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Monooxygenase- and Dioxygenase-Catalyzed Oxidative Dearomatization of Thiophenes by Sulfoxidation, cis-Dihydroxylation and Epoxidation. Int J Mol Sci 2022; 23:ijms23020909. [PMID: 35055091 PMCID: PMC8777831 DOI: 10.3390/ijms23020909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/31/2021] [Accepted: 01/05/2022] [Indexed: 11/17/2022] Open
Abstract
Enzymatic oxidations of thiophenes, including thiophene-containing drugs, are important for biodesulfurization of crude oil and drug metabolism of mono- and poly-cyclic thiophenes. Thiophene oxidative dearomatization pathways involve reactive metabolites, whose detection is important in the pharmaceutical industry, and are catalyzed by monooxygenase (sulfoxidation, epoxidation) and dioxygenase (sulfoxidation, dihydroxylation) enzymes. Sulfoxide and epoxide metabolites of thiophene substrates are often unstable, and, while cis-dihydrodiol metabolites are more stable, significant challenges are presented by both types of metabolite. Prediction of the structure, relative and absolute configuration, and enantiopurity of chiral metabolites obtained from thiophene enzymatic oxidation depends on the substrate, type of oxygenase selected, and molecular docking results. The racemization and dimerization of sulfoxides, cis/trans epimerization of dihydrodiol metabolites, and aromatization of epoxides are all factors associated with the mono- and di-oxygenase-catalyzed metabolism of thiophenes and thiophene-containing drugs and their applications in chemoenzymatic synthesis and medicine.
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Liu M, Jiang J, Zheng J, Huan T, Gao B, Fei X, Wang Y, Fang M. RTP: One Effective Platform to Probe Reactive Compound Transformation Products and Its Applications for a Reactive Plasticizer BADGE. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:16034-16043. [PMID: 34788994 DOI: 10.1021/acs.est.1c05262] [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] [Indexed: 06/13/2023]
Abstract
Reactive compounds, such as covalent toxicants/drugs, have their ubiquitous occurrences and are known to react with protein or DNA in human beings, but their reactions with endogenous metabolites are rarely understood. Currently, a viable platform is demanded for discovering their reaction products since their efficacy/toxicity may be altered after the reaction. We aim to develop a platform for identifying unknown abiotic or biotransformation products for these reactive compounds. Based on stable isotope-labeling (SIL) metabolomics, we have developed a novel and robust analytical platform, reactive compound transformation profiler (RTP), which can automatically analyze preannotated high-resolution mass spectrometry (LC-HRMS) data sets and uncover probable transformation products. Generally, RTP consists of four complementary steps: (1) selecting peak pairs of light and heavy-labeled products, (2) defining the "core structure mass" for possible reaction search, (3) constructing an endogenous metabolite reaction database, and (4) developing algorithms to propose the potential transformation products by searching against the database with a single-/multiple-site reaction. Its performance was validated using the reactive plasticizer bisphenol A diglycidyl ether (BADGE) in several sample matrices. This platform enabled the identification of novel transformation products while also demonstrating its capacity to filter out the false-positive signals and provide product annotation. The RTP is freely accessible at https://github.com/FangLabNTU/Reactive-Compound-Transformation-Profiler-RTP-.
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Affiliation(s)
- Min Liu
- School of Civil and Environmental Engineering, Nanyang Technological University, 639798 Singapore
- Nanyang Environment & Water Research Institute, Nanyang Technological University, 637141 Singapore
| | - Jie Jiang
- School of Computer Science and Engineering, Nanyang Technological University, 639798 Singapore
| | - Jie Zheng
- Singapore Phenome Centre, Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Avenue, 636921 Singapore
| | - Tao Huan
- Department of Chemistry, University of British Columbia, Vancouver Campus, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Bei Gao
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Xunchang Fei
- School of Civil and Environmental Engineering, Nanyang Technological University, 639798 Singapore
| | - Yulan Wang
- Singapore Phenome Centre, Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Avenue, 636921 Singapore
| | - Mingliang Fang
- School of Civil and Environmental Engineering, Nanyang Technological University, 639798 Singapore
- Nanyang Environment & Water Research Institute, Nanyang Technological University, 637141 Singapore
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Mirzaei MS, Ivanov MV, Taherpour AA, Mirzaei S. Mechanism-Based Inactivation of Cytochrome P450 Enzymes: Computational Insights. Chem Res Toxicol 2021; 34:959-987. [PMID: 33769041 DOI: 10.1021/acs.chemrestox.0c00483] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mechanism-based inactivation (MBI) refers to the metabolic bioactivation of a xenobiotic by cytochrome P450s to a highly reactive intermediate which subsequently binds to the enzyme and leads to the quasi-irreversible or irreversible inhibition. Xenobiotics, mainly drugs with specific functional units, are the major sources of MBI. Two possible consequences of MBI by medicinal compounds are drug-drug interaction and severe toxicity that are observed and highlighted by clinical experiments. Today almost all of these latent functional groups (e.g., thiophene, furan, alkylamines, etc.) are known, and their features and mechanisms of action, owing to the vast experimental and theoretical studies, are determined. In the past decade, molecular modeling techniques, mostly density functional theory, have revealed the most feasible mechanism that a drug undergoes by P450 enzymes to generate a highly reactive intermediate. In this review, we provide a comprehensive and detailed picture of computational advances toward the elucidation of the activation mechanisms of various known groups with MBI activity. To this aim, we briefly describe the computational concepts to carry out and analyze the mechanistic investigations, and then, we summarize the studies on compounds with known inhibition activity including thiophene, furan, alkylamines, terminal acetylene, etc. This study can be reference literature for both theoretical and experimental (bio)chemists in several different fields including rational drug design, the process of toxicity prevention, and the discovery of novel inhibitors and catalysts.
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Affiliation(s)
- M Saeed Mirzaei
- Department of Organic Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran 67149-67346
| | - Maxim V Ivanov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Avat Arman Taherpour
- Department of Organic Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran 67149-67346.,Medical Biology Research Centre, University of Medical Sciences, Kermanshah, Iran 67149-67346
| | - Saber Mirzaei
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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4
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Pan L, Zheng B, Yang X, Deng L, Li Y, Liu Q. Cyclization of Vinylketene Dithioacetals: A Synthetic Strategy for Substituted Thiophenes. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202001001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Ling Pan
- Jilin Province Key Laboratory of Organic Functional Molecular, Design & Synthesis Department of Chemistry Northeast Normal University Changchun 130024 People's Republic of China
| | - Baihui Zheng
- Jilin Province Key Laboratory of Organic Functional Molecular, Design & Synthesis Department of Chemistry Northeast Normal University Changchun 130024 People's Republic of China
| | - Xiaohui Yang
- Jilin Province Key Laboratory of Organic Functional Molecular, Design & Synthesis Department of Chemistry Northeast Normal University Changchun 130024 People's Republic of China
| | - Liping Deng
- Jilin Province Key Laboratory of Organic Functional Molecular, Design & Synthesis Department of Chemistry Northeast Normal University Changchun 130024 People's Republic of China
| | - Yifei Li
- Jilin Province Key Laboratory of Organic Functional Molecular, Design & Synthesis Department of Chemistry Northeast Normal University Changchun 130024 People's Republic of China
| | - Qun Liu
- Jilin Province Key Laboratory of Organic Functional Molecular, Design & Synthesis Department of Chemistry Northeast Normal University Changchun 130024 People's Republic of China
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Thakkar D, Kate AS. 1-(Benzo[b]thiophen-4-yl)piperazine Ring Induced Bioactivation of Brexpiprazole in Liver Microsomes: Identification and Characterization of Reactive Conjugates Using Ultra-High-Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry. Eur J Drug Metab Pharmacokinet 2020; 45:393-403. [PMID: 32002811 DOI: 10.1007/s13318-020-00606-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND OBJECTIVES Brexpiprazole is an atypical antipsychotic approved for the treatment of schizophrenia and major depressive disorders in adults. The structure of brexpiprazole contains well-known structural alerts like a thiophene ring, piperazine ring and quinolinone motifs. Additionally, the literature reveals that its structural analog, aripiprazole, could generate reactive intermediates. However, the bioactivation potential of brexpiprazole is yet unknown. Therefore, this study was planned to identify and characterize reactive adducts of brexpiprazole and its metabolites. METHODS Based on the reactivity, the potential atomic sites for a reactive intermediate generation were predicted by a xenosite web predictor tool for glutathione, cyanide, protein and DNA. To study the metabolic activation of brexpiprazole, the drug was individually incubated for 2 h at 37 °C with pooled male rat liver microsomes and human liver microsomes in microcentrifuge tubes fortified with glutathione/N-acetyl cysteine. Nicotinamide adenine dinucleotide phosphate reduced tetrasodium salt was used as a co-factor. RESULTS A total of six glutathione and N-acetyl cysteine conjugates of brexpiprazole metabolites were identified and characterized using ultra-high-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry. Reactive metabolite 1 (RM1), RM3, RM4 and RM6 reactive conjugates were formed due to reactive quinone-imine or quinone intermediates, while RM2 and RM5 reactive adducts were generated because of a thiophene-S-oxide intermediate. CONCLUSION Brexpirazole is bioactivated due to the presence of a 1-(benzo[b]thiophen-4-yl)piperazine ring in its structure. In contrast to aripiprazole, the quinolinone motif was found latent towards bioactivation in brexpiprazole.
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Affiliation(s)
- Disha Thakkar
- National Institute of Pharmaceutical Education and Research-Ahmedabad (NIPER-A), Palaj, Gandhinagar, Gujarat, 382355, India
| | - Abhijeet S Kate
- National Institute of Pharmaceutical Education and Research-Ahmedabad (NIPER-A), Palaj, Gandhinagar, Gujarat, 382355, India.
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Abstract
Methods for the preparation of thiophene S-oxides, their roles in thiophene metabolism, and the structures and chemical reactivity of these compounds, are discussed.
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Affiliation(s)
- Thies Thiemann
- Institute of Advanced Material Study, Kyushu University, 6-1, Kasuga-koh-en, Kasuga-shi, Fukuoka 816-8580, Japan
| | - Krishna Gopal Dongol
- Institute of Advanced Material Study, Kyushu University, 6-1, Kasuga-koh-en, Kasuga-shi, Fukuoka 816-8580, Japan
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Peterson K, Collins PM, Huang X, Kahl-Knutsson B, Essén S, Zetterberg FR, Oredsson S, Leffler H, Blanchard H, Nilsson UJ. Aromatic heterocycle galectin-1 interactions for selective single-digit nM affinity ligands. RSC Adv 2018; 8:24913-24922. [PMID: 35542159 PMCID: PMC9082524 DOI: 10.1039/c8ra04389b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 06/21/2018] [Indexed: 01/14/2023] Open
Abstract
A series of 3-triazole-thiogalactosides and 3,3′-triazole-thiodigalactosides substituted with different five-membered heterocycles at the C-4 triazole position were found to have high selectivity for galectin-1. Initial studies on the 3-triazole-thiogalactosides indicated that five membered heterocycles in general gave increased affinity for galectin-1 and improved selectivity over galectin-3. The selectivity profile was similar for thiodigalactosides exemplified by 3,3′ substituted thien-3-yltriazole and thiazol-2-yltriazole, both having single-digit nM galectin-1 affinity and almost 10-fold galectin-1 selectivity. The binding interactions of a thiodigalactoside based galectin-1 inhibitor with two thien-3-yltriazole moieties were studied with X-ray crystallography. One of the thiophene moieties was positioned deeper into the pocket than previously reported phenyltriazoles and formed close contacts with Val31, Ser29, Gly124, and Asp123. The affinity and structural analysis thus revealed that steric and electronic optimization of five-membered aromatic heterocycle binding in a narrow galectin-1 subsite confers high affinity and selectivity. A series of 3-triazole-thiogalactosides and 3,3′-triazole-thiodigalactosides substituted with different five-membered heterocycles at the C-4 triazole position were found to have high selectivity for galectin-1.![]()
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Affiliation(s)
- Kristoffer Peterson
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University POB 124 SE-221 00 Lund Sweden
| | - Patrick M Collins
- Institute for Glycomics, Griffith University Gold Coast Campus Queensland 4222 Australia
| | - Xiaoli Huang
- Department of Biology, Lund University SE-223 62 Lund Sweden
| | - Barbro Kahl-Knutsson
- Department of Laboratory Medicine, Section MIG, Lund University BMC-C1228b, Klinikgatan 28 SE-221 84 Lund Sweden
| | - Sofia Essén
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University POB 124 SE-221 00 Lund Sweden
| | - Fredrik R Zetterberg
- Galecto Biotech AB, Sahlgrenska Science Park Medicinaregatan 8 A SE-413 46 Gothenburg Sweden
| | - Stina Oredsson
- Department of Biology, Lund University SE-223 62 Lund Sweden
| | - Hakon Leffler
- Department of Laboratory Medicine, Section MIG, Lund University BMC-C1228b, Klinikgatan 28 SE-221 84 Lund Sweden
| | - Helen Blanchard
- Institute for Glycomics, Griffith University Gold Coast Campus Queensland 4222 Australia
| | - Ulf J Nilsson
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University POB 124 SE-221 00 Lund Sweden
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Otani T, Miyoshi M, Shibata T, Matsuo T, Hashizume D, Tamao K. Thermally Stable Monosubstituted Thiophene 1-Oxide and 1-Imides Stabilized by a Bulky Rind Group at Their 3-Position: Synthesis, Structure, and Inversion Barriers on the Sulfur Atom. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2017. [DOI: 10.1246/bcsj.20170042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Takashi Otani
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555
- Functional Elemento-Organic Chemistry Unit, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198
- Course of Chemical Engineering, National Institute of Technology, Anan College, 265 Aoki Minobayashi, Anan, Tokushima 774-0017
| | - Mayu Miyoshi
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555
| | - Takanori Shibata
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555
| | - Tsukasa Matsuo
- Functional Elemento-Organic Chemistry Unit, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198
- Department of Applied Chemistry, Faculty of Science and Engineering, Kindai University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502
| | - Daisuke Hashizume
- Materials Characterization Support Unit, RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198
| | - Kohei Tamao
- Functional Elemento-Organic Chemistry Unit, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198
- RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198
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9
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Cohen SM, Fukushima S, Gooderham NJ, Guengerich FP, Hecht SS, Rietjens IM, Smith RL, Bastaki M, Harman CL, McGowen MM, Valerio LG, Taylor SV. Safety evaluation of substituted thiophenes used as flavoring ingredients. Food Chem Toxicol 2017; 99:40-59. [DOI: 10.1016/j.fct.2016.10.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/20/2016] [Accepted: 10/22/2016] [Indexed: 10/20/2022]
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10
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Jaladanki CK, Taxak N, Varikoti RA, Bharatam PV. Toxicity Originating from Thiophene Containing Drugs: Exploring the Mechanism using Quantum Chemical Methods. Chem Res Toxicol 2015; 28:2364-76. [PMID: 26574776 DOI: 10.1021/acs.chemrestox.5b00364] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Drug metabolism of thiophene containing substrates by cytochrome P450s (CYP450) leads to toxic side effects, for example, nephrotoxicity (suprofen, ticlopidine), hepatotoxicity (tienilic acid), thrombotic thrombocytopenic purpura (clopidogrel), and aplastic anemia (ticlopidine). The origin of toxicity in these cases has been attributed to two different CYP450 mediated metabolic reactions: S-oxidation and epoxidation. In this work, the molecular level details of the bioinorganic chemistry associated with the generation of these competitive reactions are reported. Density functional theory was utilized (i) to explore the molecular mechanism for S-oxidation and epoxidation using the radical cationic center Cpd I [(iron(IV)-oxo-heme porphine system with SH(-) as the axial ligand, to mimic CYP450s] as the model oxidant, (ii) to establish the 3D structures of the reactants, transition states, and products on both the metabolic pathways, and (iii) to examine the potential energy (PE) profile for both the pathways to determine the energetically preferred toxic metabolite formation. The energy barrier required for S-oxidation was observed to be 14.75 kcal/mol as compared to that of the epoxidation reaction (13.23 kcal/mol) on the doublet PE surface of Cpd I. The formation of the epoxide metabolite was found to be highly exothermic (-23.24 kcal/mol), as compared to S-oxidation (-8.08 kcal/mol). Hence, on a relative scale the epoxidation process was observed to be thermodynamically and kinetically more favorable. The energy profiles associated with the reactions of the S-oxide and epoxide toxic metabolites were also explored. This study helps in understanding the CYP450-catalyzed toxic reactions of drugs containing the thiophene ring at the atomic level.
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Affiliation(s)
- Chaitanya K Jaladanki
- Department of Medicinal Chemistry and ‡Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER) , Sector-67, S. A. S. Nagar (Mohali), 160 062 Punjab, India
| | - Nikhil Taxak
- Department of Medicinal Chemistry and ‡Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER) , Sector-67, S. A. S. Nagar (Mohali), 160 062 Punjab, India
| | - Rohith A Varikoti
- Department of Medicinal Chemistry and ‡Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER) , Sector-67, S. A. S. Nagar (Mohali), 160 062 Punjab, India
| | - Prasad V Bharatam
- Department of Medicinal Chemistry and ‡Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER) , Sector-67, S. A. S. Nagar (Mohali), 160 062 Punjab, India
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11
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Lee D, DuBois JL, Kanai Y. Importance of excitonic effect in charge separation at quantum-dot/organic interface: first-principles many-body calculations. NANO LETTERS 2014; 14:6884-6888. [PMID: 25388898 DOI: 10.1021/nl502894b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The staggered alignment of quasiparticle energy levels is widely regarded to be the key criterion necessary for electron-hole charge separation to occur at heterogeneous material interfaces. However, staggered energy levels at nanoscale interfaces, such as those between organic molecules and inorganic quantum dots, do not necessarily imply charge separation across the interface because the excitonic effect is often significant. Using quantum Monte Carlo calculations, we perform a detailed study of the role of the excitonic effects on charge separation across a representative set of interfaces between organic molecules and quantum dots. We find that the exciton binding energy of charge transfer excitons is significantly larger than would be estimated from a simple Coulombic analysis and, at these nanoscale interfaces, can be as significant as that of Frenkel excitons. This implies that charge transfer excitons can act as trap states and facilitate electron-hole recombination instead of charge separation. We conclude that in general, for nanoscale interfaces, high-fidelity quantum many-body calculations are essential for an accurate evaluation of the detailed energetic balance between localized and delocalized excitons and, thus, are crucial for the predictive treatment of interfacial charge separation processes.
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Affiliation(s)
- Donghwa Lee
- Condensed Matter and Materials Division, Lawrence Livermore National Laboratory , Livermore, California 94550, United States
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12
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Gramec D, Peterlin Mašič L, Sollner Dolenc M. Bioactivation potential of thiophene-containing drugs. Chem Res Toxicol 2014; 27:1344-58. [PMID: 25014778 DOI: 10.1021/tx500134g] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Thiophene is a five-membered, sulfur-containing heteroaromatic ring commonly used as a building block in drugs. It is considered to be a structural alert, as its metabolism can lead to the formation of reactive metabolites. Thiophene S-oxides and thiophene epoxides are highly reactive electrophilic thiophene metabolites whose formation is cytochrome P450-dependent. These reactive thiophene-based metabolites are quite often responsible for drug-induced hepatotoxicity. Tienilic acid is an example of a thiophene-based drug that was withdrawn from the market after only a few months of use, due to severe cases of immune hepatitis. However, inclusion of the thiophene moiety in drugs does not necessarily result in toxic effects. The presence of other, less toxic metabolic pathways, as well as an effective detoxification system in our body, protects us from the bioactivation potential of the thiophene ring. Thus, the presence of a structural alert itself is insufficient to predict a compound's toxicity. The question therefore arises as to which factors significantly influence the toxicity of thiophene-containing drugs. There is no easy way to answer this question. However, the findings presented here indicate that, for a number of reasons, daily dose and alternative metabolic pathways are important factors when predicting toxicity and will therefore be discussed together with examples.
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Affiliation(s)
- Darja Gramec
- Faculty of Pharmacy, University of Ljubljana , Aškerčeva 7, 1000 Ljubljana, Slovenia
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13
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Lepailleur A, Bureau R, Halm-Lemeille MP, Bouquet M, Pecquet R, Paris-Soubayrol C, Goff JL, André V, Lecluse Y, Lebailly P, Maire MA, Vasseur P. Assessment of the genotoxic and carcinogenic potentials of 3-aminothiophene derivatives using in vitro and in silico methodologies. J Appl Toxicol 2013; 34:775-86. [PMID: 24127219 DOI: 10.1002/jat.2938] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 08/30/2013] [Accepted: 09/05/2013] [Indexed: 11/11/2022]
Abstract
Thiophene derivatives, a class of compounds widely used in products such as pharmaceuticals, agrochemicals or dyestuffs, represent chemicals of concern. Indeed, the thiophene ring is often considered as a structural moiety that may be involved in toxic effects in humans. We primarily focus on the genotoxic/mutagenic and carcinogenic potentials of the methyl 3-amino-4-methylthiophene-2-carboxylate (1), a precursor of the articaine local anesthetic (4) which falls within the scope of the European REACH (Registration, Evaluation, Authorisation and restriction of CHemicals) legislation. To discern some structure-toxicity relationships, we also studied two related compounds, namely the 3-amino 4-methylthiophene (2) and the 2-acetyl 4-chlorothiophene (3). Techniques employed to assess mutagenic and DNA-damaging effects involved the Salmonella mutagenicity assay (or Ames test) and the single-cell gel electrophoresis assay (or Comet assay). In the range of tested doses, none of these derivatives led to a positive response in the Ames tests and DNA damage was only observed in the Comet assay after high concentration exposure of 2. The study of their carcinogenic potential using the in vitro SHE (Syrian Hamster Embryo) cell transformation assay (CTA) highlighted the activity of compound 2. A combination of experimental data with in silico predictions of the reactivity of thiophene derivatives towards cytochrome P450 (CYP450), enabled us to hypothesize possible pathways leading to these toxicological profiles.
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Affiliation(s)
- Alban Lepailleur
- Normandie Univ, France; UNICAEN, CERMN (Centre d'Etudes et de Recherche sur le Médicament de Normandie, FR CNRS INC3M - SF ICORE, Université de Caen Basse - Normandie, U.F.R. des Sciences Pharmaceutiques), F-14032, Caen, France
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14
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Kapungu GP, Rukweza G, Tran T, Mbiya W, Adigun R, Ndungu P, Martincigh B, Simoyi RH. Oxyhalogen–Sulfur Chemistry: Kinetics and Mechanism of Oxidation of Captopril by Acidified Bromate and Aqueous Bromine. J Phys Chem A 2013; 117:2704-17. [DOI: 10.1021/jp312672w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Thai Tran
- Department of Chemistry, Portland State University, Portland,
Oregon 97207-0751, United States
| | - Wilbes Mbiya
- Department of Chemistry, Portland State University, Portland,
Oregon 97207-0751, United States
| | - Risikat Adigun
- Department of Chemistry, Portland State University, Portland,
Oregon 97207-0751, United States
| | - Patrick Ndungu
- School of Chemistry
and Physics, University of KwaZulu-Natal, Westville Campus, Durban 4000, South Africa
| | - Bice Martincigh
- School of Chemistry
and Physics, University of KwaZulu-Natal, Westville Campus, Durban 4000, South Africa
| | - Reuben H. Simoyi
- Department of Chemistry, Portland State University, Portland,
Oregon 97207-0751, United States
- School of Chemistry
and Physics, University of KwaZulu-Natal, Westville Campus, Durban 4000, South Africa
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15
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Dansette PM, Rosi J, Debernardi J, Bertho G, Mansuy D. Metabolic activation of prasugrel: nature of the two competitive pathways resulting in the opening of its thiophene ring. Chem Res Toxicol 2012; 25:1058-65. [PMID: 22482514 DOI: 10.1021/tx3000279] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The mechanism generally admitted for the bioactivation of the antithrombotic prodrug, prasugrel, 1c, is its two-step enzymatic conversion into a biologically active thiol metabolite. The first step is an esterase-catalyzed hydrolysis of its acetate function leading to a thiolactone metabolite 2c. The second step was described as a cytochrome P450 (P450)-dependent oxidative opening of the thiolactone ring of 2c, with intermediate formation of a reactive sulfenic acid metabolite that is eventually reduced to the corresponding active thiol 3c. This article describes a detailed study of the metabolism of 1c by human liver microsomes and human sera, with an analysis by HPLC-MS under conditions allowing a complete separation of the thiol metabolite isomers, after derivatization with 3'-methoxy phenacyl bromide. It shows that there are two competing metabolic pathways for the opening of the 2c thiolactone ring. The major one, which was previously described, results from a P450- and NADPH-dependent redox bioactivation of 2c and leads to 3c, two previously reported thiol diastereomers bearing an exocyclic double bond. It occurs with NADPH-supplemented human liver microsomes but not with human sera. The second one results from a hydrolysis of 2c and leads to an isomer of 3c, 3c endo, in which the double bond has migrated from an exocyclic to an endocyclic position in the piperidine ring. It occurs both with human liver microsomes and human sera, and does not require NADPH. However, it requires Ca(2+) and is inhibited by paraoxon, which suggests that it is catalyzed by a thioesterase such as PON-1. Chemical experiments have confirmed that hydrolytic opening of thiolactone 2c exclusively leads to derivatives of the endo thiol isomer 3c endo.
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Affiliation(s)
- Patrick M Dansette
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, Paris Cedex 06, France.
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SAFARI NASSER, BAHADORAN FARZAD, HOSEINZADEH MOHAMMADREZA, GHIASI REZA. Cytochrome P-450 model reaction: effects of substitution on the rate of aromatic hydroxylation. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1002/(sici)1099-1409(200004/05)4:3<285::aid-jpp215>3.0.co;2-r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The study of haemin-catalysed oxidation reactions was extended to substituted aromatic rings. Both electron-donating and electron-withdrawing substituents on aromatic rings act as para- and meta-directing agents in the presence of tetrakis(2,6-dichlorophenyl)porphyrin iron(III) chloride as catalyst and m-chloroperbenzoic acid as oxidant. A new kinetic method for measuring relative rates of epoxidation of alkenes and related compounds has been developed; while steric hindrance results in decreasing the rate of hydroxylation, electron-rich and electron-withdrawing substituents were found to increase the rate of hydroxylation. A linear relationship between the logarithm of the relative rate of hydroxylation and σ Hammet is obtained, although electron-donating and electron-withdrawing substituents fit separate lines. Addition of pyridine to haemin was shown to increase the yield of epoxidation but decrease the yield of aromatic hydroxylation.
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Affiliation(s)
- NASSER SAFARI
- Department of Chemistry, Shahid Beheshti University, PO Box 19397-4716, Evin, Tehran, Iran
| | - FARZAD BAHADORAN
- Department of Chemistry, Shahid Beheshti University, PO Box 19397-4716, Evin, Tehran, Iran
| | | | - REZA GHIASI
- Department of Chemistry, Shahid Beheshti University, PO Box 19397-4716, Evin, Tehran, Iran
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Koen YM, Sarma D, Williams TD, Galeva NA, Obach RS, Hanzlik RP. Identification of protein targets of reactive metabolites of tienilic acid in human hepatocytes. Chem Res Toxicol 2012; 25:1145-54. [PMID: 22462724 DOI: 10.1021/tx300103j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Tienilic acid (TA) is a uricosuric diuretic that was withdrawn from the market only months after its introduction because of reports of serious incidents of drug-induced liver injury including some fatalities. Its hepatotoxicity is considered to be primarily immunoallergic in nature. Like other thiophene compounds, TA undergoes biotransformation to a S-oxide metabolite which then reacts covalently with cellular proteins. To identify protein targets of TA metabolites, we incubated [(14)C]-TA with human hepatocytes, separated cellular proteins by 2D gel electrophoresis, and analyzed proteins in 36 radioactive spots by tryptic digestion followed by LC-MS/MS. Thirty-one spots contained at least one identifiable protein. Sixteen spots contained only one of 14 nonredundant proteins which were thus considered to be targets of TA metabolites. Six of the 14 were also found in other radioactive spots that contained from 1 to 3 additional proteins. Eight of the 14 had not been reported to be targets for any reactive metabolite other than TA. The other 15 spots each contained from 2 to 4 identifiable proteins, many of which are known targets of other chemically reactive metabolites, but since adducted peptides were not observed, the identity of the adducted protein(s) in these spots is ambiguous. Interestingly, all the radioactive spots corresponded to proteins of low abundance, while many highly abundant proteins in the mixture showed no radioactivity. Furthermore, of approximately 16 previously reported protein targets of TA in rat liver ( Methogo, R., Dansette, P., and Klarskov, K. ( 2007 ) Int. J. Mass Spectrom. , 268 , 284 -295 ), only one (fumarylacetoacetase) is among the 14 targets identified in this work. One reason for this difference may be statistical, given that each study identified a small number of targets from among thousands present in hepatocytes. Another may be the species difference (i.e., rat vs human), and still another may be the method of detection of adducted proteins (i.e., Western blot vs C-14). Knowledge of human target proteins is very limited. Of more than 350 known protein targets of reactive metabolites, only 42 are known from humans, and only 21 of these are known to be targets for more than one chemical. Nevertheless, the demonstration that human target proteins can be identified using isolated hepatocytes in vitro should enable the question of species differences to be addressed more fully in the future.
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Affiliation(s)
- Yakov M Koen
- Department of Medicinal Chemistry and ‡Mass Spectrometry Laboratory, University of Kansas, Lawrence, KS 66045, United States
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18
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Boyd DR, Sharma ND, McMurray B, Haughey SA, Allen CCR, Hamilton JTG, McRoberts WC, More O'Ferrall RA, Nikodinovic-Runic J, Coulombel LA, O'Connor KE. Bacterial dioxygenase- and monooxygenase-catalysed sulfoxidation of benzo[b]thiophenes. Org Biomol Chem 2012; 10:782-90. [DOI: 10.1039/c1ob06678a] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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20
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Affiliation(s)
- Graham F Smith
- Central Chemistry Team Lead, Merck Research Laboratories, Boston, 33 Avenue Louis Pasteur, Boston, MA 02115, USA
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21
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Badland M, Compère D, Courté K, Dublanchet AC, Blais S, Manage A, Peron G, Wrigglesworth R. Thiophene and bioisostere derivatives as new MMP12 inhibitors. Bioorg Med Chem Lett 2011; 21:528-30. [PMID: 21111619 DOI: 10.1016/j.bmcl.2010.10.087] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 10/15/2010] [Accepted: 10/16/2010] [Indexed: 10/18/2022]
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Lin HL, Zhang H, Medower C, Hollenberg PF, Johnson WW. Inactivation of cytochrome P450 (P450) 3A4 but not P450 3A5 by OSI-930, a thiophene-containing anticancer drug. Drug Metab Dispos 2010; 39:345-50. [PMID: 21068193 DOI: 10.1124/dmd.110.034074] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
An investigational anticancer agent that contains a thiophene moiety, 3-[(quinolin-4-ylmethyl)-amino]-N-[4-trifluoromethox)phenyl] thiophene-2-carboxamide (OSI-930), was tested to investigate its ability to modulate the activities of several cytochrome P450 enzymes. Results showed that OSI-930 inactivated purified, recombinant cytochrome P450 (P450) 3A4 in the reconstituted system in a mechanism-based manner. The inactivation was dependent on cytochrome b(5) and required NADPH. Catalase did not protect against the inactivation. No inactivation was observed in studies with human 2B6, 2D6, or 3A5 either in the presence or in the absence of b(5). The inactivation of 3A4 by OSI-930 was time- and concentration-dependent. The inactivation of the 7-benzyloxy-4-(trifluoromethyl)coumarin catalytic activity of 3A4 was characterized by a K(I) of 24 μM and a k(inact) of 0.04 min(-1). This K(I) is significantly greater than the clinical OSI-930 C(max) of 1.7 μM at the maximum tolerated dose, indicating that clinical drug interactions of OSI-930 via this pathway are not likely. Spectral analysis of the inactivated protein indicated that the decrease in the reduced CO spectrum at 450 nm was comparable to the amount of inactivation, thereby suggesting that the inactivation was primarily due to modification of the heme. High-pressure liquid chromatography (HPLC) analysis with detection at 400 nm showed a loss of heme comparable to the activity loss, but a modified heme was not detected. This result suggests either that the heme must have been modified enough so as not to be observed in a HPLC chromatograph or, possibly, that it was destroyed. The partition ratio for the inactivation of P450 3A4 was approximately 23, suggesting that this P450 3A4-mediated pathway occurs with approximately 4% frequency during the metabolism of OSI-930. Modeling studies on the binding of OSI-930 to the active site of the P450 3A4 indicated that OSI-930 would be oriented properly in the active site for oxidation of the thiophene sulfur to give the sulfoxide, which has previously been shown to be a significant metabolite of OSI-930. Because OSI-930 is an inactivator of P450 3A4 but does not exhibit any effect on P450 3A5 activity under the same conditions, it may be an appropriate probe for exploring unique aspects of these two very similar P450s.
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Affiliation(s)
- Hsia-lien Lin
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109-5632, USA
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Novel, achiral aminoheterocycles as selective monoamine reuptake inhibitors. Bioorg Med Chem Lett 2009; 19:4630-3. [DOI: 10.1016/j.bmcl.2009.06.076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 06/19/2009] [Accepted: 06/22/2009] [Indexed: 11/17/2022]
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24
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Beaune PH, Lecoeur S, Bourdi M, Gauffre A, Belloc C, Dansette P, Mansuy D. Anti-cytochrome P450 autoantibodies in drug-induced disease. Eur J Haematol Suppl 2009; 60:89-92. [PMID: 8987248 DOI: 10.1111/j.1600-0609.1996.tb01652.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Drugs may induce hepatitis through immune mechanisms. In this review we have used the examples of 2 drugs to elucidate the first steps leading to the triggering of such disease, namely tienilic acid (TA) and dihydralazine (DH). These drugs are transformed into reactive metabolite(s) by cytochrome P450 (2C9 for TA and 1A2 for DH) (step 1). The reactive metabolites produced are very short-lived and bind directly to the enzymes which generated them (step 2). A neoantigen is thus formed which triggers an immune response (step 3), characterized by the presence of autoantibodies in the patient's serum (step 4). The autoantibodies are directed against the cytochrome P450 which generated the metabolite(s). Although the process by which TA and DH induce-hepatitis has been elucidated, further studies are necessary to generalize this mechanism. In addition, an animal model will also be useful to fully understand the immune mechanism of this type of disease.
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Affiliation(s)
- P H Beaune
- INSERM U 75, Université René Descartes, Paris, France.
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25
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Medower C, Wen L, Johnson WW. Cytochrome P450 oxidation of the thiophene-containing anticancer drug 3-[(quinolin-4-ylmethyl)-amino]-thiophene-2-carboxylic acid (4-trifluoromethoxy-phenyl)-amide to an electrophilic intermediate. Chem Res Toxicol 2008; 21:1570-7. [PMID: 18672911 DOI: 10.1021/tx700430n] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Compounds that are enzymatically transformed to reactive intermediates are common in nature. Some drugs and many phytochemicals that contain a thiophene ring are oxidized by cytochrome P450 to biological reactive intermediates (BRI) that can covalently bind to thiol nucleophiles. The investigational anticancer agent 3-[(quinolin-4-ylmethyl)-amino]-thiophene-2-carboxylic acid (4-trifluoromethoxy-phenyl)-amide (OSI-930) contains a thiophene moiety that can be oxidized by P450s to an apparent sulfoxide, which can react via Michael-addition to the 5-position of the thiophene ring, as demonstrated by mass spectral characterization of several thioether conjugates of the presumed thiophene S-oxide. Furthermore, a stable deuterium isotope retention experiment in which solvent deuterium was incorporated into the thiophene verifies the sulfoxide pathway. Various thiol nucleophiles are shown by tandem mass spectra to bind with this BRI, which is activated by P450 3A4 and to a slight degree, P450 2D6. Yet various safe drugs, phytochemicals, and endogenous molecules, all noted for their activation to BRI, are not toxic at a normal dose. Thus, multiple features determine any consequence of a BRI, with these complexities determining why one BRI is benign while another is not. The retention of covalent protein adducts of radio-labeled intermediate rat tissue has a half-life of about 1-1.5 days; hence, modified protein is cleared and replaced relatively quickly.
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Affiliation(s)
- Christine Medower
- Drug Metabolism and Pharmacokinetics, OSI Pharmaceuticals, Boulder, Colorado 80301, USA
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27
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López-García MP, Dansette PM, Coloma J. Kinetics of tienilic acid bioactivation and functional generation of drug–protein adducts in intact rat hepatocytes. Biochem Pharmacol 2005; 70:1870-82. [PMID: 16257391 DOI: 10.1016/j.bcp.2005.09.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 09/27/2005] [Accepted: 09/28/2005] [Indexed: 11/24/2022]
Abstract
Drug-induced autoimmune hepatitis is among the most severe hepatic idiosyncratic adverse drug reactions. Considered multifactorial, the disease combines immunological and metabolic aspects, the latter being to date much better known. As for many other model drugs, studies on tienilic acid (TA)-induced hepatitis have evidenced the existence of bioactivation during the hepatic oxidation of the drug, allowing the identification of the neoantigen of anti-LKM2 autoantibodies and the pathway responsible for its formation. However, most of these results are based on the use of microsomal fractions whose relevance to the liver in vivo still needs to be established. In the more complex intact cell environment, several endogenous processes may play a significant role on triggering the reaction and should therefore be considered. In this work we have characterised the kinetics of TA biotransformation in metabolically competent hepatocytes, the influence of TA bioactivation on physiological GSH levels, and the qualitative and quantitative profile of drug-protein conjugates generated in situ, as a function of exposure time. Results confirm that intact hepatocytes reproduce in vitro the metabolic sequence that leads to the functional generation of drug-protein adducts, in conditions that simulate clinical human exposure to TA. Metabolically competent cultured hepatocytes appear as a very promising approach to investigate the early preimmunological events of drug-induced autoimmune hepatitis, adequate to identify the conditions that may modulate the formation and specificity of drug-protein adducts in vivo, to study the hepatic disposition of the TA-protein targets, and to define the specific role of the hepatocyte in the origin of this adverse reaction.
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Affiliation(s)
- M Pilar López-García
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Valencia, Valencia, Spain.
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28
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Dansette PM, Bertho G, Mansuy D. First evidence that cytochrome P450 may catalyze both S-oxidation and epoxidation of thiophene derivatives. Biochem Biophys Res Commun 2005; 338:450-5. [PMID: 16137656 DOI: 10.1016/j.bbrc.2005.08.091] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2005] [Indexed: 11/21/2022]
Abstract
Oxidation of 2-phenylthiophene (2PT) by rat liver microsomes, in the presence of NADPH and glutathione (GSH), led to three kinds of metabolites whose structures were established by 1H NMR and mass spectrometry. The first ones were 2PT-S-oxide dimers formed by Diels-Alder type dimerization of 2PT-S-oxide, while the second ones were GSH adducts derived from the 1,4-Michaël-type addition of GSH to 2PT-S-oxide. The third metabolites were GSH adducts resulting from a nucleophilic attack of GSH to the 4,5-epoxide of 2PT. Oxidation of 2PT by recombinant, human cytochrome P4501A1, in the presence of NADPH and GSH, also led to these three kinds of metabolites. These results provide the first evidence that cytochrome P450 may catalyze the oxidation of thiophene compounds with the simultaneous formation of two reactive intermediates, a thiophene-S-oxide and a thiophene epoxide.
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Affiliation(s)
- Patrick M Dansette
- Université Paris Descartes, UFR Biomédicale, CNRS UMR 8601, 45 Rue des Saints-Pères, 75270 Paris Cedex 06, France.
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29
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Evans CA, Fries HE, Ward KW. In vitro metabolic fate of a novel structural class: Evidence for the formation of a reactive intermediate on a benzothiophene moiety. Chem Biol Interact 2005; 152:25-36. [PMID: 15766920 DOI: 10.1016/j.cbi.2005.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 01/14/2005] [Accepted: 01/14/2005] [Indexed: 10/25/2022]
Abstract
The characterization of the metabolic pathways of new chemical entities with a special emphasis on detecting potentially reactive metabolites is increasingly being performed early in the drug discovery process. In the present study, the preliminary in vitro metabolic routes of a series of novel 2-substituted benzothiophene-containing discovery molecules were determined in fresh and cryopreserved hepatocyte suspensions. The objectives of this investigation were: (1) to use systematic LC/MS and LC/MS/MS analyses to provide a preliminary characterization of the in vitro metabolism of these compounds, with a particular focus on metabolites potentially arising from reactive intermediates, and (2) to identify potential lead molecules not associated with such metabolic pathways. This benzothiophene-containing series of compounds was characterized by the formation of five metabolites, at least two of which (dihydrodiol formation and glutathione adduct of the dihydrohydroxyl) were indicative of the formation of a reactive arene oxide intermediate. Tandem mass spectral analysis of the metabolites formed from a variety of structurally similar compounds demonstrated this reactive arene oxide intermediate to form on the 2-substituted benzothiophene moiety. Substitution of the benzothiophene with other functional groups eliminated these potentially toxic metabolites. The data presented here demonstrate the utility of performing metabolic route screens early in the drug discovery process prior to lengthy and costly radiolabeled studies, and furthermore, implicate a 2-substituted benzothiophene moiety as a substrate for formation of a reactive arene oxide intermediate.
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Affiliation(s)
- Christopher A Evans
- Preclinical Drug Discovery, Cardiovascular and Urogenital Centre of Excellence in Drug Discovery, GlaxoSmithKline, King of Prussia, PA 19406, USA.
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Dreiem A, Fonnum F. Thiophene is Toxic to Cerebellar Granule Cells in Culture After Bioactivation by Rat Liver Enzymes. Neurotoxicology 2004; 25:959-66. [PMID: 15474614 DOI: 10.1016/j.neuro.2004.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Accepted: 04/12/2004] [Indexed: 10/26/2022]
Abstract
Several compounds that are not neurotoxic by themselves can cause toxic effects in vivo after enzymatic bioactivation. Thiophene is an industrial solvent known to produce degeneration primarily of the granule cells in the cerebellum when administered to animals in vivo. The mechanism for thiophene toxicity is not known, although it has been suggested that thiophene metabolism may lead to formation of oxidative intermediates that could function as the ultimate toxicants. In the present work we have used rat cerebellar granule cells (CGCs) in culture combined with rat liver postmitochondrial (S9) fraction as a source of biotransformation enzymes to test the toxicity of thiophene in vitro. The results demonstrate that thiophene is toxic to rat cerebellar granule cells in culture only after biotransformation. Furthermore, the toxic effects were reduced by cytochrome P450 (CYP) inhibitors and by scavengers of reactive molecules (alpha-tocopherol, reduced glutathione, and phenyl-N-tert-butylnitrone). These findings support the hypothesis that thiophene requires metabolism to produce the ultimate toxicant, and that the cytochrome P450 enzyme system is involved in the metabolism.
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Affiliation(s)
- Anne Dreiem
- Norwegian Defence Research Establishment, Division for Protection and Materiel, P.O. Box 25, N-2027 Kjeller, Norway.
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Valcarel JI, Walton DJ, Fujii H, Thiemann T, Tanaka Y, Mataka S, Mason TJ, Lorimer JP. The sonoelectrooxidation of thiophene S-oxides. ULTRASONICS SONOCHEMISTRY 2004; 11:227-232. [PMID: 15081986 DOI: 10.1016/j.ultsonch.2004.01.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Thiophene-S-oxides (thiophene monoxides) are relatively new compounds, less stable than the better-known thiophene-S-dioxides. They are useful as synthons for a range of applications, including in the production of pharmaceuticals. They have interesting photochemical properties, but in this presentation we contrast the electro-oxidative voltammetry of differently substituted derivatives. We also compare carbocyclic compounds such as tetracyclone, the electro-oxidation of which at relatively high potentials has never been reported in silent or insonated conditions.
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Affiliation(s)
- Jesus Iniesta Valcarel
- School of Science and the Environment, Coventry University, Priory Street, Coventry CV1 5FB, UK
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Kumar S, Kumar A, Sikka HC. COMPARATIVE METABOLISM OF PHENANTHRO[3,4-B]THIOPHENE, PHENANTHRO[4,3-B]THIOPHENE AND THEIR CARBON ANALOG BENZO[C]PHENANTHRENE BY RAT LIVER MICROSOMES. Polycycl Aromat Compd 2004. [DOI: 10.1080/10406630490471582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Lu P, Schrag ML, Slaughter DE, Raab CE, Shou M, Rodrigues AD. MECHANISM-BASED INHIBITION OF HUMAN LIVER MICROSOMAL CYTOCHROME P450 1A2 BY ZILEUTON, A 5-LIPOXYGENASE INHIBITOR. Drug Metab Dispos 2003; 31:1352-60. [PMID: 14570767 DOI: 10.1124/dmd.31.11.1352] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Zileuton, a 5-lipoxygenase inhibitor, was evaluated as an inhibitor of cytochrome P450 activity in human liver microsomes. In the absence of preincubation, the racemate was found to be a weak inhibitor (IC50 > 100 microM) of phenacetin O-deethylation (POD) (CYP1A2), paclitaxel 6alpha-hydroxylation (CYP2C8), diclofenac 4'-hydroxylation (CYP2C9), (S)-mephenytoin 4'-hydroxylation (CYP2C19), bufuralol 1'-hydroxylation (CYP2D6), testosterone 6beta-hydroxylation (CYP3A4), chlorzoxazone 6-hydroxylation (CYP2E1), and bupropion hydroxylation (CYP2B6). When preincubated with NADPH-fortified human liver microsomes in the absence of substrate, zileuton (racemate) was shown to inhibit POD. The effect was NADPH-, time-, and concentration-dependent, and was characterized by a kinact (maximal rate of enzyme inactivation) and apparent KI(inhibitor concentration that supports half the maximal rate of inactivation) of 0.035 min(-1) and 117 microM, respectively (kinact/KIratio of 0.0003 min-1 microM(-1)). Preincubation-dependent inhibition of POD activity was also observed with the individual (S)-(-)- and (R)-(+)-enantiomers of zileuton [(S)-(-)-zileuton; kinact, 0.037 min(-1), KI, 98.2 microM, kinact/KIratio, 0.0004 min(-1) microM(-1); (R)-(+)-zileuton; kinact, 0.012 min(-1), KI, 66.6 microM, kinact/KIratio, 0.0002 min(-1) microM(-1)]. In addition, the inhibition of CYP1A2 was not reversed in the presence of reduced glutathione, catalase, and superoxide dismutase and was refractory to dialysis. Therefore, zileuton was characterized as a mechanism-based inhibitor of human liver microsomal CYP1A2. Mechanism-based inhibition of CYP1A2 may explain why zileuton decreases the oral clearance of antipyrine, propranolol, (R)-warfarin, and theophylline, at doses that have a minimal effect on the pharmacokinetics of (S)-warfarin, phenytoin, and terfenadine.
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Affiliation(s)
- Ping Lu
- Department of Drug Metabolism, WP75A-203, Merck Research Laboratories, West Point PA 19486, USA
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Ha-Duong NT, Dijols S, Macherey AC, Dansette PM, Mansuy D. Inhibition by ticlopidine and its derivatives of human liver cytochrome p450. Mechanism-based inactivation of CYP 2C19 by ticlopidine. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 500:145-8. [PMID: 11764927 DOI: 10.1007/978-1-4615-0667-6_18] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- N T Ha-Duong
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université René Descartes, CNRS UMR 8601, Paris, France
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Ha-Duong NT, Dijols S, Macherey AC, Goldstein JA, Dansette PM, Mansuy D. Ticlopidine as a selective mechanism-based inhibitor of human cytochrome P450 2C19. Biochemistry 2001; 40:12112-22. [PMID: 11580286 DOI: 10.1021/bi010254c] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Experiments using recombinant yeast-expressed human liver cytochromes P450 confirmed previous literature data indicating that ticlopidine is an inhibitor of CYP 2C19. The present studies demonstrated that ticlopidine is selective for CYP 2C19 within the CYP 2C subfamily. UV-visible studies on the interaction of a series of ticlopidine derivatives with CYP 2C19 showed that ticlopidine binds to the CYP 2C19 active site with a K(s) value of 2.8 +/- 1 microM. Derivatives that do not involve either the o-chlorophenyl substituent, the free tertiary amine function, or the thiophene ring of ticlopidine did not lead to such spectral interactions and failed to inhibit CYP 2C19. Ticlopidine is oxidized by CYP 2C19 with formation of two major metabolites, the keto tautomer of 2-hydroxyticlopidine (1) and the dimers of ticlopidine S-oxide (TSOD) (V(max) = 13 +/- 2 and 0.4 +/- 0.1 min(-1)). During this oxidation, CYP 2C19 was inactivated; the rate of its inactivation was time and ticlopidine concentration dependent. This process meets the chemical and kinetic criteria generally accepted for mechanism-based enzyme inactivation. It occurs in parralel with CYP 2C19-catalyzed oxidation of ticlopidine, is inhibited by an alternative well-known substrate of CYP 2C19, omeprazole, and correlates with the covalent binding of ticlopidine metabolite(s) to proteins. Moreover, CYP 2C19 inactivation is not inhibited by the presence of 5 mM glutathione, suggesting that it is due to an alkylation occurring inside the CYP 2C19 active site. The effects of ticlopidine on CYP 2C19 are very analogous with those previously described for the inactivation of CYP 2C9 by tienilic acid. This suggests that a similar electrophilic intermediate, possibly a thiophene S-oxide, is involved in the inactivation of CYP 2C19 and CYP 2C9 by ticlopidine and tienilic acid, respectively. The kinetic parameters calculated for ticlopidine-dependent inactivation of CYP 2C19, i.e., t(1/2max) = 3.4 min, k(inact) = 3.2 10(-3) s(-1), K(I) = 87 microM, k(inact)/K(I) = 37 L.mol(-1).s(-1), and r (partition ratio) = 26 (in relation with formation of 1 + TSOD), classify ticlopidine as an efficient mechanism-based inhibitor although somewhat less efficient than tienilic acid for CYP 2C9. Importantly, ticlopidine is the first selective mechanism-based inhibitor of human liver CYP 2C19 and should be a new interesting tool for studying the topology of the active site of CYP 2C19.
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Affiliation(s)
- N T Ha-Duong
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601 CNRS, Université Paris V, 45 Rue des Saints-Pères, 75270 Paris Cedex 06, France
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36
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Ratra GS, Powell CJ, Park BK, Maggs JL, Cottrell S. Methapyrilene hepatotoxicity is associated with increased hepatic glutathione, the formation of glucuronide conjugates, and enterohepatic recirculation. Chem Biol Interact 2000; 129:279-95. [PMID: 11137066 DOI: 10.1016/s0009-2797(00)00253-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanisms by which acute administration of methapyrilene, an H(1)-receptor antihistamine causes periportal necrosis to rats are unknown. This study investigated the role of the hepato-biliary system in methapyrilene hepatotoxicity following daily administration of 150 mg/kg per day over 3 consecutive days. Biliary metabolites of methapyrilene were tentatively identified. In male Han Wistar rats administration of methapyrilene significantly increased hepatic reduced glutathione (GSH) to 140% of control levels 24 h following the last dose. There were no significant changes in the activities of glutathione-related enzymes, glutathione peroxidase (GPx) and reductase (GSH), glutathione S-transferase (GST), and gamma-glutamyl cysteine synthetase (gamma-GCS) over 3 days of methapyrilene administration. Methapyrilene treatment resulted in no significant increase in excretion of biliary oxidized glutathione (GSSG), a sensitive marker of oxidative stress in vivo, following the third dose. [3H]Methapyrilene-derived radioactivity was detected in bile, to a greater extent than in feces, indicating that methapyrilene and/or metabolites underwent enterohepatic recirculation. Cannulation and exteriorization of the bile duct (to interrupt enterohepatic recirculation) afforded some protection against the hepatotoxicity, assessed by clinical chemistry and histopathology. Liquid chromatography-mass spectrometry (LC-MS) analysis of bile indicated the presence of unmetabolized methapyrilene, methapyrilene O-glucuronide and desmethyl methapyrilene O-glucuronide. These data demonstrate that acute methapyrilene hepatotoxicity in vivo is not a consequence of GSH depletion, or oxidative stress, but that enterohepatic recirculation of biliary metabolites may be important. Progressive exposure to non-oxidizing, reactive metabolic intermediates may be responsible for hepatotoxicity.
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Affiliation(s)
- G S Ratra
- Department of Toxicology, St. Bartholomew's and The Royal London School of Medicine and Dentistry, Charterhouse Square, EC1M 6BQ, London, UK.
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Park BK, Kitteringham NR, Powell H, Pirmohamed M. Advances in molecular toxicology-towards understanding idiosyncratic drug toxicity. Toxicology 2000; 153:39-60. [PMID: 11090946 DOI: 10.1016/s0300-483x(00)00303-6] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Idiosyncratic drug toxicity is a major complication of drug therapy and drug development. Such adverse drug reactions (ADRs) include anaphylaxis, blood dyscrasias, hepatotoxicity and severe cutaneous reactions. They are usually serious and can be fatal. At present, prediction of idiosyncratic ADRs at the preclinical stage of drug development is not possible because there are no suitable animal models and we do not understand the basic mechanisms involved in the toxicity when it does occur in man. Many idiosyncratic reactions appear to have an immunological aetiology. For example, there is increasing evidence for the role of T lymphocytes in severe skin reactions. Nevertheless, the sequence of events by which a simple chemical can elicit severe tissue damage remains poorly understood and alternative novel mechanisms of toxicity must also be explored. The purpose of this article will be to review the currently accepted mechanisms of idiosyncratic drug toxicity at the chemical and the molecular levels. In particular, we will consider how recent advances in cellular immunology and molecular biology can improve our understanding of both the chemical and clinical aspects of drug hypersensitivity. Recent advances in the role of both inter- and intra-cellular signalling in the regulation of the immune response to drugs and their metabolites will be discussed. The long-term aim of such research is to provide test systems for the evaluation of drug safety and patient susceptibility to idiosyncratic drug toxicity.
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Affiliation(s)
- B K Park
- Department of Pharmacology and Therapeutics, University of Liverpool, P.O. Box 147, L69 3GE, Liverpool, UK.
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38
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Nakayama J. The Latest Advances in Chemistry of Thiophene 1-Oxides and Selenophene 1-Oxides. ACTA ACUST UNITED AC 2000. [DOI: 10.1080/01961770008047957] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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39
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Nakayama J. 1-Oxides and 1,1-Dioxides of Thiophenes and Selenophenes and Related Compounds. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2000. [DOI: 10.1246/bcsj.73.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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40
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Rivera MI, Stinson SF, Vistica DT, Jorden JL, Kenney S, Sausville EA. Selective toxicity of the tricyclic thiophene NSC 652287 in renal carcinoma cell lines: differential accumulation and metabolism. Biochem Pharmacol 1999; 57:1283-95. [PMID: 10230772 DOI: 10.1016/s0006-2952(99)00046-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The tricyclic compound 2,5-bis(5-hydroxymethyl-2-thienyl)furan (NSC 652287) has shown a highly selective pattern of differential cytotoxic activity in the tumor cell lines comprising the National Cancer Institute (NCI) Anticancer Drug Screen. The mechanism underlying the selective cytotoxicity is unknown. We hypothesized that differential sensitivity to the compound observed in several renal tumor cell lines could be the result of selective accumulation or differential metabolism of this agent. We demonstrated here that the capacity of certain renal cell lines to accumulate and retain the compound, determined by accumulation of [14C]NSC 652287-derived radioactivity and by flow cytometric determination of unlabeled compound, paralleled the sensitivity of the renal cell lines to growth inhibition by NSC 652287: A-498 > TK-10 >> ACHN approximately/= to UO-31. The ability of the cell lines to metabolize [14C]NSC 652287 to a reactive species capable of binding covalently to cellular macromolecules also directly correlated with sensitivity to the compound. Different patterns of metabolites were generated by relatively more drug-sensitive cell lines in comparison with drug-resistant cell lines. The metabolizing capacity for NSC 652287 was localized primarily to the cytosolic (S100) fraction. The rate of metabolism in the cytosolic fraction from the most sensitive renal cell line, A-498, was faster than that observed in the cytosolic fractions from the other, less sensitive cell lines. The data support the hypothesis that both selective cellular accumulation and the capacity to metabolize NSC 652287 to a reactive species by certain renal carcinoma cell types are the basis for the differential cytotoxicity of this compound class.
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Affiliation(s)
- M I Rivera
- Laboratory of Drug Discovery Research and Development, Division of Cancer Treatment and Diagnosis, National Cancer Institute-Frederick Cancer Research and Development Center, MD 21702-1201, USA
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41
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42
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Synthesis of (4-chlorophenyl)-(1-oxo-1λ4-benzo[b]thien-2-yl)methanone and study of its reactivity towards sulfur- and oxygen-containing nucleophiles. Tetrahedron 1998. [DOI: 10.1016/s0040-4020(98)00929-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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43
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Mansuy D. The great diversity of reactions catalyzed by cytochromes P450. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART C, PHARMACOLOGY, TOXICOLOGY & ENDOCRINOLOGY 1998; 121:5-14. [PMID: 9972447 DOI: 10.1016/s0742-8413(98)10026-9] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- D Mansuy
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, URA 400, Université Paris V, France.
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44
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Dansette PM, Bonierbale E, Minoletti C, Beaune PH, Pessayre D, Mansuy D. Drug-induced immunotoxicity. Eur J Drug Metab Pharmacokinet 1998; 23:443-51. [PMID: 10323325 DOI: 10.1007/bf03189993] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Immune-related drug responses are one of the most common sources of idiosyncratic toxicity. A number of organs may be the target of such reactions; however, this review concentrates mostly on the liver. Drug-induced hepatitis is generally divided into two categories: acute hepatitis in which the drug or a metabolite destroys a vital target in the cell; immunoallergic hepatitis in which the drug triggers an adverse immune response directed against the liver. Their clinical features are: a) low frequency; b) dose independence; c) typical immune system manifestations such as fever, eosinophilia; d) delay between the initiation of treatment and onset of the disease; e) a shortened delay upon rechallenge; and f) occasional presence of autoantibodies in the serum of patients. Such signs have been found in cases of hepatitis triggered by drugs such as halothane, tienilic acid, dihydralazine and anticonvulsants. They will be taken as examples to demonstrate the recent progress made in determining the mechanisms responsible for the disease. The following mechanisms have been postulated: 1) the drug is first metabolized into a reactive metabolite which binds to the enzyme that generated it; 2) this produces a neoantigen which, once presented to the immune system, might trigger an immune response characterized by 3) the production of antibodies recognizing both the native and/or the modified protein; 4) rechallenge leads to increased neoantigen production, a situation in which the presence of antibodies may induce cytolysis. Toxicity is related to the nature and amount of neoantigen and also to other factors such as the individual immune system. An effort should be made to better understand the precise mechanisms underlying this kind of disease and thereby identify the drugs at risk; and also the neoantigen processes necessary for their introduction into the immune system. An animal model would be useful in this regard.
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Affiliation(s)
- P M Dansette
- Université Ren Descartes, CNRS URA 400, Paris, France
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45
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Ho MT, Treiber A, Dansette PM. Oxidation of 2-(4-chlorobenzoyl)-thiophene into 1-oxide Diels-Alder dimers, sesquioxide and a sulfone-water adduct. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)01004-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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46
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47
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Characterization of the in vitro oxidative metabolites of the COX-2 selective inhibitor L-766,112. Bioorg Med Chem Lett 1997. [DOI: 10.1016/s0960-894x(96)00581-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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48
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Abstract
Two closely related compounds, a diuretic drug tienilic acid (TA) and its isomer TAI have been found to exert very different toxic effects. In human liver microsomes TA is oxidized mainly by CYP 2C9 with formation of a reactive metabolite which covalently binds to CYP 2C9 in a rather specific manner. On the contrary, CYP 2C9-dependent oxidation of TAI leads to reactive metabolite(s) causing an intense covalent binding to several microsomal proteins. Based on these very different behaviours and fates of TA and TAI metabolites, it is proposed that the direct hepatotoxic effects of TAI could be due to an intense, non-specific covalent binding of its reactive metabolite(s) to liver proteins, whereas the toxic effects of the immunoallergic type of TA could be due to the very specific covalent binding of its sulfoxide metabolite to CYP 2C9.
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Affiliation(s)
- D Mansuy
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université Paris V, URA 400 CNRS, France
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49
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Abstract
Liver is a frequent target for drug-induced hepatitis. They can be classified in two categories: the hepatitis in which the drug or a metabolite reach a vital target in the cell and the hepatitis in which the drug triggers an adverse immune response directed against the liver. We will discuss essentially this second kind of disease. They have key clinical features such as the low frequency, the dose independence, the delay between the beginning of drug intake and the triggering of the disease, the shortening of the delay upon rechallenge and very often the presence of autoantibodies in the serum of the patients. Such signs were found in hepatitis triggered by drugs such as halothane, tienilic acid, dihydralazine, anticonvulsants. They will be taken as examples to show the recent progress in the understanding of the mechanisms leading to the disease. It has been postulated that the drug is metabolised into a reactive metabolite binding to the enzyme which generated it; therefore the neoantigen might trigger an immune response characterised by the production of antibodies recognising the native and or the modified protein. Most of these steps were proven in the cases of halothane, tienilic acid and dihydralazine. Several points seem important in the development of the disease; the equilibrium between toxication and detoxication pathways, the nature and amount of neoantigen, the individual immune response. However, many points remain unclear: for instance, the reason for the very low frequency of this kind of disease; the precise mechanism of the adverse immune response; the risk factors for developing such adverse reactions. Efforts should be made to better understand the mechanisms of this kind of disease: for instance, an animal model, tests to identify drugs at risk for such reactions, the role of these drugs in the processing of P450s and the processing of the neoantigens for their presentation to the immune system.
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Affiliation(s)
- P H Beaune
- Université René Descartes, INSERM U 75, Faculté de Médecine Necker, Paris, France.
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50
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Brown KN, Espenson JH. Stepwise Oxidation of Thiophene and Its Derivatives by Hydrogen Peroxide Catalyzed by Methyltrioxorhenium(VII). Inorg Chem 1996; 35:7211-7216. [PMID: 11666909 DOI: 10.1021/ic960607+] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The oxidation of thiophene derivatives by hydrogen peroxide is catalyzed by methyltrioxorhenium(VII) (CH(3)ReO(3)). This compound reacts with hydrogen peroxide to form 1:1 and 1:2 rhenium peroxides, each of which transfers an oxygen atom to the sulfur atom of thiophene and its derivatives. Complete oxidation to the sulfone occurs readily by way of its sulfoxide intermediate. The rates for each oxidation step of dibenzothiophenes, benzothiophenes, and substituted thiophenes were determined. The rate constants for the oxidation of the thiophenes are 2-4 orders of magnitude smaller than those for the oxidation of aliphatic sulfides, whereas the rate constants are generally the same for the oxidation of the thiophene oxides and aliphatic sulfoxides. The rate constant for conversion of a sulfide to a sulfoxide (thiophene oxide) increases when a more electron-donating substituent is introduced into the molecule, whereas the opposite trend was found for the reaction that converts a sulfoxide to a sulfone (thiophene dioxide). Mechanisms consistent with this are proposed. The first trend reflects the attack of the nucleophilic sulfur atom of a thiophene center on a peroxide that has been electrophilically activated by coordination to rhenium. The second, more subtle, trend arises when both sulfoxide and peroxide are coordinated to rhenium; the inherently greater nucleophilicity of peroxide then takes control.
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Affiliation(s)
- Kylie N. Brown
- Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011
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