1
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Lerdsri J, Upan J, Jakmunee J. Nafion mixed carbon nanotube modified screen-printed carbon electrode as a disposable electrochemical sensor for quantification of Amitraz in honey and longan samples. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.140050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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2
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A weight of evidence assessment of the genotoxicity of 2,6-xylidine based on existing and new data, with relevance to safety of lidocaine exposure. Regul Toxicol Pharmacol 2021; 119:104838. [DOI: 10.1016/j.yrtph.2020.104838] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/31/2020] [Accepted: 12/03/2020] [Indexed: 12/25/2022]
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3
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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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4
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Adsorptive square wave voltammetric determination of amitraz in Argentine honeys with a microwave-assisted sample treatment. Microchem J 2019. [DOI: 10.1016/j.microc.2019.104068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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5
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Kobets T, Duan JD, Brunnemann KD, Vock E, Deschl U, Williams GM. DNA-damaging activities of twenty-four structurally diverse unsubstituted and substituted cyclic compounds in embryo-fetal chicken livers. Mutat Res 2019; 844:10-24. [PMID: 31326031 DOI: 10.1016/j.mrgentox.2019.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 05/28/2019] [Accepted: 06/13/2019] [Indexed: 01/28/2023]
Abstract
DNA-damaging activities of twenty-four structurally diverse unsubstituted and substituted cyclic compounds were assessed in embryo-fetal chicken livers. Formation of DNA adducts and strand breaks were measured using the nucleotide 32P-postlabelling (NPL) and comet assays, respectively. Unsubstituted monocyclic benzene, polycyclic fused ring compound naphthalene, covalently connected polycyclic ring compound biphenyl, and heterocyclic ring compound fluorene did not produce DNA damage. Amino-substituted monocyclic compounds, aniline and p-phenylenediamine, as well as polycyclic 1-naphthylamine were also negative. In contrast, carcinogenic monocyclic methyl-substituted anilines: o-toluidine, 2,6-xylidine, 3,4-dimethylaniline, 4-chloro-o-toluidine; 2 methoxy-substituted methylaniline: p-cresidine; 2,4 and 2,6 diamino- or dinitro- substituted toluenes all produced DNA damage. Genotoxic polycyclic amino-substituted 2-naphthylamine, 4-aminobiphenyl, benzidine, methyl-substituted 3,2'-dimethyl-4-aminobiphenyl and 4-dimethylaminoazobenzene as well as amino- and nitro- fluorenes substituted at the 1 or 2 positions also were positive in at least one of the assays. Overall, the DNA damaging activity of cyclic compounds in embryo-fetal chicken livers reflected the type and position of the substitution on the aromatic ring. Additionally, substituted polycyclic compounds exhibited higher DNA-damaging potency compared to monocyclic chemicals. These results are congruent with in vivo findings in other species, establishing chicken eggs as a reliable system for structure-activity assessment of members of groups of related chemicals.
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Affiliation(s)
- Tetyana Kobets
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA.
| | - Jian-Dong Duan
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA.
| | - Klaus D Brunnemann
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA.
| | - Esther Vock
- Boehringer Ingelheim Pharma GmbH & Co, Biberach an der Riss, Germany.
| | - Ulrich Deschl
- Boehringer Ingelheim Pharma GmbH & Co, Biberach an der Riss, Germany.
| | - Gary M Williams
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA.
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Wan WX, Chen Y, Zhang J, Shen F, Luo L, Deng SH, Xiao H, Zhou W, Deng OP, Yang H, Xiao YL, Huang CR, Tian D, He JS, Wang YJ. Mechanism-based structure-activity relationship (SAR) analysis of aromatic amines and nitroaromatics carcinogenicity via statistical analyses based on CPDB. Toxicol In Vitro 2019; 58:13-25. [PMID: 30878698 DOI: 10.1016/j.tiv.2019.03.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 12/24/2022]
Abstract
Cancer is a leading cause of human mortality around the globe. In this study, mechanism-based SAR (Structure-Activity Relationship) was employed to investigate the carcinogenicity of aromatic amines and nitroaromatics based on CPDB. Principal component analysis and cluster analysis were used to construct the SAR model. Principle component analysis generated three principal components from 12 mechanism-based descriptors. The extracted principal components were later used for cluster analysis, which divided the selected 55 chemicals into six clusters. The three principal components were proposed to describe the "transport", "reactivity" and "electrophilicity" properties of the chemicals. Cluster analysis indicated that the relevant "transport" properties positively correlated with the carcinogenic potential and were contributing factors in determining the carcinogenicity of the studied chemicals. The mechanism-based SAR analysis suggested the electron donating groups, electron withdrawing groups and planarity are significant factors in determining the carcinogenic potency for studied aromatic compounds. The present study may provide insights into the relationship between the three proposed properties and the carcinogenesis of aromatic amines and nitroaromatics.
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Affiliation(s)
- Wen-Xin Wan
- Institute of Ecological and Environmental Science, Sichuan Agriculture University, Chengdu 611130, Sichuan province, China; Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China
| | - Yi Chen
- Environmental Monitoring Center of Chengdu, Sichuan province, Chengdu, 610041, Sichuan, China
| | - Jing Zhang
- Institute of Ecological and Environmental Science, Sichuan Agriculture University, Chengdu 611130, Sichuan province, China; Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China; State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610056, Sichuan province, China.
| | - Fei Shen
- Institute of Ecological and Environmental Science, Sichuan Agriculture University, Chengdu 611130, Sichuan province, China; Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China
| | - Ling Luo
- Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China
| | - Shi-Huai Deng
- Institute of Ecological and Environmental Science, Sichuan Agriculture University, Chengdu 611130, Sichuan province, China; Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China
| | - Hong Xiao
- Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China
| | - Wei Zhou
- College of Resource, Sichuan Agricultural University, Chengdu, 610030, Sichuan province, China
| | - Ou-Ping Deng
- College of Resource, Sichuan Agricultural University, Chengdu, 610030, Sichuan province, China
| | - Hua Yang
- College of Forestry, Sichuan Agricultural University, Chengdu, 610030, Sichuan province, China
| | - Yin-Long Xiao
- Institute of Ecological and Environmental Science, Sichuan Agriculture University, Chengdu 611130, Sichuan province, China
| | - Chu-Rui Huang
- Institute of Ecological and Environmental Science, Sichuan Agriculture University, Chengdu 611130, Sichuan province, China
| | - Dong Tian
- Institute of Ecological and Environmental Science, Sichuan Agriculture University, Chengdu 611130, Sichuan province, China; Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China
| | - Jin-Song He
- Institute of Ecological and Environmental Science, Sichuan Agriculture University, Chengdu 611130, Sichuan province, China; Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China
| | - Ying-Jun Wang
- Colleges of the Environment, Sichuan Agricultural University, Chengdu, 611130, Sichuan province, China
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Guo J, Villalta PW, Weight CJ, Bonala R, Johnson F, Rosenquist TA, Turesky RJ. Targeted and Untargeted Detection of DNA Adducts of Aromatic Amine Carcinogens in Human Bladder by Ultra-Performance Liquid Chromatography-High-Resolution Mass Spectrometry. Chem Res Toxicol 2018; 31:1382-1397. [PMID: 30387604 PMCID: PMC6424598 DOI: 10.1021/acs.chemrestox.8b00268] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Epidemiological studies have linked aromatic amines (AAs) from tobacco smoke and some occupational exposures with bladder cancer risk. Several epidemiological studies have also reported a plausible role for structurally related heterocyclic aromatic amines present in tobacco smoke or formed in cooked meats with bladder cancer risk. DNA adduct formation is an initial biochemical event in bladder carcinogenesis. We examined paired fresh-frozen (FR) and formalin-fixed paraffin-embedded (FFPE) nontumor bladder tissues from 41 bladder cancer patients for DNA adducts of 4-aminobiphenyl (4-ABP), a bladder carcinogen present in tobacco smoke, and 2-amino-9 H-pyrido[2,3- b]indole, 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine and 2-amino-3,8-dimethylimidazo[4,5- f]quinoxaline, possible human carcinogens, which occur in tobacco smoke and cooked meats. These chemicals are present in urine of tobacco smokers or omnivores. Targeted DNA adduct measurements were done by ultra-performance liquid chromatography-electrospray ionization multistage hybrid Orbitrap MS. N-(2'-Deoxyguanosin-8-yl)-4-ABP ( N-(dG-C8)-4-ABP) was the sole adduct detected in FR and FFPE bladder tissues. Twelve subjects (29%) had N-(dG-C8)-4-ABP levels above the limit of quantification, ranging from 1.4 to 33.8 adducts per 109 nucleotides (nt). DNA adducts of other human AA bladder carcinogens, including 2-naphthylamine (2-NA), 2-methylaniline (2-MA), 2,6-dimethylaniline (2,6-DMA), and lipid peroxidation (LPO) adducts, were screened for in bladder tissue, by our untargeted data-independent adductomics method, termed wide-selected ion monitoring (wide-SIM)/MS2. Wide-SIM/MS2 successfully detected N-(dG-C8)-4-ABP, N-(2'-deoxyadenosin-8-yl)-4-ABP and the presumed hydrazo linked adduct, N-(2'-deoxyguanosin- N2-yl)-4-ABP, and several LPO adducts in bladder DNA. Wide-SIM/MS2 detected multiple DNA adducts of 2-NA, 2-MA, and, 2,6-DMA, when calf thymus DNA was modified with reactive intermediates of these carcinogens. However, these AA-adducts were below the limit of detection in unspiked human bladder DNA (<1 adduct per 108 nt). Wide-SIM/MS2 can screen for many types of DNA adducts formed with exogenous and endogenous electrophiles and will be employed to identify DNA adducts of other chemicals that may contribute to the etiology of bladder cancer.
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Affiliation(s)
- Jingshu Guo
- Masonic Cancer Center, College of Pharmacy, 2231 Sixth Street SE, Minneapolis, Minnesota 55455
- Department of Medicinal Chemistry, College of Pharmacy, 2231 Sixth Street SE, Minneapolis, Minnesota 55455
| | - Peter W. Villalta
- Masonic Cancer Center, College of Pharmacy, 2231 Sixth Street SE, Minneapolis, Minnesota 55455
| | - Christopher J. Weight
- Department of Urology, University of Minnesota, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - Radha Bonala
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794
| | - Francis Johnson
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794
| | - Thomas A. Rosenquist
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794
| | - Robert J. Turesky
- Masonic Cancer Center, College of Pharmacy, 2231 Sixth Street SE, Minneapolis, Minnesota 55455
- Department of Medicinal Chemistry, College of Pharmacy, 2231 Sixth Street SE, Minneapolis, Minnesota 55455
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Kohara A, Matsumoto M, Hirose A, Hayashi M, Honma M, Suzuki T. Mutagenic properties of dimethylaniline isomers in mice as evaluated by comet, micronucleus and transgenic mutation assays. Genes Environ 2018; 40:18. [PMID: 30151062 PMCID: PMC6103965 DOI: 10.1186/s41021-018-0106-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/17/2018] [Indexed: 11/10/2022] Open
Abstract
Background The carcinogenic potential of dimethylaniline (DMA) isomers in rodents and humans has been previously reported, and there is sufficient evidence for the carcinogenicity of 2,6-DMA in experimental animals. The target organ of carcinogenesis of 2,6-DMA is the nasal cavity. In the current study, six DMA isomers, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-DMA, were evaluated for mutagenic properties. Results Male ddY mice (3/group) were treated intragastrically (i.g.) with 200 mg/kg of one of the six DMAs, and a comet assay was performed on samples of bone marrow, kidney, liver and lung at 3 and 24 h after the treatment. Positive responses were observed in the kidney, liver and lungs of mice from all of the DMA treatment groups after 3 h and in the bone marrow of mice treated with either 3,4- or 3,5-DMA after 3 h; however, these effects were diminished at the 24 h time point. The micronucleus induction in the bone marrow was analysed in the same mouse at 24 h after the treatment. No induction of micronucleated polychromatic erythrocytes was observed after treatment with any of the DMAs.Male transgenic Muta™ mice (five/group) were treated i.g. with 2,5-, 2,6- or 3,5-DMA at 100 mg/kg bw weekly for 4 weeks, and the lacZ and the cII mutation frequencies were examined in the nasal cavity, liver and bone marrow at 7 days after the last treatment. Statistically significant increases in the mutation frequencies of the lacZ and/or cII genes were observed in the nasal cavity of 2,5-DMA or 2,6-DMA treated mice. Sequence analysis showed increased incidences of AT to GC and GC to TA mutations in the nasal tissues. Conclusions These findings suggest that the carcinogenic activities of DMAs are associated with mutagenic events.
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Affiliation(s)
- Arihiro Kohara
- JCRB Cell Bank, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan
| | - Mariko Matsumoto
- 2Division of Risk Assessment, National Institute of Health Sciences, Kawasaki, Japan
| | - Akihiko Hirose
- 2Division of Risk Assessment, National Institute of Health Sciences, Kawasaki, Japan
| | - Makoto Hayashi
- 3Division of Genetics and Mutagenesis, National Institute of Health Sciences, Kawasaki, Japan
| | - Masamitsu Honma
- 3Division of Genetics and Mutagenesis, National Institute of Health Sciences, Kawasaki, Japan
| | - Takayoshi Suzuki
- 4Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki, 210-9501 Japan
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Murray AT, Surendranath Y. Reversing the Native Aerobic Oxidation Reactivity of Graphitic Carbon: Heterogeneous Metal-Free Alkene Hydrogenation. ACS Catal 2017. [DOI: 10.1021/acscatal.7b00395] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alexander T. Murray
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yogesh Surendranath
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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10
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Gadaleta D, Manganelli S, Manganaro A, Porta N, Benfenati E. A knowledge-based expert rule system for predicting mutagenicity (Ames test) of aromatic amines and azo compounds. Toxicology 2016; 370:20-30. [PMID: 27644887 DOI: 10.1016/j.tox.2016.09.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 09/14/2016] [Accepted: 09/15/2016] [Indexed: 11/29/2022]
Abstract
Cancer is one of the main causes of death in Western countries, and a major issue for human health. Prolonged exposure to a number of chemicals was observed to be one of the primary causes of cancer in occupationally exposed persons. Thus, the development of tools for identifying hazardous chemicals and the increase of mechanistic understanding of their toxicity is a major goal for scientific research. We constructed a new knowledge-based expert system accounting the effect of different substituents for the prediction of mutagenicity (Ames test) of aromatic amines, a class of compounds of major concern because of their widespread application in industry. The herein presented model implements a series of user-defined structural rules extracted from a database of 616 primary aromatic amines, with their Ames test outcomes, aimed at identifying mutagenic and non-mutagenic chemicals. The chemical rationale behind such rules is discussed. Besides assessing the model's ability to correctly classify aromatic amines, its predictivity was further evaluated on a second database of 354 azo dyes, another class of chemicals of major concern, whose toxicity has been predicted on the basis of the toxicity of aromatic amines potentially generated from the metabolic reduction of the azo bond. Good performance in classification on both the amine (MCC, Matthews Correlation Coefficient=0.743) and the azo dye (MCC=0.584) datasets confirmed the predictive power of the model, and its suitability for use on a wide range of chemicals. Finally, the model was compared with a series of well-known mutagenicity predicting software. The good performance of our model compared with other mutagenicity models, especially in predicting azo dyes, confirmed the usefulness of this expert system as a reliable support to in vitro mutagenicity assays for screening and prioritization purposes. The model has been fully implemented as a KNIME workflow and is freely available for downstream users.
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Affiliation(s)
- Domenico Gadaleta
- Laboratory of Environmental Chemistry and Toxicology, Department of Environmental Health Sciences, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan, Italy.
| | - Serena Manganelli
- Laboratory of Environmental Chemistry and Toxicology, Department of Environmental Health Sciences, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan, Italy
| | | | - Nicola Porta
- Laboratory of Environmental Chemistry and Toxicology, Department of Environmental Health Sciences, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan, Italy
| | - Emilio Benfenati
- Laboratory of Environmental Chemistry and Toxicology, Department of Environmental Health Sciences, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan, Italy
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11
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Dunnick JK, Shockley KR, Morgan DL, Brix A, Travlos GS, Gerrish K, Michael Sanders J, Ton TV, Pandiri AR. Hepatic transcriptomic alterations for N,N-dimethyl-p-toluidine (DMPT) and p-toluidine after 5-day exposure in rats. Arch Toxicol 2016; 91:1685-1696. [PMID: 27638505 DOI: 10.1007/s00204-016-1831-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/24/2016] [Indexed: 12/17/2022]
Abstract
N,N-dimethyl-p-toluidine (DMPT), an accelerant for methyl methacrylate monomers in medical devices, was a liver carcinogen in male and female F344/N rats and B6C3F1 mice in a 2-year oral exposure study. p-Toluidine, a structurally related chemical, was a liver carcinogen in mice but not in rats in an 18-month feed exposure study. In this current study, liver transcriptomic data were used to characterize mechanisms in DMPT and p-toluidine liver toxicity and for conducting benchmark dose (BMD) analysis. Male F344/N rats were exposed orally to DMPT or p-toluidine (0, 1, 6, 20, 60 or 120 mg/kg/day) for 5 days. The liver was examined for lesions and transcriptomic alterations. Both chemicals caused mild hepatic toxicity at 60 and 120 mg/kg and dose-related transcriptomic alterations in the liver. There were 511 liver transcripts differentially expressed for DMPT and 354 for p-toluidine at 120 mg/kg/day (false discovery rate threshold of 5 %). The liver transcriptomic alterations were characteristic of an anti-oxidative damage response (activation of the Nrf2 pathway) and hepatic toxicity. The top cellular processes in gene ontology (GO) categories altered in livers exposed to DMPT or p-toluidine were used for BMD calculations. The lower confidence bound benchmark doses for these chemicals were 2 mg/kg/day for DMPT and 7 mg/kg/day for p-toluidine. These studies show the promise of using 5-day target organ transcriptomic data to identify chemical-induced molecular changes that can serve as markers for preliminary toxicity risk assessment.
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Affiliation(s)
- June K Dunnick
- Toxicology Branch, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA.
| | - Keith R Shockley
- Biostatistics and Computational Biology Branch, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA
| | - Daniel L Morgan
- NTP Laboratory, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA
| | - Amy Brix
- Experimental Pathology Laboratories, Inc., National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA
| | - Gregory S Travlos
- Cellular and Molecular Pathology Branch, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA
| | - Kevin Gerrish
- Molecular Genomics Core, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA
| | - J Michael Sanders
- National Cancer Institute at NIEHS, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA
| | - T V Ton
- Cellular and Molecular Pathology Branch, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA
| | - Arun R Pandiri
- Cellular and Molecular Pathology Branch, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, NC, 27709, USA
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12
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Pereira L, Mondal PK, Alves M. Aromatic Amines Sources, Environmental Impact and Remediation. POLLUTANTS IN BUILDINGS, WATER AND LIVING ORGANISMS 2015. [DOI: 10.1007/978-3-319-19276-5_7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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13
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Dunnick JK, Brix A, Sanders JM, Travlos GS. N,N-dimethyl-p-toluidine, a component in dental materials, causes hematologic toxic and carcinogenic responses in rodent model systems. Toxicol Pathol 2013; 42:603-15. [PMID: 23867143 DOI: 10.1177/0192623313489604] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Because of the potential for exposure to N,N-dimethyl-p-toluidine (DMPT) in medical devices and the lack of toxicity and carcinogenicity information available in the literature, the National Toxicology Program conducted toxicity and carcinogenicity studies of DMPT in male and female F344/N rats and B6C3F1/N mice. In these studies, a treatment-related macrocytic regenerative anemia characterized by increased levels of methemoglobin and Heinz body formation developed within a few weeks of DMPT exposure in rats and mice. DMPT induced nasal cavity, splenic, and liver toxicity in rats and mice at 3 months and 2 years. DMPT carcinogenic effects were seen in the liver of male and female rats and mice, the nasal cavity of male and female rats, and the lung and forestomach of female mice. In rodents, DMPT is distributed to many of the sites where toxic and carcinogenic effects occurred. DMPT-induced oxidative damage at these target sites may be one mechanism for the treatment-related lesions. Methemoglobinemia, as seen in these DMPT studies, is caused by oxidation of the heme moiety, and this end point served as an early alert for other target organ toxicities and carcinogenic responses that followed with longer term exposure.
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Affiliation(s)
- June K Dunnick
- 1National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
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15
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Naiman K, Dracínský M, Hodek P, Martínková M, Schmeiser HH, Frei E, Stiborová M. Formation, persistence, and identification of DNA adducts formed by the carcinogenic environmental pollutant o-anisidine in rats. Toxicol Sci 2012; 127:348-59. [PMID: 22403159 DOI: 10.1093/toxsci/kfs104] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
2-Methoxyaniline (o-anisidine) is an industrial and environmental pollutant causing tumors of urinary bladder in rodents. Here, we investigated the formation and persistence of DNA adducts in the Wistar rat. Using the (32)P-postlabeling method, three o-anisidine-derived DNA adducts were found in several organs of rats treated with a total dose of 0.53 mg o-anisidine/kg body wt (0.15, 0.18, and 0.2 mg/kg body wt ip in the first, second, and third day, respectively), of which the urinary bladder had the highest levels. At four posttreatment times (1 day, 13 days, 10 weeks, and 36 weeks), DNA adducts in bladder, liver, kidney, and spleen of rats were analyzed to study their persistence. In all time points, the highest total adduct levels were found in urinary bladder (39 adducts per 10(7) nucleotides after 1 day and 15 adducts per 10(7) nucleotides after 36 weeks) where 39% adducts remained. In contrast to the urinary bladder, no persistence was detected in other organs. All three DNA adducts were identified as deoxyguanosine adducts. When deoxyguanosine was reacted with the oxidative metabolite of o-anisidine, N-(2-methoxyphenyl)hydroxylamine, three adducts could be separated by high-performance liquid chromatography (HPLC) and were identified by mass spectroscopy and/or nuclear magnetic resonance spectrometry. All adducts are products of the nitrenium/carbenium ions, the reactive species generated from N-(2-methoxyphenyl)hydroxylamine. The major adduct was identified to be N-(deoxyguanosin-8-yl)-2-methoxyaniline. Using cochromatography on HPLC, this adduct was found to be identical to the major adduct generated by activation of o-anisidine in vitro and in vivo.
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Affiliation(s)
- Karel Naiman
- Department of Biochemistry, Faculty of Science, Charles University, 128 40 Prague 2, Czech Republic
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Skipper PL, Kim MY, Sun HLP, Wogan GN, Tannenbaum SR. Monocyclic aromatic amines as potential human carcinogens: old is new again. Carcinogenesis 2010; 31:50-8. [PMID: 19887514 PMCID: PMC2802674 DOI: 10.1093/carcin/bgp267] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 10/24/2009] [Accepted: 10/26/2009] [Indexed: 12/02/2022] Open
Abstract
Alkylanilines are a group of chemicals whose ubiquitous presence in the environment is a result of the multitude of sources from which they originate. Exposure assessments indicate that most individuals experience lifelong exposure to these compounds. Many alkylanilines have biological activity similar to that of the carcinogenic multi-ring aromatic amines. This review provides an overview of human exposure and biological effects. It also describes recent investigations into the biochemical mechanisms of action that lead to the assessment that they are most probably more complex than those of the more extensively investigated multi-ring aromatic amines. Not only is nitrenium ion chemistry implicated in DNA damage by alkylanilines but also reactions involving quinone imines and perhaps reactive oxygen species. Recent results described here indicate that alkylanilines can be potent genotoxins for cultured mammalian cells when activated by exogenous or endogenous phase I and phase II xenobiotic-metabolizing enzymes. The nature of specific DNA damage products responsible for mutagenicity remains to be identified but evidence to date supports mechanisms of activation through obligatory N-hydroxylation as well as subsequent conjugation by sulfation and/or acetylation. A fuller understanding of the mechanisms of alkylaniline genotoxicity is expected to provide important insights into the environmental and genetic origins of one or more human cancers and may reveal a substantial role for this group of compounds as potential human chemical carcinogens.
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Affiliation(s)
| | | | | | | | - Steven R. Tannenbaum
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Backhaus C, Rahman H, Scheffler S, Laatsch H, Hardeland R. NO scavenging by 3-hydroxyanthranilic acid and 3-hydroxykynurenine: N-nitrosation leads via oxadiazoles to o-quinone diazides. Nitric Oxide 2008; 19:237-44. [DOI: 10.1016/j.niox.2008.07.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2007] [Revised: 06/21/2008] [Accepted: 07/09/2008] [Indexed: 11/28/2022]
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18
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Bomhard EM, Herbold BA. Genotoxic Activities of Aniline and its Metabolites and Their Relationship to the Carcinogenicity of Aniline in the Spleen of Rats. Crit Rev Toxicol 2008; 35:783-835. [PMID: 16468500 DOI: 10.1080/10408440500442384] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Aniline (in the form of its hydrochloride) has been shown to induce a rather rare spectrum of tumors in the spleen of Fischer 344 rats. The dose levels necessary for this carcinogenic activity were in a range where also massive effects on the blood and non-neoplastic splenotoxicity as a consequence of methemoglobinemia were to be observed. This review aimed at clarifying if aniline itself or one of its metabolites has a genotoxic potential which would explain the occurrence of the spleen tumors in rats as a result of a primary genetic activity. The database for aniline and its metabolites is extremely heterogeneous. With validated assays it ranges from a few limited Ames tests (o- and m-hydroxyacetanilide, phenylhydroxylamine, nitrosobenzene) to a broad range of studies covering all genetic endpoints partly with several studies of the same or different test systems (aniline, p-aminophenol, p-hydroxyacetanilide). This makes a direct comparison rather difficult. In addition, a varying number of results with as yet not validated systems are available for aniline and its metabolites. Most results, especially those with validated and well performed/documented studies, did not indicate a potential of aniline to induce gene mutations. In five different mouse lymphoma tests, where colony sizing was performed only in one test, aniline was positive. If this indicates a peculiar feature of a point mutagenic potential or does represent a part of the clastogenic activity for which there is evidence in vitro as well as in vivo remains to be investigated. There is little evidence for a DNA damaging potential of aniline. The clastogenic activity in vivo is confined to dose levels, which are close to lethality essentially due to hematotoxic effects. The quantitatively most important metabolites for experimental animals as well as for humans (p-aminophenol, p-hydroxyacetanilide) seem to have a potential for inducing chromosomal damage in vitro and, at relatively high dose levels, also in vivo. This could be the explanation for the clastogenic effects that have been observed after high doses/concentrations with aniline. They do not induce gene mutations and there is little evidence for a DNA damaging potential. None of these metabolites revealed a splenotoxic potential comparable to that of aniline in studies with repeated or long-term administration to rats. The genotoxicity database on those metabolites with a demonstrated and marked splenotoxic potential, i.e. phenylhydroxylamine, nitrosobenzene, is unfortunately very limited and does not allow to exclude with certainty primary genotoxic events in the development of spleen tumors. But quite a number of considerations by analogy from other investigations support the conclusion that the effects in the spleen do not develop on a primary genotoxic basis. The weight of evidences suggests that the carcinogenic effects in the spleen of rats are the endstage of a chronic high-dose damage of the blood leading to a massive overload of the spleen with iron, which causes chronic oxidative stress. This conclusion, based essentially on pathomorphological observations, and analogy considerations thereof by previous authors, is herewith reconfirmed under consideration of the more recently reported studies on the genotoxicity of aniline and its metabolites, on biochemical measurements indicating oxidative stress, and on the metabolism of aniline. It is concluded that there is no relationship between the damage to the chromosomes at high, toxic doses of aniline and its major metabolites p-aminophenol/p-hydroxyacetanilide and the aniline-induced spleen tumors in the rat.
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Affiliation(s)
- Ernst M Bomhard
- Institute of Toxicology, Bayer Healthcare AG, D-42096 Wuppertal, Germany.
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19
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The SAR studies of novel CB2 selective agonists, benzimidazolone derivatives. Bioorg Med Chem Lett 2008; 18:3310-4. [DOI: 10.1016/j.bmcl.2008.04.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2008] [Revised: 04/06/2008] [Accepted: 04/11/2008] [Indexed: 11/21/2022]
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20
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Duan JD, Jeffrey AM, Williams GM. Assessment of the Medicines Lidocaine, Prilocaine, and Their Metabolites, 2,6-Dimethylaniline and 2-Methylaniline, for DNA Adduct Formation in Rat Tissues. Drug Metab Dispos 2008; 36:1470-5. [DOI: 10.1124/dmd.107.019950] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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21
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Cui L, Sun HL, Wishnok JS, Tannenbaum SR, Skipper PL. Identification of adducts formed by reaction of N-acetoxy-3,5-dimethylaniline with DNA. Chem Res Toxicol 2007; 20:1730-6. [PMID: 18020398 PMCID: PMC2573389 DOI: 10.1021/tx700306c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aromatic amines constitute one of the most extensively studied classes of chemical carcinogens. Although monocyclic aromatic amines are generally regarded as weak carcinogens, a recent epidemiologic study of bladder cancer found that the arylamine 3,5-dimethylaniline (3,5-DMA) may play a significant role in the etiology of this disease in man. Investigations using experimental animals also strongly suggested that DNA adducts-of indeterminate structure-formed by 3,5-DMA might account for its presumptive activity. The present study was undertaken to determine the structures of the major DNA adducts formed in vitro by the known, and possibly carcinogenic, N-hydroxylated metabolite. Calf thymus DNA (ct-DNA) was modified by reaction with N-acetoxy-3,5-dimethylaniline (N-AcO-3,5-DMA). After enzymatic hydrolysis of DNA to individual 2'-deoxyribonucleosides, adduct profiles were determined using HPLC/MS. 3,5-DMA formed four major DNA adducts, one to 2'-deoxyguanosine (dG), two to 2'-deoxyadenosine (dA), and one to 2'-deoxycytidine (dC). Reactions of N-AcO-3,5-DMA with dG, dA, and dC produced the same adducts as reaction with ct-DNA with very similar profiles. Adducts were isolated chromatographically and unambiguously characterized as N-(deoxyguanosin-8-yl)-3,5-dimethylaniline (dG-C8-3,5-DMA), 4-(deoxyadenosin- N(6)-yl)-3,5-dimethylaniline (dA- N(6)-3,5-DMA), N-(deoxyadenosin-8-yl)-3,5-dimethylaniline (dA-C8-3,5-DMA), and N-(deoxycytidin-5-yl)-3,5-dimethylaniline (dC-C5-3,5-DMA) by high-resolution mass spectra (HR-MS) and NMR spectroscopy including (1)H NMR, (13)C NMR, and two-dimensional NMR. This report includes the first detailed description of a dC adduct of an aromatic amine. The present results provide chemical support for a carcinogenic mechanism of action by 3,5-DMA based on N-hydroxylation and the intermediacy of a nitrenium ion in the formation of DNA adducts.
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Affiliation(s)
| | | | | | | | - Paul L. Skipper
- To whom correspondence should be addressed, Massachusetts Institute of Technology, 56−753, 77 Massachusetts Avenue, Cambridge, MA 02139. Phone: 617−253−-0983 Fax: 617−-252−1787
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Kulkarni SA, Moir D, Zhu J. Influence of structural and functional modifications of selected genotoxic carcinogens on metabolism and mutagenicity - a review. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2007; 18:459-514. [PMID: 17654335 DOI: 10.1080/10629360701430090] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Alterations in molecular structure are responsible for the differential biological response(s) of a chemical inside a biosystem. Structural and functional parameters that govern a chemical's metabolic course and determine its ultimate outcome in terms of mutagenic/carcinogenic potential are extensively reviewed here. A large number of environmentally-significant organic chemicals are addressed under one or more broadly classified groups each representing one or more characteristic structural feature. Numerous examples are cited to illustrate the influence of key structural and functional parameters on the metabolism and DNA adduction properties of different chemicals. It is hoped that, in the event of limited experimental data on a chemical's bioactivity, such knowledge of the likely roles played by key molecular features should provide preliminary information regarding its bioactivation, detoxification and/or mutagenic potential and aid the process of screening and prioritising chemicals for further testing.
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Affiliation(s)
- S A Kulkarni
- Chemistry Research Division, Safe Environments Programme, Health Canada, AL: 0800C, Ottawa, Ontario, K1A 0L2, Canada
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Beyerbach A, Farmer PB, Sabbioni G. Biomarkers for Isocyanate Exposure: Synthesis of Isocyanate DNA Adducts. Chem Res Toxicol 2006; 19:1611-8. [PMID: 17173374 DOI: 10.1021/tx0600853] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Isocyanates are important intermediates in industrial manufacturing. DNA adducts and protein adducts are important tools to biomonitor people exposed to xenobiotics. In the present work, the formation of DNA adducts deriving from 4-chlorophenyl isocyanate (4CPI) and 4-methylphenyl isocyanate (4MPI) were explored. The adducts of 4CPI and/or 4MPI with 2'-deoxyadenosine, 2'-deoxyguanosine, and 2'-deoxycytidine were synthesized and characterized by NMR and MS. For low level detection, an LC-MS/MS method was developed. The formation of DNA adducts was confirmed in in vitro reactions with DNA.
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Affiliation(s)
- Armin Beyerbach
- Institute of Environmental and Occupational Toxicology, Casella Postale 108, CH-6780 Airolo, Switzerland
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24
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Skipper PL, Trudel LJ, Kensler TW, Groopman JD, Egner PA, Liberman RG, Wogan GN, Tannenbaum SR. DNA adduct formation by 2,6-dimethyl-, 3,5-dimethyl-, and 3-ethylaniline in vivo in mice. Chem Res Toxicol 2006; 19:1086-90. [PMID: 16918249 DOI: 10.1021/tx060082q] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aromatic amines such as 2-naphthylamine and 4-aminobiphenyl are established human bladder carcinogens. Experimental evidence for carcinogenicity of monocylic aromatic amines is limited mostly to other organs, but a recent epidemiologic study of bladder cancer found that 2,6-dimethyl- (2,6-DMA), 3,5-dimethyl- (3,5-DMA), and 3-ethylaniline (3-EA) may play a significant role in the etiology of this disease in man. The present work was undertaken to test whether a genotoxic mechanism can account for the presumptive activity of 2,6-DMA, 3,5-DMA, and 3-EA by quantifying the binding of these compounds to DNA in vivo. Each of these three [(14)C]alkylanilines was administered at approximately 100 microg/kg to C57BL/6 mice, which were subsequently sacrificed 2, 4, 8, 16, and 24 h post-dosing. Bladder, colon, kidney, liver, lung, and pancreas were harvested from each animal, and DNA was isolated from each tissue. Adduct levels were determined by quantifying bound isotope using accelerator mass spectrometry. Adducts were detectable in the bladder and liver DNA samples from every animal at every time point at levels that ranged from 3 per 10(9) to 1.5 per 10(7) nucleotides. Adduct levels were highest in animals given 3,5-DMA and lowest in those given 3-EA. Levels in both bladder and liver declined by severalfold over the course of the experiment. Adducts were detected less frequently in the other four tissues. Taken together, the results strongly suggest that these three alkylanilines are metabolized in vivo to electrophilic intermediates that covalently bind to DNA and that adducts are formed in the DNA of bladder, which is a putative target organ for these alkylanilines.
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Affiliation(s)
- Paul L Skipper
- Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. skipper@ mit.edu
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25
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Stiborová M, Miksanová M, Sulc M, Rýdlová H, Schmeiser HH, Frei E. Identification of a genotoxic mechanism for the carcinogenicity of the environmental pollutant and suspected human carcinogen o-anisidine. Int J Cancer 2005; 116:667-78. [PMID: 15828049 DOI: 10.1002/ijc.21122] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
2-methoxyaniline (o-anisidine) is an industrial and environmental pollutant and a bladder carcinogen for rodents. The mechanism of its carcinogenicity was investigated with 2 independent methods, 32P-postlabeling and 14C-labeled o-anisidine, to show that o-anisidine binds covalently to DNA in vitro after its activation by human hepatic microsomes. We also investigated the capacity of o-anisidine to form DNA adducts in vivo. Rats were treated i.p. with o-anisidine (0.15 mg/kg daily for 5 days) and DNA from several organs was analyzed by 32P-postlabeling. Two o-anisidine-DNA adducts, identical to those found in DNA incubated with o-anisidine and human microsomes in vitro, were detected in urinary bladder (4.1 adducts per 10(7) nucleotides), the target organ, and, to a lesser extent, in liver, kidney and spleen. These DNA adducts were identified as deoxyguanosine adducts derived from a metabolite of o-anisidine, N-(2-methoxyphenyl)hydroxylamine. This metabolite was identified in incubations with human microsomes. With 9 human hepatic microsomal preparations, we identified the specific CYP catalyzing the formation of the o-anisidine metabolites by correlation studies and by examining the effects of CYP inhibitors. On the basis of these analyses, oxidation of o-anisidine was attributed mainly to CYP2E1. Using recombinant human CYP (in Supersomes) and purified CYPs, the participation of CYP2E1 in o-anisidine oxidation was confirmed. In Supersomes, CYP1A2 was even more efficient in oxidizing o-anisidine than CYP2E1, followed by CYP2B6, 1A1, 2A6, 2D6 and 3A4. The results, the first report on the potential of the human microsomal CYP enzymes to activate o-anisidine, strongly suggest a carcinogenic potential of this rodent carcinogen for humans.
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
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26
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Jones CR, Sabbioni G. Identification of DNA adducts using HPLC/MS/MS following in vitro and in vivo experiments with arylamines and nitroarenes. Chem Res Toxicol 2004; 16:1251-63. [PMID: 14565767 DOI: 10.1021/tx020064i] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Arylamines and nitroarenes are suspected of playing a key role in chemical carcinogenesis. Therefore, the study of DNA adduct formation is an important step to determine the genotoxic potential of these compounds. Calf thymus DNA was modified in vitro by reaction with activated N-hydroxyarylamines: 2-chloroaniline (2CA), 4-chloroaniline (4CA), 2-methylaniline (2MA), 4-methylaniline (4MA), 2,4-dimethylaniline (24DMA), 2,6-dimethylaniline (26DMA), 2-aminobiphenyl (2ABP), 3-aminobiphenyl (3ABP), and 4-aminobiphenyl (4ABP). Female Wistar rats (n = 2) were given a single dose of the above arylamines and their analogous nitro derivatives by oral gavage and sacrificed after 24 h. Hepatic DNA and in vitro modified DNA were hydrolyzed enzymatically to individual 2'-deoxyribonucleosides. Adducts were determined using HPLC/MS/MS by comparison to synthesized standards. The hydrolysis efficiency was monitored by HPLC with UV detection. Each arylamine described above formed adducts to 2'-deoxyguanosine and 2'-deoxyadenosine after in vitro reaction with DNA. DNA adducts were found in rats dosed with 4ABP or with 4-nitrobiphenyl. DNA adducts were not detected in rats dosed with 2CA, 4CA, 2MA, 4MA, 24DMA, 26DMA, 2ABP, 3ABP, 2-chloronitrobenzene, 4-chloronitrobenzene, 2-nitrotoluene, and 4-nitrotoluene. All compounds formed hydrolyzable hemoglobin adducts. Therefore, biologically available N-hydroxyarylamines yielded hemoglobin adducts but not hepatic DNA adducts, except for 4ABP.
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Affiliation(s)
- Christopher R Jones
- Department of Environmental & Occupational Medicine, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4HH, England
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Li L, Chiarelli MP, Branco PS, Antunes AM, Marques MM, Gonçalves LL, Beland FA. Differentiation of isomeric C8-substituted alkylaniline adducts of guanine by electrospray ionization and tandem quadrupole ion trap mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2003; 14:1488-1492. [PMID: 14652195 DOI: 10.1016/j.jasms.2003.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Product ion spectra from thirteen C8-substituted alkylaniline adducts of guanine and deoxyguanosine were generated using electrospray ionization and quadrupole ion trap mass spectrometry and studied to investigate the possibility of differentiating isomeric adduct structures based upon the relative abundances of fragment ions derived from the alkylaniline-modified guanine bases (BH2(+) ions). The structural discrimination of the BH2(+) ions formed by attachment of isomeric alkylanilines to the C8 position of guanine is a challenging problem because the ions tend to yield product ion spectra that are qualitatively identical upon collisional activation. In this study, a statistical method, referred to as a similarity index, was used to compare the product ion spectra of isomeric BH2(+) ions and differentiate their structures. All the adducts investigated could be distinguished from SIs calculated using 5-6 product ions. These results suggest that a searchable database of product ion spectra may be created and used to characterize DNA adducts from aromatic amines whenever they are detected at levels amenable to mass spectral analysis.
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Affiliation(s)
- Linge Li
- Department of Chemistry, Loyola University, Chicago, Illinois 60626, USA
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Abstract
The potential of o-nitrotoluene and p-nitrotoluene to cause cancer in mammalian species was studied in male and female F344/N rats and B6C3F1 mice. These chemicals are on the EPA list of high production chemicals and there is potential for human exposure (High Production Volume Chemical List (2000) http://oaspub.cpa.gov/opptintr/chemrtk/volchall.htm.). o-Nitrotoluene, administered in the feed for up to 2 years, caused clear evidence for cancer at multiple sites in rats and mice. Male rats, receiving o-nitrotoluene in the feed ( approximately 0, 25, 50, or 90 mg/kg per day), developed treatment-related mesotheliomas, subcutaneous skin neoplasms, mammary gland fibroadenomas, and liver neoplasms. By 2 years, mesotheliomas, skin, liver, mammary gland and liver tumors also occurred in 'stop-study' male rats that received o-nitrotoluene at 125 or 315 mg/kg per day for only the first 3 months of study. These 'stop-studies' showed that the critical events leading to tumor formation occurred after 3 months of dosing, and these events were irreversible and eventually led to cancer at multiple sites. o-Nitrotoluene given in the feed to female rats (approximately 0, 30, 60, or 100 mg/kg per day) and to male and female mice (approximately 0, 150, 320, or 700 mg/kg per day) also caused a carcinogenic response. In female rats, treatment-related subcutaneous skin neoplasms and mammary gland fibroadenomas occurred. Hemangiosarcomas and carcinomas of the large intestine (cecum) were seen in treated male and female mice. In contrast to o-nitrotoluene, p-nitrotoluene given in the feed over approximately the same exposure levels caused only equivocal evidence of carcinogenic activity in male rats (subcutaneous skin neoplasms); some evidence of carcinogenic activity in female rats (clitoral gland neoplasms); equivocal evidence of carcinogenic activity in male mice (lung neoplasms); and no evidence of carcinogenic activity in female mice. Differences in the o-nitrotoluene and p-nitrotoluene carcinogenic activity may be due to differences in the metabolism of the parent compound to carcinogenic metabolites.
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Affiliation(s)
- June K Dunnick
- National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA.
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Totsuka Y, Takamura-Enya T, Kawahara N, Nishigaki R, Sugimura T, Wakabayashi K. Structure of DNA adduct formed with aminophenylnorharman, being responsible for the comutagenic action of norharman with aniline. Chem Res Toxicol 2002; 15:1288-94. [PMID: 12387627 DOI: 10.1021/tx020007p] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A mutagenic heterocyclic amine (HCA), 9-(4'-aminophenyl)-9H-pyrido[3,4-b]indole (aminophenylnorharman, APNH), is produced in the presence of S9 mix by the reaction of norharman and aniline, both of which are nonmutagenic and abundantly present in our environment. It has been previously reported that APNH-DNA adducts were detected in DNA of Salmonella typhimurium strain incubated with APNH and S9 mix. In the present study, we examined the structures of APNH-DNA adducts using the (32)P-postlabeling method and various spectrometry techniques. When the reaction mixture of N-acetoxy-APNH and 2'-deoxyguanosine 3'-monophosphate (3'-dGp) was analyzed, three adduct spots (two major and one minor) were observed by (32)P-postlabeling under modified-standard conditions. No adduct formation was observed for reaction mixtures of N-acetoxy-APNH with 3'-dAp, 3'-dTp, or 3'-dCp. The two major adduct spots (spots 1 and 2) detected by TLC were extracted and subjected to HPLC along with the standards 3',5'-pdGp-C8-APNH and 5'-pdG-C8-APNH, which were independently chemically synthesized. On the basis of the results of co-chromatography, spots 1 and 2 were identified to be 5'-monophosphate and 3',5'-diphosphate forms of dG-C8-APNH. When the extract of spot 2 (3',5'-pdGp-C8-APNH) was further digested with nuclease P1 and phosphodiesterase I, a spot corresponding to spot 1 (5'-pdG-C8-APNH) was newly observed on TLC. From these observations, both of the two major spots were concluded to be dG-C8-APNH. A similar DNA adduct pattern to that apparent in vitro was observed in various organs of F344 rats fed 40 ppm of APNH for 4 weeks. The levels of APNH-DNA adducts were highest in the liver and colon, with RAL values of 1.31 +/- 0.26 and 1.32 +/- 0.11 adducts/10(7)nucleotides, respectively. Thus, APNH was demonstrated to form DNA adducts primarily at the C-8 position of guanine residues in vitro and in vivo, like other mutagenic and carcinogenic HCAs.
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Affiliation(s)
- Yukari Totsuka
- Cancer Prevention Division, National Cancer Center Research Institute, 1-1 Tsukiji 5-chome, Chuo-ku, Tokyo 104-0045, Japan
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Matilde Marques M, Gamboa da Costa G, Blankenship LR, Culp SJ, Beland FA. The effect of deuterium and fluorine substitution upon the mutagenicity of N-hydroxy-2,6-dimethylaniline. Mutat Res 2002; 506-507:41-8. [PMID: 12351143 DOI: 10.1016/s0027-5107(02)00150-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
2,6-Dimethylaniline (2,6-DMA) is an intermediate in the manufacture of several products, including pesticides, dyestuffs, and synthetic resins. It is also present in nanogram amounts in tobacco smoke, and is a major metabolite of the potent anesthetic and antiarrhythmic drug lidocaine, as well as a nasal carcinogen in rats. As with other aromatic amines, 2,6-DMA can undergo metabolic activation through cytochrome p450-mediated N-hydroxylation, followed by O-esterification to a reactive derivative capable of forming DNA adducts. We have recently characterized four DNA adducts resulting from this metabolic pathway. Three of the adducts arose from reaction of the exocyclic heteroatoms of deoxyadenosine and deoxyguanosine with the carbon para to the arylamine nitrogen. The fourth adduct resulted from reaction of the 2,6-DMA nitrogen with the C8 atom of deoxyguanosine. In order to investigate the relative contribution of the exocyclic heteroatom adducts as compared to the C8-deoxyguanosine adduct to the toxicities elicited by 2,6-DMA, we synthesized and compared the mutagenicity of N-hydroxy-2,6-DMA, N-hydroxy-4-deutero-2,6-DMA, 2,6-dimethylnitrosobenzene, 4-deutero-2,6-dimethylnitrosobenzene, and N-hydroxy-4-fluoro-2,6-DMA. In Salmonella typhimurium TA100, the two deuterated compounds and their non-deuterated analogues gave similar mutagenic responses ( approximately 25 revertants/nmol). Likewise in S. typhimurium TA98, a similar mutant frequency ( approximately 0.7 revertants/nmol) was obtained with the four compounds. With N-hydroxy-4-fluoro-2,6-DMA, the mutant frequency was reduced by approximately 90% in S. typhimurium TA100 and approximately 50% in S. typhimurium TA98. The results suggest that multiple adducts contribute to base substitution mutations detected by S. typhimurium TA100 while the C8-deoxyguanosine adduct is primarily responsible for the frameshift mutations detected by S. typhimurium TA98.
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Affiliation(s)
- M Matilde Marques
- Centro de Qui;mica Estrutural, Instituto Superior Técnico, Complexo I, Av Rovisco Pais, 1049-001, Lisboa, Portugal.
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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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Esteves MA, Narender N, Marcelo-Curto MJ, Gigante B. Synthetic derivatives of abietic acid with radical scavenging activity. JOURNAL OF NATURAL PRODUCTS 2001; 64:761-766. [PMID: 11421739 DOI: 10.1021/np000501y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In this work, studies on the arylation of anilines derived from dehydroabietic acid, the main component of disproportionated rosin, are presented. The redox properties of the new diarylamines were investigated by cyclic voltammetry, and their free radical scavenging activity was tested by reduction of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. Three of the diarylamines with lower oxidation potential proved to be as active as isopropyldiphenylamine (IPPD) and superior to tert-butylhydroxytoluene (BHT), both commercially available synthetic antioxidants.
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Affiliation(s)
- M A Esteves
- INETI, Departamento de Tecnologia de Indústrias Químicas, Estrada do Paço do Lumiar, 22, 1649-038 Lisboa, Portugal
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Gan J, Skipper PL, Tannenbaum SR. Oxidation of 2,6-dimethylaniline by recombinant human cytochrome P450s and human liver microsomes. Chem Res Toxicol 2001; 14:672-7. [PMID: 11409937 DOI: 10.1021/tx000181i] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2,6-Dimethylaniline (2,6-DMA) is classified as a rodent nasal cavity carcinogen and a possible human carcinogen. The major metabolite of 2,6-DMA in rats and dogs is 4-amino-3,5-dimethylphenol (DMAP) but oxidization of the amino group to produce metabolites such as N-(2,6-dimethylphenyl)hydroxylamine (DMHA) is also indicated by the occurrence of hemoglobin adducts of 2,6-DMA in human and rats. Previous studies have shown a large interindividual variability in human 2,6-DMA hemoglobin adduct levels. In the present study, 2,6-DMA oxidation in vitro by human liver microsomes and recombinant human P450 enzymes was investigated to assess whether the hemoglobin adduct variability could be attributed to metabolic differences. At micromolar concentrations, the only product detectable (UV) was DMAP, while at 10 nM, DMHA was a substantial product. 2E1 and 2A6 were identified as the major P450s in human liver microsomes responsible for the production of DMAP by using P450-specific chemical inhibitors and mouse monoclonal antibodies that selectively inhibit human P450 2E1 and 2A6. 2A6 was identified as the major P450 responsible for the N-hydroxylation. Native P450 2E1 and human liver microsomes catalyzed the rearrangement of DMHA to DMAP independent of NADPH. Consistent with a mechanism involving oxygen rebound to the heme iron center, labeled oxygen was not incorporated into DMAP from either 18O2 gas or H2 18O in this rearrangement. Results presented here suggest much of the observed interindividual variability of 2,6-DMA hemoglobin adduct levels could be due to differences in the relative amounts of hepatic 2E1 and 2A6.
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Affiliation(s)
- J Gan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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34
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Gonçalves LL, Beland FA, Marques MM. Synthesis, characterization, and comparative 32P-postlabeling efficiencies of 2,6-dimethylaniline-DNA adducts. Chem Res Toxicol 2001; 14:165-74. [PMID: 11258965 DOI: 10.1021/tx0002031] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
2,6-Dimethylaniline (2,6-diMeA) is a ubiquitous environmental pollutant that is used in industry as a synthetic intermediate. It is also found in tobacco smoke and as a major metabolite of lidocaine. Although the potential carcinogenicity of 2,6-diMeA in humans is presently uncertain, this aromatic amine has been classified as a rodent carcinogen. In addition, it is known to form hemoglobin adducts in humans, which indicates a profile of metabolic activation similar to that of typical arylamine carcinogens. Like other aromatic amines, 2,6-diMeA has been shown to yield N-(deoxyguanosin-8-yl)-2,6-dimethylaniline (dG-C8-2,6-diMeA) as a major DNA adduct in vitro. In this study, we show that 2,6-diMeA yields an unusual pattern of DNA adducts. In addition to dG-C8-2,6-diMeA, we have isolated two new adducts, 4-(deoxyguanosin-N(2)-yl)-2,6-dimethylaniline (dG-N(2)-2,6-diMeA) and 4-(deoxyguanosin-O(6)-yl)-2,6-dimethylaniline (dG-O(6)-2,6-diMeA), from the reaction of N-acetoxy-2,6-dimethylaniline with deoxyguanosine. A similar reaction conducted with deoxyadenosine yielded 4-(deoxyadenosin-N(6)-yl)-2,6-dimethylaniline (dA-N(6)-2,6-diMeA). All four adducts were detected in DNA reacted with N-acetoxy-2,6-dimethylaniline, with the relative yields being 46% for dA-N(6)-2,6-diMeA, 22% for dG-N(2)-2,6-diMeA, 20% for dG-O(6)-2,6-diMeA, and 12% for dG-C8-2,6-diMeA. This product profile contrasts markedly with the usual pattern of adducts obtained with aromatic amines, where C8-substituted deoxyguanosine products typically predominate. We further analyzed the kinetics of the T(4) polynucleotide kinase (PNK)-catalyzed phosphorylation of the C8 and N(2) deoxyguanosine 3'-phosphate adducts from 2,6-diMeA. The kinetic parameters obtained with these two structurally different adducts are compared to those determined with the parent nucleotide (dG3'p), and with (+/-)-anti-10-(deoxyguanosin-N(2)-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene 3'-phosphate, the major adduct derived from the environmental pollutant benzo[a]pyrene. The results indicate that all the adducts were labeled with lower efficiencies than dG3'p, stressing the likely underestimation of adduct levels in typical 32P-postlabeling protocols. Nonetheless, the N(2) adducts derived from 2,6-diMeA and benzo[a]pyrene were both labeled with higher efficiencies than the C8 adduct derived from 2,6-diMeA, with the benzo[a]pyrene adduct being the best substrate for PNK. Thus, the data suggest that N(2) adducts from dG3'p are intrinsically better substrates than their C8 analogues for PNK, and that bulkier aromatic fragments may favor the enzyme-substrate interaction during the labeling step.
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Affiliation(s)
- L L Gonçalves
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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Branco PS, Antunes AM, Marques MM, Chiarelli MP, Lobo AM, Prabhakar S. New syntheses of DNA adducts from methylated anilines present in tobacco smoke. Chem Res Toxicol 1999; 12:1223-33. [PMID: 10604872 DOI: 10.1021/tx9901229] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new synthetic pathway for the formation of deoxyguanosine-monoarylamine adducts is described, involving the generation and use of arylnitrenes as electrophilic synthons. Photolysis of aryl azides, the most common method for generating arylnitrenes, was tested in the presence of 2'-deoxyguanosine. N-(2'-Deoxyguanosin-8-yl)monoarylamine (dG-C8-Ar) adducts were obtained, but the yields were typically low. Deoxygenation of nitro- and nitrosoarenes by triethyl phosphite in the presence of 2'-deoxyguanosine proved to be an effective method, by which dG-C8-Ar, (2'-deoxyguanosin-N1-yl)monoarylamine (dG-N1-Ar), and (2'-deoxyguanosin-O(6)-yl)monoarylamine (dG-O(6)-Ar) adducts were obtained in acceptable yields.
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Affiliation(s)
- P S Branco
- Departamento de Química, Faculdade de Ciências e Tecnologia, Centro de Química Fina e Biotecnologia, 2825-114 Caparica, Portugal
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36
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Chiarelli M, Wu H, Antunes AM, Branco PS. Post-source decay production studies of aniline and methylaniline adducts of deoxyguanosine. Anal Chim Acta 1999. [DOI: 10.1016/s0003-2670(99)00410-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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37
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Mourato LL, Beland FA, Marques MM. 32P-Postlabeling of N-(deoxyguanosin-8-yl)arylamine adducts: a comparative study of labeling efficiencies. Chem Res Toxicol 1999; 12:661-9. [PMID: 10409407 DOI: 10.1021/tx990038t] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
32P-Postlabeling is an extremely powerful technique for the detection of DNA adducts. Typically, the quantitation of DNA adducts by (32)P-postlabeling is achieved by relative adduct labeling, via comparison of the radioactivity incorporated into the adducts to that associated with the normal nucleotides. This approach is based on a number of assumptions, the foremost being that normal and adducted nucleotide 3'-phosphates are converted to 3', 5'-bisphosphates with similar efficiencies. To evaluate labeling efficiencies for specific DNA adducts, we conducted a comparative study of the kinetics of phosphorylation by T(4) polynucleotide kinase using 2'-deoxyguanosine 3'-phosphate (dG3'p) and a series of N-(deoxyguanosin-8-yl)arylamine 3'-phosphate adduct standards (dG3'p-C8-Ar, Ar being 4-aminobiphenyl, 3- and 4-methylaniline, and 2,4- and 3,4-dimethylaniline). Phosphorylation of dG3'p and the dG3'p-C8-Ar adducts followed Michaelis-Menten kinetics. The apparent turnover numbers were 40-240-fold lower when labeling dG3'p-C8-Ar adducts compared to that when labeling dG3'p. The apparent specificity constant calculated for dG3'p-C8-4-aminobiphenyl (1.4 microM(-)(1) min(-)(1)) was approximately 4-fold lower than that (5. 4 microM(-)(1) min(-)(1)) found for dG3'p. Apparent specificity constants for the monoarylamine adducts were even lower (0.043-0.23 microM(-)(1) min(-)(1)) and decreased in the following order: 4-methylaniline > 3,4-dimethylaniline > 3-methylaniline > 2, 4-dimethylaniline. Similar experiments conducted with dG3'p-C8-Ar standards for 2-methylaniline and 2,3-dimethylaniline produced very poor and irreproducible labeling. These results indicate that (32)P-postlabeling of dG3'p-C8-Ar adducts is less efficient than that of dG3'p and suggest that normal nucleotides will be labeled preferentially to the arylamine adducts under kinetically controlled conditions. The data also indicate a further decrease in labeling efficiency upon substitution ortho to the amino group (e.g., 2, 4-dimethylaniline). In addition, the ATP concentrations required for optimal labeling were found to be substantially higher than those used in typical (32)P-postlabeling assays. Since the high specific activity of carrier-free [gamma-(32)P]ATP precludes increasing the ATP concentration to a significant extent, these data emphasize the need for using highly efficient adduct enrichment procedures when conducting (32)P-postlabeling analyses of DNA adducts.
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Affiliation(s)
- L L Mourato
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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38
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Chiarelli MP, Wu HP, Antunes AM, Branco PS. Product ion studies of some novel arylamine adducts of deoxyguanosine by matrix-assisted laser desorption/ionization and post-source decay. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 1999; 13:2004-2010. [PMID: 10510412 DOI: 10.1002/(sici)1097-0231(19991030)13:20<2004::aid-rcm745>3.0.co;2-m] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The product ions of the BH(2)(+) ions formed by the glycosidic cleavage of N-(deoxyguanosin-O(6)-yl)-2-methylaniline, 4-(deoxyguanosin-8-yl)-2-methylaniline, and N-(deoxyguanosin-1-yl)-2-methylaniline have been studied using matrix-assisted laser desorption/ionization (MALDI) and post-source decay (PSD) to identify fragment ions and pathways that may be used to differentiate their structures. All three isomers may be distinguished based on their PSD product ion spectra using only femtomole quantities of sample. N-(Deoxyguanosin-O(6)-yl)-2-methylaniline produces product ions at m/z 107 and 134 that are diagnostic for 2-methylaniline attachment to the O(6) position of guanine. The BH(2)(+) ion from 4-(deoxyguanosin-8-yl)-2-methylaniline yields a product ion formed by the consecutive losses of 17 and 42 u neutral fragments that may be regarded as specific for guanine-arylamine adducts that possess two primary amine groups. The BH(2)(+) ion from 4-(deoxyguanosin-8-yl)-2-methylaniline yields no product ions that correlate with specificity for guanine N1 substitution. However, the product ion abundance ratio of the protonated arylamine to that of the ammonia loss ion may be used to differentiate an adduct formed by N1 substitution from other arylamine adducts of guanine studied thus far.
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Affiliation(s)
- M P Chiarelli
- Dept. of Chemistry, Loyola University, 6525 N Sheridan Rd., Chicago, IL 60626 USA
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39
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Enya T, Kawanishi M, Suzuki H, Matsui S, Hisamatsu Y. An unusual DNA adduct derived from the powerfully mutagenic environmental contaminant 3-nitrobenzanthrone. Chem Res Toxicol 1998; 11:1460-7. [PMID: 9860488 DOI: 10.1021/tx980104b] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The covalent binding of an N-hydroxy metabolite of the powerfully mutagenic 3-nitrobenzanthrone (NBA) to 2'-deoxyguanosine (dG) and calf thymus DNA has been investigated in vitro. The major adduct obtained from the reaction of the N-acetoxy-N-acetyl derivative (N-Aco-N-Ac-ABA) of 3-aminobenzanthrone (ABA) and dG was identified as N-acetyl-3-amino-2-(2'-deoxyguanosin-8-yl)benzanthrone (dG-N-Ac-ABA) by 1H NMR and mass spectroscopies as well as by the reaction of N-Aco-N-Ac-ABA with the double-stranded calf thymus DNA. The coupling with the dG moiety occurred exclusively at C-2 of benzanthrone (BA), suggesting a significant contribution of a resonance-stabilized arenium ion intermediate derived from BA to the production of this new type of adduct. The preferred conformation of the adduct has been shown to be syn by 1H and 13C NMR.
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Affiliation(s)
- T Enya
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan. Community Environmental Science
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