1
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Matthee C, Terre'Blanche G, Janse van Rensburg HD, Aucamp J, Legoabe LJ. Chalcone-inspired rA 1 /A 2A adenosine receptor ligands: Ring closure as an alternative to a reactive substructure. Chem Biol Drug Des 2021; 99:416-437. [PMID: 34878728 DOI: 10.1111/cbdd.13999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/21/2021] [Accepted: 10/30/2021] [Indexed: 11/30/2022]
Abstract
Over the past few years, great progress has been made in the development of high-affinity adenosine A1 and/or A2A receptor antagonists-promising agents for the potential treatment of Parkinson's disease. Unfortunately, many of these compounds raise structure-related concerns. The present study investigated the effect of ring closures on the rA1 /A2A affinity of compounds containing a highly reactive α,β-unsaturated carbonyl system, hence providing insight into the potential of heterocycles to address these concerns. A total of 12 heterocyclic compounds were synthesised and evaluated in silico and in vitro. The test compounds performed well upon qualitative assessment of drug-likeness and were generally found to be free from potentially problematic fragments. Most also showed low/weak cytotoxicity. Results from radioligand binding experiments confirm that heterocycles (particularly 2-substituted 3-cyanopyridines) can replace the promiscuous α,β-unsaturated ketone functional group without compromising A1 /A2A affinity. Structure-activity relationships highlighted the importance of hydrogen bonds in binding to the receptors of interest. Compounds 3c (rA1 Ki = 16 nM; rA2A Ki = 65 nM) and 8a (rA1 Ki = 102 nM; rA2A Ki = 37 nM), which both act as A1 antagonists, showed significant dual A1 /A2A affinity and may, therefore, inspire further investigation into heterocycles as potentially safe and potent adenosine receptor antagonists.
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Affiliation(s)
- Chrisna Matthee
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
| | - Gisella Terre'Blanche
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa.,Pharmaceutical Chemistry, School of Pharmacy, North-West University, Potchefstroom, South Africa
| | | | - Janine Aucamp
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
| | - Lesetja J Legoabe
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
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2
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Leshabane M, Dziwornu GA, Coertzen D, Reader J, Moyo P, van der Watt M, Chisanga K, Nsanzubuhoro C, Ferger R, Erlank E, Venter N, Koekemoer L, Chibale K, Birkholtz LM. Benzimidazole Derivatives Are Potent against Multiple Life Cycle Stages of Plasmodium falciparum Malaria Parasites. ACS Infect Dis 2021; 7:1945-1955. [PMID: 33673735 DOI: 10.1021/acsinfecdis.0c00910] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The continued emergence of resistance to front-line antimalarial treatments is of great concern. Therefore, new compounds that potentially have a novel target in various developmental stages of Plasmodium parasites are needed to treat patients and halt the spread of malaria. Here, several benzimidazole derivatives were screened for activity against the symptom-causing intraerythrocytic asexual blood stages and the transmissible gametocyte stages of P. falciparum. Submicromolar activity was obtained for 54 compounds against asexual blood stage parasites with 6 potent at IC50 < 100 nM while not displaying any marked toxicity against mammalian cells. Nanomolar potency was also observed against gametocytes with two compounds active against early stage gametocytes and two compounds active against late-stage gametocytes. The transmission-blocking potential of the latter was confirmed as they could prevent male gamete exflagellation and the lead compound reduced transmission by 72% in an in vivo mosquito feeding model. These compounds therefore have activity against multiple stages of Plasmodium parasites with potential for differential targets.
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Affiliation(s)
- Meta Leshabane
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | | | - Dina Coertzen
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Phanankosi Moyo
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Kelly Chisanga
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | | | - Richard Ferger
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Erica Erlank
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Nelius Venter
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Lizette Koekemoer
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
- South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
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3
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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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4
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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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5
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Lesuisse D, Malanda A, Peyronel JF, Evanno Y, Lardenois P, De-Peretti D, Abécassis PY, Barnéoud P, Brunel P, Burgevin MC, Cegarra C, Auger F, Dommergue A, Lafon C, Even L, Tsi J, Luc TPH, Almario A, Olivier A, Castel MN, Taupin V, Rooney T, Vigé X. Development of a novel NURR1/NOT agonist from hit to lead and candidate for the potential treatment of Parkinson's disease. Bioorg Med Chem Lett 2019; 29:929-932. [DOI: 10.1016/j.bmcl.2019.01.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/12/2019] [Accepted: 01/17/2019] [Indexed: 12/11/2022]
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6
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Muz M, Krauss M, Kutsarova S, Schulze T, Brack W. Mutagenicity in Surface Waters: Synergistic Effects of Carboline Alkaloids and Aromatic Amines. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:1830-1839. [PMID: 28045503 DOI: 10.1021/acs.est.6b05468] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
For decades, mutagenicity has been observed in many surface waters with a possible link to the presence of aromatic amines. River Rhine is a well-known example of this phenomenon but responsible compound(s) are still unknown. To identify the mutagenic compounds, we applied effect-directed analysis (EDA) utilizing novel analytical and biological approaches to a water sample extract from the lower Rhine. We could identify 21 environmental contaminants including two weakly mutagenic aromatic amines, and the known alkaloid comutagen norharman along with two related β-carboline alkaloids, carboline, and 5-carboline, which were reported the first time in surface waters. Results of mixture tests showed a strong synergism of the identified aromatic amines not only with norharman, but also with carboline and 5-carboline. Additionally, other nitrogen-containing compounds also contributed to the mutagenicity when aromatic amines were present. Thus, comutagenicity of β-carboline alkaloids with aromatic amines is shown to occur in surface waters. These results strongly suggest that surface water mutagenicity is highly complex and driven by synergistic mechanisms of a complex compound mixture (of which many are yet unidentified) rather than by single compounds. Therefore, mixture effects should be considered not only from mutagens alone, but also including possible comutagens and nonmutagenic compounds.
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Affiliation(s)
- Melis Muz
- Department Effect-Directed Analysis, Helmholtz Centre for Environmental Research - UFZ , Permoserstraße 15, 04318 Leipzig, Germany
- RWTH Aachen University , Department of Ecosystem Analyses, Institute for Environmental Research,Worringerweg 1, 52074 Aachen, Germany
| | - Martin Krauss
- Department Effect-Directed Analysis, Helmholtz Centre for Environmental Research - UFZ , Permoserstraße 15, 04318 Leipzig, Germany
| | - Stela Kutsarova
- Laboratory of Mathematical Chemistry, University "Prof. Assen Zlatarov" , 1 Yakimov Street, 8010 Bourgas, Bulgaria
| | - Tobias Schulze
- Department Effect-Directed Analysis, Helmholtz Centre for Environmental Research - UFZ , Permoserstraße 15, 04318 Leipzig, Germany
| | - Werner Brack
- Department Effect-Directed Analysis, Helmholtz Centre for Environmental Research - UFZ , Permoserstraße 15, 04318 Leipzig, Germany
- RWTH Aachen University , Department of Ecosystem Analyses, Institute for Environmental Research,Worringerweg 1, 52074 Aachen, Germany
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7
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Fluidized-bed Fenton process as alternative wastewater treatment technology—A review. J Taiwan Inst Chem Eng 2016. [DOI: 10.1016/j.jtice.2016.07.021] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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8
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Meanwell NA. 2015 Philip S. Portoghese Medicinal Chemistry Lectureship. Curing Hepatitis C Virus Infection with Direct-Acting Antiviral Agents: The Arc of a Medicinal Chemistry Triumph. J Med Chem 2016; 59:7311-51. [PMID: 27501244 DOI: 10.1021/acs.jmedchem.6b00915] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The development of direct-acting antiviral agents that can cure a chronic hepatitis C virus (HCV) infection after 8-12 weeks of daily, well-tolerated therapy has revolutionized the treatment of this insidious disease. In this article, three of Bristol-Myers Squibb's HCV programs are summarized, each of which produced a clinical candidate: the NS3 protease inhibitor asunaprevir (64), marketed as Sunvepra, the NS5A replication complex inhibitor daclatasvir (117), marketed as Daklinza, and the allosteric NS5B polymerase inhibitor beclabuvir (142), which is in late stage clinical studies. A clinical study with 64 and 117 established for the first time that a chronic HCV infection could be cured by treatment with direct-acting antiviral agents alone in the absence of interferon. The development of small molecule HCV therapeutics, designed by medicinal chemists, has been hailed as "the arc of a medical triumph" but may equally well be described as "the arc of a medicinal chemistry triumph".
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Affiliation(s)
- Nicholas A Meanwell
- Department of Discovery Chemistry, Bristol-Myers Squibb Research & Development , Wallingford, Connecticut 06492, United States
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9
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Edwards JW, Priestly BG. Biological and Biological-Effect Monitoring of Workers Exposed to 4, 4' -Methylene-bis (2-chloroaniline). Hum Exp Toxicol 2016; 11:229-36. [PMID: 1352119 DOI: 10.1177/096032719201100312] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
4,4'-Methylene- bis (2-chloroaniline) (MOCA), a curing agent used in polyurethane manufacture, is a genotoxic and carcinogenic amine. This study aimed to assess occupational exposure to MOCA using as indices: (1) the post-work urinary output of MOCA; (2) urinary thioethers, assuming that conjugation with glutathione might be a significant pathway for the elimination of putative electrophilic metabolites of MOCA; and (3) sister-chromatid exchange (SCE) frequency in peripheral lymphocytes as an indicator of genetic damage. Process workers at a polyurethane production unit were found to have up to 38 μmol MOCA mol -1 creatinine in their urine at the end of a work shift. Smaller quantities were found in the urine of laboratory and supervisory staff, but none was detected in the urine of a group of office and sales staff from an unrelated industry, who served as unexposed controls. There was no evidence of MOCA-related urinary thioether output. There was a graded increase in SCE frequency from controls to process workers, consistent with their apparent exposure to MOCA. Administration of MOCA to rats (5 daily i.p. injections of 125 or 250 mg kg-1 resulted in dose-related increases in MOCA excretion and in lymphocyte SCE frequency, but there was no change in thioether output. These results indicate that urinary thioether excretion is inappropriate for monitoring MOCA exposure, but that where MOCA exposure can be demonstrated, by the presence of MOCA in urine, this is associated with genetic damage in both man and in the rat.
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Affiliation(s)
- J W Edwards
- Department of Clinical and Experimental Pharmacology, University of Adelaide, South Australia
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10
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Lu J, Zhou F, Li L, Zhang Z, Meng F, Zhou N, Zhu X. Novel cyclic azobenzene-containing vesicles: photo/reductant responsiveness and potential applications in colon disease treatment. RSC Adv 2016. [DOI: 10.1039/c6ra12751g] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The vesicles formed by an amphiphilic copolymer with cyclic azobenzene pendants revealed higher drug loading content and better photo/reductant responsiveness than an analogue of the amphiphilic copolymer with linear azobenzene units.
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Affiliation(s)
- Jinjie Lu
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
| | - Feng Zhou
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
| | - Lishan Li
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
| | - Zhengbiao Zhang
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
| | - Fenghua Meng
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
| | - Nianchen Zhou
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
| | - Xiulin Zhu
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
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11
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Novel benzidine and diaminofluorene prolinamide derivatives as potent hepatitis C virus NS5A inhibitors. Eur J Med Chem 2015; 101:163-78. [PMID: 26134551 DOI: 10.1016/j.ejmech.2015.06.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 06/14/2015] [Accepted: 06/15/2015] [Indexed: 12/21/2022]
Abstract
Our study describes the discovery of a series of highly potent hepatitis C virus (HCV) NS5A inhibitors based on symmetrical prolinamide derivatives of benzidine and diaminofluorene. Through modification of benzidine, l-proline, and diaminofluorene derivatives, we developed novel inhibitor structures, which allowed us to establish a library of potent HCV NS5A inhibitors. After optimizing the benzidine prolinamide backbone, we identified inhibitors embedding meta-substituted benzidine core structures that exhibited the most potent anti-HCV activities. Furthermore, through a battery of studies including hERG ligand binding assay, CYP450 binding assay, rat plasma stability test, human liver microsomal stability test, and pharmacokinetic studies, the identified compounds 24, 26, 27, 42, and 43 are found to be nontoxic, and are expected to be effective therapeutic anti-HCV agents.
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12
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Abstract
The resolution of inflammation (RoI), once believed to be a passive process, has lately been shown to be an active and delicately orchestrated process. During the resolution phase of acute inflammation, novel mediators, including lipoxins and resolvins, which are members of the specialized pro-resolving mediators of inflammation, are produced. FPR2/ALXR, a receptor modulated by some of these lipids as well as by peptides (e.g., annexin A1), has been shown to be one of the receptors involved in the RoI. The aim of this perspective is to present the concept of the RoI from a medicinal chemistry point of view and to highlight the effort of the research community to discover and develop anti-inflammatory/pro-resolution small molecules to orchestrate inflammation by activation of FPR2/ALXR.
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Affiliation(s)
- Olivier Corminboeuf
- Actelion Pharmaceuticals Ltd. , Gewerbestrasse 16, CH-4123 Allschwil, Switzerland
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13
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Chao MW, Erkekoglu P, Tseng CY, Ye W, Trudel LJ, Skipper PL, Tannenbaum SR, Wogan GN. Intracellular generation of ROS by 3,5-dimethylaminophenol: persistence, cellular response, and impact of molecular toxicity. Toxicol Sci 2014; 141:300-13. [PMID: 24973092 DOI: 10.1093/toxsci/kfu127] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Epidemiological studies have demonstrated extensive human exposure to the monocyclic aromatic amines, particularly to 3,5-dimethylaniline, and found an association between exposure to these compounds and risk for bladder cancer. Little is known about molecular mechanisms that might lead to the observed risk. We previously suggested that the hydroxylated 3,5-dimethylaniline metabolite, 3,5-dimethylaminophenol (3,5-DMAP), played a central role in effecting genetic change through the generation of reactive oxygen species (ROS) in a redox cycle with 3,5-dimethylquinoneimine. Experiments here characterize ROS generation by 3,5-DMAP exposure in nucleotide repair-proficient and -deficient Chinese hamster ovary cells as a function of time. Besides, various cellular responses discussed herein indicate that ROS production is the principal cause of cytotoxicity. Fluorescence microscopy of cells exposed to 3,5-DMAP confirmed that ROS production occurs in the nuclear compartment, as suggested by a previous study demonstrating covalent linkage between 3,5-DMAP and histones. 3,5-DMAP was also compared with 3,5-dimethylhydroquinone to determine whether substitution of one of the phenolic hydroxyl groups by an amino group had a significant effect on some of the investigated parameters. The comparatively much longer duration of observable ROS produced by 3,5-DMAP (7 vs. 1 day) provides further evidence that 3,5-DMAP becomes embedded in the cellular matrix in a form capable of continued redox cycling. 3,5-DMAP also induced dose-dependent increase of H2O2 and ·OH, which were determined as the major free radicals contributing to the cytotoxicity and apoptosis mediated via caspase-3 activation. Overall, this study provides insight into the progression of alkylaniline-induced toxicity.
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Affiliation(s)
- Ming-Wei Chao
- Department of Bioscience Technology, Chung Yuan Christian University, Chungli City, Taoyuan 32023, Taiwan Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Pinar Erkekoglu
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Department of Toxicology, Faculty of Pharmacy, Hacettepe University, Sihhiye-Ankara, Turkey
| | - Chia-Yi Tseng
- Department of Biomedical Engineering, Chung Yuan Christian University, Chungli City, Taoyuan 32023, Taiwan
| | - Wenjie Ye
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Laura J Trudel
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Paul L Skipper
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Steven R Tannenbaum
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Gerald N Wogan
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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14
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Belema M, Meanwell NA. Discovery of daclatasvir, a pan-genotypic hepatitis C virus NS5A replication complex inhibitor with potent clinical effect. J Med Chem 2014; 57:5057-71. [PMID: 24749835 DOI: 10.1021/jm500335h] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The discovery and development of the first-in-class hepatitis C virus (HCV) NS5A replication complex inhibitor daclatasvir (6) provides a compelling example of the power of phenotypic screening to identify leads engaging novel targets in mechanistically unique ways. HCV NS5A replication complex inhibitors are pan-genotypic in spectrum, and this mechanistic class provides the most potent HCV inhibitors in vitro that have been described to date. Clinical trials with 6 demonstrated a potent effect on reducing plasma viral load and, in combination with mechanistically orthogonal HCV inhibitors, established the ability to cure even the most difficult infections without the need for immune stimulation. In this Drug Annotation, we describe the discovery of the original high-throughput screening lead 7 and the chemical conundrum and challenges resolved in optimizing to 6 as a clinical candidate and finally we summarize the results of select clinical studies.
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Affiliation(s)
- Makonen Belema
- Department of Discovery Chemistry, Bristol-Myers Squibb Research and Development , 5 Research Parkway, Wallingford, Connecticut 06492, United States
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15
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Belema M, Lopez OD, Bender JA, Romine JL, St Laurent DR, Langley DR, Lemm JA, O'Boyle DR, Sun JH, Wang C, Fridell RA, Meanwell NA. Discovery and development of hepatitis C virus NS5A replication complex inhibitors. J Med Chem 2014; 57:1643-72. [PMID: 24621191 DOI: 10.1021/jm401793m] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Lead inhibitors that target the function of the hepatitis C virus (HCV) nonstructural 5A (NS5A) protein have been identified by phenotypic screening campaigns using HCV subgenomic replicons. The demonstration of antiviral activity in HCV-infected subjects by the HCV NS5A replication complex inhibitor (RCI) daclatasvir (1) spawned considerable interest in this mechanistic approach. In this Perspective, we summarize the medicinal chemistry studies that led to the discovery of 1 and other chemotypes for which resistance maps to the NS5A protein and provide synopses of the profiles of many of the compounds currently in clinical trials. We also summarize what is currently known about the NS5A protein and the studies using NS5A RCIs and labeled analogues that are helping to illuminate aspects of both protein function and inhibitor interaction. We conclude with a synopsis of the results of notable clinical trials with HCV NS5A RCIs.
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Affiliation(s)
- Makonen Belema
- Department of Discovery Chemistry, ‡Department of Virology Discovery, and §Department of Computer-Assisted Drug Design, Bristol-Myers Squibb Research and Development , 5 Research Parkway, Wallingford, Connecticut 06492, United States
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16
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Belema M, Nguyen VN, Romine JL, St. Laurent DR, Lopez OD, Goodrich JT, Nower PT, O’Boyle DR, Lemm JA, Fridell RA, Gao M, Fang H, Krause RG, Wang YK, Oliver AJ, Good AC, Knipe JO, Meanwell NA, Snyder LB. Hepatitis C Virus NS5A Replication Complex Inhibitors. Part 6: Discovery of a Novel and Highly Potent Biarylimidazole Chemotype with Inhibitory Activity Toward Genotypes 1a and 1b Replicons. J Med Chem 2014; 57:1995-2012. [DOI: 10.1021/jm4016203] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Makonen Belema
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Van N. Nguyen
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Jeffrey L. Romine
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Denis R. St. Laurent
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Omar D. Lopez
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Jason T. Goodrich
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Peter T. Nower
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Donald R. O’Boyle
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Julie A. Lemm
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Robert A. Fridell
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Min Gao
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Hua Fang
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Rudolph G. Krause
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Ying-Kai Wang
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - A. Jayne Oliver
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Andrew C. Good
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Jay O. Knipe
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Nicholas A. Meanwell
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Lawrence B. Snyder
- Departments of Discovery Chemistry, ‡Virology, §Lead Discovery and Optimization, ∥Computer-Assisted
Drug Design, and ⊥Metabolism and Pharmacokinetics, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
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17
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Further investigations into the genotoxicity of 2,6-xylidine and one of its key metabolites. Regul Toxicol Pharmacol 2012; 62:151-9. [DOI: 10.1016/j.yrtph.2011.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 08/22/2011] [Accepted: 08/24/2011] [Indexed: 11/23/2022]
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18
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Behnia K, Cornelius G, Wang J, Shipkova P, Johnghar S, Washburn W, Brigance R, Stetsko P, Henwood A, Wojciechowski JP, Marathe P, Rodrigues AD, Humphreys WG. Estimation of the Extent ofin VivoFormation of a Mutagenic Aromatic Amine from a Potent Thyromimetic Compound: Correlation ofin Vitroandin VivoFindings. Chem Res Toxicol 2011; 24:905-12. [DOI: 10.1021/tx200087q] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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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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20
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Scientific Opinion on the safety evaluation of the substance bis(2,6‐diisopropylphenyl)carbodiimide for use in food contact materials. EFSA J 2010. [DOI: 10.2903/j.efsa.2010.1928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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21
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Discovery of potent and orally active 3-alkoxy-5-phenoxy-N-thiazolyl benzamides as novel allosteric glucokinase activators. Bioorg Med Chem 2009; 17:2733-43. [DOI: 10.1016/j.bmc.2009.02.038] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 02/16/2009] [Accepted: 02/19/2009] [Indexed: 11/20/2022]
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22
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Finlay HJ, Lloyd J, Nyman M, Conder ML, West T, Levesque P, Atwal K. Pyrano-[2,3b]-pyridines as potassium channel antagonists. Bioorg Med Chem Lett 2008; 18:2714-8. [DOI: 10.1016/j.bmcl.2008.03.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 03/04/2008] [Accepted: 03/06/2008] [Indexed: 12/01/2022]
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23
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Jeffrey AM, Iatropoulos MJ, Williams GM. Nasal cytotoxic and carcinogenic activities of systemically distributed organic chemicals. Toxicol Pathol 2007; 34:827-52. [PMID: 17178686 DOI: 10.1080/01926230601042494] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Toxicity and carcinogenicity in the mucosa of the nasal passages in rodents has been produced by a variety of organic chemicals which are systemically distributed. In this review, 14 such chemicals or classes were identified that produced rodent nasal cytotoxicity, but not carcinogenicity, and 11 were identified that produced nasal carcinogenicity. Most chemicals that affect the nasal mucosa were either concentrated in that tissue or readily activated there, or both. All chemicals with effects in the nasal mucosa that were DNA-reactive, were also carcinogenic, if adequately tested. None of the rodent nasal cytotoxins has been identified as a human systemic nasal toxin. This may reflect the lesser biotransformation activity of human nasal mucosa compared to rodent and the much lower levels of human exposures. None of the rodent carcinogens lacking DNA reactivity has been identified as a nasal carcinogen or other cancer hazard to humans. Some DNA-reactive rodent carcinogens that affect the nasal mucosa, as well as other tissues, have been associated with cancer at various sites in humans, but not the nasal cavity. Thus, findings in only the rodent nasal mucosa do not necessarily predict either a toxic or carcinogenic hazard to that tissue in humans.
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Affiliation(s)
- Alan M Jeffrey
- Department of Pathology, New York Medical College, Valhalla, New York 10595, USA
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24
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Chen HI, Liou SH, Loh CH, Uang SN, Yu YC, Shih TS. Bladder cancer screening and monitoring of 4,4'-methylenebis(2-chloroaniline) exposure among workers in Taiwan. Urology 2005; 66:305-10. [PMID: 16098360 DOI: 10.1016/j.urology.2005.02.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 02/03/2005] [Accepted: 02/28/2005] [Indexed: 11/21/2022]
Abstract
OBJECTIVES Transitional cell carcinoma of the urinary bladder is associated with occupational exposure to 4,4'-methylenebis(2-chloroaniline) (MBOCA). A program to monitor MBOCA levels in the work environment and to screen for bladder cancer was performed at four MBOCA manufacturing factories. METHODS The U.S. Occupational Safety and Health Administration analytic method No. 24 was adopted in this study to measure air MBOCA concentrations. A total of 70 MBOCA-exposed workers and another 92 nonexposed workers were recruited for screening. Urine occult blood tests, urine cytology, tests for the urine tumor marker nuclear matrix protein, and abdominal ultrasonography were performed in all patients. Intravenous urography and cystoscopy were used to confirm the presence of bladder cancer. RESULTS The air concentration of MBOCA was greatest in the purification area (0.23 to 0.41 mg/m3), followed by the washing area (less than 0.02 to 0.08 mg/m3) and neutralization area (less than 0.05 to 0.06 mg/m3). This study identified a current worker with proved bladder cancer. In addition, we also identified 1 worker with suspected malignant cells on urine cytology and 1 worker with atypical cytology combined with gross hematuria. Although the prevalence of atypical urinary cells and the nuclear matrix protein 22 tumor marker was not significantly different between the MBOCA-exposed workers and nonexposed workers as a whole or when grouped by sex, the prevalence of positive occult blood was marginally significantly (P = 0.055) greater in male exposed workers (18%) than in male nonexposed workers (7%). CONCLUSIONS The findings of this study support the conclusions from other studies that MBOCA is potentially carcinogenic to humans. Control measures are needed to prevent overexposure from inhalation and skin absorption.
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Affiliation(s)
- Hong-I Chen
- Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Nei-Hu, Taipei, Taiwan, Republic of China.
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25
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Mattioni BE, Kauffman GW, Jurs PC, Custer LL, Durham SK, Pearl GM. Predicting the genotoxicity of secondary and aromatic amines using data subsetting to generate a model ensemble. JOURNAL OF CHEMICAL INFORMATION AND COMPUTER SCIENCES 2003; 43:949-63. [PMID: 12767154 DOI: 10.1021/ci034013i] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Binary quantitative structure-activity relationship (QSAR) models are developed to classify a data set of 334 aromatic and secondary amine compounds as genotoxic or nongenotoxic based on information calculated solely from chemical structure. Genotoxic endpoints for each compound were determined using the SOS Chromotest in both the presence and absence of an S9 rat liver homogenate. Compounds were considered genotoxic if assay results indicated a positive genotoxicity hit for either the S9 inactivated or S9 activated assay. Each compound in the data set was encoded through the calculation of numerical descriptors that describe various aspects of chemical structure (e.g. topological, geometric, electronic, polar surface area). Furthermore, five additional descriptors that focused on the secondary and aromatic nitrogen atoms in each molecule were calculated specifically for this study. Descriptor subsets were examined using a genetic algorithm search engine interfaced with a k-Nearest Neighbor fitness evaluator to find the most information-rich subsets, which ultimately served as the final predictive models. Models were chosen for their ability to minimize the total number of misclassifications, with special attention given to those models that possessed fewer occurrences of positive toxicity hits being misclassified as nontoxic (false negatives). In addition, a subsetting procedure was used to form an ensemble of models using different combinations of compounds in the training and prediction sets. This was done to ensure that consistent results could be obtained regardless of training set composition. The procedure also allowed for each compound to be externally validated three times by different training set data with the resultant predictions being used in a "majority rules" voting scheme to produce a consensus prediction for each member of the data set. The individual models produced an average training set classification rate of 71.6% and an average prediction set classification rate of 67.7%. However, the model ensemble was able to correctly classify the genotoxicity of 72.2% of all prediction set compounds.
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Affiliation(s)
- Brian E Mattioni
- Department of Chemistry, The Pennsylvania State University, 152 Davey Laboratory, University Park, Pennsylvania 16802, USA
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26
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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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27
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Chamberlain PL, Brynes SD. The regulatory status of xylazine for use in food-producing animals in the United States. J Vet Pharmacol Ther 1998; 21:322-9. [PMID: 9731956 DOI: 10.1046/j.1365-2885.1998.00140.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Xylazine is commonly used in veterinary medicine as a tranquillizer or adjunct to surgical anaesthesia. Although its use is approved in companion animals and certain species of deer, xylazine remains unapproved for use in food-producing animals in the United States. This paper reviews existing toxicological and residue chemistry information on xylazine in food animals, particularly cattle, and discusses the regulatory status of the drug in the US, as well as the conclusions reached by the Joint FAO/WHO Expert Committee on Food Additives in its recent evaluation of xylazine.
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Affiliation(s)
- P L Chamberlain
- Center for Veterinary Medicine, United States Food and Drug Administration, Rockville, MD 20855, USA
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28
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Reid TM, DeBord DG, Cheever KL, Savage RE. Mutagenicity of N-OH-MOCA (4-amino-4'-hydroxylamino-bis-3,3'-dichlorodiphenylmethane) and PBQ (2-phenyl-1,4-benzoquinone) in human lymphoblastoid cells. Toxicol Lett 1998; 95:205-10. [PMID: 9704822 DOI: 10.1016/s0378-4274(98)00039-3] [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: 02/08/2023]
Abstract
The genotoxic potential of two occupationally significant chemicals, 4,4'-methylene-bis-2-chloroaniline (MOCA) and 2-phenyl-1,4-benzoquinone (PBQ), was explored by monitoring the induction of mutations at the HPRT locus of AHH-1 human lymphoblastoid cells. Exposure of AHH-1 cells to the putative carcinogenic metabolite of MOCA, N-OH-MOCA, induced a 6-fold increase in mutant frequency and resulted in base pair substitutions primarily at A:T base pairs. In contrast, exposure to PBQ did not result in an increased mutant frequency although this compound was significantly more cytotoxic than N-OH-MOCA at equimolar doses. The induction of mutations at A:T sites by N-OH-MOCA is consistent with the type of DNA damage known to be produced by MOCA and provides a specific marker of genotoxic damage for exposed populations.
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Affiliation(s)
- T M Reid
- Division of Biomedical and Behavioral Sciences, National Institute for Occupational Safety and Health, Cincinnati, OH 45226, USA.
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29
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Rozinova E, Khalil M, Bonin AM. MOCA and some proposed substitutes (Cyanacure, Conacure, Polacure 740M and Ethacure 300) as two-stage skin carcinogens in HRA/Skh hairless mice. Mutat Res 1998; 398:111-21. [PMID: 9626971 DOI: 10.1016/s0027-5107(97)00247-9] [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: 02/07/2023]
Abstract
4,4'-Methylenebis(2-chlororaniline) (MOCA) is a suspect human carcinogen that has wide use as an industrial compound. Occupationally, exposure may occur through inhalation and ingestion, but skin absorption is the main route by which this compound gains entry into the body. Because of the justified concern about the continued use of MOCA, a number of substitutes have been proposed, including 1,2-bis(2-aminophenylthio)ethane (Cyanacure), Conacure, trimethylene glycol di-p-aminobenzoate (Polacure 740M) and 3,5-dimethylthio-2,4-toluenediamine/3,5-dimethylthio-2,6-tol uenediamine (Ethacure 300). There is very little information available about these substances, but they share the property of belonging to the same class (aromatic amines) as MOCA. Furthermore, at least two (Ethacure 300 and Cyanacure) are mutagenic in Salmonella. This study was undertaken to investigate if MOCA and substitutes, Polacure 740M, Ethacure 300, Cyanacure and Conacure have the potential to cause papillomas in a two stage initiation/promotion protocol in HRA/Skh hairless mice. When a maximum dose of 100 mg of substance was applied to the dorsal skin of these mice, Ethacure 300 and Cyanacure were markedly toxic. All of the compounds had little or no effect on skin tumor initiating activity following 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion. One experiment with MOCA suggested that, at lower and less toxic dose, this substance may have promotional activity. Therefore, caution should still be exercised when using these compounds and it cannot be excluded that they may be active in other strains of mice or other laboratory animal species.
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Affiliation(s)
- E Rozinova
- National Institute of Occupational Health and Safety (Worksafe Australia), Sydney, NSW
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30
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Hill AB, Jefferies PR, Quistad GB, Casida JE. Dialkylquinoneimine metabolites of chloroacetanilide herbicides induce sister chromatid exchanges in cultured human lymphocytes. Mutat Res 1997; 395:159-71. [PMID: 9465927 DOI: 10.1016/s1383-5718(97)00163-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Some of the most widely-used herbicides are the chloroacetanilides exemplified by alachlor and butachlor (derived from 2,6-diethylaniline) and metolachlor and acetochlor (synthesized from 2-ethyl-6-methylaniline). This investigation tests the hypothesis that the previously-observed oncogenicity of these herbicides is due to genotoxic intermediates such as diethylbenzoquinoneimine, a purported alachlor metabolite. Syntheses are reported here for the corresponding 2,6-dialkylbenzoquinoneimines, selected chloroacetyldialkylbenzoquinoneimines and several other candidate or known metabolites. The possible mutagenicity of diethylbenzoquinoneimine was tested in Salmonella typhimurium strains TA98 and TA100 with a weakly-positive response in the TA100 strain indicating induction of base-pair substitution mutations. The frequency of sister chromatid exchange (SCE) in Chinese hamster ovary cells was increased by alachlor at 10 microM and diethylaniline but not ethylmethylaniline at 30 and 3 microM. Isolated and cultured peripheral lymphocytes (mostly T cells) were used from two human donors to study the effects of the chloroacetanilides and their metabolites on primary human cells. In tests at 10 microM, the SCE frequency was increased by alachlor and possibly acetochlor but not by butachlor, metolachlor, dimethachlor (a 2,6-dimethyl analog) and dimethenamid (an analog based on 2,4-dimethyl-3-thienylamine). At 0.3 microM in cultured human lymphocytes, alachlor, the corresponding chloroacetanilide (N-dealkyl-alachlor) and aniline metabolites (and their 4-hydroxy derivatives), and diethylbenzoquinone were inactive or active in only one of the two donors whereas at 0.1-0.3 microM the SCE ratio for treated cells divided by the controls was always higher for diethylbenzoquinoneimine than for ethylmethyl- and dimethylbenzoquinoneimines. All the tested compounds were toxic to lymphocytes, but the depression of the mitotic index and increased duration of the cell cycle were not directly linked with SCE induction. Previous investigations have suggested that chloroacetanilide herbicides such as alachlor derived from 2,6-dialkylanilines are metabolized to 2,6-dialkylbenzoquinoneimines and the present study provides the first direct evidence that these metabolites are genotoxic in human lymphocytes.
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Affiliation(s)
- A B Hill
- Department of Environmental Science, Policy and Management, University of California, Berkeley 94720-3112, USA
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31
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Schuler M, Rupa DS, Eastmond DA. A critical evaluation of centromeric labeling to distinguish micronuclei induced by chromosomal loss and breakage in vitro. Mutat Res 1997; 392:81-95. [PMID: 9269333 DOI: 10.1016/s0165-1218(97)00047-5] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The in vitro micronucleus assay in conjunction with CREST-staining and fluorescence in situ hybridization (FISH) with centromere-specific DNA probes is being increasingly utilized for the detection of clastogenic and aneuploidy-inducing agents. Although potentially powerful techniques, both methods have unique characteristics that can influence sample processing and the interpretation of results. In this article, the use of the CREST and the FISH modifications of the in vitro micronucleus assay have been used to characterize the origin of the micronuclei induced by cyclophosphamide, 4,4'-methylene-bis(2-chloroaniline), 4-nitroquinoline N-oxide and ionizing radiation in metabolically competent MCL-5 cells or a derived cell line lacking metabolic activation. Using these results and our previous experiences with these techniques, a detailed comparison including the strengths and limitations of each technique as well as potential problems in performing each assay and in analyzing the data is discussed. In spite of their limitations, our results to date indicate that CREST-staining as well as FISH with centromere-specific DNA probes can be used to accurately distinguish micronuclei formed from chromosome loss from those originating from chromosome breakage and that these techniques can be valuable complements to the in vitro micronucleus assay.
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Affiliation(s)
- M Schuler
- Department of Entomology, University of California, Riverside 92521, USA
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Kelso JM, Bai CL, Ahokas JT, Wright PF. In vitro effects of MOCA and dapsone on rat hepatic and splenic immune cells. IMMUNOPHARMACOLOGY 1997; 35:183-93. [PMID: 9043931 DOI: 10.1016/s0162-3109(96)00146-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The industrial curing agent 4,4'-methylene-bis(2-chloroaniline) (MOCA) and the structurally related medicinal agent 4,4'-sulphonyldianiline (dapsone), are two commonly used aromatic amine compounds and documented animal carcinogens. In this study the effects of in vitro exposure to MOCA and dapsone (over a dose range of 1-200 microM on spleen and liver immune cell functions were investigated. MOCA exposure caused a dose-dependent inhibition of natural immune activities (i.e. natural killer, NK and natural P815 killer, NPK) and mitogen-stimulated proliferation of T- and B-lymphocytes, with 50% inhibition (IC50) of splenic-cell activities occurring at 145, 85, 21 and 31 microM, respectively. Liver NK and NPK activities were less sensitive to MOCA exposure and exhibited higher IC50's of 165 and 160 microM, respectively. Dapsone exposure slightly enhanced both T- and B-cell mitogenesis at low doses (1 microM) but decreased B-cell mitogenesis at high doses (IC50 = 130 microM). Natural tumouricidal activities were generally unaffected by dapsone, whilst natural cytotoxic (NC) activity was unaffected by both compounds. These results indicate that MOCA is generally immunotoxic in vitro, and may have the potential to enhance the carcinogenic effects of its genotoxic metabolite by inhibiting the tumour surveillance activities of the immune system. The relationship between immune effects and the carcinogenicity of dapsone remains unclear.
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Affiliation(s)
- J M Kelso
- Key Centre for Applied and Nutritional Toxicology, RMIT University, Melbourne, Vic., Australia
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Taningher M, Pasquini R, Bonatti S. Genotoxicity analysis of N,N-dimethylaniline and N,N-dimethyl-p-toluidine. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1993; 21:349-356. [PMID: 8491214 DOI: 10.1002/em.2850210406] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
N,N-Dimethylaniline (DMA, CAS No. 121-69-7) and N,N-dimethyl-p-toluidine (DMPT, CAS No. 99-97-8) belong to the N-dialkylaminoaromatics, a chemical class structurally alerting to DNA reactivity. Their applications may be industrial (dye and pesticide intermediates, polymerizing agents) and surgical (polymerization accelerators for the manufacture of bone cements and prosthetic devices), thus implying heterogeneous types of human exposure. Findings of carcinogenicity in rodents and some nonexhaustive genotoxicity data are available for DMA, but to our knowledge no information is available on DMPT concerning either carcinogenicity or any kind of genetic toxicity. To investigate their mechanism of action and mutagenic/carcinogenic potential, DMA and DMPT were analyzed for complementary genotoxicity endpoints, namely, gene mutation in Salmonella (Ames test), structural and numerical chromosome aberrations in hamster V79 cells (micronucleus test, matched with an immunofluorescent staining for kinetochore proteins), and in vivo DNA damage in mouse and rat liver (alkaline DNA elution test). The results essentially indicate that both chemicals are chromosome damaging agents. Indeed, at the maximum nontoxic doses, they proved nonmutagenic in Salmonella (although their toxicity did not allow concentrations > 70 micrograms/plate to be tested) and weakly positive in inducing DNA damage (increases in DNA elution rates at most approximately 2.4 times control value). Conversely, they proved clearly positive in inducing numerical chromosome alterations, with dose-dependent increases up to more than five times the control value for DMPT. At the highest dose tested, both chemicals also showed a significant clastogenic effect.
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Affiliation(s)
- M Taningher
- Institute of Oncology-CIRC, University of Genoa/National Institute for Cancer Research, Italy
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Thompson DC, Josephy PD, Chu JW, Eling TE. Enhanced mutagenicity of anisidine isomers in bacterial strains containing elevated N-acetyltransferase activity. Mutat Res 1992; 279:83-9. [PMID: 1375342 DOI: 10.1016/0165-1218(92)90249-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In previous studies on the mutagenicity of anisidine isomers, the ortho isomer was considered to be mutagenic towards standard Ames tester strains, while the para isomer gave equivocal results. In the present study we show that both para- and ortho-anisidine isomers are mutagenic in a Salmonella typhimurium tester strain containing elevated levels of N-acetyltransferase (YG1029). p-Anisidine gave a positive mutagenic response using either hamster S9 or ram seminal vesicle microsomes (RSVM) as an activating system, while o-anisidine gave a positive response only with the hamster S9 fraction. The mutagenic response from p-anisidine was greater than with o-anisidine in each case. In tests with p-anisidine and RSVM, the addition of arachidonic acid was not necessary to observe a mutagenic response. Catalase produced a dose-dependent decrease in the mutagenic response with p-anisidine and RSVM; this indicates that endogenous hydrogen peroxide from the bacteria acts as a substrate for the peroxidase activity of RSVM prostaglandin H synthase. These results demonstrate that both anisidine isomers are mutagenic and that N-acetyltransferase enzymes play an important role in their metabolism to mutagenic species.
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Affiliation(s)
- D C Thompson
- Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
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McQueen CA, Williams GM. Review of the genotoxicity and carcinogenicity of 4,4'-methylene-dianiline and 4,4'-methylene-bis-2-chloroaniline. Mutat Res 1990; 239:133-42. [PMID: 2200958 DOI: 10.1016/0165-1110(90)90034-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
4,4'-Methylene-dianiline (MDA) and 4,4'-methylene-bis-2-chloroaniline (MOCA) are polycyclic aromatic amines that are currently used in industry. Both compounds have been found to be bacterial mutagens and to be positive in a number of assays for genotoxicity. In animal studies, MDA has induced thyroid and liver neoplasms while exposure to MOCA resulted in a variety of tumors including those of the liver, mammary gland and bladder. Epidemiologic proof of human carcinogenicity of both compounds is lacking; however, there is evidence that MOCA can be metabolized to mutagenic products by human tissue. In this paper, the major finding concerning the biotransformation, genotoxicity and carcinogenicity of MDA and MOCA are reviewed.
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Affiliation(s)
- C A McQueen
- American Health Foundation, Valhalla, NY 10595
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Sabbioni G, Neumann HG. Quantification of haemoglobin binding of 4,4'-methylenebis(2-chloroaniline) (MOCA) in rats. Arch Toxicol 1990; 64:451-8. [PMID: 1703404 DOI: 10.1007/bf01977626] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
4,4'-Methylenebis(2-chloroaniline) (MOCA) is used as a curing agent in the production of polyurethane. MOCA is carcinogenic in experimental animals. Haemoglobin adducts have been proposed as dosimeters of aromatic amines for biological monitoring. A quantitative method to determine the adduct has now been worked out in female Wistar rats dosed per os with 3.82, 14.2 and 16.2 mumol/kg 14C-ring labeled MOCA or 0.25 and 0.50 mmol/kg unlabeled MOCA. MOCA bound in decreasing amounts to DNA, RNA and proteins of the lung, liver and kidney. Fractions of 0.19% and 0.026% of the dose were bound to the blood proteins haemoglobin and albumin, respectively. MOCA released by hydrolysis from haemoglobin was determined by HPLC with electrochemical detection or by GC-MS. Albumin did not form any hydrolysable adducts with MOCA.
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Affiliation(s)
- G Sabbioni
- Institut für Pharmakologie und Toxikologie, Universität Würzburg, Federal Republic of Germany
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