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Xenobiotica-metabolizing enzymes in the lung of experimental animals, man and in human lung models. Arch Toxicol 2019; 93:3419-3489. [PMID: 31673725 DOI: 10.1007/s00204-019-02602-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/15/2019] [Indexed: 12/15/2022]
Abstract
The xenobiotic metabolism in the lung, an organ of first entry of xenobiotics into the organism, is crucial for inhaled compounds entering this organ intentionally (e.g. drugs) and unintentionally (e.g. work place and environmental compounds). Additionally, local metabolism by enzymes preferentially or exclusively occurring in the lung is important for favorable or toxic effects of xenobiotics entering the organism also by routes other than by inhalation. The data collected in this review show that generally activities of cytochromes P450 are low in the lung of all investigated species and in vitro models. Other oxidoreductases may turn out to be more important, but are largely not investigated. Phase II enzymes are generally much higher with the exception of UGT glucuronosyltransferases which are generally very low. Insofar as data are available the xenobiotic metabolism in the lung of monkeys comes closed to that in the human lung; however, very few data are available for this comparison. Second best rate the mouse and rat lung, followed by the rabbit. Of the human in vitro model primary cells in culture, such as alveolar macrophages and alveolar type II cells as well as the A549 cell line appear quite acceptable. However, (1) this generalization represents a temporary oversimplification born from the lack of more comparable data; (2) the relative suitability of individual species/models is different for different enzymes; (3) when more data become available, the conclusions derived from these comparisons quite possibly may change.
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2
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Quesne MG, Silveri F, de Leeuw NH, Catlow CRA. Advances in Sustainable Catalysis: A Computational Perspective. Front Chem 2019; 7:182. [PMID: 31032245 PMCID: PMC6473102 DOI: 10.3389/fchem.2019.00182] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/07/2019] [Indexed: 11/13/2022] Open
Abstract
The enormous challenge of moving our societies to a more sustainable future offers several exciting opportunities for computational chemists. The first principles approach to "catalysis by design" will enable new and much greener chemical routes to produce vital fuels and fine chemicals. This prospective outlines a wide variety of case studies to underscore how the use of theoretical techniques, from QM/MM to unrestricted DFT and periodic boundary conditions, can be applied to biocatalysis and to both homogeneous and heterogenous catalysts of all sizes and morphologies to provide invaluable insights into the reaction mechanisms they catalyze.
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Affiliation(s)
- Matthew G Quesne
- School of Chemistry, Cardiff University, Cardiff, United Kingdom
| | - Fabrizio Silveri
- School of Chemistry, Cardiff University, Cardiff, United Kingdom
| | - Nora H de Leeuw
- School of Chemistry, Cardiff University, Cardiff, United Kingdom
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3
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Chen G, Wen H, Mao Z, Song J, Jiang H, Wang W, Yang Y, Miao Y, Wang C, Huang Z, Wang X. Assessment of the Pig-a, micronucleus, and comet assay endpoints in rats treated by acute or repeated dosing protocols with procarbazine hydrochloride and ethyl carbamate. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:56-71. [PMID: 30240497 DOI: 10.1002/em.22227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 06/12/2018] [Accepted: 06/24/2018] [Indexed: 06/08/2023]
Abstract
The utility and sensitivity of the newly developed flow cytometric Pig-a gene mutation assay have become a great concern recently. In this study, we have examined the feasibility of integrating the Pig-a assay as well as micronucleus and Comet endpoints into acute and subchronic general toxicology studies. Male Sprague-Dawley rats were treated for 3 or 28 consecutive days by oral gavage with procarbazine hydrochloride (PCZ) or ethyl carbamate (EC) up to the maximum tolerated dose. The induction of CD59-negative reticulocytes and erythrocytes, micronucleated reticulocytes in peripheral blood, micronucleated polychromatic erythrocytes in bone marrow, and Comet responses in peripheral blood, liver, kidney, and lung were evaluated at one, two, or more timepoints. Both PCZ and EC produced positive responses at most analyzed timepoints in all tissue types, both with the 3-day and 28-day treatment regimens. Furthermore, comparison of the magnitude of the genotoxicity responses indicated that the micronucleus and Comet endpoints generally produced greater responses with the higher dose, short-term treatments in the 3-day study, while the Pig-a assay responded better to the cumulative effects of the lower dose, but repeated subchronic dosing in the 28-day study. Collectively, these results indicate that integration of several in vivo genotoxicity endpoints into a single routine toxicology study is feasible and that the Pig-a assay may be particularly suitable for integration into subchronic dose studies based on its ability to accumulate the mutations that result from repeated treatments. This characteristic may be especially important for assaying lower doses of relatively weak genotoxicants. Environ. Mol. Mutagen. 60:56-71, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Gaofeng Chen
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
- Center of Safety Evaluation on New Drug, School of Pharmaceutical Science, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Hairuo Wen
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
| | - Zhihui Mao
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
- Center of Safety Evaluation on New Drug, School of Pharmaceutical Science, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Jie Song
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
| | - Hua Jiang
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
| | - Weifan Wang
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
| | - Ying Yang
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
| | - Yufa Miao
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
| | - Chao Wang
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
| | - Zhiying Huang
- Center of Safety Evaluation on New Drug, School of Pharmaceutical Science, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Xue Wang
- Key Laboratory of Beijing for Safety Evaluation of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China
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4
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Guo M, Hu Y, Wang L, Brodelius PE, Sun L. A facile synthesis of molecularly imprinted polymers and their properties as electrochemical sensors for ethyl carbamate analysis. RSC Adv 2018; 8:39721-39730. [PMID: 35558015 PMCID: PMC9092230 DOI: 10.1039/c8ra08213h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 11/20/2018] [Indexed: 11/28/2022] Open
Abstract
New molecularly imprinted polymers (MIPs), which exhibit specific recognition of ethyl carbamate (EC) have been synthesized and studied. In this process, EC was the template molecule and β-cyclodextrin derivatives were employed as functional monomers in the molecular imprinting technique (MIT). An EC molecularly imprinted sensor (EC-MIS) was prepared by using MIT surface modification. The EC-MIS was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry. EC detection performance, binding parameters and dynamics mechanism were investigated. The result showed that the synthetic route designed was appropriate and that new MIP and EC-MIS were successfully prepared. The EC-MIS exhibited a good molecular recognition of EC. A linear relationship between current and EC concentration was observed using cyclic voltammetry and the detection limit was 5.86 μg L−1. The binding constant (K = 4.75 × 106 L mol−1) between EC and the EC-MIS, as well as, the number of binding sites (n = 1.48) has been determined. The EC-MIS recognition mechanism for the EC is a two-step process. The sensor was applied for the determination of EC in Chinese yellow wines, and the results were in good agreement with the gas chromatography-mass spectrometry (GC-MS) method. An ethyl carbamate (EC) molecularly imprinted sensor (EC-MIS) has been prepared. The molecular recognition properties of EC were investigated, the binding parameters determined, and the dynamic mechanism of EC-MIS recognizing EC explored.![]()
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Affiliation(s)
- Ming Guo
- Department of Chemistry
- Zhejiang Agricultural & Forestry University
- Hangzhou 311300
- China
| | - Yinglu Hu
- Department of Chemistry
- Zhejiang Agricultural & Forestry University
- Hangzhou 311300
- China
| | - Lixia Wang
- School of Agriculture and Food Science
- Zhejiang Agricultural & Forestry University
- Hangzhou 311300
- China
| | - Peter E. Brodelius
- Department of Chemistry and Biomedical Sciences
- Linnaeus University
- 391 82 Kalmar
- Sweden
| | - Liping Sun
- Department of Chemistry
- Zhejiang Agricultural & Forestry University
- Hangzhou 311300
- China
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5
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Narumi K, Fujiishi Y, Okada E, Ohyama W. Detection of Pig-a gene mutants in rat peripheral blood following a single urethane treatment: A comparison of the RBC Pig-a and PIGRET assays. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2016; 811:129-134. [PMID: 27931806 DOI: 10.1016/j.mrgentox.2016.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 02/15/2016] [Indexed: 10/22/2022]
Abstract
The rat red blood cell (RBC) Pig-a assay has been recommended by an expert working group of the International Workshop on Genotoxicity Testing as a potential new method to evaluate in vivo gene mutations in regulatory genotoxicity risk assessments. In a collaborative study in Japan, an improved Pig-a assay using reticulocytes (PIGRET assay) with magnetic enrichment of CD71-positive cells was evaluated, and it was revealed that this assay could detect the mutagenicity of chemicals earlier than the RBC Pig-a assay could. To verify further the suitability of the PIGRET assay for an in vivo short-term genotoxicity screening test, a joint research study was conducted by the Japanese Environmental Mutagen Society, and 24 compounds were evaluated. One of the compounds evaluated in this study was urethane, a multi-organ rodent carcinogen. Urethane (250, 500, and 1000mg/kg body weight) was orally administered once to 8-week-old male Crl:CD (SD) rats. Blood samples were collected at 1, 2, and 4 weeks after the administration and processed for the RBC Pig-a and PIGRET assays. In the PIGRET assay, the Pig-a mutant frequency (MF) significantly increased at both 2 and 4 weeks after the treatment of 1000mg/kg of urethane. However, in the RBC Pig-a assay, a significant increase in the Pig-a MF was observed only at 1 week after the treatment with 500mg/kg, but the MF value was within our historical control range; therefore, it was judged to be negative. These results suggest that the PIGRET assay might be useful for evaluating the in vivo mutagenicity more clearly than the RBC Pig-a assay after a single treatment of test compounds.
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Affiliation(s)
- Kazunori Narumi
- Yakult Central Institute, Yakult Honsha Co., Ltd., 5-11 Izumi, Kunitachi-shi, Tokyo 186-8650, Japan.
| | - Yohei Fujiishi
- Yakult Central Institute, Yakult Honsha Co., Ltd., 5-11 Izumi, Kunitachi-shi, Tokyo 186-8650, Japan
| | - Emiko Okada
- Yakult Central Institute, Yakult Honsha Co., Ltd., 5-11 Izumi, Kunitachi-shi, Tokyo 186-8650, Japan
| | - Wakako Ohyama
- Yakult Central Institute, Yakult Honsha Co., Ltd., 5-11 Izumi, Kunitachi-shi, Tokyo 186-8650, Japan
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Stankowski LF, Aardema MJ, Lawlor TE, Pant K, Roy S, Xu Y, Elbekai R. Integration of Pig-a, micronucleus, chromosome aberration and comet assay endpoints in a 28-day rodent toxicity study with urethane. Mutagenesis 2015; 30:335-42. [PMID: 25934985 PMCID: PMC4506322 DOI: 10.1093/mutage/gev013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
As part of the international Pig-a validation trials, we examined the induction of Pig-a mutant reticulocytes and red blood cells (RET(CD59-) and RBC(CD59-), respectively) in peripheral blood of male Sprague Dawley(®) rats treated with urethane (25, 100 and 250mg/kg/day) or saline by oral gavage for 29 days. Additional endpoints integrated into this study were: micronucleated reticulocytes (MN-RET) in peripheral blood; chromosome aberrations (CAb) and DNA damage (%tail intensity via the comet assay) in peripheral blood lymphocytes (PBL); micronucleated polychromatic erythrocytes (MN-PCE) in bone marrow; and DNA damage (comet) in various organs at termination (the 29th dose was added for the comet endpoint at sacrifice). Ethyl methanesulfonate (EMS; 200mg/kg/day on Days 3, 4, 13, 14, 15, 27, 28 and 29) was evaluated as the concurrent positive control (PC). All animals survived to termination and none exhibited overt toxicity, but there were significant differences in body weight and body weight gain in the 250-mg/kg/day urethane group, as compared with the saline control animals. Statistically significant, dose-dependent increases were observed for urethane for: RET(CD59-) and RBC(CD59-) (on Days 15 and 29); MN-RET (on Days 4, 15 and 29); and MN-PCE (on Day 29). The comet assay yielded positive results in PBL (Day 15) and liver (Day 29), but negative results for PBL (Days 4 and 29) and brain, kidney and lung (Day 29). No significant increases in PBL CAb were observed at any sample time. Except for PBL CAb (likely due to excessive cytotoxicity), EMS-induced significant increases in all endpoints/tissues. These results compare favorably with earlier in vivo observations and demonstrate the utility and sensitivity of the Pig-a in vivo gene mutation assay, and its ability to be easily integrated, along with other standard genotoxicity endpoints, into 28-day rodent toxicity studies.
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Affiliation(s)
| | - Marilyn J Aardema
- BioReliance Corporation, Rockville, MD 20850, USA, Marilyn Aardema Consulting LLC, Fairfield, OH 45014, USA
| | | | - Kamala Pant
- BioReliance Corporation, Rockville, MD 20850, USA
| | - Shambhu Roy
- BioReliance Corporation, Rockville, MD 20850, USA
| | - Yong Xu
- BioReliance Corporation, Rockville, MD 20850, USA
| | - Reem Elbekai
- BioReliance Corporation, Rockville, MD 20850, USA
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7
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Ji L, Faponle AS, Quesne MG, Sainna MA, Zhang J, Franke A, Kumar D, van Eldik R, Liu W, de Visser SP. Drug metabolism by cytochrome p450 enzymes: what distinguishes the pathways leading to substrate hydroxylation over desaturation? Chemistry 2015; 21:9083-92. [PMID: 25924594 DOI: 10.1002/chem.201500329] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Indexed: 01/05/2023]
Abstract
Cytochrome P450 enzymes are highly versatile biological catalysts in our body that react with a broad range of substrates. Key functions in the liver include the metabolism of drugs and xenobiotics. One particular metabolic pathway that is poorly understood relates to the P450 activation of aliphatic groups leading to either hydroxylation or desaturation pathways. A DFT and QM/MM study has been carried out on the factors that determine the regioselectivity of aliphatic hydroxylation over desaturation of compounds by P450 isozymes. The calculations establish multistate reactivity patterns, whereby the product distributions differ on each of the spin-state surfaces; hence spin-selective product formation was found. The electronic and thermochemical factors that determine the bifurcation pathways were analysed and a model that predicts the regioselectivity of aliphatic hydroxylation over desaturation pathways was established from valence bond and molecular orbital theories. Thus, the difference in energy of the OH versus the OC bond formed and the π-conjugation energy determines the degree of desaturation products. In addition, environmental effects of the substrate binding pocket that affect the regioselectivities were identified. These studies imply that bioengineering P450 isozymes for desaturation reactions will have to include modifications in the substrate binding pocket to restrict the hydroxylation rebound reaction.
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Affiliation(s)
- Li Ji
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058 (China)
| | - Abayomi S Faponle
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN (UK)
| | - Matthew G Quesne
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN (UK)
| | - Mala A Sainna
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN (UK)
| | - Jing Zhang
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058 (China)
| | - Alicja Franke
- Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen (Germany)
| | - Devesh Kumar
- Department of Applied Physics, School for Physical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Rai Bareilly Road, Lucknow 226 025 (India)
| | - Rudi van Eldik
- Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen (Germany).,Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)
| | - Weiping Liu
- College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058 (China).
| | - Sam P de Visser
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN (UK).
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8
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Jiao Z, Dong Y, Chen Q. Ethyl Carbamate in Fermented Beverages: Presence, Analytical Chemistry, Formation Mechanism, and Mitigation Proposals. Compr Rev Food Sci Food Saf 2014; 13:611-626. [DOI: 10.1111/1541-4337.12084] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Accepted: 03/26/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Zhihua Jiao
- Dept. of Food Science and Nutrition; Zhejiang Univ; Nr. 866, Yuhangtang Road Xihu District Hangzhou 310058 China
| | - Yachen Dong
- Dept. of Food Science and Nutrition; Zhejiang Univ; Nr. 866, Yuhangtang Road Xihu District Hangzhou 310058 China
| | - Qihe Chen
- Dept. of Food Science and Nutrition; Zhejiang Univ; Nr. 866, Yuhangtang Road Xihu District Hangzhou 310058 China
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9
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Abstract
Considerable support exists for the roles of metabolism in modulating the carcinogenic properties of chemicals. In particular, many of these compounds are pro-carcinogens that require activation to electrophilic forms to exert genotoxic effects. We systematically analyzed the existing literature on the metabolism of carcinogens by human enzymes, which has been developed largely in the past 25 years. The metabolism and especially bioactivation of carcinogens are dominated by cytochrome P450 enzymes (66% of bioactivations). Within this group, six P450s--1A1, 1A2, 1B1, 2A6, 2E1, and 3A4--accounted for 77% of the P450 activation reactions. The roles of these P450s can be compared with those estimated for drug metabolism and should be considered in issues involving enzyme induction, chemoprevention, molecular epidemiology, interindividual variations, and risk assessment.
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10
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Abstract
Vinyl carbamate (VC) and ethyl carbamate (EC) induce the formation of lung tumors. The mechanism involves a two-step oxidation of EC to VC and VC to an epoxide, both of which are mediated mainly by CYP2E1. Interaction of the epoxide with DNA leads to the formation of DNA adducts, including 1,N(6)ethenodeoxyadenosine and 1,N(4)-ethenodeoxycytidine. The production of DNA adducts correlated with capacities for the bioactivation of VC, which are higher in the lungs of A/J than in C57BL/6 mice. Importantly, CYP2E1 is higher in the lungs of A/J than in C57BL/6 mice. Studies using F(1) (Big Blue x A/J) transgenic mice revealed the formation of mutations in the lambda cII gene after treatment with VC. Mutations induced by VC were mainly A:T-->G:C transitions and A:T-->T:A transversions, while mutations induced by EC were mainly G:C-->A:T transitions. An EC dose that was 17-fold higher than that for VC was required to produce a similar level of mutant frequency in the lung. Pretreatment of mice with the CYP2E1 inhibitor, diallyl sulfone, significantly inhibited the mutant frequencies induced by VC. Mutations in the endogeneous Kras2 gene were found in codon 61 of exon 2 and were identified as A:T transversions and A-->G transitions in the second base and A-->T transversions in the third base. These mutations were reduced by treatment of mice with diallyl sulfone before VC and coincided with a reduction in the number of lung tumors with Kras2 mutations. These findings affirmed that the metabolism of EC and VC is a prerequisite for, or at least substantially contributes to, initiation of the cascade of events leading to lung tumor formation.
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Affiliation(s)
- Poh-Gek Forkert
- Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada
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11
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Toyo’oka T. Recent advances in separation and detection methods for thiol compounds in biological samples. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:3318-30. [DOI: 10.1016/j.jchromb.2009.03.034] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 03/19/2009] [Accepted: 03/23/2009] [Indexed: 11/28/2022]
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Kartha JS, Skordos KW, Sun H, Hall C, Easterwood LM, Reilly CA, Johnson EF, Yost GS. Single mutations change CYP2F3 from a dehydrogenase of 3-methylindole to an oxygenase. Biochemistry 2008; 47:9756-70. [PMID: 18717595 DOI: 10.1021/bi8005658] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pulmonary cytochrome P450 2F3 (CYP2F3) catalyzes the dehydrogenation of the pneumotoxin 3-methylindole (3MI) to an electrophilic intermediate, 3-methyleneindolenine, which is responsible for the toxicity of the parent compound. Members of the CYP2F subfamily are the only enzymes known to exclusively dehydrogenate 3MI, without detectable formation of oxygenation products. Thus, CYP2F3 is an attractive model to study dehydrogenation mechanisms. The purpose of this study was to identify specific residues that could facilitate 3MI dehydrogenation. Both single and double mutations were constructed to study the molecular mechanisms that direct dehydrogenation. Double mutations in substrate recognition sites (SRS) 1 produced an inactive enzyme, while double mutants in SRS 4 did not alter 3MI metabolism. However, double mutations in SRS 5 and SRS 6 successfully introduced oxygenase activity to CYP2F3. Single mutations in SRS 5, SRS 6 and near SRS 2 also introduced 3MI oxygenase activity. Mutants S474H and D361T oxygenated 3MI but also increased dehydrogenation rates, while G214L, E215Q and S475I catalyzed 3MI oxygenation exclusively. A homology model of CYP2F3 was precisely consistent with specific dehydrogenation of 3MI via initial hydrogen atom abstraction from the methyl group. In addition, intramolecular kinetic deuterium isotope studies demonstrated an isotope effect ( K H/ K D) of 6.8. This relatively high intramolecular deuterium isotope effect confirmed the initial hydrogen abstraction step; a mutant (D361T) that retained the dehydrogenation reaction exhibited the same deuterium isotope effect. The results showed that a single alteration, such as a serine to isoleucine change at residue 475, dramatically switched catalytic preference from dehydrogenation to oxygenation.
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Affiliation(s)
- Jaya S Kartha
- Department of Pharmacology and Toxicology, 30 South 2000 East, Room 201, University of Utah, Salt Lake City, Utah 84112, USA
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Hernandez LG, Forkert PG. Inhibition of vinyl carbamate-induced mutagenicity and clastogenicity by the garlic constituent diallyl sulfone in F1 (Big Blue® × A/J) transgenic mice. Carcinogenesis 2007; 28:1824-30. [PMID: 17341656 DOI: 10.1093/carcin/bgm051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vinyl carbamate (VC) is a metabolite of ethyl carbamate (EC), a naturally occurring compound found in fermented foods and alcoholic beverages. CYP2E1 mediates the sequential oxidation of EC to VC and subsequently to the vinyl carbamate epoxide, which is believed to be the ultimate carcinogenic species. Here, we have tested the hypothesis that bioactivation of VC by CYP2E1 plays a central role in the development of its mutagenicity and clastogenicity, and further that inhibition of CYP2E1 by diallyl sulfone (DASO(2)) leads to diminution in their incidences. DASO(2) is a garlic constituent that is oxidized by CYP2E1, leading to inactivation of this P450. F(1) (Big Blue x A/J) transgenic mice harboring the lambda cII gene were used for in vivo identification and quantitation of mutations in the lung and small intestine. Mice were pre-treated with DASO(2) (12.5-200 mg/kg, p.o.), treated 2 h later with VC (60 mg/kg, i.p.) and were killed 4 weeks later. Our results showed that pre-treatment of mice with DASO(2) at doses of 50-200 mg/kg significantly decreased the VC-induced mutant frequencies (MFs) by 50-70%. In the small intestine, pre-treatment with 200 mg/kg of DASO(2) decreased the MF by approximately 40%. Clastogenicity, as assessed by the frequency of micronucleated reticulocytes, was significantly decreased (33-44%) by pre-treatment with DASO(2) (50-200 mg/kg). These results demonstrated that bioactivation of VC by CYP2E1 plays a valid role in the development of mutagenicity and clastogenicity, and further that inhibition of this pathway by DASO(2) produces a protective effect.
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Affiliation(s)
- Lya G Hernandez
- Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada
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14
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Forkert PG, Kaufmann M, Black G, Bowers R, Chen H, Collins K, Sharma A, Jones G. Oxidation of vinyl carbamate and formation of 1,N6-ethenodeoxyadenosine in murine lung. Drug Metab Dispos 2007; 35:713-20. [PMID: 17296623 DOI: 10.1124/dmd.106.013805] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vinyl carbamate (VC) is derived from ethyl carbamate, a carcinogen formed in fermentation of food and alcoholic products. We have undertaken studies to test the hypothesis that an epoxide generated from VC oxidation leads to formation of 1,N6-ethenodeoxyadenosine (epsilon dAS). We have developed approaches using liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry for identification and quantitation of epsilon dAS. Scanning and fragment ion analyses confirmed the identity of epsilon dAS based on the molecular ion [M + H]+ m/z 276 and the specific fragment ion m/z 160. Chemical oxidation of VC in reactions containing 2'-deoxyadenosine produced epsilon dAS with 1H NMR, chromatographic, and mass spectral characteristics identical to those of the authentic epsilon dAS, suggesting DNA alkylation by the VC epoxide. Subsequent studies evaluated formation of epsilon dAS in incubations of murine lung microsomes or recombinant CYP2E1 with VC. The formation of epsilon dAS in incubations of lung microsomes or recombinant CYP2E1 with VC was dependent on protein concentrations, CYP2E1 enzyme levels, and incubation time. The rates of epsilon dAS formation were highly correlated with VC concentrations. Peak rates were produced by lung microsomes and recombinant CYP2E1 at 3.0 and 2.5 mM VC, respectively. In inhibitory studies, incubations of VC were performed using lung microsomes from mice treated with the CYP2E1 inhibitor diallyl sulfone (100 mg/kg, p.o.). Results from these studies showed significantly decreased epsilon dAS formation in microsomes incubated with VC, with an inhibition of 70% at 3.0 mM. These findings suggested that CYP2E1 is a major enzyme mediating VC oxidation, leading to the formation of a metabolite that alkylates DNA to form the epsilon dAS adduct.
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Affiliation(s)
- Poh-Gek Forkert
- Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
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15
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Tweats DJ, Blakey D, Heflich RH, Jacobs A, Jacobsen SD, Morita T, Nohmi T, O'Donovan MR, Sasaki YF, Sofuni T, Tice R. Report of the IWGT working group on strategy/interpretation for regulatory in vivo tests II. Identification of in vivo-only positive compounds in the bone marrow micronucleus test. Mutat Res 2007; 627:92-105. [PMID: 17113817 PMCID: PMC2790421 DOI: 10.1016/j.mrgentox.2006.10.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 07/31/2006] [Accepted: 08/14/2006] [Indexed: 05/12/2023]
Abstract
A survey conducted as part of an International Workshop on Genotoxicity Testing (IWGT) has identified a number of compounds that appear to be more readily detected in vivo than in vitro. The reasons for this property varies from compound to compound and includes metabolic differences; the influence of gut flora; higher exposures in vivo compared to in vitro; effects on pharmacology, in particular folate depletion or receptor kinase inhibition. It is possible that at least some of these compounds are detectable in vitro if a specific in vitro test is chosen as part of the test battery, but the 'correct' choice of test may not always be obvious when testing a compound of unknown genotoxicity. It is noted that many of the compounds identified in this study interfere with cell cycle kinetics and this can result in either aneugenicity or chromosome breakage. A decision tree is outlined as a guide for the evaluation of compounds that appear to be genotoxic agents in vivo but not in vitro. The regulatory implications of these findings are discussed.
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Affiliation(s)
- D J Tweats
- Centre for Molecular Genetics and Toxicology, University of Wales Swansea, UK.
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16
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Hernandez LG, Forkert PG. In vivomutagenicity of vinyl carbamate and ethyl carbamate in lung and small intestine of F1(Big Blue® × A/J) transgenic mice. Int J Cancer 2007; 120:1426-33. [PMID: 17205523 DOI: 10.1002/ijc.22502] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Vinyl carbamate (VC) is a metabolite of ethyl carbamate (EC), a chemical found in alcoholic beverages and fermented foods. We undertook this study to: (i) evaluate the ability of both EC and VC to induce gene mutations in lung and various extrapulmonary tissues, and (ii) identify the type of mutations induced by the two compounds in various tissues. F1 (Big Blue x A/J) transgenic mice harboring the lambda cII transgene were used for identification and quantitation of mutations in vivo. Time-course studies in lung showed a plateau in mutant frequency (MF) 4 weeks after VC treatment, at which time mutations were fixed and were about 4-fold higher than in controls. Dose-dependent increases in MF were detected in the lung and small intestine (SI) after treatment with 15-75 mg/kg, i.p., of VC. VC was mutagenic in the lung and SI at doses of 45, 60 and 75 mg/kg. Sequencing of the cII gene in lung and SI showed that VC induced mainly A:T-->G:C transitions and A:T-->T:A transversions. EC was also mutagenic in the lung at 500 and 1,000 mg/kg and elicited mainly G:C-->A:T transitions. A VC dose of 60 mg/kg elicited a similar level of MF as an EC dose of 1,000 mg/kg. At 4 weeks after treatment, neither VC nor EC elicited mutations in the colon, bone marrow or kidney. These results demonstrated that VC and EC are mutagenic in vivo and affirm that VC is a more potent mutagen than EC.
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Affiliation(s)
- Lya G Hernandez
- Department of Anatomy and Cell Biology, Queen's University, Kingston, ON, Canada
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17
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Wang G, Hsieh Y, Wang L, Prelusky D, Korfmacher WA, Morrison R. High-performance liquid chromatography–atmospheric pressure chemical ionization/tandem mass spectrometry for the determination of a thiol compound in plasma. Anal Chim Acta 2003. [DOI: 10.1016/s0003-2670(03)00767-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Hoffler U, El-Masri HA, Ghanayem BI. Cytochrome P450 2E1 (CYP2E1) Is the Principal Enzyme Responsible for Urethane Metabolism: Comparative Studies Using CYP2E1-Null and Wild-Type Mice. J Pharmacol Exp Ther 2003. [DOI: 10.1124/jpet.103.049072] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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19
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Miyano J, Motoyama H, Fukuoka M, Yamamoto S, Narimatsu S, Ogura K, Watabe T, Nishimura M, Ueda N, Naito S. Effects of Pretreatment of Hep G2 Cells with .BETA.-Naphthoflavone on Cytotoxicity of Propranolol and its Active Metabolite 4-Hydroxypropranolol. ACTA ACUST UNITED AC 2003. [DOI: 10.1248/jhs.49.292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Junko Miyano
- Laboratories of Health Chemistry, Faculty of Pharmaceutical Sciences, Okayama University
| | - Harumi Motoyama
- Laboratories of Health Chemistry, Faculty of Pharmaceutical Sciences, Okayama University
| | - Masako Fukuoka
- Laboratories of Health Chemistry, Faculty of Pharmaceutical Sciences, Okayama University
| | - Shigeo Yamamoto
- Biomolecular Science, Faculty of Pharmaceutical Sciences, Okayama University
| | - Shizuo Narimatsu
- Laboratories of Health Chemistry, Faculty of Pharmaceutical Sciences, Okayama University
| | - Kenichiro Ogura
- Department of Drug Metabolism and Molecular Toxicology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Tadashi Watabe
- Department of Drug Metabolism and Molecular Toxicology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
- Institute of Natural Medicine, Toyama Medical and Pharmaceutical University
| | - Masuhiro Nishimura
- Division of Pharmacology, Drug Safety and Metabolism, Otsuka Pharmaceutical Factory, Inc
| | - Nobuhiko Ueda
- Division of Pharmacology, Drug Safety and Metabolism, Otsuka Pharmaceutical Factory, Inc
| | - Shinsaku Naito
- Division of Pharmacology, Drug Safety and Metabolism, Otsuka Pharmaceutical Factory, Inc
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20
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Yost GS. Bioactivation of toxicants by cytochrome p450-mediated dehydrogenation mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 500:53-62. [PMID: 11764993 DOI: 10.1007/978-1-4615-0667-6_6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- G S Yost
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City 84112-5820, USA
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21
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Abstract
This chapter is an update of the data on substrates, reactions, inducers, and inhibitors of human CYP enzymes published previously by Rendic and DiCarlo (1), now covering selection of the literature through 2001 in the reference section. The data are presented in a tabular form (Table 1) to provide a framework for predicting and interpreting the new P450 metabolic data. The data are formatted in an Excel format as most suitable for off-line searching and management of the Web-database. The data are presented as stated by the author(s) and in the case when several references are cited the data are presented according to the latest published information. The searchable database is available either as an Excel file (for information contact the author), or as a Web-searchable database (Human P450 Metabolism Database, www.gentest.com) enabling the readers easy and quick approach to the latest updates on human CYP metabolic reactions.
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Affiliation(s)
- Slobodan Rendic
- Faculty of Pharmacy and Biochemistry, University of Zagreb, Croatia.
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22
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Itoh J, Kashida Y, Watanabe T, Yasuhara K, Takizawa T, Ueda M, Yoshimura H, Hirose M, Mitsumori K. Lack of Modifying Effect of Glycerol in Pulmonary Carcinogenesis in rasH2 Mice Induced by Urethane or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). J Toxicol Pathol 2002. [DOI: 10.1293/tox.15.215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Junko Itoh
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology
| | - Yoko Kashida
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology
| | - Takao Watanabe
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology
| | - Kazuo Yasuhara
- Division of Pathology, National Institute of Health Sciences
| | | | - Makoto Ueda
- Division of Pathology, National Institute of Health Sciences
| | | | - Masao Hirose
- Division of Pathology, National Institute of Health Sciences
| | - Kunitoshi Mitsumori
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology
- Division of Pathology, National Institute of Health Sciences
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23
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Forkert PG, Premdas PD, Bowers RJ. Epoxide formation from diallyl sulfone is associated with CYP2E1 inactivation in murine and human lungs. Am J Respir Cell Mol Biol 2000; 23:687-95. [PMID: 11062148 DOI: 10.1165/ajrcmb.23.5.4149] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We tested the hypothesis that an epoxide formed from diallyl sulfone (DASO(2)) is responsible for inactivation of CYP2E1 in murine and human lungs. An epoxide (1,2-epoxypropyl-3,3'-sulfonyl-1'-propene [DASO(3)]) was synthesized from DASO(2) and conjugated with glutathione (GSH) to produce the conjugates S-(1R, S-[[1-hydroxymethyl-2,3' -sulfonyl]-1' -propenyl]ethyl)glutathione (diastereomers) and S-(1-[[2R,S-hydroxypropyl]-3, 3'-sulfonyl]-1'-propenyl)glutathione (diastereomers). Analysis of these conjugates by high performance liquid chromatography revealed a major peak eluting at 20.5 min. This peak was detected in incubations of murine and human lung microsomes containing DASO(2) and nicotinamide adenine dinucleotide phosphate (NADPH), and was not detected in incubations performed in the absence of DASO(2) or NADPH. The amounts of epoxide-derived GSH conjugates formed in the incubations were concentration-dependent and achieved saturation at 0.75 mM DASO(2). Formation of the conjugates was also time-dependent and peaked at 2.0 h after DASO(2). The peak containing the GSH conjugates was also detected in incubations of CYP2E1-expressed lymphoblastoid microsomes, NADPH, and DASO(2). Maximal amounts of DASO(3), as estimated by formation of a 4-(p-nitrobenzyl)pyridine derivatized product, were detected in murine lung microsomes incubated for 35 min with 1 mM DASO(2). The derivatized DASO(3) was not detectable in incubations of human lung microsomes. p-Nitrophenol hydroxylation, a catalytic activity associated with CYP2E1, was reduced in murine and human lung microsomes incubated with DASO(2), with decreases that were concentration-dependent. Dose-dependent decreases in hydroxylase activity were also found in microsomes from mice treated in vivo with DASO(2) (25 to 200 mg/kg). These results supported the premise that an epoxide formed from DASO(2) mediates inactivation of lung CYP2E1. Furthermore, the findings suggested that the mouse model is relevant for studies of DASO(2) in human lung.
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Affiliation(s)
- P G Forkert
- Departments of Anatomy and Cell Biology and Chemistry, Queen's University, Kingston, Ontario, Canada.
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24
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Cha SW, Gu HK, Lee KP, Lee MH, Han SS, Jeong TC. Immunotoxicity of ethyl carbamate in female BALB/c mice: role of esterase and cytochrome P450. Toxicol Lett 2000; 115:173-81. [PMID: 10814887 DOI: 10.1016/s0378-4274(00)00176-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ethyl carbamate, a potent carcinogen, has been characterized to be metabolized by cytochrome P450 (P450) and esterase. It has recently been demonstrated that P450 may activate ethyl carbamate to immunotoxic metabolites. To investigate the role of esterase in ethyl carbamate-induced immunosuppression, mice were pretreated intraperitoneally with an esterase inhibitor, diazinon, at 20 mg/kg 30 min prior to the administration of ethyl carbamate intraperitoneally at 100 and 400 mg/kg for 7 consecutive days. Pretreatment with diazinon completely blocked the serum esterase activity. Histopathologically splenic and thymic atrophy was observed when mice were treated with ethyl carbamate, which was potentiated by the pretreatment with diazinon. In spleen, lymphocytes in the periarteriolar lymphoid sheath and the marginal zone appeared to be depleted in the white pulps. In thymus, ethyl carbamate caused a marked depletion of cells in cortex. The antibody response to sheep red blood cells (SRBCs) was more suppressed by ethyl carbamate in diazinon-pretreated groups than in corn oil-pretreated groups. These results suggest that the metabolism of ethyl carbamate by esterase may be an inactivation pathway in ethyl carbamate-induced immunosuppression. In addition, ethyl N-hydroxycarbamate, a P450 metabolite, suppressed the lymphoproliferative response induced by lipopolysaccharide and concanavalin A in splenocyte cultures. These results indicate that the metabolism of ethyl carbamate by P450 may be an activation pathway in immunosuppression by ethyl carbamate.
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Affiliation(s)
- S W Cha
- Toxicology Research Center, Korea Research Institute of Chemical Technology, Taejon, South Korea
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