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Prasanthkumar KP, Valayankadan F, Aravindakumar CT, P A, Babu A, Alvarez-Idaboy JR. Identifying the Transients and Transformation Products in Hydroxyl Radical-Methimazole Reactions Using DFT and UPLC-Q-TOF MS/MS Approaches. J Phys Chem B 2024; 128:1448-1460. [PMID: 38320124 DOI: 10.1021/acs.jpcb.3c07913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Oxidative reactions of the hydroxyl radical (·OH) with methimazole (MMI), an antithyroid drug, are crucial for understanding its fate in oxidizing environments. By synergistically integrating density functional theory and ultraperformance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF MS/MS) techniques, we elucidated the transients and transformation products (TPs) arising from the ·OH-MMI reactions. We probed two hydrogen-atom abstraction (HA) reactions, three radical adduct formation reactions, and single electron transfer (SET) at the M06-2X/6-311++G(d,p)/SMD(water) level. All proposed reaction channels, except for HA from the methyl group and SET, were found to be barrier-free. SET is the dominant oxidation pathway, accounting for 44% of oxidations, as determined by branching ratio analysis. The selenium analogue, MSeI, exhibited minor reactivity differences compared to MMI, yet its overall patterns resembled those of ·OH-MMI reactions. TPs were generated experimentally by reacting MMI with ·OH produced by UV-photolysis of H2O2. Eight TPs were identified from an approximately 24% degradation of MMI using UPLC-Q-TOF MS/MS analysis, and an additional two TPs were identified from the approximately 52% degraded MMI sample. The exact identities of all of the TPs were established through their corresponding fragmentation patterns. This study elucidates the drug's susceptibility to free radical species under physiologically relevant conditions.
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Affiliation(s)
- Kavanal P Prasanthkumar
- Post Graduate and Research Department of Chemistry, Maharaja's College, Ernakulam 682 011, India
| | - Faseelath Valayankadan
- Post Graduate and Research Department of Chemistry, Maharaja's College, Ernakulam 682 011, India
| | - Charuvila T Aravindakumar
- School of Environmental Sciences, Mahatma Gandhi University, Kottayam 686 560, India
- Inter-University Instrumentation Centre, Mahatma Gandhi University, Kottayam 686 560, India
| | - Arun P
- Inter-University Instrumentation Centre, Mahatma Gandhi University, Kottayam 686 560, India
| | - Aswathy Babu
- Post Graduate and Research Department of Chemistry, Maharaja's College, Ernakulam 682 011, India
| | - Juan R Alvarez-Idaboy
- Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, México D. F. 04510, Mexico
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Aragoni M, Arca M, Caltagirone C, Castellano C, Demartin F, Jones PG, Pivetta T, Podda E, Lippolis V, Murgia S, Picci G. Role of the Solvent in the Reactivity of Bis-4-imidazoline-2-selone Derivatives toward I 2: An Experimental and Theoretical Approach. J Org Chem 2022; 87:15448-15465. [DOI: 10.1021/acs.joc.2c01982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- M.Carla Aragoni
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy
| | - Massimiliano Arca
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy
| | - Claudia Caltagirone
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy
| | - Carlo Castellano
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, I-20133Milano, Italy
| | - Francesco Demartin
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, I-20133Milano, Italy
| | - Peter G. Jones
- Institut für Anorganische und Analytische Chemie der Technischen Universität Braunschweig, Hagenring 30, D-38106Braunschweig, Germany
| | - Tiziana Pivetta
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy
| | - Enrico Podda
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy
- Centro Servizi di Ateneo per la Ricerca-CeSAR, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, 09042 Monserrato, Cagliari, Italy
| | - Vito Lippolis
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy
| | - Sergio Murgia
- Dipartimento di Scienze della Vita e dell’ambiente, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy
| | - Giacomo Picci
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, I-09042 Monserrato, Cagliari, Italy
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Agoitrous Graves' Hyperthyroidism with Markedly Elevated Thyroid Stimulating Immunoglobulin Titre displaying Rapid Response to Carbimazole with Discordant Thyroid Function. J ASEAN Fed Endocr Soc 2021; 35:224-232. [PMID: 33442195 PMCID: PMC7784233 DOI: 10.15605/jafes.035.02.13] [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: 09/24/2020] [Accepted: 11/12/2020] [Indexed: 11/30/2022] Open
Abstract
We characterize the clinical and laboratory characteristics of 5 patients with Graves’ thyrotoxicosis whose serum free thyroxine (fT4) concentration decreased unexpectedly to low levels on conventional doses of carbimazole (CMZ) therapy. The initial fT4 mean was 40.0 pM, range 25–69 pM. Thyroid volume by ultrasound measured as mean 11 ml, range 9.0–15.6 ml. Initial TSI levels measured 1487% to >4444%. Serum fT4 fell to low-normal or hypothyroid levels within 3.6 to 9.3 weeks of initiating CMZ 5 to 15 mg daily, and subsequently modulated by fine dosage adjustments. In one patient, serum fT4 fluctuated in a “yo-yo” pattern. There also emerged a pattern of low normal/low serum fT4 levels associated with discordant low/mid normal serum TSH levels respectively, at normal serum fT3 levels. The long-term daily-averaged CMZ maintenance dose ranged from 0.7 mg to 3.2 mg. Patients with newly diagnosed Graves’ hyperthyroidism who have small thyroid glands and markedly elevated TSI titres appear to be “ATD dose sensitive.” Their TFT on ATD therapy may display a “central hypothyroid” pattern. We suggest finer CMZ dose titration at closer follow-up intervals to achieve biochemical euthyroidism.
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Ranjan A, Yerande R, Wakchaure PB, Yerande SG, Dethe DH. Base-Mediated Hydroamination of Propargylamine: A Regioselective Intramolecular 5-exo-dig Cycloisomerization en Route to Imidazole-2-thione. Org Lett 2014; 16:5788-91. [DOI: 10.1021/ol502871r] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Alok Ranjan
- Department
of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Ragini Yerande
- Acoris Research (A Division of Hikal Ltd.), 3A International Biotech Park, Hinjewadi, Pune 411057, Maharashtra, India
| | - Prasad B. Wakchaure
- Acoris Research (A Division of Hikal Ltd.), 3A International Biotech Park, Hinjewadi, Pune 411057, Maharashtra, India
| | - Swapnil G. Yerande
- Acoris Research (A Division of Hikal Ltd.), 3A International Biotech Park, Hinjewadi, Pune 411057, Maharashtra, India
| | - Dattatraya H. Dethe
- Department
of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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Roy G, Jayaram PN, Mugesh G. Inhibition of lactoperoxidase-catalyzed oxidation by imidazole-based thiones and selones: a mechanistic study. Chem Asian J 2013; 8:1910-21. [PMID: 23737077 DOI: 10.1002/asia.201300274] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/08/2013] [Indexed: 11/10/2022]
Abstract
Herein, we describe the synthesis and biomimetic activity of a series of N,N-disubstituted thiones and selones that contain an imidazole pharmacophore. The N,N-disubstituted thiones do not show any inhibitory activity towards LPO-catalyzed oxidation reactions, but their corresponding N,N-disubstituted selones exhibit inhibitory activity towards LPO-catalyzed oxidation reactions. Substituents on the N atom of the imidazole ring appear to have a significant effect on the inhibition of LPO-catalyzed oxidation and iodination reactions. Selones 16, 17, and 19, which contain methyl, ethyl, and benzyl substituents, exhibit similar inhibition activities towards LPO-catalyzed oxidation reactions with IC50 values of 24.4, 22.5, and 22.5 μM, respectively. However, their activities are almost three-fold lower than that of the commonly used anti-thyroid drug methimazole (MMI). In contrast, selone 21, which contains a N-CH2CH2OH substituent, exhibits high inhibitory activity, with an IC50 value of 7.2 μM, which is similar to that of MMI. The inhibitory activity of these selones towards LPO-catalyzed oxidation/iodination reactions is due to their ability to decrease the concentrations of the co-substrates (H2O2 and I2), either by catalytically reducing H2O2 (anti-oxidant activity) or by forming stable charge-transfer complexes with oxidized iodide species. The inhibition of LPO-catalyzed oxidation/iodination reactions by N,N-disubstituted selones can be reversed by increasing the concentration of H2O2. Interestingly, all of the N,N-disubstituted selones exhibit high anti-oxidant activities and their glutathione peroxidase (GPx)-like activity is 4-12-fold higher than that of the well-known GPx-mimic ebselen. These experimental and theoretical studies suggest that the selones exist as zwitterions, in which the imidazole ring contains a positive charge and the selenium atom carries a large negative charge. Therefore, the selenium moieties of these selones possess highly nucleophilic character. The (77)Se NMR chemical shifts for the selones show large upfield shift, thus confirming the zwitterionic structure in solution.
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Affiliation(s)
- Gouriprasanna Roy
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.
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Bhabak KP, Bhowmick D. Synthesis and structural characterization of some trisulfide analoges of thiouracil-based antithyroid drugs. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2012.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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7
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Yang J, Cui Y, Zong S, Zhang R, Song C, Wang Z. Tracking Multiplex Drugs and Their Dynamics in Living Cells Using the Label-Free Surface-Enhanced Raman Scattering Technique. Mol Pharm 2012; 9:842-9. [DOI: 10.1021/mp200667d] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jing Yang
- Advanced
Photonics Center, Southeast University,
2# Sipailou, Nanjing 210096, Jiangsu, People’s Republic
of China
| | - Yiping Cui
- Advanced
Photonics Center, Southeast University,
2# Sipailou, Nanjing 210096, Jiangsu, People’s Republic
of China
| | - Shenfei Zong
- Advanced
Photonics Center, Southeast University,
2# Sipailou, Nanjing 210096, Jiangsu, People’s Republic
of China
| | - Ruohu Zhang
- Advanced
Photonics Center, Southeast University,
2# Sipailou, Nanjing 210096, Jiangsu, People’s Republic
of China
| | - Chunyuan Song
- Advanced
Photonics Center, Southeast University,
2# Sipailou, Nanjing 210096, Jiangsu, People’s Republic
of China
| | - Zhuyuan Wang
- Advanced
Photonics Center, Southeast University,
2# Sipailou, Nanjing 210096, Jiangsu, People’s Republic
of China
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8
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Yellol GS, Chou C, Chang W, Maiti B, Sun C. Microwave‐Enhanced Efficient Regioselective Synthesis of 1,3,4‐Trisubstituted 2‐Mercaptoimidazoles on a Soluble Support. Adv Synth Catal 2012. [DOI: 10.1002/adsc.201100640] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Gorakh S. Yellol
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan
| | - Cheng‐Ting Chou
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan
| | - Wang‐Jin Chang
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan
| | - Barnali Maiti
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan
| | - Chung‐Ming Sun
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan
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9
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Bhabak KP, Mugesh G. Inhibition of peroxidase-catalyzed protein tyrosine nitration by antithyroid drugs and their analogues. Inorganica Chim Acta 2010. [DOI: 10.1016/j.ica.2010.03.048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Guziec FS, Sanfilippo LJ, Wasmund LM. CONVENIENT PREPARATION OF METABOLITES OF 6-n-PROPYLTHIOURACIL. ORG PREP PROCED INT 2009. [DOI: 10.1080/00304949009356333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- F. S. Guziec
- a New Mexico State University, Department of Chemistry , Las Cruces, NM, 88003, USA
| | | | - Loide Mayer Wasmund
- a New Mexico State University, Department of Chemistry , Las Cruces, NM, 88003, USA
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11
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Affiliation(s)
- Gouriprasanna Roy
- a epartment of Inorganic & Physical Chemistry , Indian Institute of Science , Bangalore, India
| | - Govindasamy Mugesh
- a epartment of Inorganic & Physical Chemistry , Indian Institute of Science , Bangalore, India
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12
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Dalan R, Leow MKS, Ng DCE. High iodine (substrate) turnover Graves' disease: the intriguing 'rapid responder' variant of thyrotoxicosis. Ann Clin Biochem 2008; 45:612-5. [PMID: 18941129 DOI: 10.1258/acb.2008.008098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Factors determining the responsiveness to antithyroid drugs (ATDs) in Graves' disease are not fully known. Notwithstanding the typical pattern and tempo of thyroid hormone responses to thionamides, the existence of an unusual subset of Graves' disease with extraordinarily rapid thyroid hormone responses to ATDs will prove challenging even to the expert clinician. Termed 'rapid responder Graves' disease' or 'high turnover Graves' disease', the serum thyroxine (FT4) and triiodothyronine (FT3) of patients with this variant of thyrotoxicosis can decline precipitously during the initiation of ATDs and yet escalate acutely upon discontinuation of pharmacological intervention. We describe a case that presented with low serum FT4 and FT3 in association with suppressed serum thyrotropin (TSH) concentrations soon after starting carbimazole even at a low dose. The erratic clinical course comprising largely of serum FT4 nadirs and peaks is elaborated to facilitate appreciation of the difficulty in the stabilization of the thyroid with ATDs. The possible pathogenetic mechanisms for the chaotic fluctuations in thyroid hormones to minor changes in thionamide dose adjustments are discussed as well.
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Affiliation(s)
- Rinkoo Dalan
- Department of Endocrinology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433.
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13
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Krause RJ, Elfarra AA. Reduction of L-methionine selenoxide to seleno-L-methionine by endogenous thiols, ascorbic acid, or methimazole. Biochem Pharmacol 2008; 77:134-40. [PMID: 18930712 DOI: 10.1016/j.bcp.2008.09.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 09/12/2008] [Accepted: 09/17/2008] [Indexed: 11/24/2022]
Abstract
Seleno-L-methionine (SeMet) can be oxidized to L-methionine selenoxide (MetSeO) by flavin-containing monooxygenase 3 (FMO3) and rat liver microsomes in the presence of NADPH. MetSeO can be reduced by GSH to yield SeMet and GSSG. In the present study, the potential reduction of MetSeO to SeMet by other cellular components and antioxidants was investigated. Besides GSH, other thiols (L-cysteine, or N-acetyl-L-cysteine) and antioxidants (ascorbic acid and methimazole) also reduced MetSeO to SeMet. This reduction is unique to MetSeO since methionine sulfoxide was not reduced to methionine under similar conditions. The MetSeO reduction by thiols was instaneous and much faster than the reduction by ascorbic acid or methimazole. However, only one molar equivalent of ascorbic acid or methimazole was needed to complete the reduction, as opposed to two molar equivalents of thiols. Whereas the disulfides produced by the reactions of MetSeO with thiols are chemically stable, methimazole disulfide readily decomposed at pH 7.4, 37 degrees C to yield methimazole, methimazole-sulfenic acid, methimazole sulfinic acid, methimazole S-sulfonate, 1-methylimidazole (MI) and sulfite anion. Collectively, the results demonstrate reduction of MetSeO to SeMet by multiple endogenous thiols, ascorbic acid, and methimazole. Thus, oxidation of SeMet to MetSeO may result in depletion of endogenous thiols and antioxidant molecules. Furthermore, the novel reduction of MetSeO by methimazole provides clear evidence that methimazole should not be used as an alternative FMO substrate when studying FMO-mediated oxidation of SeMet.
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Affiliation(s)
- Renee J Krause
- Department of Comparative Biosciences and the Center for Molecular and Environmental Toxicology, University of Wisconsin-Madison, Madison, WI 53706, United States
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Aouad MR, Rezki NT, El Ahsry ESH. Regioselectivity of the reactions of 4,5-diphenylimidazole-2-thione with 1-chloro-2,3-epoxy-propane and 1-bromo-propene, efficient precursors for imidazo[2,1-b]thiazine and thiazole. Effect of microwave and solid support. J Heterocycl Chem 2008. [DOI: 10.1002/jhet.5570450511] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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15
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Jayaram PN, Roy G, Mugesh G. Effect of thione—thiol tautomerism on the inhibition of lactoperoxidase by anti-thyroid drugs and their analogues. J CHEM SCI 2008. [DOI: 10.1007/s12039-008-0017-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Roy G, Mugesh G. Selenium Analogues of Antithyroid Drugs – Recent Developments. Chem Biodivers 2008; 5:414-39. [DOI: 10.1002/cbdv.200890042] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Methimazole-disulfide as an Anti-Thyroid Drug Metabolite Catalyzed the Highly Regioselective Conversion of Epoxides to Halohydrins with Elemental Halogens. B KOREAN CHEM SOC 2008. [DOI: 10.5012/bkcs.2008.29.1.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Roy G, Mugesh G. Bioinorganic chemistry in thyroid gland: effect of antithyroid drugs on peroxidase-catalyzed oxidation and iodination reactions. Bioinorg Chem Appl 2006; 2006:23214. [PMID: 17497002 PMCID: PMC1794076 DOI: 10.1155/bca/2006/23214] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Accepted: 08/29/2006] [Indexed: 01/12/2023] Open
Abstract
Propylthiouracil (PTU) and methimazole (MMI) are the most commonly used antithyroid drugs. The available data suggest that these drugs may block the thyroid hormone synthesis by inhibiting the thyroid peroxidase (TPO) or diverting oxidized iodides away from thyroglobulin. It is also known that PTU inhibits the selenocysteine-containing enzyme ID-1 by reacting with the selenenyl iodide intermediate (E-SeI). In view of the current interest in antithyroid drugs, we have recently carried out biomimetic studies to understand the mechanism by which the antithyroid drugs inhibit the thyroid hormone synthesis and found that the replacement of sulfur with selenium in MMI leads to an interesting compound that may reversibly block the thyroid hormone synthesis. Our recent results on the inhibition of lactoperoxidase (LPO)-catalyzed oxidation and iodination reactions by antithyroid drugs are described.
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Affiliation(s)
- Gouriprasanna Roy
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India
| | - G. Mugesh
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India
- *G. Mugesh:
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Aragoni MC, Arca M, Demartin F, Devillanova FA, Garau A, Isaia F, Lippolis V, Verani G. Anti-thyroid drug methimazole: X-ray characterization of two novel ionic disulfides obtained from its chemical oxidation by I(2). J Am Chem Soc 2002; 124:4538-9. [PMID: 11971682 DOI: 10.1021/ja012731k] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Interaction of methimazole (MMI, 1-methyl-imidazole-2-thione) with I2 in solvents having different polarity gives two new stable compounds containing a dication disulfide and a monocation disulfide arranged in dimers, respectively. These two species could represent effective intermediates in the reaction of MMI with an active iodine species in the thyroid gland and therefore shed more light on the mechanism of action of MMI as an antithyroid drug.
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Affiliation(s)
- M Carla Aragoni
- Dipartimento di Chimica Inorganica ed Analitica, S.S. 554 bivio per Sestu, I-09042 Monserrato (CA), Italy
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21
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Wagner BA, Buettner GR, Oberley LW, Darby CJ, Burns CP. Myeloperoxidase is involved in H2O2-induced apoptosis of HL-60 human leukemia cells. J Biol Chem 2000; 275:22461-9. [PMID: 10801811 DOI: 10.1074/jbc.m001434200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We examined the mechanism of H(2)O(2)-induced cytotoxicity and its relationship to oxidation in human leukemia cells. The HL-60 promyelocytic leukemia cell line was sensitive to H(2)O(2), and at concentrations up to about 20-25 micrometer, the killing was mediated by apoptosis. There was limited evidence of lipid peroxidation, suggesting that the effects of H(2)O(2) do not involve hydroxyl radical. When HL-60 cells were exposed to H(2)O(2) in the presence of the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN), we detected a 12-line electron paramagnetic resonance spectrum assigned to the POBN/POBN(.) N-centered spin adduct previously described in peroxidase-containing cell-free systems. Generation of this radical by HL-60 cells had the same H(2)O(2) concentration dependence as initiation of apoptosis. In contrast, studies with the K562 human erythroleukemia cell line, which is often used for comparison with the HL-60, and with high passaged HL-60 cells (spent HL-60) studied under the same conditions failed to generate POBN(.). Cellular levels of antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase did not explain the differences between these cell lines. Interestingly, the K562 and spent HL-60 cells, which did not generate the radical, also failed to undergo H(2)O(2)-induced apoptosis. Based on this we reasoned that the difference in H(2)O(2)-induced apoptosis might be due to the enzyme myeloperoxidase. Only the apoptosis-manifesting HL-60 cells contained appreciable immunoreactive protein or enzymatic activity of this cellular enzyme. When HL-60 cells were incubated with methimazole or 4-aminobenzoic acid hydrazide, which are inhibitors of myeloperoxidase, they no longer underwent H(2)O(2)-induced apoptosis. Hypochlorous acid stimulated apoptosis in both HL-60 and spent HL-60 cells, indicating that another oxidant generated by myeloperoxidase induces apoptosis and that it may be the direct mediator of H(2)O(2)-induced apoptosis. Taken together these observations indicate that H(2)O(2)-induced apoptosis in the HL-60 human leukemia cell is mediated by myeloperoxidase and is linked to a non-Fenton oxidative event marked by POBN(.).
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Affiliation(s)
- B A Wagner
- Departments of Medicine and Radiology (Free Radical and Radiation Biology Graduate Program), The University of Iowa College of Medicine and The University of Iowa Cancer Center, Iowa City, Iowa 52242, USA
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Sugawara M, Sugawara Y, Wen K. Methimazole and propylthiouracil increase cellular thyroid peroxidase activity and thyroid peroxidase mRNA in cultured porcine thyroid follicles. Thyroid 1999; 9:513-8. [PMID: 10365684 DOI: 10.1089/thy.1999.9.513] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Methimazole (MMI) and propylthiouracil (PTU) are common antithyroid drugs for treating hyperthyroidism because the 2 drugs inhibit thyroid peroxidase (TPO)-catalyzed thyroid hormone formation. We studied whether the 2 drugs actually inhibit cellular TPO activity in cultured porcine follicles. Porcine follicles were cultured in the presence of 1 mU/mL thyrotropin (TSH) for 7 days. Then follicles were exposed to MMI or PTU in the presence of 0.1 microM Kl for 2 days. TPO activity was measured in the 100,000 x g-pellet of the thyroid sonicate by the guaiacol oxidation method. Exposure to MMI (1 microM and 10 microM) or PTU (10 microM and 100 microM) for 2 days caused a significant increase in cellular TPO activity; 100 microM MMI inhibited cellular TPO activity. The presence of cyclic adenosine monophosphate (cAMP)-generating system (forskolin) in TSH-free medium increased MMI-mediated TPO activity. Cyclohexamide inhibited MMI-mediated TPO activation, indicating that new protein synthesis is required for increased TPO activity. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed an increase in TPO mRNA by PTU or MMI. In conclusion, MMI and PTU at therapeutic concentrations can increase TPO mRNA and cellular TPO activity, although the 2 drugs inhibit the TPO-H2O2-mediated catalytic reaction.
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Affiliation(s)
- M Sugawara
- West Los Angeles Veterans Affair Medial Center and Department of Medicine, UCLA School of Medicine, California 90073, USA.
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Bergman U, Brittebo EB. Methimazole toxicity in rodents: covalent binding in the olfactory mucosa and detection of glial fibrillary acidic protein in the olfactory bulb. Toxicol Appl Pharmacol 1999; 155:190-200. [PMID: 10053173 DOI: 10.1006/taap.1998.8590] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Methimazole is an antithyroid drug reported to affect the sense of smell and taste in humans. The aim of the present study was to examine the distribution and effects of methimazole on the olfactory system in rodents. Autoradiography showed a selective covalent binding of 3H-labeled methimazole in the Bowman's glands in the olfactory mucosa, bronchial epithelium in the lungs, and centrilobular parts of the liver following an iv injection in mice. Histopathology showed an extensive lesion in the olfactory mucosa that was efficiently repaired 3 months after two consecutive ip doses of methimazole. The effect of methimazole on various brain regions was studied by determining levels and location of glial fibrillary acidic protein (GFAP). The results showed a threefold increase of GFAP in the olfactory bulb 2 weeks after treatment with methimazole whereas no change was observed 4 days after treatment. Pretreatment of mice with thyroxine did not protect against the methimazole-induced toxicity in the olfactory mucosa and bulb. In contrast, pretreatment with the cytochrome P450 inhibitor metyrapone completely prevented the covalent binding and toxicity of methimazole in the olfactory mucosa and bulb. The present results suggest that the methimazole-induced toxicity in the olfactory mucosa is mediated by a cytochrome P450-dependent metabolic activation of the compound into reactive metabolites that are bound to various tissues including the olfactory mucosa. The increase of GFAP in the olfactory bulb of methimazole-treated mice is suggested to be a secondary phenomenon due to the primary damage in the olfactory mucosa.
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Affiliation(s)
- U Bergman
- Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Uppsala, S-751 23, Sweden
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Bandyopadhyay U, Bhattacharyya DK, Chatterjee R, Banerjee RK. Irreversible inactivation of lactoperoxidase by mercaptomethylimidazole through generation of a thiyl radical: its use as a probe to study the active site. Biochem J 1995; 306 ( Pt 3):751-7. [PMID: 7702570 PMCID: PMC1136585 DOI: 10.1042/bj3060751] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The mechanism of suicidal inactivation of lactoperoxidase (LPO) by mercaptomethylimidazole (MMI) has been studied. Analogue studies indicate a specific requirement for the thiol group of MMI for inactivation of LPO in the presence of H2O2. MMI is oxidized via one-electron transfer by LPO compound II as demonstrated by a spectral shift from 430 to 412 nm through an isosbestic point at 421 nm. A decrease in Soret absorbance at 412 nm and the appearance of visible peaks at 592 and 636 nm are the characteristics of the inactivated enzyme. The one-electron oxidation product of MMI was identified by e.s.r. spectroscopy as the 5,5'-dimethyl-l-pyrroline N-oxide (DMPO) adduct of the sulphur-centred thiyl radical. Both inactivation and spectral change are prevented by the radical trap DMPO, suggesting involvement of the thiyl radical in inactivation. pH-dependent inactivation kinetics indicate the involvement of an ionizable group on LPO (pKa 6.1), deprotonation of which favours inactivation. The enzyme is protected by iodide and not by guaiacol, suggesting that MMI interacts at or near the iodide-binding site which is away from the aromatic-donor-binding site. The inactive enzyme can form compound II and bind aromatic donor, indicating that the MMI oxidation product does not attack haem iron or aromatic-donor-binding site. We suggest that MMI interacts at the iodide-binding site for oxidation and the reactive product, probably the thiyl radical, is incorporated into the adjacent electron-rich site of haem porphyrin to cause inactivation.
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Affiliation(s)
- U Bandyopadhyay
- Department of Physiology, Indian Institute of Chemical Biology, Calcutta
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25
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Brittebo EB. Metabolism-dependent toxicity of methimazole in the olfactory nasal mucosa. PHARMACOLOGY & TOXICOLOGY 1995; 76:76-9. [PMID: 7753763 DOI: 10.1111/j.1600-0773.1995.tb00107.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In mice given a single intraperitoneal injection of the antithyroid drug methimazole (0.44 mmol/kg; 50 mg/kg) detachment of the olfactory neuroepithelium and necrosis of the Bowman's glands in the lamina propria was observed 24 hr after administration. Three days after administration there was an atypical epithelium throughout the olfactory region and the Bowman's glands had disappeared. Pretreatment with the olfactory cytochrome P450 inhibitor metyrapone protected against the methimazole-induced changes at this site. In mice injected with the methimazole analogues 1-methylimidazole or 4-methylimidazole (0.44 mmol/kg; 36 mg/kg) or the antithyroid drug propylthiuracil (0.22 mmol/kg; 38 mg/kg) no morphological changes were observed in the olfactory mucosa. The results suggest that methimazole-induced toxicity in the olfactory mucosa is related to metabolism-dependent changes of the thiol group.
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Affiliation(s)
- E B Brittebo
- Department of Pharmacology, University of Lund, Sweden
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Taurog A, Dorris ML, Guziec LJ, Guziec FS. The selenium analog of methimazole. Measurement of its inhibitory effect on type I 5'-deiodinase and of its antithyroid activity. Biochem Pharmacol 1994; 48:1447-53. [PMID: 7524506 DOI: 10.1016/0006-2952(94)90569-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Methimazole (MMI), unlike propylthiouracil (PTU) is a poor inhibitor of type I iodothyronine deiodinase (ID-1). Inhibition of the enzyme by PTU was attributed initially to formation of a mixed disulfide between PTU and a cysteine residue at the active site. Presumably, MMI was unable to form a stable mixed disulfide and thus did not inhibit the enzyme. However, it has been demonstrated recently that ID-1 is a selenium-containing enzyme, with selenocysteine, rather than cysteine, at the active site. This observation raised the possibility that the selenium analog of MMI, methyl selenoimidazole (MSeI), might be a better inhibitor of ID-1 than MMI itself, as formation of the Se-Se bond with the enzyme would be expected to occur more readily than formation of the S-SE bond. To test this possibility, we developed a procedure for the synthesis of MSeI and compared MSeI with MMI and PTU for inhibition of ID-1 and for antithyroid activity. For inhibition of ID-1, MMI and MSeI were tested at concentrations of 10-300 microM. No significant inhibition was observed with MMI. MSeI showed slight but significant inhibition only in the 100-300 microM range. PTU, on the other hand, showed marked inhibition at 1 microM. Thus, replacement of the sulfur in MMI with selenium only marginally increases its inhibitory effect on ID-1. As an inhibitor of ID-1, MSeI is much less than 1% as potent as PTU. MMI and MSeI were also compared for antithyroid activity, both in vivo and in vitro. As an inhibitor of the catalytic activity of thyroid peroxidase, MMI was 4-5 times more potent than MSeI in a guaiacol assay, but only twice as potent in an iodination assay. In in vivo experiments with rats, MMI was at least 50 times more potent than MSeI in inhibiting thyroidal organic iodine formation. The relatively low potency of MSeI in vivo suggests that it is much less well concentrated by the thyroid than in MMI.
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Affiliation(s)
- A Taurog
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041
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Abstract
Myeloperoxidase (MPO), which displays considerable amino acid sequence homology with thyroid peroxidase (TPO) and lactoperoxidase (LPO), was tested for its ability to catalyze iodination of thyroglobulin and coupling of two diiodotyrosyl residues within thyroglobulin to form thyroxine. After 1 min of incubation in a system containing goiter thyroglobulin, I-, and H2O2, the pH optimum of MPO-catalyzed iodination was markedly acidic (approximately 4.0), compared to LPO (approximately 5.4) and TPO (approximately 6.6). The presence of 0.1 N Cl- or Br- shifted the pH optimum for MPO to about 5.4 but had little or no effect on TPO- or LPO-catalyzed iodination. At pH 5.4, 0.1 N Cl- and 0.1 N Br- had a marked stimulatory effect on MPO-catalyzed iodination. At pH 4.0, however, iodinating activity of MPO was almost completely inhibited by 0.1 N Cl- or Br-. Inhibition of chlorinating activity of MPO by Cl- at pH 4.0 has been previously described. When iodination of goiter thyroglobulin was performed with MPO plus the H2O2 generating system, glucose-glucose oxidase, at pH 7.0, the iodinating activity was markedly increased by 0.1 N Cl-. Under these conditions iodination and thyroxine formation were comparable to values observed with TPO. MPO and TPO were also compared for coupling activity in a system that measures coupling of diiodotyrosyl residues in thyroglobulin in the absence of iodination. MPO displayed very significant coupling activity, and, like TPO, this activity was stimulated by a low concentration of free diiodotyrosine (1 microM). The thioureylene drugs, propylthiouracil and methimazole, inhibited MPO-catalyzed iodination both reversibly and irreversibly, in a manner similar to that previously described for TPO-catalyzed iodination.
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Affiliation(s)
- A Taurog
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235
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Po HN, Shariff Z, Masse JA, Freeman F, Keindl-yu MC. THERMODYNAMIC AND ELECTROCHEMICAL PROPERTIES OF IMIDAZOLE-2-THIOLS (IMIDAZOLE-2(3H)-THIONES). PHOSPHORUS SULFUR 1991. [DOI: 10.1080/10426509108029421] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Sayo H, Saito M. Hydrogen peroxide-dependent oxidation metabolism of 1-methyl-2-mercaptoimidazole (methimazole) catalysed by myeloperoxidase. Xenobiotica 1991; 21:1217-24. [PMID: 1664996 DOI: 10.3109/00498259109039562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. Myeloperoxidase catalysed the H2O2-supported oxidation of 1-methyl-2-mercaptoimidazole (MMI) in the presence of Cl-. The rate of MMI oxidation was determined by monitoring a decrease in the absorbance at 251 nm. The pH optimum of the oxidation was around 4.5. The rate of MMI oxidation showed typical Michaelis-Menten saturation kinetics with respect to H2O2. Inhibition by excess H2O2 was not seen. 2. When the H2O2/MMI ratio was 0.5, MMI was oxidized by hyochlorous acid produced by the myeloperoxidase-H2O2-Cl- system giving bis-(1-methyl-2-imidazolyl)disulphide (MMI-disulphide) as an initial product, which gradually underwent disproportionation and subsequent hydrolysis giving 1-methylimidazole and MMI as the final products stoichiometrically. 3. When the H2O2/MMI ratio was one or above, hypochlorous acid produced in excess reacted with MMI-disulphide to give unidentified compounds. The sum of the amounts of 1-methylimidazole formed and of MMI reformed was less than 81% of the MMI added.
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Affiliation(s)
- H Sayo
- Faculty of Pharmaceutical Sciences, Kobe-Gakuin University, Japan
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Affiliation(s)
- D S Sitar
- Clinical Pharmacology Section, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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