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Tennant RE, Ponting DJ, Thresher A. A deep dive into historical Ames study data for N-nitrosamine compounds. Regul Toxicol Pharmacol 2023; 143:105460. [PMID: 37495012 DOI: 10.1016/j.yrtph.2023.105460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/09/2023] [Accepted: 07/19/2023] [Indexed: 07/28/2023]
Abstract
Mutagenicity data is a core component of the safety assessment data required by regulatory agencies for acceptance of new drug compounds, with the OECD-471 bacterial reverse mutation (Ames) assay most widely used as a primary screen to assess drug impurities for potential mutagenic risk. N-Nitrosamines are highly potent mutagenic carcinogens in rodent bioassays and their recent detection as impurities in pharmaceutical products has sparked increased interest in their safety assessment. Previous literature reports indicated that the Ames test might not be sensitive enough to detect the mutagenic potential of N-nitrosamines in order to accurately predict a risk of carcinogenicity. To explore this hypothesis, public Ames and rodent carcinogenicity data pertaining to the N-nitrosamine class of compounds was collated for analysis. Here we present how variations to the OECD 471-compliant Ames test, including strain, metabolic activation, solvent type and pre-incubation/plate incorporation methods, may impact the predictive performance for carcinogenicity. An understanding of optimal conditions for testing of N-nitrosamines may improve both the accuracy and confidence in the ability of the Ames test to identify potential carcinogens.
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Affiliation(s)
- Rachael E Tennant
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds, West Yorkshire, LS11 5PS, UK.
| | - David J Ponting
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds, West Yorkshire, LS11 5PS, UK
| | - Andrew Thresher
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds, West Yorkshire, LS11 5PS, UK
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2
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Ponting DJ, Foster RS. Drawing a Line: Where Might the Cohort of Concern End? Org Process Res Dev 2023. [DOI: 10.1021/acs.oprd.3c00008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Affiliation(s)
- David J. Ponting
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds LS11 5PS, United Kingdom
| | - Robert S. Foster
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds LS11 5PS, United Kingdom
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3
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Detection of Two Genotoxic Impurities in Drug Substance and Preparation of Imatinib Mesylate by LC–MS/MS. Chromatographia 2020. [DOI: 10.1007/s10337-020-03903-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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4
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Development of a luminescent mutagenicity test for high-throughput screening of aquatic samples. Toxicol In Vitro 2018; 46:350-360. [DOI: 10.1016/j.tiv.2017.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 06/07/2017] [Accepted: 09/05/2017] [Indexed: 11/21/2022]
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5
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Identification of cancer chemopreventive isothiocyanates as direct inhibitors of the arylamine N-acetyltransferase-dependent acetylation and bioactivation of aromatic amine carcinogens. Oncotarget 2017; 7:8688-99. [PMID: 26840026 PMCID: PMC4890997 DOI: 10.18632/oncotarget.7086] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/15/2016] [Indexed: 11/25/2022] Open
Abstract
Aromatic amines (AAs) are chemicals of industrial, pharmacological and environmental relevance. Certain AAs, such as 4-aminobiphenyl (4-ABP), are human carcinogens that require enzymatic metabolic activation to reactive chemicals to form genotoxic DNA adducts. Arylamine N-acetyltransferases (NAT) are xenobiotic metabolizing enzymes (XME) that play a major role in this carcinogenic bioactivation process. Isothiocyanates (ITCs), including benzyl-ITC (BITC) and phenethyl-ITC (PEITC), are phytochemicals known to have chemopreventive activity against several aromatic carcinogens. In particular, ITCs have been shown to modify the bioactivation and subsequent mutagenicity of carcinogenic AA chemicals such as 4-ABP. However, the molecular and biochemical mechanisms by which these phytochemicals may modulate AA carcinogens bioactivation and AA-DNA damage remains poorly understood. This manuscript provides evidence indicating that ITCs can decrease the metabolic activation of carcinogenic AAs via the irreversible inhibition of NAT enzymes and subsequent alteration of the acetylation of AAs. We demonstrate that BITC and PEITC react with NAT1 and inhibit readily its acetyltransferase activity (ki = 200 M−1.s−1 and 66 M−1.s−1 for BITC and PEITC, respectively). Chemical labeling, docking approaches and substrate protection assays indicated that inhibition of the acetylation of AAs by NAT1 was due to the chemical modification of the enzyme active site cysteine. Moreover, analyses of AAs acetylation and DNA adducts in cells showed that BITC was able to modulate the endogenous acetylation and bioactivation of 4-ABP. In conclusion, we show that direct inhibition of NAT enzymes may be an important mechanism by which ITCs exert their chemopreventive activity towards AA chemicals.
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Tyler JH, Nazari SH, Patterson RH, Udumula V, Smith SJ, Michaelis DJ. Synthesis of N- aryl and N -heteroaryl hydroxylamines via partial reduction of nitroarenes with soluble nanoparticle catalysts. Tetrahedron Lett 2017. [DOI: 10.1016/j.tetlet.2016.11.105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Tafurt-Cardona Y, Suares-Rocha P, Fernandes TCC, Marin-Morales MA. Cytotoxic and genotoxic effects of two hair dyes used in the formulation of black color. Food Chem Toxicol 2015; 86:9-15. [PMID: 26404083 DOI: 10.1016/j.fct.2015.09.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 08/19/2015] [Accepted: 09/18/2015] [Indexed: 11/29/2022]
Abstract
According to the International Agency for Research on Cancer (IARC), some hair dyes are considered mutagenic and carcinogenic in in vitro assays and exposed human populations. Epidemiological studies indicate that hairdressers occupationally exposed to hair dyes have a higher risk of developing bladder cancer. In Brazil, 26% of the adults use hair dye. In this study, we investigated the toxic effects of two hair dyes, Basic Red 51 (BR51) and Basic Brown 17 (BB17), which are temporary dyes of the azo group (R-N=N-R'), used in the composition of the black hair dye. To this end, MTT and trypan blue assays (cytotoxicity), comet and micronucleus assay (genotoxicity) were applied, with HepG2 cells. For cytotoxic assessment, dyes were tested in serial dilutions, being the highest concentrations those used in the commercial formula for hair dyes. For genotoxic assessment concentrations were selected according to cell viability. Results showed that both dyes induced significant cytotoxic and genotoxic effects in the cells, in concentrations much lower than those used in the commercial formula. Genotoxic effects could be related to the azo structure present in the composition of the dyes, which is known as mutagenic and carcinogenic. These results point to the hazard of the hair dye exposure to human health.
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Affiliation(s)
- Yaliana Tafurt-Cardona
- UNESP- São Paulo State University "Júlio de Mesquita Filho" Institut of Biosciences, Department of Biology, Rio Claro Campus, Av. 24-A, 1515, Bela Vista, Rio Claro, São Paulo, 13506-900, Brazil
| | - Paula Suares-Rocha
- UNESP- São Paulo State University "Júlio de Mesquita Filho" Institut of Biosciences, Department of Biology, Rio Claro Campus, Av. 24-A, 1515, Bela Vista, Rio Claro, São Paulo, 13506-900, Brazil
| | - Thaís Cristina Casimiro Fernandes
- UNESP- São Paulo State University "Júlio de Mesquita Filho" Institut of Biosciences, Department of Biology, Rio Claro Campus, Av. 24-A, 1515, Bela Vista, Rio Claro, São Paulo, 13506-900, Brazil
| | - Maria Aparecida Marin-Morales
- UNESP- São Paulo State University "Júlio de Mesquita Filho" Institut of Biosciences, Department of Biology, Rio Claro Campus, Av. 24-A, 1515, Bela Vista, Rio Claro, São Paulo, 13506-900, Brazil.
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Microbial Degradation of 2,4,6-Trinitrotoluene In Vitro and in Natural Environments. ENVIRONMENTAL SCIENCE AND ENGINEERING 2014. [DOI: 10.1007/978-3-319-01083-0_2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Stopiglia CDO, Carissimi M, Daboit TC, Stefani V, Corbellini VA, Scroferneker ML. Application of 6-nitrocoumarin as a substrate for the fluorescent detection of nitroreductase activity in Sporothrix schenckii. Rev Inst Med Trop Sao Paulo 2013; 55:353-6. [PMID: 24037291 PMCID: PMC4105074 DOI: 10.1590/s0036-46652013000500010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 03/18/2013] [Indexed: 11/25/2022] Open
Abstract
Introduction Sporothrix schenckii is a thermal dimorphic pathogenic fungus causing a subcutaneous mycosis, sporotrichosis. Nitrocoumarin represents a fluorogenic substrate class where the microbial nitroreductase activity produces several derivatives, already used in several other enzyme assays. The objective of this study was the analysis of 6-nitrocoumarin (6-NC) as a substrate to study the nitroreductase activity in Sporothrix schenckii. Methods Thirty-five samples of S. schenckii were cultivated for seven, 14 and 21 days at 35 °C in a microculture containing 6-nitrocoumarin or 6-aminocoumarin (6-AC) dissolved in dimethyl sulfoxide or dimethyl sulfoxide as a negative control, for posterior examination under an epifluorescence microscope. The organic layer of the seven, 14 and 21-day cultures was analyzed by means of direct illumination with 365 nm UV light and by means of elution on G silica gel plate with hexane:ethyl acetate 1:4 unveiled with UV light. Results All of the strains showed the presence of 6-AC (yellow fluorescence) and 6-hydroxylaminocoumarin (blue fluorescence) in thin layer chromatography, which explains the green fluorescence observed in the fungus structure. Conclusion The nitroreductase activity is widely distributed in the S. schenckii complex and 6-NC is a fluorogenic substrate of easy access and applicability for the nitroreductase activity detection.
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Alvarez-Fitz P, Alvarez L, Marquina S, Luna-Herrera J, Navarro-García VM. Enzymatic reduction of 9-methoxytariacuripyrone by Saccharomyces cerevisiae and its antimycobacterial activity. Molecules 2012; 17:8464-70. [PMID: 22790562 PMCID: PMC6268768 DOI: 10.3390/molecules17078464] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 07/05/2012] [Accepted: 07/05/2012] [Indexed: 11/20/2022] Open
Abstract
Biotransformation processes have been successfully utilized to obtain products of pharmaceutical, chemical, food, and agricultural interest, which are difficult to obtain by classic chemical methods. The compound with antituberculous activity, 9-methoxy-tariacuripyrone (1), isolated from Aristolochia brevipes, was submitted to biotransformation with the yeast Saccharomyces cerevisiae under culture, yielding 5-amino-9-methoxy-3,4-dihydro-2H-benzo[h]chromen-2-one (2). The structure of 2 was elucidated on the basis of spectroscopic analyses. The results mainly show the reduction of the double bond and the nitro group of compound 1. Metabolite 2 demonstrated an increase in anti-tuberculous activity (MIC = 3.12 µg/mL) against the drug-sensitive Mycobacterium tuberculosis (H37Rv) strain, with respect to that shown by 1.
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Affiliation(s)
- Patricia Alvarez-Fitz
- Laboratory of Microbiology, Biomedical Research Center of the South (IMSS), Argentina 1, Col. Centro, 62790 Xochitepec, Morelos, Mexico
- Center for Development of Biotic Products(IPN), Carretera Yautepec-Jojutla, Km. 6, Calle Ceprobi 8, Col San Isidro, Apdo. Postal 24, 62731 Yautepec, Morelos, Mexico
| | - Laura Alvarez
- Chemical Research Center, University of Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos, Mexico
| | - Silvia Marquina
- Chemical Research Center, University of Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos, Mexico
| | - Julieta Luna-Herrera
- Immunochemistry Laboratory II, Department of Immunology, National School of Sciences Biology (IPN), Prolongación Carpio y Plan de Ayala S/N, 11340, D.F., Mexico
| | - Víctor Manuel Navarro-García
- Laboratory of Microbiology, Biomedical Research Center of the South (IMSS), Argentina 1, Col. Centro, 62790 Xochitepec, Morelos, Mexico
- Author to whom correspondence should be addressed; ; Tel.: +52-777-361-21-94
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Bang SY, Kim JH, Lee PY, Bae KH, Lee JS, Kim PS, Lee DH, Myung PK, Park BC, Park SG. Confirmation of Frm2 as a novel nitroreductase in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2012; 423:638-41. [PMID: 22687599 DOI: 10.1016/j.bbrc.2012.05.156] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 05/28/2012] [Indexed: 11/18/2022]
Abstract
Nitroreductases comprise a group of FMN- or FAD-dependent enzymes that reduce nitrosubstituted compounds by using NAD(P)H, and are found in bacterial species and yeast. Although there is little information on the biological functions of nitroreductases, some studies suggest their possible involvement in oxidative stress responses. In the yeast Saccharomyces cerevisiae, a putative nitroreductase protein, Frm2, has been identified based on its sequence similarity with known bacterial nitroreductases. Frm2 has been reported to function in the lipid signaling pathway. To study the functions of Frm2, we measured the nitroreductase activity of purified Frm2 on 4-nitroquinoline-N-oxide (4-NQO) using NADH. LC-MS analysis of the reaction products revealed that Frm2 reduced NQO into 4-aminoquinoline-N-oxide (4-AQO) via 4-hydroxyaminoquinoline (4-HAQO). An Frm2 deletion mutant exhibited growth inhibition in the presence of 4-NQO. Thus, in this study, we demonstrate a novel nitroreductase activity of Frm2 and its involvement in the oxidative stress defense system.
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Affiliation(s)
- Seo Young Bang
- Medical Proteomics Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
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Uliana CV, Garbellini GS, Yamanaka H. Electrochemical reduction of disperse orange 1 textile dye at a boron-doped diamond electrode. J APPL ELECTROCHEM 2012. [DOI: 10.1007/s10800-012-0403-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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13
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Jeun JA, Cho HJ, Jun HJ, Lee JH, Jia YY, Cho KS, Kim ES, Lee SJ. Mutagenic and Antimutagenic Effects of Hemp Seed Oil Evaluated by Ames Salmonella Testing. ACTA ACUST UNITED AC 2011. [DOI: 10.9721/kjfst.2011.43.3.396] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Benigni R, Bossa C. Mechanisms of Chemical Carcinogenicity and Mutagenicity: A Review with Implications for Predictive Toxicology. Chem Rev 2011; 111:2507-36. [PMID: 21265518 DOI: 10.1021/cr100222q] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Romualdo Benigni
- Istituto Superiore di Sanita’, Environment and Health Department, Viale Regina Elena, 299 00161 Rome, Italy
| | - Cecilia Bossa
- Istituto Superiore di Sanita’, Environment and Health Department, Viale Regina Elena, 299 00161 Rome, Italy
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Kirkland D, Reeve L, Gatehouse D, Vanparys P. A core in vitro genotoxicity battery comprising the Ames test plus the in vitro micronucleus test is sufficient to detect rodent carcinogens and in vivo genotoxins. Mutat Res 2011; 721:27-73. [PMID: 21238603 DOI: 10.1016/j.mrgentox.2010.12.015] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 11/12/2010] [Accepted: 12/15/2010] [Indexed: 01/27/2023]
Abstract
In vitro genotoxicity testing needs to include tests in both bacterial and mammalian cells, and be able to detect gene mutations, chromosomal damage and aneuploidy. This may be achieved by a combination of the Ames test (detects gene mutations) and the in vitro micronucleus test (MNvit), since the latter detects both chromosomal aberrations and aneuploidy. In this paper we therefore present an analysis of an existing database of rodent carcinogens and a new database of in vivo genotoxins in terms of the in vitro genotoxicity tests needed to detect their in vivo activity. Published in vitro data from at least one test system (most were from the Ames test) were available for 557 carcinogens and 405 in vivo genotoxins. Because there are fewer publications on the MNvit than for other mammalian cell tests, and because the concordance between the MNvit and the in vitro chromosomal aberration (CAvit) test is so high for clastogenic activity, positive results in the CAvit test were taken as indicative of a positive result in the MNvit where there were no, or only inadequate data for the latter. Also, because Hprt and Tk loci both detect gene-mutation activity, a positive Hprt test was taken as indicative of a mouse-lymphoma Tk assay (MLA)-positive, where there were no data for the latter. Almost all of the 962 rodent carcinogens and in vivo genotoxins were detected by an in vitro battery comprising Ames+MNvit. An additional 11 carcinogens and six in vivo genotoxins would apparently be detected by the MLA, but many of these had not been tested in the MNvit or CAvit tests. Only four chemicals emerge as potentially being more readily detected in MLA than in Ames+MNvit--benzyl acetate, toluene, morphine and thiabendazole--and none of these are convincing cases to argue for the inclusion of the MLA in addition to Ames+MNvit. Thus, there is no convincing evidence that any genotoxic rodent carcinogens or in vivo genotoxins would remain undetected in an in vitro test battery consisting of Ames+MNvit.
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Affiliation(s)
- David Kirkland
- Kirkland Consulting, PO Box 79, Tadcaster LS24 0AS, United Kingdom.
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Takenaka Y, Kiyosu T, Choi JC, Sakakura T, Yasuda H. Selective synthesis of N-alkyl hydroxylamines by hydrogenation of nitroalkanes using supported palladium catalysts. CHEMSUSCHEM 2010; 3:1166-1168. [PMID: 20722045 DOI: 10.1002/cssc.201000137] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Affiliation(s)
- Yasumasa Takenaka
- National Institute of Advanced Industrial Science and Technology, Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
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Devillers J, Mombelli E. Evaluation of the OECD QSAR Application Toolbox and Toxtree for estimating the mutagenicity of chemicals. Part 1. Aromatic amines. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2010; 21:753-769. [PMID: 21120760 DOI: 10.1080/1062936x.2010.528959] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The Ames Salmonella typhimurium mutagenicity assay is a short-term bacterial reverse mutation test that was designed to detect mutagens. For several decades, it has been used in research laboratories and by regulatory agencies throughout the world for the detection and characterization of potential mutagens among natural products and man-made chemicals. Faced with the ever-growing number of chemicals available on the market, congeneric and non-congeneric (Q)SAR models have been designed from Ames test results obtained on specific S. typhimurium strains such as TA 100 or TA 98. Such models have great potential for a quick and cheap identification and classification of large numbers of potential chemical mutagens. The OECD QSAR Application Toolbox and Toxtree, which were developed for facilitating the practical use of (Q)SAR approaches in regulatory contexts, include two mechanistic SAR models for predicting the mutagenicity of aromatic amines and α-β unsaturated aliphatic aldehydes. The aim of this study was to estimate the interest and limitations of the former model. The model was first re-computed to check its transparency and to verify its statistical validity. Then, it was tested on about 150 chemicals not previously used for the design of the model but belonging to its domain of application. A critical analysis of the results was performed and proposals were made for increasing the model performances.
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Affiliation(s)
- J Devillers
- CTIS, 3 Chemin de la Gravière, 69140 Rillieux La Pape, France.
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de Oliveira IM, Zanotto-Filho A, Moreira JCF, Bonatto D, Henriques JAP. The role of two putative nitroreductases, Frm2p and Hbn1p, in the oxidative stress response in Saccharomyces cerevisiae. Yeast 2010; 27:89-102. [PMID: 19904831 DOI: 10.1002/yea.1734] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The nitroreductase family is comprised of a group of FMN- or FAD-dependent enzymes that are able to metabolize nitrosubstituted compounds using the reducing power of NAD(P)H. These nitroreductases can be found in bacterial species and, to a lesser extent, in eukaryotes. There is little information on the biochemical functions of nitroreductases. Some studies suggest their possible involvement in the oxidative stress response. In the yeast Saccharomyces cerevisiae, two nitroreductase proteins, Frm2p and Hbn1p, have been described. While Frm2p appears to act in the lipid signalling pathway, the function of Hbn1p is completely unknown. In order to elucidate the functions of Frm2p and Hbn1p, we evaluated the sensitivity of yeast strains, proficient and deficient in both oxidative stress proteins, for respiratory competence, antioxidant-enzyme activities, intracellular reactive oxygen species (ROS) production and lipid peroxidation. We found reduced basal activity of superoxide dismutase (SOD), ROS production, lipid peroxidation and petite induction and higher sensitivity to 4-nitroquinoline-oxide (4-NQO) and N-nitrosodiethylamine (NDEA), as well as higher basal activity of catalase (CAT) and glutathione peroxidase (GPx) and reduced glutathione (GSH) content in the single and double mutant strains frm2Delta and frm2Delta hbn1Delta. These strains exhibited less ROS accumulation and lipid peroxidation when exposed to peroxides, H(2)O(2) and t-BOOH. In summary, the Frm1p and Hbn1p nitroreductases influence the response to oxidative stress in S. cerevisae yeast by modulating the GSH contents and antioxidant enzymatic activities, such as SOD, CAT and GPx.
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Affiliation(s)
- Iuri Marques de Oliveira
- Departamento de Biofísica/Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Av Bento Gonçalves 9500, 91507-970 Porto Alegre, RS, Brazil
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Nitropolycyclic aromatic hydrocarbons are inducers of mitotic homologous recombination in the wing-spot test of Drosophila melanogaster. Food Chem Toxicol 2008; 46:2344-8. [DOI: 10.1016/j.fct.2008.03.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 02/26/2008] [Accepted: 03/12/2008] [Indexed: 11/22/2022]
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Caballero A, Lázaro JJ, Ramos JL, Esteve-Núñez A. PnrA, a new nitroreductase-family enzyme in the TNT-degrading strain Pseudomonas putida JLR11. Environ Microbiol 2005; 7:1211-9. [PMID: 16011758 DOI: 10.1111/j.1462-2920.2005.00801.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitroreductases are a group of proteins that catalyse pyridine nucleotide-dependent reduction of nitroaromatics compounds, showing significant human health and environmental implications. In this study we have identified the nitroreductase-family enzymes PnrA and PnrB from the TNT-degrading strain Pseudomonas putida. The enzyme encoded by the pnrA gene was expressed in Escherichia coli, purified to homogeneity and shown to be a flavoprotein that used 2 mol of NADPH to reduce 1 mol of 2,4,6-trinitrotoluene (TNT) to 4-hydroxylamine-2,6-dinitrotoluene, using a ping-pong bi-bi mechanism. The PnrA enzyme also recognized as substrates as a number of other nitroaromatic compounds, i.e. 2,4-dinitrotoluene, 3-nitrotoluene, 3- and 4-nitrobenzoate, 3,5-dinitrobenzamide and 3,5-dinitroaniline expanding the substrates profile from previously described nitroreductases. However, TNT resulted to be the most efficient substrate examined according to the Vmax/Km parameter. Expression analysis of pnrA- and pnrB-mRNA isolated from cells growing on different nitrogen sources suggested that expression of both genes was constitutive and that its level of expression was relatively constant regardless of the growth substrate. This is in agreement with enzyme-specific activity determined with cells growing with different N-sources.
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Affiliation(s)
- Antonio Caballero
- Department of Biochemistry and Molecular and Cellular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Apdo Correos 419, E-18008 Granada, Spain
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González Borroto JI, Pérez G, Creus A, Marcos R. Genotoxicity testing of the furylethylene derivative 1-(5-bromofur-2-yl)-2-bromo-2-nitroethene in cultured human lymphocytes. Food Chem Toxicol 2004; 42:187-93. [PMID: 14667464 DOI: 10.1016/j.fct.2003.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The genotoxic potential of the compound 1-(5-bromofur-2-yl)-2-bromo-2-nitroethene (G-1) was evaluated in peripheral blood lymphocytes cultured in vitro, at concentrations ranging from 1 to 20 microg/ml. Micronuclei (MN) and sister-chromatid exchanges (SCE) were scored as biomarkers of genotoxic effects. To detect the role of metabolic enzymes on the genotoxicity of this furylethylenic derivative, cultures for MN and SCE demonstrations were treated for 3 h with and without the S9 microsomal fraction as well as for 48 h without S9. Under the conditions of the study, the test agent did not induce significant increases in the frequency of micronucleated cells, irrespective of the presence/absence of the metabolic fraction. Nevertheless, a slight/moderate increase in the SCE frequency was observed in those cultures treated without the S9 mix. In addition, cytotoxic/cytostatic effects of the G-1 compound were observed mainly in cultures without S9 fraction, as indicated by the reduction of cell proliferation measured by the cytokinesis block proliferation index (CBPI) and the proliferative rate index (PRI).
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Affiliation(s)
- Jorge I González Borroto
- Grup de Mutagènesi, Departament de Genètica i de Microbiologia, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
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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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Glende C, Klein M, Schmitt H, Erdinger L, Boche G. Transformation of mutagenic aromatic amines into non-mutagenic species by alkyl substituents. Part II: alkylation far away from the amino function. Mutat Res 2002; 515:15-38. [PMID: 11909752 DOI: 10.1016/s1383-5718(01)00345-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Alkyl and trifluoromethyl derivatives of 4-aminobiphenyl (1) (4ABP) and 2-aminofluorene (7) (2AF) were synthesised and assayed for mutagenicity using Salmonella typhimurium tester strains TA98 and TA100 with and without the addition of S9 mix. Modification of 1 was achieved by attachment of alkyl groups (methyl, ethyl, iso-propyl, n-butyl, tert-butyl) and a trifluoromethyl group (CF(3)) in the 4'-position, the 3'-position (Me, CF(3)) and the 3'-, 5'-positions (DiMe, DiCF(3)). Compound 7 was modified by introduction of alkyl groups (methyl, tert-butyl, adamantyl) and a trifluoromethyl group (CF(3)) in the 7-position. The derivatives of 1 and 7 show for groups with growing steric demand decreased mutagenic activity. The bulkiest groups (CF(3), tert-butyl and adamantyl) induce the strongest effects on the mutagenicity. It was even possible to eliminate the mutagenicity of 1 and 7 by introduction of such substituents. In the last part of the work, we compared the experimental mutagenicities with calculated values derived from QSAR correlations. Our findings show that the predictions for aromatic amines with bulky substituents were generally too high. The strongest deviations were observed in the case of the CF(3)-, tert-butyl- and the adamantyl-group. Only the parent compounds and derivatives with small alkyl groups were predicted well. These investigations show that "large" substituents have an influence on the mutagenicity caused by their steric demand. To predict the correct mutagenicities of such compounds, it is necessary to introduce steric parameters in the respective QSAR equations which will be done in a forthcoming paper.
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Affiliation(s)
- Carsten Glende
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str., 35032, Marburg, Germany
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Glende C, Schmitt H, Erdinger L, Engelhardt G, Boche G. Transformation of mutagenic aromatic amines into non-mutagenic species by alkyl substituents. Part I. Alkylation ortho to the amino function. Mutat Res 2001; 498:19-37. [PMID: 11673068 DOI: 10.1016/s1383-5718(01)00259-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Alkyl-substituted derivatives of 2-aminonaphthalene (2-AN) 1, 2-aminofluorene (2-AF) 6 and 4-aminobiphenyl (4-ABP) 11 were synthesized and the mutagenic activity of these compounds determined in Salmonella typhimurium strains TA98 and TA100 with and without S9 mix. In the case of the ortho-substituted 4-aminobiphenyls 12-15 (3-alkyl=ethyl, iso-propyl, n-butyl, tert-butyl) the substituent with the strongest steric demand (3-tert-butyl) shows the strongest influence on the decrease of mutagenicity if compared with the parent compound. In the series of the bis-ortho-disubstituted compounds 16-18 (3,5-dimethyl-, 3,5-diethyl- and 3,5-diisopropyl-4-aminobiphenyl) generation of non-mutagenic species occurs already with the introduction of two ethyl groups. For the 4-aminobiphenyl derivatives 12-15 and 16-18, as well as for the 1-alkylated 2-aminofluorenes 7-10 and the 1-alkylated 2-aminonaphthalenes 2-5 a smaller mutagenicity was observed if compared with predicted mutagenicities as calculated by the QSAR equations of Debnath et al. (Environ. Mol. Mutagen. 19 (1992) 37). The largest differences resulted in the cases of the tert-butyl substituted compounds. Only with smaller alkyl groups like ethyl the QSAR predictions and the experimentally determined mutagenicities come close to each other. Thus, these results show that appropriate alkyl substitution reduces (eliminates) mutagenicity, secondly, it is necessary to introduce steric parameters to predict the mutagenicity of such compounds correctly.
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Affiliation(s)
- C Glende
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein Strasse, 35032 Marburg, Germany
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