroxylamine adducts of 2'-deoxyguanosine under weakly basic conditions. CHEMOSPHERE 2020; 252:126530. [PMID: 32224358 DOI: 10.1016/j.chemosphere.2020.126530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/14/2020] [Accepted: 03/16/2020] [Indexed: 06/10/2023]
Abstract
Aromatic amines are a class of chemical carcinogens that are activated by cytochrome P450 enzymes to form arylhydroxylamines that are conjugated to form N-acetoxyarylamines or N-sulfonyloxyarylamines. These conjugates undergo N-O bond cleavage to become reactive nitrenium ions that may form DNA adducts. Numerous studies in the past using N-acetoxyarylamines to investigate DNA adduct formation were conducted, however, less is known in regard to DNA adduct formation directly from arylhydroxylamines - especially under conditions that mimic the physiological conditions of cells such as weakly basic conditions. In this study, 2'-deoxyguanosine (dG) was exposed to N-(2,6-dimethylphenyl)hydroxylamine (2,6-DMPHA) and N-phenylhydroxylamine (PHA) at pH 7.4 without enzymes and analyzed by liquid chromatography high resolution mass spectrometry (LC-HRMS). 2,6-DMPHA exposure resulted in the production of relatively low amounts of adducts however the identities of at least six different adducts that were formed through reactions with carbon, nitrogen and oxygen of 2'-deoxyguanosine were proposed based upon different analytical approaches including HRMS CID fragmentation and NMR analyses. Contrastively, PHA exposure under identical conditions resulted in one adduct at the C8 position. It was concluded from these results and results of theoretical calculations that nitrenium ions produced from 2,6-DMPHA were relatively more stable resulting in longer nitrenium ion lifetimes which ultimately led to greater potential for 2,6-DMPHA nitrenium ions to react with multiple sites on dG.
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Affiliation(s)
- Takuya Matsui
- Department of Life and Environmental System Science, Graduate School of Nanobiosciences, Yokohama City University, 22-2 Seto, Kanazawa, Kanagawa, Yokohama, 236-0027, Japan; Toxicology Research Laboratories, Central Pharmaceutical Research Institute Japan Tobacco Inc., 1-13-2 Fukuura, Kanazawa-ku, Yokohama-city, Kanagawa, 236-0004, Japan
| | - Naohito Yamada
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute Japan Tobacco Inc., 1-13-2 Fukuura, Kanazawa-ku, Yokohama-city, Kanagawa, 236-0004, Japan
| | - Hideyuki Kuno
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute Japan Tobacco Inc., 1-13-2 Fukuura, Kanazawa-ku, Yokohama-city, Kanagawa, 236-0004, Japan
| | - Robert A Kanaly
- Department of Life and Environmental System Science, Graduate School of Nanobiosciences, Yokohama City University, 22-2 Seto, Kanazawa, Kanagawa, Yokohama, 236-0027, Japan.
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2
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Du L, Yan Z, Zhu Z, Cheng SC, Zhang Y, Li X, Tang W, Phillips DL. Time-Resolved Spectroscopic Observation of Diphenylnitrenium Ion Reactions with Guanosine. J Org Chem 2020; 85:8792-8797. [PMID: 32527081 DOI: 10.1021/acs.joc.0c00517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Arylnitrenium ions have gained attention for their high reactivity toward guanosine, which in some cases has been linked to carcinogenesis. Although many studies have examined covalent addition reactions between arylnitrenium ions and guanosine, there is still some uncertainty regarding the attack position of nitrenium ions on guanosine and its derivatives. In this paper, we employ nanosecond transient absorption and nanosecond time-resolved resonance Raman spectroscopy to investigate the reaction between the N,N-di(4-bromophenyl) nitrenium ion (2) and guanosine. Our time-resolved spectroscopic results and photochemical product analysis results show that the reaction of guanosine with 2 generates an N7 intermediate that subsequently undergoes rearrangement and deprotonation to produce a C8 adduct. Comparing these results to our previous study between the 2-fluorenylnitrenium ion and guanosine indicates that the structure and properties of arylnitrenium ions are able to influence the reaction pathways and intermediate structures.
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Affiliation(s)
- Lili Du
- Department of Chemistry, The University of Hong Kong, Hong Kong S.A.R., P. R. China.,School of Life Sciences, Jiangsu University, Zhenjiang 212013, P. R. China
| | - Zhiping Yan
- Department of Chemistry, The University of Hong Kong, Hong Kong S.A.R., P. R. China.,Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing 211816, P. R. China
| | - Zhiyuan Zhu
- Department of Chemistry, The University of Hong Kong, Hong Kong S.A.R., P. R. China
| | - Shun-Cheung Cheng
- Department of Chemistry, The University of Hong Kong, Hong Kong S.A.R., P. R. China
| | - Yue Zhang
- Department of Chemistry, The University of Hong Kong, Hong Kong S.A.R., P. R. China
| | - Xuechen Li
- Department of Chemistry, The University of Hong Kong, Hong Kong S.A.R., P. R. China
| | - Wenjian Tang
- School of Pharmacy, Anhui Medical University, Meishan Road 81, Hefei 230032, P. R. China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Hong Kong S.A.R., P. R. China
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3
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Kleinpenning F, Eising S, Berkenbosch T, Garzero V, Schaart JM, Bonger KM. Subcellular Protein Labeling by a Spatially Restricted Arylamine N-Acetyltransferase. ACS Chem Biol 2018; 13:1932-1937. [PMID: 29851463 PMCID: PMC6143282 DOI: 10.1021/acschembio.8b00178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Mapping proteins at a specific subcellular location is essential to gaining detailed insight on local protein dynamics. We have developed an enzymatic strategy to label proteins on a subcellular level using arylamine N-acetyltransferase (NAT). The NAT enzyme activates an arylhydroxamic acid functionality into a nitrenium ion that reacts fast, covalently, and under neutral conditions with nucleophilic residues of neighboring proteins. The electron density on the aromatic ring proved important for probe activation as strong labeling was only observed with an arylhydroxamic acid bearing an electron donating substituent. We further demonstrate that, using this electron rich arylhydroxamic acid, clear labeling was achieved on a subcellular level in living cells that were transfected with a genetically targeted NAT to the nucleus or the cytosol.
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Affiliation(s)
- Fleur Kleinpenning
- Department of Biomolecular Chemistry, Institute of Molecules and Materials, Radboud University, Nijmegen, Heyendaalseweg 135, 6525 AJ, The Netherlands
| | - Selma Eising
- Department of Biomolecular Chemistry, Institute of Molecules and Materials, Radboud University, Nijmegen, Heyendaalseweg 135, 6525 AJ, The Netherlands
| | - Tim Berkenbosch
- Department of Biomolecular Chemistry, Institute of Molecules and Materials, Radboud University, Nijmegen, Heyendaalseweg 135, 6525 AJ, The Netherlands
| | - Veronica Garzero
- Department of Biomolecular Chemistry, Institute of Molecules and Materials, Radboud University, Nijmegen, Heyendaalseweg 135, 6525 AJ, The Netherlands
| | - Judith M. Schaart
- Department of Biomolecular Chemistry, Institute of Molecules and Materials, Radboud University, Nijmegen, Heyendaalseweg 135, 6525 AJ, The Netherlands
| | - Kimberly M. Bonger
- Department of Biomolecular Chemistry, Institute of Molecules and Materials, Radboud University, Nijmegen, Heyendaalseweg 135, 6525 AJ, The Netherlands
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4
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Shimizu D, Fujimoto K, Osuka A. Stable Diporphyrinylaminyl Radical and Nitrenium Ion. Angew Chem Int Ed Engl 2018; 57:9434-9438. [PMID: 29882340 DOI: 10.1002/anie.201805385] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Indexed: 11/10/2022]
Abstract
Nitrenium ions, isoelectronic nitrogen counterparts of carbenes, are important intermediates in various biological and chemical processes. Herein we describe the first synthesis and characterization of a stable nitrenium ion without resonance stabilization by adjoining amino groups. Namely, a stable salt of a diporphyrinylnitrenium ion was synthesized by stepwise oxidation of the corresponding diporphyrinylamine through a stable aminyl radical. The nitrenium ion exhibits characteristic features such as a singlet ground state, enhanced double-bond character of the central C-N bonds, no reactivity toward water and methanol, and negative solvatochromic behavior.
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Affiliation(s)
- Daiki Shimizu
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Keisuke Fujimoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Atsuhiro Osuka
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
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5
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Shimizu D, Fujimoto K, Osuka A. Stable Diporphyrinylaminyl Radical and Nitrenium Ion. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201805385] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Daiki Shimizu
- Department of Chemistry; Graduate School of Science; Kyoto University; Sakyo-ku Kyoto 606-8502 Japan
| | - Keisuke Fujimoto
- Department of Chemistry; Graduate School of Science; Kyoto University; Sakyo-ku Kyoto 606-8502 Japan
| | - Atsuhiro Osuka
- Department of Chemistry; Graduate School of Science; Kyoto University; Sakyo-ku Kyoto 606-8502 Japan
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6
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Qiu Y, Fischer LJ, Dutton AS, Winter AH. Aryl Nitrenium and Oxenium Ions with Unusual High-Spin π,π* Ground States: Exploiting (Anti)Aromaticity. J Org Chem 2017; 82:13550-13556. [PMID: 29087717 DOI: 10.1021/acs.joc.7b02698] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrenium and oxenium ions are important reactive intermediates in synthetic and biological processes, and their ground electronic configurations are of great interest due to having distinct reactivities and properties. In general, the closed-shell singlet state of these intermediates usually react as electrophiles, while reactions of the triplet states of these ions react like typical diradicals (e.g., H atom abstractions). Nonsubstituted phenyl nitrenium ions (Ph-NH+) and phenyl oxenium ions (Ph-O+) have closed-shell singlet ground states with large singlet-triplet gaps resulting from a strong break in the degeneracy of the p orbitals on the formal nitrenium/oxenium center. Remarkably, we find computationally (CBS-QB3 and G4MP2) that azulenyl nitrenium and oxenium ions can have triplet ground states depending upon the attachment position on the azulene core. For instance, CBS-QB3 predicts that 1-azulenyl nitrenium ion and 1-azulenyl oxenium ion are singlet ground-state species with considerable singlet-triplet gaps of -47 and -45 kcal/mol to the lowest-energy triplet state, respectively. In contrast, 6-azulenyl nitrenium ion and 6-azulenyl oxenium ion have triplet ground states with a singlet-triplet gap of +7 and +10 kcal/mol, respectively. Moreover, the triplet states are π,π* states, rather than the typical n,π* states seen for many aryl nitrenium or oxenium ions. This dramatic switch in favored electronic states can be ascribed to changes in ring aromaticity/antiaromaticity, with the switch from ground-state singlet ions to triplet-favored ions resulting from both a destabilized singlet state (Hückel antiaromatic) and a stabilized triplet (Baird aromatic) state. Density functional theory (UB3LYP/6-31+G(d,p)) was used to determine substituent effects on the singlet-triplet energy gap for azulenyl nitrenium and oxenium ions, and we find that the unusual ground triplet states can be further tuned by employing electron-donating or -withdrawing groups on the azulene ring. This work demonstrates that azulenyl nitrenium and oxenium ions can have triplet π,π* ground states and provides a simple recipe for making ionic intermediates with distinct electronic configurations and consequent prediction of unique reactivity and magnetic properties from these species.
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Affiliation(s)
- Yunfan Qiu
- Department of Chemistry, Iowa State University , 2101 Hach Hall, Ames, Iowa 50010, United States
| | - Logan J Fischer
- Department of Chemistry, Iowa State University , 2101 Hach Hall, Ames, Iowa 50010, United States
| | - Andrew S Dutton
- Department of Chemistry, Iowa State University , 2101 Hach Hall, Ames, Iowa 50010, United States
| | - Arthur H Winter
- Department of Chemistry, Iowa State University , 2101 Hach Hall, Ames, Iowa 50010, United States
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7
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Ebert C, Simon N, Schneider S, Carell T. Structural Insights into the Recognition of N
2
-Aryl- and C8-Aryl DNA Lesions by the Repair Protein XPA/Rad14. Chembiochem 2017; 18:1379-1382. [DOI: 10.1002/cbic.201700169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Indexed: 01/28/2023]
Affiliation(s)
- Charlotte Ebert
- Center for Integrated Protein Science at the Department of Chemistry; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 81377 München Germany
| | - Nina Simon
- Center for Integrated Protein Science at the Department of Chemistry; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 81377 München Germany
| | - Sabine Schneider
- Center for Integrated Protein Science at the Department of Chemistry; Technische Universität München; Lichtenbergstrasse 4 85748 Garching Germany
| | - Thomas Carell
- Center for Integrated Protein Science at the Department of Chemistry; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 81377 München Germany
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8
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Xue J, Li Y, Du L, Du Y, Tang W, Zheng X, Phillips DL. Direct Observation of 4-Phenoxyphenylnitrenium Ion: A Transient Absorption and Transient Resonance Raman Study. J Phys Chem B 2015; 119:14720-7. [PMID: 26503835 DOI: 10.1021/acs.jpcb.5b07218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Femtosecond (fs) and nanosecond (ns) transient absorption (TA) and single pulse transient resonance Raman spectroscopic investigation of the intermediates after laser photolysis of 4-phenoxyphenyl azide in acetonitrile and mixed aqueous solution is reported. fs-TA results show that the singlet 4-phenoxyphenylnitrene was produced immediately after photolysis of the azide. Then, the singlet nitrene underwent intersystem crossing (ISC) and ring expansion to generate triplet nitrene and ketenimine in acetonitrile with t = 346 ps or protonation in mixed aqueous solution with t = 37 ps, respectively, a little slower than the counterparts of the methoxy one (108 and 5.4 ps for ISC and protonation processes, respectively). The transient Raman spectrum combined density functional theory (DFT) calculation predicting the structure and vibrational frequencies suggested that phenoxyphenylnitrenium ion has a comparable quinoidal character to that of methoxy- and ethoxy-phenylnitrenium ions. All of these results indicated that the phenoxy substitution has some impact on the reactivity of phenylnitrene but a slight influence on the structure of phenylnitrenium ion.
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Affiliation(s)
- Jiadan Xue
- Engineering Research Center for Eco-Dyeing & Finishing of Textiles, Ministry of Education, Zhejiang Sci-Tech University , Hangzhou, 310018, China.,Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou, 310018, China
| | - Yafang Li
- Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou, 310018, China
| | - Lili Du
- Department of Chemistry, The University of Hong Kong , Hong Kong, S. A. R., China
| | - Yong Du
- Centre for THz Research, China Jiliang University , Hangzhou, 310018, China
| | - Wenjian Tang
- School of Pharmacy, Anhui Medical University , Hefei, 230032, China
| | - Xuming Zheng
- Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou, 310018, China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong , Hong Kong, S. A. R., China
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9
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Králík A, Linhart I, Váňa L, Moulisová A. Identification of New DNA Adducts of Phenylnitrenium. Chem Res Toxicol 2015; 28:1317-25. [DOI: 10.1021/acs.chemrestox.5b00120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Antonín Králík
- Department of Organic Chemistry,
Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 1905, CZ-166
28 Prague, Czech Republic
| | - Igor Linhart
- Department of Organic Chemistry,
Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 1905, CZ-166
28 Prague, Czech Republic
| | - Lubomír Váňa
- Department of Organic Chemistry,
Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 1905, CZ-166
28 Prague, Czech Republic
| | - Alena Moulisová
- Department of Organic Chemistry,
Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 1905, CZ-166
28 Prague, Czech Republic
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10
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Xue J, Du L, Zhu R, Huang J, Phillips DL. Direct time-resolved spectroscopic observation of arylnitrenium ion reactions with guanine-containing DNA oligomers. J Org Chem 2014; 79:3610-4. [PMID: 24665944 DOI: 10.1021/jo500484s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The metabolic activation of a number of aromatic amine compounds to arylnitrenium ions that can react with DNA to form covalent adducts has been linked to carcinogenesis. Guanine in DNA has been shown to be the main target of N-containing carcinogens, and many monomeric guanine derivatives have been utilized as models for product analysis and spectroscopic investigations to attempt to better understand the reaction mechanisms of DNA with arylnitrenium ions. However, there are still important unresolved issues regarding how arylnitrenium ions attack guanine residues in DNA oligomers. In this article, we employed ns-TA and ns-TR(3) spectroscopies to directly observe the reaction of the 2-fluorenylnitrenium ion with selected DNA oligomers, and we detected an intermediate possessing a similar C8 structure as the intermediates produced from the reaction of monomeric guanosine derivatives with arylnitrenium ions. Our results suggest that the oligomeric structure can lead to a faster reaction rate of arylnitrenium ions with guanine residues in DNA oligomers and the reaction of arylnitrenium ions take place in a manner similar to reactions with monomeric guanosine derivatives.
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Affiliation(s)
- Jiadan Xue
- Department of Chemistry, The University of Hong Kong , Hong Kong S.A.R., China
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11
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Kuska MS, Witham AA, Sproviero M, Manderville RA, Majdi Yazdi M, Sharma P, Wetmore SD. Structural Influence of C8-Phenoxy-Guanine in the NarI Recognition DNA Sequence. Chem Res Toxicol 2013; 26:1397-408. [DOI: 10.1021/tx400252g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Michael S. Kuska
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Aaron A. Witham
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Michael Sproviero
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Richard A. Manderville
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Mohadeseh Majdi Yazdi
- Department
of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
| | - Purshotam Sharma
- Department
of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
| | - Stacey D. Wetmore
- Department
of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
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12
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Palamarchuk GV, Shishkin OV, Gorb L, Leszczynski J. Nucleic acid bases in anionic 2'-deoxyribonucleotides: a DFT/B3LYP study of structures, relative stability, and proton affinities. J Phys Chem B 2013; 117:2841-9. [PMID: 23425497 DOI: 10.1021/jp311363c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Protonation of nucleobases in anions of canonical 2'-deoxyribonucleotides has been investigated by the DFT computational study at the B3LYP/aug-cc-pvdz level of theory. It is demonstrated that the protonation leads to a significant decrease of conformational space of purine nucleotides while almost all conformers found for non-protonated molecules correspond to minima of the potential energy surface for protonated mdTMP and mdCMP. However, in all nucleotides, only one conformer is populated. This applies to all tautomers of protonated molecules except the mdTMP and mdCMP with the proton attached to the carbonyl group where a minor population of second conformer is observed. Protonation of nucleobase leads to significant elongation of the N-glycosidic bond. These findings agree well with suggestions that protonation of nucleobase is a first step in cleavage of the glycosidic bond. The oxygen atoms of both carbonyl groups of thymine and the N3 atom of the pyrimidine ring of cytosine, guanine, and adenine represent the most preferable sites for protonation of anions of 2'-deoxyrobonucleotides. The highest proton affinity is observed for the base in mdGMP and the lowest for the thymine moiety in mdTMP. It should be noted that calculated values of the proton affinities in anionic nucleotides are significantly higher (by 2-3 eV) than for nucleosides and neutral nucleotides. This allows assuming that the proton affinity of the base in DNA macromolecule may be tuned by changing the extent of shielding or neutralization of negative charge of the phosphate group.
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Affiliation(s)
- Gennady V Palamarchuk
- STC Institute for Single Crystals, National Academy of Sciences of Ukraine, 60 Lenina ave., Kharkiv 61001, Ukraine
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13
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Shamovsky I, Ripa L, Blomberg N, Eriksson LA, Hansen P, Mee C, Tyrchan C, O'Donovan M, Sjö P. Theoretical Studies of Chemical Reactivity of Metabolically Activated Forms of Aromatic Amines toward DNA. Chem Res Toxicol 2012; 25:2236-52. [DOI: 10.1021/tx300313b] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Igor Shamovsky
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Lena Ripa
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Niklas Blomberg
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Leif A. Eriksson
- Department of Chemistry and Molecular Biology, University of Gothenburg, S-412 96 Göteborg, Sweden
| | - Peter Hansen
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Christine Mee
- Genetic Toxicology, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire, SK10 4TG, United Kingdom
| | - Christian Tyrchan
- Department of Medicinal Chemistry, CVGI iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Mike O'Donovan
- Genetic Toxicology, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire, SK10 4TG, United Kingdom
| | - Peter Sjö
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
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14
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Bercovici DA, Brewer M. Stereospecific Intramolecular C–H Amination of 1-Aza-2-azoniaallene Salts. J Am Chem Soc 2012; 134:9890-3. [PMID: 22680985 DOI: 10.1021/ja303054c] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daniel A. Bercovici
- Department of Chemistry, The University
of Vermont,
82 University Place, Burlington, Vermont 05405, United States
| | - Matthias Brewer
- Department of Chemistry, The University
of Vermont,
82 University Place, Burlington, Vermont 05405, United States
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15
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16
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QI SHIFEI, WANG XIAONAN, YANG ZHONGZHI. INSIGHT INTO MECHANISM OF FORMATION OF C8 ADDUCTS IN CARCINOGENIC REACTIONS OF ARYLNITRENIUM IONS WITH PURINE NUCLEOSIDES II: AB INITIO, DFT, AND ABEEM/MM-MD SIMULATION STUDIES OF CHEMICAL REACTIONS CONCERNING N9-SUBSTITUTED PURINE BASES WITH 4-BIPHENYLYLNITRENIUM ION. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2011. [DOI: 10.1142/s0219633609005222] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Theoretical insight into the mechanism of C8 adducts formation in a series of complicated carcinogenic reactions has been provided in a previous work. However, two important issues involved in this mechanism still need to be elucidated in detail. Hence, in this paper, we first present a new theoretical model to study the direct formation mechanism of C8 adduct. It is found that this model can well reflect the actual interactions in the real carcinogenic reactions. Thus, a better theoretical model to simulate other properties of these complicated reactions is found using ab initio and density functional theory (DFT) methods. Second, we simulate the formation process of C8 adduct in this new theoretical model using ABEEM/MM-MD method. According to the MD study, we approve that the higher aqueous-phase activation energy for transition state in this kind of reaction contributes to weaker interactions between central sites of reaction and water compared with those for reactants. This study once more supports the mechanism of formation of C8 adducts in the actual carcinogenic reactions where arylnitrenium ions directly attack at C8 positions of nucleoside bases in DNA.
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Affiliation(s)
- SHI-FEI QI
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen, 041004, P. R. China
| | - XIAO-NAN WANG
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen, 041004, P. R. China
| | - ZHONG-ZHI YANG
- Chemistry and Chemical Engineering Faculty, Liaoning Normal University, Dalian 116029, P. R. China
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17
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Millen AL, Kamenz BL, Leavens FMV, Manderville RA, Wetmore SD. Conformational flexibility of C8-phenoxylguanine adducts in deoxydinucleoside monophosphates. J Phys Chem B 2011; 115:12993-3002. [PMID: 21942470 DOI: 10.1021/jp2057332] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
M06-2X/6-31G(d,p) is used to calculate the structure of all natural deoxydinucleoside monophosphates with G in the 5' or 3' position, the anti or syn conformation, and each natural (A, C, G, T) base in the corresponding flanking position. When the ortho or para C8-phenoxyl-2'-deoxyguanosine (C8-phenoxyl-dG) adduct replaces G in each model, there is little change in the relative base-base orientation or backbone conformation. However, the orientation of the C8-phenoxyl group can be characterized according to the position (5' versus 3'), conformation (anti versus syn), and isomer (ortho versus para) of damage. Although the degree of coplanarity between the phenoxyl ring and G base in the ortho adduct is highly affected by the sequence since the hydroxyl group can interact with neighboring bases, the para adduct generally does not exhibit discrete interactions with flanking bases. For both adducts, steric clashes between the phenoxyl group and the backbone or flanking base destabilize the anti conformation preferred by the natural nucleotide and thereby result in a clear preference for the syn conformation regardless of the sequence or position. This contrasts the conclusions drawn from smaller (nucleoside, nucleotide) models previously used in the literature, which stresses the importance of using models that address the steric constraints present due to the surrounding environment. Since replication errors for other C8-dG bulky adducts have been linked to a preference for the syn conformation, our findings provide insight into the possible mutagenicity of phenolic adducts.
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Affiliation(s)
- Andrea L Millen
- Department of Chemistry, University of Lethbridge, Lethbridge, Alberta, Canada
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18
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Turesky RJ, Le Marchand L. Metabolism and biomarkers of heterocyclic aromatic amines in molecular epidemiology studies: lessons learned from aromatic amines. Chem Res Toxicol 2011; 24:1169-214. [PMID: 21688801 PMCID: PMC3156293 DOI: 10.1021/tx200135s] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Aromatic amines and heterocyclic aromatic amines (HAAs) are structurally related classes of carcinogens that are formed during the combustion of tobacco or during the high-temperature cooking of meats. Both classes of procarcinogens undergo metabolic activation by N-hydroxylation of the exocyclic amine group to produce a common proposed intermediate, the arylnitrenium ion, which is the critical metabolite implicated in toxicity and DNA damage. However, the biochemistry and chemical properties of these compounds are distinct, and different biomarkers of aromatic amines and HAAs have been developed for human biomonitoring studies. Hemoglobin adducts have been extensively used as biomarkers to monitor occupational and environmental exposures to a number of aromatic amines; however, HAAs do not form hemoglobin adducts at appreciable levels, and other biomarkers have been sought. A number of epidemiologic studies that have investigated dietary consumption of well-done meat in relation to various tumor sites reported a positive association between cancer risk and well-done meat consumption, although some studies have shown no associations between well-done meat and cancer risk. A major limiting factor in most epidemiological studies is the uncertainty in quantitative estimates of chronic exposure to HAAs, and thus, the association of HAAs formed in cooked meat and cancer risk has been difficult to establish. There is a critical need to establish long-term biomarkers of HAAs that can be implemented in molecular epidemioIogy studies. In this review, we highlight and contrast the biochemistry of several prototypical carcinogenic aromatic amines and HAAs to which humans are chronically exposed. The biochemical properties and the impact of polymorphisms of the major xenobiotic-metabolizing enzymes on the biological effects of these chemicals are examined. Lastly, the analytical approaches that have been successfully employed to biomonitor aromatic amines and HAAs, and emerging biomarkers of HAAs that may be implemented in molecular epidemiology studies are discussed.
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Affiliation(s)
- Robert J Turesky
- Division of Environmental Health Sciences, Wadsworth Center , Albany, New York 12201, United States.
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19
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Novak M, Chakraborty M. Reactions of a putative metabolite of the model antitumor drug 2-(4-aminophenyl)benzothiazole with purines and pyrimidines. J PHYS ORG CHEM 2011. [DOI: 10.1002/poc.1905] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Michael Novak
- Department of Chemistry and Biochemistry; Miami University; Oxford OH 45056 USA
| | - Mrinal Chakraborty
- Department of Chemistry and Biochemistry; Miami University; Oxford OH 45056 USA
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20
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Qi SF, Wang XN, Yang ZZ, Xu XH. Evidence of direct formation of C8 adducts in carcinogenic reactions of arylnitrenium ions with purine nucleosides: Theoretical study of C8 deprotonation process. COMPUT THEOR CHEM 2011. [DOI: 10.1016/j.comptc.2011.01.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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Priestap HA, de los Santos C, Quirke JME. Identification of a reduction product of aristolochic acid: implications for the metabolic activation of carcinogenic aristolochic acid. JOURNAL OF NATURAL PRODUCTS 2010; 73:1979-86. [PMID: 21141875 PMCID: PMC3040066 DOI: 10.1021/np100296y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Aristolochic acids are nephrotoxic and carcinogenic natural products that have been implicated both in endemic nephropathy in the Balkan region and in ailments caused by ingestion of herbal remedies. Aristolochic acids are metabolized to active intermediates that bind to DNA. In this study, reduction of aristolochic acid I with zinc in acetic acid afforded a new product that was characterized as 9-methoxy-7-methyl-2H-1,3-oxazolo[5',4'-10,9]phenanthro[3,4-d]-1,3-dioxolane-5-carboxylic acid, designated as aristoxazole, along with the expected aristolactam I. This new compound is a condensation product of aristolochic acid and acetic acid that may be related to the aristolochic acid-DNA adducts. The proposed mechanism of formation of aristoxazole involves nucleophilic attack of acetic acid on the nitrenium ion of aristolochic acid I. On the basis of these studies, a route to the metabolic activation of aristolochic acids and formation of adducts with DNA in in vitro systems is proposed and discussed.
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Affiliation(s)
- Horacio A Priestap
- Department of Biological Sciences, Florida International University, 11200 Southwest 8th Street, Miami, FL 33199, USA.
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22
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Chakraborty M, Jin KJ, Glover SA, Novak M. Characterization of the 4-(benzothiazol-2-yl)phenylnitrenium ion from a putative metabolite of a model antitumor drug. J Org Chem 2010; 75:5296-304. [PMID: 20670034 DOI: 10.1021/jo101275y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 4-(benzothiazol-2-yl)phenylnitrenium ion 11 is generated from hydrolysis or photolysis of O-acetoxy-N-(4-(benzothiazol-2-yl)phenyl)hydroxylamine 8, a model metabolite of 2-(4-aminophenyl)benzothiazole 1 and its ring-substituted derivatives that are being developed for a variety of medicinal applications, including antitumor, antibacterial, antifungal, and imaging agents. Previously, we showed that 11 had an aqueous solution lifetime of 530 ns, similar to the 560 ns lifetime of the 4-biphenylylnitrenium ion 12 derived from the well-known chemical carcinogen 4-aminobiphenyl. We now show that the analogy between these two cations extends well beyond their lifetimes. The initial product of hydration of 11 is the quinolimine 16, which can be detected as a long-lived reactive intermediate that hydrolyzes in a pH-dependent manner into the final hydrolysis product, the quinol 15. This hydrolysis behavior is equivalent to that previously described for a large number of ester metabolites of carcinogenic arylamines, including 4-aminobiphenyl. The major azide trapping product (90% of azide products) of 11, 20, is generated by substitution on the carbons ortho to the nitrenium ion center of 11. This product is a direct analogue of the major azide adducts, such as 22, generated from trapping of the nitrenium ions of carcinogenic arylamines. The azide/solvent selectivity for 11, k(az)/k(s), is also nearly equivalent to that of 12. A minor product of the reaction of 11 with N(3)(-), 21, contains no azide functionality but may be generated by a process in which N(3)(-) attacks 11 at the nitrenium ion center with loss of N(2) to generate a diazene 25 that subsequently decomposes into 21 with loss of another N(2). The adduct derived from attack of 2'-deoxyguanosine (d-G) on 11, 28, is a familiar C-8 adduct of the type generated from the reaction of d-G with a wide variety of arylnitrenium ions derived from carcinogenic arylamines. The rate constant for reaction of d-G with 11, k(d-G), is very similar to that observed for the reaction of d-G with 12. The similar lifetimes and chemical reactivities of 11 and 12 can be rationalized by B3LYP/6-31G(d) calculations on the two ions that show that they are of nearly equivalent stability relative to their respective hydration products. The calculations also help to rationalize the different regiochemistry observed for the reaction of N(3)(-) with 11 and its oxenium ion analogue, 13. Since 8 is the likely active metabolite of 1 and a significant number of derivatives of 1 are being developed as pharmaceutical agents, the similarity of the chemistry of 11 to that of carcinogenic arylnitrenium ions is of considerable importance. Consideration should be given to this chemistry in continued development of pharmaceuticals containing the 2-(4-aminophenyl)benzothiazole moiety.
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Affiliation(s)
- Mrinal Chakraborty
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, USA
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23
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Guo Z, Xue J, Ke Z, Phillips DL, Zhao C. Influence of Water Hydrogen Bonding on the Reactions of Arylnitrenium Ions With Guanosine: Hydrogen-Bonding Effects Can Favor Reaction at the C8 Site. J Phys Chem B 2009; 113:6528-32. [DOI: 10.1021/jp8104584] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhen Guo
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, People’s Republic of China, and Ministry of Education Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China
| | - Jiadan Xue
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, People’s Republic of China, and Ministry of Education Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China
| | - Zhuofeng Ke
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, People’s Republic of China, and Ministry of Education Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, People’s Republic of China, and Ministry of Education Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China
| | - Cunyuan Zhao
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, People’s Republic of China, and Ministry of Education Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China
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24
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Qi SF, Wang XN, Yang ZZ, Xu XH. Effect of N7-Protonated Purine Nucleosides on Formation of C8 Adducts in Carcinogenic Reactions of Arylnitrenium Ions with Purine Nucleosides: A Quantum Chemistry Study. J Phys Chem B 2009; 113:5645-52. [DOI: 10.1021/jp811262x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shi-Fei Qi
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, People’s Republic of China, and Chemistry and Chemical Engineering Faculty, Liaoning Normal University, Dalian 116029, People’s Republic of China
| | - Xiao-Nan Wang
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, People’s Republic of China, and Chemistry and Chemical Engineering Faculty, Liaoning Normal University, Dalian 116029, People’s Republic of China
| | - Zhong-Zhi Yang
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, People’s Republic of China, and Chemistry and Chemical Engineering Faculty, Liaoning Normal University, Dalian 116029, People’s Republic of China
| | - Xiao-Hong Xu
- School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, People’s Republic of China, and Chemistry and Chemical Engineering Faculty, Liaoning Normal University, Dalian 116029, People’s Republic of China
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25
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Yang ZZ, Qi SF, Zhao DX, Gong LD. Insight into mechanism of formation of c8 adducts in carcinogenic reactions of arylnitrenium ions with purine nucleosides. J Phys Chem B 2009; 113:254-9. [PMID: 19072693 DOI: 10.1021/jp804128s] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
For the most important arylnitrenium ion-guanosine C8 adducts in the reactions involving arylamine-initiated carcinogenesis, a detailed mechanism of their formation still remains unclear. In this paper, we employ quantum chemistry methods to explore this issue. Our study indicates that formation of these C8 adducts proceeds directly by additions of arylnitrenium ions to C8 position of nucleoside bases in DNA. The good agreements of theoretical rate constants, pK(a) value, and NMR chemical shifts of C8 intermediate with experimental data support this theoretical finding. Excitingly, predictions of what adducts can be observed in reactions of arylnitrenium ions with guanine and hypoxanthine are in fair agreement with experimental observations. This study answers an important question, in carcinogenesis researches, of what is the mechanism for formation of C8 adducts.
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Affiliation(s)
- Zhong-Zhi Yang
- Chemistry and Chemical Engineering Faculty, Liaoning Normal University, Dalian 116029, People's Republic of China.
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26
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Structural and biological impact of radical addition reactions with DNA nucleobases. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2009. [DOI: 10.1016/s0065-3160(08)00005-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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27
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Xue J, Du Y, Guan X, Guo Z, Phillips DL. Reaction of the 4-biphenylnitrenium ion with 4-biphenyl azide to produce a 4,4'-azobisbiphenyl stable product: a time-resolved resonance Raman and density functional theory study. J Phys Chem A 2008; 112:11582-9. [PMID: 18956852 DOI: 10.1021/jp805353q] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A time-resolved resonance Raman (TR(3)) and density functional theory (DFT) study of the reaction of the 4-biphenylnitrenium ion with 4-biphenyl azide in a mixed aqueous solution is reported. The reaction of the 4-biphenylnitrenium ion with its unphotolyzed precursor 4-biphenyl azide in a mixed aqueous solution generates a 4,4'-azobisbiphenyl stable product via an intermediate species. With the aid of DFT calculations for likely transient species, this intermediate was tentatively assigned to a 4,4'-azobisbiphenyl cation. The DFT calculations predict this reaction can take place via two pathways that compete with one another to produce the trans and cis 4,4'-azobisbiphenyl product. The observation of the 4,4'-azobisbiphenyl cation intermediate demonstrates that the reaction of the arylnitrenium ion with its aryl azide to produce a stable azo product occurs via a stepwise mechanism.
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Affiliation(s)
- Jiadan Xue
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China
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28
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Density functional theory study of water-assisted deprotonation of the C8 intermediate in the reaction of the 2-fluorenylnitrenium ion with guanosine to form a C8 adduct. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.theochem.2007.09.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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29
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Takamura-Enya T, Kawanishi M, Yagi T, Hisamatsu Y. Structural identification of DNA adducts derived from 3-nitrobenzanthrone, a potent carcinogen present in the atmosphere. Chem Asian J 2007; 2:1174-85. [PMID: 17712830 DOI: 10.1002/asia.200700061] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
3-Nitrobenzanthrone is a powerful bacterial mutagen and carcinogen to mammals. To obtain precise information on DNA-adduct formation by 3-nitrobenzanthrone, a number of DNA adducts, including N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone (13 a), 2-(2'-deoxyguanosin-N2-yl)-3-aminobenzanthrone (14 a), N-(2'-deoxyadenosin-8-yl)-3-aminobenzanthrone (15 a), 2-(2'-deoxyadenosin-N6-yl)-3-aminobenzanthrone (16 a), and their N-acetylated counterparts 13 b, 14 b, 15 b, and 16 b were synthesized by palladium-catalyzed aryl amination of the corresponding nucleoside and bromobenzanthrone derivatives. Among these DNA adducts, DNA adducts 13 a, 13 b, 14 a, 14 b, and 16 a were identified in the reaction mixture of nucleosides (2'-deoxyguanosine, 2'-deoxyadenosine, or DNA) with N-acetoxy-3-aminobenzanthrone or N-acetyl-N-acetoxy-3-aminobenzanthrone, both of which are recognized as activated metabolites of 3-nitrobenzanthrone. The formation of these multiple DNA adducts may help explain the potent mutacarcinogenicity of 3-nitrobenzanthrone.
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Affiliation(s)
- Takeji Takamura-Enya
- Department of Applied Chemistry, Kanagawa Institute of Technology, 1030 Shimo-Ogino, Atsugi-shi 243-0292, Japan.
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30
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Jamin EL, Arquier D, Canlet C, Rathahao E, Tulliez J, Debrauwer L. New insights in the formation of deoxynucleoside adducts with the heterocyclic aromatic amines PhIP and IQ by means of ion trap MSn and accurate mass measurement of fragment ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2007; 18:2107-2118. [PMID: 17936011 DOI: 10.1016/j.jasms.2007.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 09/14/2007] [Accepted: 09/14/2007] [Indexed: 05/25/2023]
Abstract
The formation of adducts by reaction of active metabolites of two heterocyclic aromatic amines (NHOH-PhIP and NHOH-IQ) at nucleophilic sites of deoxynucleosides has been studied by LC-MS(n) analyses of the obtained reaction mixtures. Sequential MS(3) experiments were carried out on an ion trap mass spectrometer to gain extensive structural information on each adduct detected in the first MS step. Attribution of ions was supported by accurate mass measurements performed on an Orbitrap mass analyzer. Particular attention was given to ions diagnostic of the linking between the heterocyclic aromatic amine (HAA) and the deoxynucleoside. By this way, the structures of five adducts have been characterized in this study, among which two are new compounds: dG-N7-IQ and dA-N(6)-IQ. No depurinating adduct was found in the reactions investigated therein. As expected, the C8 and N(2) atoms of dG were found as the most reactive sites of deoxynucleosides, resulting in the formation of two different adducts with IQ and one adduct with PhIP. An unusual non-depurinating dG-N7-IQ adduct has been characterized and a mechanism is proposed for its formation on the basis of the reactivity of arylamines. A dA-N(6)-IQ adduct has been identified for the first time in this work, showing that HAAs can generate DNA adducts with bases other than dG.
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Affiliation(s)
- Emilien L Jamin
- UMR 1089 Xenobiotiques INRA-ENVT, 180 Chemin de Tournefeuille, Toulouse, France
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31
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Qi SF, Yang ZZ. Modeling Mechanisms of Unusual Benzene Imine N6 Adduct Formation in Carcinogenic Reactions of Arylnitrenium Ions with Adenosine. J Org Chem 2007; 72:10058-64. [DOI: 10.1021/jo701980y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Shi-Fei Qi
- Chemistry and Chemical Engineering Faculty, Liaoning Normal University, Dalian 116029, People's Republic of China
| | - Zhong-Zhi Yang
- Chemistry and Chemical Engineering Faculty, Liaoning Normal University, Dalian 116029, People's Republic of China
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32
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Zayas B, Beyley J, Terron M, Cordero M, Hernandez W, Alegría AE, Cox O. Comparison of the nucleic acid covalent binding capacity of two nitro-substituted benzazolo[3,2-a]quinolinium salts upon enzymatic reduction. Toxicol In Vitro 2007; 21:1155-64. [PMID: 17466486 PMCID: PMC2001286 DOI: 10.1016/j.tiv.2007.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 02/16/2007] [Accepted: 03/03/2007] [Indexed: 11/16/2022]
Abstract
The DNA binding capacity of two nitro-substituted benzazolo[3,2-a]quinolinium chlorides (NBQs), NBQ-38 and NBQ-95, was evaluated upon their enzymatic reduction with hypoxanthine (HX)/xanthine oxidase (XO) under anaerobic conditions. In the presence of 2'-deoxyguanosine (2'-dG) or calf thymus DNA, covalent-addition products were monitored. Reactions of each NBQ with 2'-dG or DNA differed in the NBQ to HX molar ratio. Control reactions, one without HX/OX and another under aerobic conditions, were also analyzed. Adducts were isolated and characterized by high performance liquid chromatography (HPLC) and electrospray ionization-mass spectrometry (ESI-MS). Authentic samples of the reduced forms of these NBQs, identified as ABQ-38 and ABQ-95, were synthesized as standards to monitor bioreduction processes. HPLC analysis showed that the yield of formation of an unknown product (possibly, 2'-dG-NHBQ-38 adduct) from the reaction of NBQ-38 with 2'-dG and DNA was proportional to the HX to NBQ-38 molar ratio. ESI-MS analysis of the DNA hydrolysates showed evidence of an adduct formed upon bioreduction of NBQ-38 by the ions detection at m/z 528.3 and 454.8, consistent with chemical structures of a 2'-dG-NHBQ-38 adduct and a fragment ion. DNA adducts were not observed with NBQ-95, although the corresponding bioreduction product ABQ-95 was detected by ESI-MS. This study provides mechanistic information of these bioreductively-activated pro-drugs with potential therapeutic applications.
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Affiliation(s)
- Beatriz Zayas
- School of Environmental Affairs, Universidad Metropolitana, San Juan, Puerto Rico.
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33
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N-Acyloxy-N-alkoxyamides – structure, properties, reactivity and biological activity. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2007. [DOI: 10.1016/s0065-3160(07)42002-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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34
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Thomas SI, Falvey DE. Fast reactions of arylnitrenium ions with amino acids and proteins: a laser flash photolysis study. J PHYS ORG CHEM 2006. [DOI: 10.1002/poc.1031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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35
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Glover SA, Novak M. Computational studies of the properties of phenyloxenium ions A comparison with phenylnitrenium and phenylcarbenium ions. CAN J CHEM 2005. [DOI: 10.1139/v05-149] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Properties of phenyloxenium ion 13a, phenylnitrenium ion 14a, and their 4-methyl and 4-phenyl analogues have been studied at the HF/6-31G* and pBP/DN*//HF/6-31G* levels to explain differences in their relative ease of formation and their stabilities. The phenyloxenium ions 13 are ground-state singlets but S0T1 gaps are smaller than those of the corresponding nitrenium ions. The S0 states are stabilized by donor methyl and phenyl substituents in both classes of ions, but phenyloxenium ion has much greater charge localization on the ring, primarily at the 4 position. Evidence for this difference stems from ground-state HF/6-31G*geometries, dipole moments, and vibrational frequencies. Nitrenium ions exhibit some quinoidal character, but the calculated CN bond lengths are longer than those of their 4-hydroxy-2,5-cyclohexadienone imine hydration products 17 and the symmetric C-N stretching frequencies are ca. 60100 cm1 less than those of 17. However, the CO bond lengths and stretching frequencies of the phenyloxenium ions are slightly shorter and greater, respectively, than those of their 4-hydroxy-2,5-cyclohexadienone hydration products (16). The oxenium ions are best described by their 4-oxo-2,5-cyclohexadienyl carbenium resonance structures. Accordingly, a 4-phenyl group stabilizes the phenyloxenium ion more than the phenylnitrenium ion leading to a planar geometry and considerably more charge in the distal ring, thus accounting for regioselectivities of azide reactions. Isodesmic comparisons of the energy difference between phenyloxenium and phenylnitrenium ions and their neutral hydration products explains their relative stabilities under aqueous conditions; whereas 4-biphenylyloxenium ion 13c has a lifetime in water of 12 ns as opposed to the corresponding nitrenium ion 14c (300 ns), the 4-methylphenyloxenium ion 13b is less stable to hydration by 18.7 kcal mol1 (1 cal = 4.184 J) and cannot be observed under the conditions used to generate 13c.Key words: oxenium ions, nitrenium ions, computational chemistry, nucleophilic addition, singlet state properties.
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36
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Chen H, Chen H, Cooks RG, Bagheri H. Generation of arylnitrenium ions by nitro-reduction and gas-phase synthesis of N-heterocycles. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2004; 15:1675-1688. [PMID: 15519236 DOI: 10.1016/j.jasms.2004.07.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2004] [Revised: 07/27/2004] [Accepted: 07/30/2004] [Indexed: 05/24/2023]
Abstract
Nitro-reduction by the vinyl halide radical cation CH2 = CH-X+* (X = Cl or Br) converts nitroaromatics into arylnitrenium ions, significant intermediates in carcinogenesis, and the present study reports on the scope and regioselectivity of this versatile reaction. The reaction is general for different kinds of substituted nitroaromatics; para/meta substitutents have little effect on the reaction while ortho substitutents result in low yields of arylnitrenium ions. The phenylnitrenium ion PhNH+ can be generated by chemical ionization (CI) of nitrobenzene using 1,2-dichloroethane as the reagent gas or by atmospheric pressure chemical ionization (APCI) of 1,2-dichloroethane solution doped with nitrobenzene. The chemical reactivities of the arylnitrenium ions include one-step ion/molecule reactions with nucleophiles ethyl vinyl ether and 1,3-dioxolanes, respectively, involving the direct formation of new CN bonds and synthesis of indole and benzomorpholine derivatives. The indole formation reaction parallels known condensed phase chemistry, while the concise morpholine-forming reaction remains to be sought in solution. The combination of collision-induced dissociation (CID) with novel ion/molecule reactions should provide a selective method for the detection of explosives such as TNT, RDX and HMX in mixtures using mass spectrometry. In addition to the reduction of the nitro group, reduction of methyl phenyl sulfone PhS(O)2Me to the thioanisole radical cation PhSMe+* occurs using the same chemical ionization reagent 1,2-dichloroethane. This probably involves an analogous reduction reaction by the reagent ion CH2 = CH-Cl+*.
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Affiliation(s)
- Hao Chen
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA
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Abstract
Arylamines and nitroarenes are very important intermediates in the industrial manufacture of dyes, pesticides and plastics, and are significant environmental pollutants. The metabolic steps of N-oxidation and nitroreduction to yield N-hydroxyarylamines are crucial for the toxic properties of arylamines and nitroarenes. Nitroarenes are reduced by microorganisms in the gut or by nitroreductases and aldehyde dehydrogenase in hepatocytes to nitrosoarenes and N-hydroxyarylamines. N-Hydroxyarylamines can be further metabolized to N-sulphonyloxyarylamines, N-acetoxyarylamines or N-hydroxyarylamine N-glucuronide. These highly reactive intermediates are responsible for the genotoxic and cytotoxic effects of this class of compounds. N-Hydroxyarylamines can form adducts with DNA, tissue proteins, and the blood proteins albumin and haemoglobin in a dose-dependent manner. DNA and protein adducts have been used to biomonitor humans exposed to such compounds. All these steps are dependent on enzymes, which are present in polymorphic forms. This article reviews the metabolism of arylamines and nitroarenes and the biomonitoring studies performed in animals and humans exposed to these substances.
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Affiliation(s)
- Gabriele Sabbioni
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Nussbaumstrasse 26, D-80336 München, Germany.
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Abstract
Aryl and heterocyclic amines are of particular interest because of their carcinogenicity. The N-hydroxy derivatives are formed by oxidation, usually by the cytochrome P450 (P450) enzymes and most often by P450 family 1. The mechanism of oxidation appears to resemble that of other P450 reactions. The N-hydroxy products can be conjugated to yield esters, which are unstable and form nitrenium ions. Reaction with DNA is most common at the N2 atom and particularly at the C8 atom of guanine. A mechanism involving initial formation of an N7-guanyl adduct can be utilized in explaining the C 8-guanyl adducts plus several other side reactions. The high mutagenicity of N-hydroxy heterocyclic amines in bacterial systems has provided a useful tool for the development of models useful for screening and chemoprevention and for the generation of P450 enzymes with altered properties.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry, Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA.
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McClelland RA, Sanchez C, Sauer E, Vukovic S. Reaction of the tamoxifen cation and the bis-(4-methoxyphenyl)methyl cation in aqueous solutions containing 2'-deoxyguanosine. CAN J CHEM 2002. [DOI: 10.1139/v02-011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The competition between 2'-deoxyguanosine (dG) and water has been quantitatively evaluated for the allylic carbocation derived from tamoxifen and for the stabilized diarylmethyl cation (bis-(4-methoxyphenyl)methyl). Both systems were examined by the competition kinetics method, in which the products were quantitatively analyzed after the SN1 solvolysis of the corresponding acetate esters in aqueous solutions containing the nucleoside. The principal product of the reaction of both cations with dG is the adduct at the NH2 group, a characteristic of delocalized carbocations. The tamoxifen cation was also examined by laser flash photolysis, with absolute rate constants for the reaction with dG and water being obtained and converted into rate constant ratios. The principal result of this study is that there is a three orders of magnitude difference in the reactivity of these cations towards the neutral form of dG and its conjugate base. Under acidic conditions where the reaction occurs with neutral dG, the guaninewater selectivity is low. Even at relatively high concentrations of dG, the majority of the product is alcohol derived from the water reaction. At pH 10 to 11, in contrast, dG is present as the anion and this is highly competitive. Yields of adduct as high as 90% can be attained. A consequence of the large difference in reactivities is that at neutral pH the majority of the reaction of the cation with dG is actually occurring via the small amount of conjugate base present. A further feature of the results is that the NH2 adduct is the predominant stable product from the anion. To explain the high rate constant for the reaction forming this product, a mechanism is proposed whereby one of the protons of the NH2 group is transferred to N1 as the N2-cation bond is forming.Key words: guanine, DNA adduct, carbocation, tamoxifen.
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Glover SA, Mo G. Hindered ester formation by SN2 azidation of N-acetoxy-N-alkoxyamides and N-alkoxy-N-chloroamides—novel application of HERON rearrangements. ACTA ACUST UNITED AC 2002. [DOI: 10.1039/b111250n] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Parks JM, Ford GP, Cramer CJ. Quantum chemical characterization of the reactions of guanine with the phenylnitrenium ion. J Org Chem 2001; 66:8997-9004. [PMID: 11749633 DOI: 10.1021/jo016066+] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Density functional calculations at the B3LYP/6-311+G(2d,p)//pBP/DN level predict all cationic adducts combining guanine, at either its N2, O6, N7, or C8 positions, with phenylnitrenium ion, at either its N, 2, or 4 positions, to be lower in energy than the separated reactants. This relative stability of all adducts is preserved after addition of aqueous solvation free energies computed at the SM2 level, although some leveling of the adduct relative energies one to another is predicted. Cations having the lowest relative energies in solution correspond structurally to those adducts most commonly found when guanine reacts with larger, biologically relevant nitrenium ions in vitro and in vivo. One of these, the N-C8 adduct, is stabilized both by a rearomatized phenyl ring and by the operation of an anomeric effect not found in any of the others. On the basis of energetic analysis, direct conversion of an N-N7 cation to an N-C8 cation according to a previously proposed mechanism is unlikely; however, an alternative rearrangement converting a 2-N7 cation to an N-C8 cation via the intermediacy of a five-membered ring may be operative in nitrenium ions with aromatic frameworks better able than phenyl to stabilize endocyclic cationic charge.
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Affiliation(s)
- J M Parks
- Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314, USA
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Cheng B, McClelland RA. Reaction of arylnitrenium ions with guanine derivatives: N1-methylguanosine and N2,N2-dimethylguanosine. CAN J CHEM 2001. [DOI: 10.1139/v01-179] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A prior flash photolysis study of the direct reaction of arylnitrenium ions with 2'-deoxyguanosine identified a second intermediate that grew in as the transient nitrenium ion reacted with the nucleoside. This intermediate was identified as the the product of the addition of the nitrenium ion to the C-8 position of guanine prior to loss of the C-8 proton the C-8 intermediate. A feature of the C-8 intermediate is that it exists in acidbase forms. This behavior was evident in both a spectroscopic analysis as well as in the ratepH profile, which showed a break around pH 4 from a pH-independent reaction to a reaction that was first-order in H+. The present study was designed to identify the structure of the conjugate base form. This involved a kinetic study of the decay of the C-8 intermediate derived from the reaction of the 2-fluorenylnitrenium ion with N1-methylguanosine and N2,N2-dimethylguanosine. The rationale was that the former is unable to lose the N-1 proton, while the latter cannot deprotonate at the NH2 group. The ratepH profiles clearly show that it is the N-1 proton that is acidic. The rate constants for the C-8 intermediate of N2,N2-dimethylguanosine show the same downward break observed with 2'-deoxyguanosine and guanosine associated with conversion to the conjugate base form. In contrast, the rate constants for the N1-methylguanosine intermediate are independent of pH. Rate constants for the reaction forming the C-8 intermediate are also reported. These show that the reaction of nitrenium ions with the N2,N2-dimethylguanine derivative is significantly faster (except where the reactions are diffusion controlled). This is consistent with the initial step of the reaction of an arylnitrenium ion and guanine occurring by direct addition at C-8. The developing positive charge in such a reaction can be delocalized to the C-2 position where π donors such as NH2 and NMe2 can exert a stabilizing effect.Key words: nitrenium, arylnitrenium, guanosine, DNA adduct.
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Ruane PH, McClelland RA. Kinetic stabilizing effect of the 4-N-methylacetamido substituent on the phenylnitrenium ion. CAN J CHEM 2001. [DOI: 10.1139/v01-178] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Photolysis of 4-(N-methylacetamido)phenyl azide in aqueous solution results in quantitative formation of the 4-(N-methylacetamido)phenylnitrenium ion, this cation arising from solvent protonation of an initially formed singlet arylnitrene. The cation is observed by flash photolysis, and is identified through characteristic quenching by azide ion and by 2'-deoxyguanosine, both excellent nucleophiles for arylnitrenium ions in water. The nitrenium ion is protonated in acidic solutions to form the 4-(N-methylacetamido)aniline dication, whose pKa is determined to be 1.5 based on the ratepH profile. This means that the nitrenium ion is relatively basic, which suggests that there is significant positive charge on the N-methylacetamido group. Further evidence for this is seen in the remarkably long lifetime (5 ms) of the nitrenium ion in water. In fact, the 4-(N-methylacetamido)phenylnitrenium ion is 5000-fold longer-lived than the 4-methoxy-substituted analog. A 4-methoxy substituent on a phenyl ring is more electron donating according to σ+ values (0.78 for MeO vs. 0.60 for NMeAc). The dramatic reversal in the arylnitrenium ions is another example of the failure of these to follow the carbocation scale.Key words: nitrenium ion, flash photolysis, amide substituent.
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N-arylnitreniurn ions. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2001. [DOI: 10.1016/s0065-3160(01)36005-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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McClelland RA, Ren D, D'Sa R, Ahmed AR. Acidity constants and reactivities of the benzidine and N, N-dimethylbenzidine dications, the two electron oxidation intermediates of benzidine carcinogens. CAN J CHEM 2000. [DOI: 10.1139/v00-123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This paper describes the behavior in aqueous solutions of the two electron oxidation products of the carcinogens benzidine and N,N-dimethylbenzidine. In biological systems there is evidence that these diamines are oxidized by peroxidases, and that a product of this oxidation may be partly responsible for carcinogenicity. Entry into the oxidation products in the present study was provided through the bis-perchlorate salts of dications obtained upon chemical oxidation and through the irradiation of 4'-amino and 4'-N,N-dimethylamino-4-azidobiphenyls. The benzidine oxidation product exists in three conjugate acid-base forms, a dication, a monocation and neutral bisimine, with pKa(1) = 5.0 and pKa(2) = 9.0. These values stand in marked contrast to ones previously obtained for the two electron oxidation product of p-phenylenediamine, pKa(1) < 1.5 and pKa(2) = 5.75. The dimethylamino derivative, blocked from forming the neutral form, exists as a dication and monocation, with pKa= 5.0. Both systems are quite long-lived in aqueous solution, but they do decay on the minutes-to-hours time scale. The kinetics can be explained by reactions of both the dication and the monocation with water, with a reaction of hydroxide and the monocation becoming important around pH 10. One surprising result is that the monocations are two orders of magnitude more reactive than the dications. Thus, at neutral pH the form that exists in both systems is the monocation, and this is the species that is the most reactive towards the solvent. One of the resonance contributors in the monocation is a 4-biphenylylnitrenium ion. Comparison with other 4'-substituted-4-biphenylylnitrenium ions studied by laser flash photolysis shows that the 4'-amino- and 4'-dimethylamino substituents are highly kinetically stabilizing. These cations, for example, are a billion-fold longer-lived in aqueous solution than the parent 4-biphenylylnitrenium ion.Key words: quinone bisimine, nitrenium, aryl azide.
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Kaiya T, Aoyama S, Kohda K. Reactions of chloride salts of 7-amino-9-ethylguanine and 1-amino-3-methylbenzimidazoles with lead(IV) acetate: formation of 8-aza-9-ethylguanine and 1-methyl-1H-benzotriazoles. Bioorg Med Chem Lett 1999; 9:961-4. [PMID: 10230620 DOI: 10.1016/s0960-894x(99)00123-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Reaction of 7-amino-9-ethylguaninium chloride with lead(IV) acetate (LTA) in MeOH yielded 8-aza-9-ethylguanine. Similarly, the reaction of 1-amino-3-methylbenzimidazolium chloride or its substituted derivatives (6-methyl, 5,6-dimethyl and 5-nitro) with LTA gave the corresponding 1-methyl-1H-benzotriazole (or 1-methyl-2-azabenzimidazole) derivatives along with N-methylformananilide derivatives.
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Affiliation(s)
- T Kaiya
- Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
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Gadosy TA, McClelland RA. Photochemistry of 2-Azido-1-methylimidazole in Aqueous Solutions. Observation of the 1-Methyl-2-imidazolylnitrenium Ion. J Am Chem Soc 1999. [DOI: 10.1021/ja9827090] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Timothy A. Gadosy
- Contribution from the Department of Chemistry, University of Toronto, Toronto, Ontario M5A 3H6, Canada
| | - Robert A. McClelland
- Contribution from the Department of Chemistry, University of Toronto, Toronto, Ontario M5A 3H6, Canada
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Abstract
This review surveys the chemical and biological factors that are correlated with the mutagenic activity of the aromatic and heterocyclic amines. Particular attention is given to the predicted quantum chemical properties of the parent amines and their metabolites. A number of chemical properties have been found to correlate well with measured mutagenic potency, including log P, the energies of the frontier orbitals of the parent amines, and the thermodynamic stability of the nitrenium ion, possibly the ultimate DNA-binding species. These correlations are intriguing clues to the mutagenic activity of the aromatic amines; however, many factors still await final explanation, including the exact mechanisms of the metabolic enzymes, the identity(s) of the ultimate DNA-binding species, the reaction mechanism in the DNA-adduction, the role of sequence context in the covalent and non-covalent binding of the adducts, and the role of DNA repair.
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Affiliation(s)
- M E Colvin
- Biology and Biotechnology Research Program Lawrence Livermore National Laboratory, Mailstop L-452, Livermore, CA 94550, USA.
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Novak M, Kennedy SA. Inhibitory effect of DNA structure on the efficiency of reaction of guanosine moieties with a nitrenium ion. J PHYS ORG CHEM 1998. [DOI: 10.1002/(sici)1099-1395(199801)11:1<71::aid-poc973>3.0.co;2-h] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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