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Voros C, Dias J, Timperley CM, Nachon F, Brown RCD, Baati R. The risk associated with organophosphorus nerve agents: from their discovery to their unavoidable threat, current medical countermeasures and perspectives. Chem Biol Interact 2024; 395:110973. [PMID: 38574837 DOI: 10.1016/j.cbi.2024.110973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/13/2024] [Accepted: 03/21/2024] [Indexed: 04/06/2024]
Abstract
The first organophosphorus nerve agent was discovered accidently during the development of pesticides, shortly after the first use of chemical weapons (chlorine, phosgene) on the battlefield during World War I. Despite the Chemical Weapons Convention banning these substances, they have still been employed in wars, terrorist attacks or political assassinations. Characterised by their high lethality, they target the nervous system by inhibiting the acetylcholinesterase (AChE) enzyme, preventing neurotransmission, which, if not treated rapidly, inevitably leads to serious injury or the death of the person intoxicated. The limited efficacy of current antidotes, known as AChE reactivators, pushes research towards new treatments. Numerous paths have been explored, from modifying the original pyridinium oximes to developing hybrid reactivators seeking a better affinity for the inhibited AChE. Another crucial approach resides in molecules more prone to cross the blood-brain barrier: uncharged compounds, bio-conjugated reactivators or innovative formulations. Our aim is to raise awareness on the threat and toxicity of organophosphorus nerve agents and to present the main synthetic efforts deployed since the first AChE reactivator, to tackle the task of efficiently treating victims of these chemical warfare agents.
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Affiliation(s)
- Camille Voros
- Ecole de Chimie Polymère et Matériaux ECPM, Université de Strasbourg, ICPEES UMR CNRS 7515, 25 rue Becquerel, F-67087, Strasbourg, France.
| | - José Dias
- Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, F-91220 Brétigny-sur-Orge, France
| | - Christopher M Timperley
- Chemical, Biological and Radiological (CBR) Division, Dstl, Porton Down, Salisbury, Wiltshire, SP4 0JQ, UK.
| | - Florian Nachon
- Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, F-91220 Brétigny-sur-Orge, France
| | - Richard C D Brown
- Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, UK.
| | - Rachid Baati
- Ecole de Chimie Polymère et Matériaux ECPM, Université de Strasbourg, ICPEES UMR CNRS 7515, 25 rue Becquerel, F-67087, Strasbourg, France; OPGS Pharmaceuticals, Paris BioTech Santé, 24 rue du Faubourg Saint-Jacques, F-75014, Paris, France.
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2
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Lindgren C, Forsgren N, Hoster N, Akfur C, Artursson E, Edvinsson L, Svensson R, Worek F, Ekström F, Linusson A. Broad‐Spectrum Antidote Discovery by Untangling the Reactivation Mechanism of Nerve‐Agent‐Inhibited Acetylcholinesterase. Chemistry 2022; 28:e202200678. [PMID: 35420233 PMCID: PMC9400889 DOI: 10.1002/chem.202200678] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Indexed: 11/13/2022]
Abstract
Reactivators are vital for the treatment of organophosphorus nerve agent (OPNA) intoxication but new alternatives are needed due to their limited clinical applicability. The toxicity of OPNAs stems from covalent inhibition of the essential enzyme acetylcholinesterase (AChE), which reactivators relieve via a chemical reaction with the inactivated enzyme. Here, we present new strategies and tools for developing reactivators. We discover suitable inhibitor scaffolds by using an activity‐independent competition assay to study non‐covalent interactions with OPNA‐AChEs and transform these inhibitors into broad‐spectrum reactivators. Moreover, we identify determinants of reactivation efficiency by analysing reactivation and pre‐reactivation kinetics together with structural data. Our results show that new OPNA reactivators can be discovered rationally by exploiting detailed knowledge of the reactivation mechanism of OPNA‐inhibited AChE.
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Affiliation(s)
| | - Nina Forsgren
- CBRN Defense and Security Swedish Defense Research Agency 906 21 Umeå Sweden
| | - Norman Hoster
- Department of Chemistry Umeå University 901 87 Umeå Sweden
| | - Christine Akfur
- CBRN Defense and Security Swedish Defense Research Agency 906 21 Umeå Sweden
| | - Elisabet Artursson
- CBRN Defense and Security Swedish Defense Research Agency 906 21 Umeå Sweden
| | | | - Richard Svensson
- Biomedicinskt Centrum BMC Uppsala University 752 37 Uppsala Sweden
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology 80937 Munich Germany
| | - Fredrik Ekström
- CBRN Defense and Security Swedish Defense Research Agency 906 21 Umeå Sweden
| | - Anna Linusson
- Department of Chemistry Umeå University 901 87 Umeå Sweden
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3
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Crnčević D, Krce L, Cvitković M, Brkljača Z, Sabljić A, Vuko E, Primožič I, Odžak R, Šprung M. New Membrane Active Antibacterial and Antiviral Amphiphiles Derived from Heterocyclic Backbone of Pyridinium-4-Aldoxime. Pharmaceuticals (Basel) 2022; 15:ph15070775. [PMID: 35890073 PMCID: PMC9315884 DOI: 10.3390/ph15070775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/15/2022] [Accepted: 06/20/2022] [Indexed: 02/06/2023] Open
Abstract
Quaternary ammonium salts (QAS) are irreplaceable membrane-active antimicrobial agents that have been widely used for nearly a century. Cetylpyridinium chloride (CPC) is one of the most potent QAS. However, recent data from the literature indicate that CPC activity against resistant bacterial strains is decreasing. The major QAS resistance pathway involves the QacR dimer, which regulates efflux pump expression. A plausible approach to address this issue is to structurally modify the CPC structure by adding other biologically active functional groups. Here, a series of QAS based on pyridine-4-aldoxime were synthesized, characterized, and tested for antimicrobial activity in vitro. Although we obtained several potent antiviral candidates, these candidates had lower antibacterial activity than CPC and were not toxic to human cell lines. We found that the addition of an oxime group to the pyridine backbone resulted in derivatives with large topological polar surfaces and with unfavorable cLog P values. Investigation of the antibacterial mode of action, involving the cell membrane, revealed altered cell morphologies in terms of corrugated and/or disrupted surface, while 87% of the cells studied exhibited a permeabilized membrane after 3 h of treatment at 4 × minimum inhibitory concentration (MIC). Molecular dynamic (MD) simulations of the interaction of QacR with a representative candidate showed rapid dimer disruption, whereas this was not observed for QacR and QacR bound to the structural analog CPC. This might explain the lower bioactivity of our compounds, as they are likely to cause premature expression of efflux pumps and thus activation of resistance.
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Affiliation(s)
- Doris Crnčević
- Department of Chemistry, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia; (D.C.); (A.S.)
- Doctoral Study of Biophysics, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia
| | - Lucija Krce
- Department of Physics, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia; (L.K.); (M.C.)
| | - Mislav Cvitković
- Department of Physics, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia; (L.K.); (M.C.)
| | - Zlatko Brkljača
- Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička c. 54, 10 000 Zagreb, Croatia;
- Selvita Ltd., Prilaz Baruna Filipovića 29, 10 000 Zagreb, Croatia
| | - Antonio Sabljić
- Department of Chemistry, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia; (D.C.); (A.S.)
- Doctoral Study of Biophysics, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia
| | - Elma Vuko
- Department of Biology, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia;
| | - Ines Primožič
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10 000 Zagreb, Croatia;
| | - Renata Odžak
- Department of Chemistry, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia; (D.C.); (A.S.)
- Correspondence: (R.O.); (M.Š.)
| | - Matilda Šprung
- Department of Chemistry, Faculty of Science, University of Split, R. Bošković 33, 21 000 Split, Croatia; (D.C.); (A.S.)
- Correspondence: (R.O.); (M.Š.)
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4
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Jebli N, Arfaoui Y, Van Hecke K, Cavalier JF, Touil S. Experimental and computational investigation of Z/E isomerism, X-ray crystal structure and molecular docking study of (2-(hydroxyimino)cyclohexyl)diphenylphosphine sulfide, a potential antibacterial agent. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Targeting organophosphorus compounds poisoning by novel quinuclidine-3 oximes: development of butyrylcholinesterase-based bioscavengers. Arch Toxicol 2020; 94:3157-3171. [PMID: 32583098 DOI: 10.1007/s00204-020-02811-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/15/2020] [Indexed: 01/04/2023]
Abstract
A library of 14 mono-oxime quinuclidinium-based compounds with alkyl or benzyl substituent were synthesized and characterized in vitro as potential antidotes for organophosphorus compounds (OP) poisoning treatment. We evaluated their potency for reversible inhibition and reactivation of OP inhibited human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and evaluated interactions by molecular docking studies. The reactivation was notable for both AChE and BChE inhibited by VX, cyclosarin, sarin and paraoxon, if quinuclidinium compounds contained the benzyl group attached to the quinuclidinium moiety. Out of all 14, oxime Q8 [4-bromobenzyl-3-(hydroxyimino)quinuclidinium bromide] was singled out as having the highest determined overall reactivation rate of approximately 20,000 M-1 min-1 for cyclosarin-inhibited BChE. Furthermore, this oxime in combination with BChE exhibited a capability to act as a bioscavenger of cyclosarin, degrading within 2 h up to 100-fold excess of cyclosarin concentration over the enzyme. Molecular modeling revealed that the position of the cyclohexyl moiety conjugated with the active site serine of BChE directs the favorable positioning of the quinuclidinium ring and the bromophenyl moiety of Q8, which makes phosphonylated-serine easily accessible for the nucleophilic displacement by the oxime group of Q8. This result presents a novel scaffold for the development of new BChE-based bioscavengers. Furthermore, a cytotoxic effect was not observed for Q8, which also makes it promising for further in vivo reactivation studies.
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Zorbaz T, Mišetić P, Probst N, Žunec S, Zandona A, Mendaš G, Micek V, Maček Hrvat N, Katalinić M, Braïki A, Jean L, Renard PY, Gabelica Marković V, Kovarik Z. Pharmacokinetic Evaluation of Brain Penetrating Morpholine-3-hydroxy-2-pyridine Oxime as an Antidote for Nerve Agent Poisoning. ACS Chem Neurosci 2020; 11:1072-1084. [PMID: 32105443 DOI: 10.1021/acschemneuro.0c00032] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Nerve agents, the deadliest chemical warfare agents, are potent inhibitors of acetylcholinesterase (AChE) and cause rapid cholinergic crisis with serious symptoms of poisoning. Oxime reactivators of AChE are used in medical practice in the treatment of nerve agent poisoning, but the search for novel improved reactivators with central activity is an ongoing pursuit. For numerous oximes synthesized, in vitro reactivation is a standard approach in biological evaluation with little attention given to the pharmacokinetic properties of the compounds. This study reports a comprehensive physicochemical, pharmacokinetic, and safety profiling of five lipophilic 3-hydroxy-2-pyridine aldoximes, which were recently shown to be potent AChE reactivators with a potential to be centrally active. The oxime JR595 was singled out as highly metabolically stable in human liver microsomes, noncytotoxic oxime for SH-SY5Y neuroblastoma and 1321N1 astrocytoma cell lines, and its pharmacokinetic profile was determined after intramuscular administration in mice. JR595 was rapidly absorbed into blood after 15 min with simultaneous distribution to the brain at up to about 40% of its blood concentration; however, it was eliminated from both the brain and blood within an hour. In addition, the MDCKII-MDR1 cell line assay showed that oxime JR595 was not a P-glycoprotein efflux pump substrate. Finally, the preliminary antidotal study against multiple LD50 doses of VX and sarin in mice showed the potential of JR595 to provide desirable therapeutic outcomes with future improvements in its circulation time.
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Affiliation(s)
- Tamara Zorbaz
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
| | - Petra Mišetić
- Fidelta Ltd, Prilaz baruna Filipovića 29, HR-10000 Zagreb, Croatia
| | - Nicolas Probst
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), 76000 Rouen, France
| | - Suzana Žunec
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
| | - Antonio Zandona
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
| | - Gordana Mendaš
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
| | - Vedran Micek
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
| | - Nikolina Maček Hrvat
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
| | - Maja Katalinić
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
| | - Anissa Braïki
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), 76000 Rouen, France
| | - Ludovic Jean
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), 76000 Rouen, France
| | - Pierre-Yves Renard
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), 76000 Rouen, France
| | - Vesna Gabelica Marković
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, HR-10000 Zagreb, Croatia
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia
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7
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Ochoa R, Rodriguez CA, Zuluaga AF. Prediction of Ligands Binding Acetylcholinesterase with Potential Antidotal Activity: A Virtual Screening Approach. Mol Inform 2019; 38:e1800126. [PMID: 30950246 DOI: 10.1002/minf.201800126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 03/04/2019] [Indexed: 12/11/2022]
Abstract
Intoxications caused by organophosphorus compounds (OPs) are associated with the reversible, and sometimes irreversible interaction with acetylcholinesterase (AChE). OPs are commonly used as pesticides mainly in developing countries, where the associated poisoning is a major health problem related to suicidal attempts, careless manipulation, and chemical warfare. The current antidotes are oxime-based drugs that can regenerate the AChE catalytic activity. Nevertheless, challenges associated with lack of efficiency and difficulties for crossing blood-brain barrier have motivated the design of novel alternatives. We used a validated molecular docking approach for the virtual screening of 579,890 synthetic ligands and 478 drugs against a human AChE in its apo conformation, and a murine AChE conjugated with the OP tabun. After filtering, 7 hits were selected as potential competitors due to the formation of key interactions within the active site gorge of the AChE structure, and potential reactivators based on interactions with amino acids of the catalytic triad in the presence of organophosphorus compounds. The selected candidates will be further evaluated through in vitro and in vivo assays.
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Affiliation(s)
- Rodrigo Ochoa
- CIEMTO: Centro de Información y Estudio de Medicamentos y Tóxicos, Departamento de Farmacología, Facultad de Medicina, Universidad de Antioquia, Calle 70 No. 52-21, Medellín, Colombia
| | - Carlos A Rodriguez
- CIEMTO: Centro de Información y Estudio de Medicamentos y Tóxicos, Departamento de Farmacología, Facultad de Medicina, Universidad de Antioquia, Calle 70 No. 52-21, Medellín, Colombia.,GRIPE: Grupo Investigador de Problemas en Enfermedades Infecciosas, Facultad de Medicina, Universidad de Antioquia, Calle 70 No. 52-21, Medellín, Colombia
| | - Andres F Zuluaga
- CIEMTO: Centro de Información y Estudio de Medicamentos y Tóxicos, Departamento de Farmacología, Facultad de Medicina, Universidad de Antioquia, Calle 70 No. 52-21, Medellín, Colombia.,GRIPE: Grupo Investigador de Problemas en Enfermedades Infecciosas, Facultad de Medicina, Universidad de Antioquia, Calle 70 No. 52-21, Medellín, Colombia
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8
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Ash T, Debnath T, Sarkar S, Gurey P, Das AK. Exploration of assisting behavior of molecular-MO2 (M = Ti, Zr) reagents towards the detoxication of tabun: A DFT study. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.01.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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9
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Novel Group of AChE Reactivators-Synthesis, In Vitro Reactivation and Molecular Docking Study. Molecules 2018; 23:molecules23092291. [PMID: 30205495 PMCID: PMC6225275 DOI: 10.3390/molecules23092291] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/03/2018] [Accepted: 09/05/2018] [Indexed: 11/24/2022] Open
Abstract
The acetylcholinesterase (AChE) reactivators (e.g., obidoxime, asoxime) became an essential part of organophosphorus (OP) poisoning treatment, together with atropine and diazepam. They are referred to as a causal treatment of OP poisoning, because they are able to split the OP moiety from AChE active site and thus renew its function. In this approach, fifteen novel AChE reactivators were determined. Their molecular design originated from former K-oxime compounds K048 and K074 with remaining oxime part of the molecule and modified part with heteroarenium moiety. The novel compounds were prepared, evaluated in vitro on human AChE (HssAChE) inhibited by tabun, paraoxon, methylparaoxon or DFP and compared to commercial HssAChE reactivators (pralidoxime, methoxime, trimedoxime, obidoxime, asoxime) or previously prepared compounds (K048, K074, K075, K203). Some of presented oxime reactivators showed promising ability to reactivate HssAChE comparable or higher than the used standards. The molecular modelling study was performed with one compound that presented the ability to reactivate GA-inhibited HssAChE. The SAR features concerning the heteroarenium part of the reactivator’s molecule are described.
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Maček Hrvat N, Zorbaz T, Šinko G, Kovarik Z. The estimation of oxime efficiency is affected by the experimental design of phosphylated acetylcholinesterase reactivation. Toxicol Lett 2017; 293:222-228. [PMID: 29180286 DOI: 10.1016/j.toxlet.2017.11.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/10/2017] [Accepted: 11/22/2017] [Indexed: 11/27/2022]
Abstract
Reactivation of acetylcholinesterase (AChE), an essential enzyme in neurotransmission, is a key point in the treatment of acute poisoning by nerve agents and pesticides, which structurally belong to organophosphorus compounds (OP). Due to the high diversity of substituents on the phosphorous atom, there is a variety of OP-AChE conjugates deriving from AChE inhibition, and therefore not only is there no universal reactivator efficient enough for the most toxic OPs, but for some nerve agents there is still a lack of any reactivator at all. The endeavor of many chemists to find more efficient reactivators resulted in thousands of newly-designed and synthesized oximes-potential reactivators of AChE. For an evaluation of the oximés reactivation efficiency, many research groups employ a simple spectrophotometric Ellman method. Since parameters that describe reactivator efficiency are often incomparable among laboratories, we tried to emphasize the critical steps in the determination of reactivation parameters as well as in the experimental design of a reactivation assay. We highlighted the important points in evaluation of reactivation kinetic parameters with an aim to achieve better agreement and comparability between the results obtained by different laboratories and overall, a more efficient evaluation of in vitro reactivation potency.
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Affiliation(s)
- Nikolina Maček Hrvat
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia.
| | - Tamara Zorbaz
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia.
| | - Goran Šinko
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia.
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia.
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11
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New Cinchona Oximes Evaluated as Reactivators of Acetylcholinesterase and Butyrylcholinesterase Inhibited by Organophosphorus Compounds. Molecules 2017; 22:molecules22071234. [PMID: 28737687 PMCID: PMC6151989 DOI: 10.3390/molecules22071234] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 11/17/2022] Open
Abstract
For the last six decades, researchers have been focused on finding efficient reactivators of organophosphorus compound (OP)-inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). In this study, we have focused our research on a new oxime scaffold based on the Cinchona structure since it was proven to fit the cholinesterases active site and reversibly inhibit their activity. Three Cinchona oximes (C1, C2, and C3), derivatives of the 9-oxocinchonidine, were synthesized and investigated in reactivation of various OP-inhibited AChE and BChE. As the results showed, the tested oximes were more efficient in the reactivation of BChE and they reactivated enzyme activity to up to 70% with reactivation rates similar to known pyridinium oximes used as antidotes in medical practice today. Furthermore, the oximes showed selectivity towards binding to the BChE active site and the determined enzyme-oxime dissociation constants supported work on the future development of inhibitors in other targeted studies (e.g., in treatment of neurodegenerative disease). Also, we monitored the cytotoxic effect of Cinchona oximes on two cell lines Hep G2 and SH-SY5Y to determine the possible limits for in vivo application. The cytotoxicity results support future studies of these compounds as long as their biological activity is targeted in the lower micromolar range.
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12
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Bušić V, Katalinić M, Šinko G, Kovarik Z, Gašo-Sokač D. Pyridoxal oxime derivative potency to reactivate cholinesterases inhibited by organophosphorus compounds. Toxicol Lett 2016; 262:114-122. [PMID: 27693733 DOI: 10.1016/j.toxlet.2016.09.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/23/2016] [Accepted: 09/28/2016] [Indexed: 10/20/2022]
Abstract
Organophosphorus (OP) nerve agents (sarin, tabun VX and soman) inhibit the enzyme acetylcholinesterase (AChE, EC 3.1.1.7) by binding to its active site while preventing neurotransmission in the cholinergic synapses. The protection and treatment of this kind of poisoning are still a challenge as we are yet to discover an antidote that would be effective in all cases of poisoning. To aid the search for more efficient antidotes, we evaluated the ability of nine pyridoxal oxime derivatives, prepared by a novel synthetic pathway, to reactivate recombinant human AChE and the related purified human plasma butyrylcholinesterase (BChE, EC 3.1.1.8) inhibited by VX, tabun and paraoxon. Oximes are derivatives of vitamin B6 bearing a phenacyl moiety attached to the quaternary nitrogen atom and having various substituents on the phenyl ring. As the results have shown, the tested oximes were in general more efficient in the reactivation of OP-inhibited BChE than AChE. The highest observed rate was in the case of VX-inhibited BChE reactivation, where kobs was 0.0087min-1 and the reactivation maximum of 90% was achieved within 5h. The cholinesterases displayed a binding affinity for these derivatives in a μmolar range no matter the substituent on their rings which was in accordance with the molecular modelling results showing a similar binding pattern for all oximes within the active site of both AChE and BChE. Such a positioning reveals also that hydroxy and a metoxy substituents at the vicinity of the oxime moiety present a possible steric hindrance explaining the reactivation results.
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Affiliation(s)
- Valentina Bušić
- Josip Juraj Strossmayer University of Osijek, Faculty of Food Technology, Kuhačeva 20, HR-31000 Osijek, Croatia
| | - Maja Katalinić
- Institute for Medical Research and Occupational Health, Ksaverska c. 2, HR-10001 Zagreb, Croatia.
| | - Goran Šinko
- Institute for Medical Research and Occupational Health, Ksaverska c. 2, HR-10001 Zagreb, Croatia
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Ksaverska c. 2, HR-10001 Zagreb, Croatia
| | - Dajana Gašo-Sokač
- Josip Juraj Strossmayer University of Osijek, Faculty of Food Technology, Kuhačeva 20, HR-31000 Osijek, Croatia
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Valiveti AK, Acharya J, Pratap A, Halve AK, Kaushik MP. Synthesis and in vitro screening of N-phenacylpyridinium oximes as reactivators of organophosphorus (OP)-inhibited electric eel acetylcholinesterase (AChE). Med Chem Res 2015. [DOI: 10.1007/s00044-015-1384-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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14
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Valiveti AK, Bhalerao UM, Acharya J, Karade HN, Gundapu R, Halve AK, Kaushik MP. Synthesis and in vitro kinetic study of novel mono-pyridinium oximes as reactivators of organophosphorus (OP) inhibited human acetylcholinesterase (hAChE). Chem Biol Interact 2015; 237:125-32. [DOI: 10.1016/j.cbi.2015.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/26/2015] [Accepted: 06/03/2015] [Indexed: 10/23/2022]
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Valiveti AK, Bhalerao UM, Acharya J, Karade HN, Acharya BN, Raviraju G, Halve AK, Kaushik MP. Synthesis and in vitro kinetic evaluation of N-thiazolylacetamido monoquaternary pyridinium oximes as reactivators of sarin, O-ethylsarin and VX inhibited human acetylcholinesterase (hAChE). Bioorg Med Chem 2015; 23:4899-4910. [PMID: 26043948 DOI: 10.1016/j.bmc.2015.05.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 05/13/2015] [Accepted: 05/15/2015] [Indexed: 11/29/2022]
Abstract
Presently available medications for treatment of organiphosphorus poisoning are not sufficiently effective due to various pharmacological and toxicological reasons. In this regard, herein we report the synthesis of a series of N-thiazolylacetamide monoquaternary pyridinium oximes and its analogs (1a-1b to 6a-6b) with diversely substituted thiazole ring and evaluation of their in vitro reactivation efficacies against nerve agent (sarin, O-ethylsarin and VX) inhibited human erythrocyte acetylcholinesterase (hAChE). Reactivation kinetics was performed to determine dissociation constant (KD), reactivity rate constant (kr) and the second order rate constant (kr2) for all the compounds and compared their efficacies with commercial antidotes viz. 2-PAM and obidoxime. All the newly synthesized oximes were evaluated for their physicochemical parameters (pKa) and correlated with their respective reactivation efficacies to assess the capability of the oxime reactivator. Three of these novel compounds showed promising reactivation efficacies toward OP inhibited hAChE. Molecular docking studies were performed in order to correlate the reactivation efficacies with their interactions in the active site of the AChE.
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Affiliation(s)
- Aditya Kapil Valiveti
- Process Technology Development Division, Defence Research & Development Establishment, Jhansi Road, Gwalior 474 002, India
| | - Uma M Bhalerao
- Process Technology Development Division, Defence Research & Development Establishment, Jhansi Road, Gwalior 474 002, India
| | - Jyotiranjan Acharya
- Process Technology Development Division, Defence Research & Development Establishment, Jhansi Road, Gwalior 474 002, India.
| | - Hitendra N Karade
- Process Technology Development Division, Defence Research & Development Establishment, Jhansi Road, Gwalior 474 002, India
| | - Badri Narayan Acharya
- Process Technology Development Division, Defence Research & Development Establishment, Jhansi Road, Gwalior 474 002, India
| | - G Raviraju
- Process Technology Development Division, Defence Research & Development Establishment, Jhansi Road, Gwalior 474 002, India
| | - Anand K Halve
- School of Studies in Chemistry, Jiwaji University, Gwalior, India
| | - Mahabir Parshad Kaushik
- Process Technology Development Division, Defence Research & Development Establishment, Jhansi Road, Gwalior 474 002, India
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Pd(II) complexes of acetylcholinesterase reactivator obidoxime. Interdiscip Toxicol 2014; 7:139-45. [PMID: 26109891 PMCID: PMC4434107 DOI: 10.2478/intox-2014-0019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 06/24/2014] [Accepted: 06/25/2014] [Indexed: 12/02/2022] Open
Abstract
The ability of the acetylcholinesterase reactivator obidoxime (H2L2+) to bind palladium(II) cations was evaluated spectrophotometrically at different reaction conditions (pH, reaction time, metal-to-ligand molar ratio). The results showed that immediately after mixing the reagents, pH 7.4, complex species of composition [PdHL]3+ existed predominantly with a value of conditional stability constant lgβ‘=6.52. The reaction was completed within 24 hours affording the formation of species [Pd2L]4+ with significantly increased stability (lgβ‘=9.34). The spectral data suggest that obidoxime coordinates metal(II) ions through the oximate functional groups. The in vitro reactivation assay of paraoxon-inhibited rat brain acetylcholinesterase revealed that the new complex species were much less active than the non-coordinated obidoxime. The lack of reactivation ability could be explained by the considerable stability of complexes in solution as well as by the deprotonation of oxime groups essential for recovery of the enzymatic activity.
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Dong L, Shi J, Liu Y. Theoretical studies on the interaction of biphenyl inhibitors with Mycobacterium tuberculosis protein tyrosine phosphatase MptpB. J Mol Model 2012; 18:3847-56. [DOI: 10.1007/s00894-012-1384-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Accepted: 02/15/2012] [Indexed: 10/28/2022]
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Acharya J, Rana H, Aditya Kapil V, Kaushik MP. In vitro reactivation of organophosphorus (OP)-inhibited electric eel acetylcholinesterase by novel monoquaternary pyridinium oximes. Med Chem Res 2012. [DOI: 10.1007/s00044-012-0128-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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19
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In vitro reactivation potency of novel symmetrical bis-pyridinium oximes for electric eel acetylcholinesterase inhibited by nerve agent sarin. Toxicol In Vitro 2011; 25:2135-9. [DOI: 10.1016/j.tiv.2011.06.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 05/17/2011] [Accepted: 06/20/2011] [Indexed: 11/20/2022]
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20
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Acharya J, Rana H, Kaushik M. Synthesis and in vitro evaluation of xylene linked carbamoyl bis-pyridinium monooximes as reactivators of organophosphorus (OP) inhibited electric eel acetylcholinesterase (AChE). Eur J Med Chem 2011; 46:3926-33. [DOI: 10.1016/j.ejmech.2011.05.064] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 04/18/2011] [Accepted: 05/26/2011] [Indexed: 10/18/2022]
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21
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Acharya J, Dubey DK, Srivastava AK, Raza SK. In vitro reactivation of sarin-inhibited human acetylcholinesterase (AChE) by bis-pyridinium oximes connected by xylene linkers. Toxicol In Vitro 2011; 25:251-6. [DOI: 10.1016/j.tiv.2010.07.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 07/06/2010] [Accepted: 07/28/2010] [Indexed: 11/26/2022]
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22
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Ling B, Zhang R, Wang Z, Dong L, Liu Y, Zhang C, Liu C. Theoretical studies on the interaction of guanine riboswitch with guanine and its closest analogues. MOLECULAR SIMULATION 2010. [DOI: 10.1080/08927022.2010.492833] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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23
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Synthesis and evaluation of novel analogues of vitamin B6 as reactivators of tabun and paraoxon inhibited acetylcholinesterase. Chem Biol Interact 2010; 187:234-7. [DOI: 10.1016/j.cbi.2010.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 01/29/2010] [Accepted: 02/01/2010] [Indexed: 11/18/2022]
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24
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Musilek K, Holas O, Misik J, Pohanka M, Novotny L, Dohnal V, Opletalova V, Kuca K. Monooxime-monocarbamoyl Bispyridinium Xylene-Linked Reactivators of Acetylcholinesterase-Synthesis, In vitro and Toxicity Evaluation, and Docking Studies. ChemMedChem 2010; 5:247-54. [DOI: 10.1002/cmdc.200900455] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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25
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Ekström F, Hörnberg A, Artursson E, Hammarström LG, Schneider G, Pang YP. Structure of HI-6*sarin-acetylcholinesterase determined by X-ray crystallography and molecular dynamics simulation: reactivator mechanism and design. PLoS One 2009; 4:e5957. [PMID: 19536291 PMCID: PMC2693926 DOI: 10.1371/journal.pone.0005957] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 04/24/2009] [Indexed: 11/18/2022] Open
Abstract
Organophosphonates such as isopropyl metylphosphonofluoridate (sarin) are extremely toxic as they phosphonylate the catalytic serine residue of acetylcholinesterase (AChE), an enzyme essential to humans and other species. Design of effective AChE reactivators as antidotes to various organophosphonates requires information on how the reactivators interact with the phosphonylated AChEs. However, such information has not been available hitherto because of three main challenges. First, reactivators are generally flexible in order to change from the ground state to the transition state for reactivation; this flexibility discourages determination of crystal structures of AChE in complex with effective reactivators that are intrinsically disordered. Second, reactivation occurs upon binding of a reactivator to the phosphonylated AChE. Third, the phosphorous conjugate can develop resistance to reactivation. We have identified crystallographic conditions that led to the determination of a crystal structure of the sarin(nonaged)-conjugated mouse AChE in complex with [(E)-[1-[(4-carbamoylpyridin-1-ium-1-yl)methoxymethyl]pyridin-2-ylidene]methyl]-oxoazanium dichloride (HI-6) at a resolution of 2.2 A. In this structure, the carboxyamino-pyridinium ring of HI-6 is sandwiched by Tyr124 and Trp286, however, the oxime-pyridinium ring is disordered. By combining crystallography with microsecond molecular dynamics simulation, we determined the oxime-pyridinium ring structure, which shows that the oxime group of HI-6 can form a hydrogen-bond network to the sarin isopropyl ether oxygen, and a water molecule is able to form a hydrogen bond to the catalytic histidine residue and subsequently deprotonates the oxime for reactivation. These results offer insights into the reactivation mechanism of HI-6 and design of better reactivators.
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Affiliation(s)
- Fredrik Ekström
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - Andreas Hörnberg
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - Elisabet Artursson
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | | | - Gunter Schneider
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Yuan-Ping Pang
- Computer-Aided Molecular Design Laboratory, Mayo Clinic, Rochester, Minnesota, United States of America
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Khan MTH. Molecular interactions of cholinesterases inhibitors using in silico methods: current status and future prospects. N Biotechnol 2009; 25:331-46. [PMID: 19491049 DOI: 10.1016/j.nbt.2009.03.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a low amount of acetylcholine (ACh) in hippocampus and cortex. Acetylcholinesterase (AChE) is one of the most important enzymes in many living organisms including human being and other vertebrates, insects like mosquitoes, among others. Several reports have been published where it has been clearly shown that the genesis of amyloid protein plaques associated with AD is connected to modifications of both AChE and butyrylcholinesterase (BChE), since the plaque is significantly decreased in AD patients using cholinesterase inhibitors (ChEIs). This review gives some examples of these inhibitors discovered during past couple of years that have shown very prominent interactions at the active site triad of the proteins as well as different other parts of the active site like, peripheral anionic site (PAS), oxyanionic hole, anionic subsite or acyl binding pocket (ABP). Most of the inhibition and their interactions have been visualized by X-ray crystallography, but some of the other inhibitors have been studied either by molecular docking or molecular dynamic (MD) simulations or by both the in silico methods. Some of these prominent studies have been crucially observed and reported here.
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Affiliation(s)
- Mahmud Tareq Hassan Khan
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, 9037 Tromsø, Norway(1)
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27
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Theoretical studies on the interaction of modified pyrimidines and purines with purine riboswitch. J Mol Graph Model 2009; 28:37-45. [PMID: 19380244 DOI: 10.1016/j.jmgm.2009.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 03/18/2009] [Accepted: 03/21/2009] [Indexed: 12/25/2022]
Abstract
Recent experimental study [S.D. Gilbert, S.J. Mediatore, R.T. Batey, Modified pyrimidine specifically bind the purine riboswitch, J. Am. Chem. Soc. 128 (2006) 14214-14215] demonstrated that the purine riboswitch could specifically bind some ligands other than purines such as amino-pyrimidines, and the authors proposed that the five-membered ring of purine was not required for recognition. To get insight into the interaction details, we used molecular docking method to investigate the interactions of a mutant form of guanine riboswitch with a series of amino-purines, amino-pyrimidines and imidazole derivatives, and employed molecular simulation method to study the dynamic behavior of the selected complexes. The calculation results reveal that (1) all the amino-purines and amino-pyrimidines bind in a same cavity composed of four nucleobases including U22, U47, U51 and U74, which is consistent with the experimental results, while the two imidazole derivatives adopt other binding modes; (2) the purines are engulfed within three-way junction motifs, but most pyrimidines only form two-way junctions with the riboswitch; (3) the number and position of amino substituents could seriously affect the binding of pyrimidines. As riboswitches are potentially excellent candidates for antibiotic therapeutics, these findings may be useful for understanding the range of compounds that riboswitch can specifically recognize.
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28
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Kovarik Z, Čalić M, Šinko G, Bosak A, Berend S, Vrdoljak AL, Radić B. Oximes: Reactivators of phosphorylated acetylcholinesterase and antidotes in therapy against tabun poisoning. Chem Biol Interact 2008; 175:173-9. [DOI: 10.1016/j.cbi.2008.04.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 04/07/2008] [Accepted: 04/10/2008] [Indexed: 11/26/2022]
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29
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Musilek K, Kucera J, Jun D, Dohnal V, Opletalova V, Kuca K. Monoquaternary pyridinium salts with modified side chain-synthesis and evaluation on model of tabun- and paraoxon-inhibited acetylcholinesterase. Bioorg Med Chem 2008; 16:8218-23. [PMID: 18676153 DOI: 10.1016/j.bmc.2008.07.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 07/08/2008] [Accepted: 07/16/2008] [Indexed: 10/21/2022]
Abstract
Acetylcholinesterase reactivators are crucial antidotes for the treatment of organophosphate intoxication. Eighteen monoquaternary reactivators of acetylcholinesterase with modified side chain were developed in an effort to extend the properties of pralidoxime. The known reactivators (pralidoxime, HI-6, obidoxime, trimedoxime, methoxime) and the prepared compounds were tested in vitro on a model of tabun- and paraoxon-inhibited AChE. Monoquaternary reactivators were not able to exceed the best known compounds for tabun poisoning, but some of them did show reactivation better or comparable with pralidoxime for paraoxon poisoning. However, extensive differences were found by a SAR study for various side chains on the non-oxime part of the reactivator molecule.
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Affiliation(s)
- Kamil Musilek
- Department of Toxicology, Faculty of Military Health Sciences, Trebesska 1575, 500 01 Hradec Kralove, Czech Republic.
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30
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Musilek K, Jampilek J, Dohnal J, Jun D, Gunn-Moore F, Dolezal M, Kuca K. RP-HPLC determination of the lipophilicity of bispyridinium reactivators of acetylcholinesterase bearing a but-2-ene connecting linker. Anal Bioanal Chem 2008; 391:367-72. [DOI: 10.1007/s00216-008-2018-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Revised: 02/12/2008] [Accepted: 02/21/2008] [Indexed: 11/29/2022]
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31
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Musilek K, Holas O, Jun D, Dohnal V, Gunn-Moore F, Opletalova V, Dolezal M, Kuca K. Monooxime reactivators of acetylcholinesterase with (E)-but-2-ene linker—Preparation and reactivation of tabun- and paraoxon-inhibited acetylcholinesterase. Bioorg Med Chem 2007; 15:6733-41. [PMID: 17764957 DOI: 10.1016/j.bmc.2007.08.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 07/27/2007] [Accepted: 08/03/2007] [Indexed: 11/19/2022]
Abstract
Acetylcholinesterase reactivators are crucial antidotes for the treatment of organophosphate intoxication. Fifteen new monooxime reactivators of acetylcholinesterase with a (E)-but-2-ene linker were developed in an effort to extend the properties of K-oxime (E)-1-(4-carbamoylpyridinium)-4-(4-hydroxyiminomethylpyridinium)-but-2-ene dibromide (K203). The known reactivators (pralidoxime, HI-6, obidoxime, K075, K203) and the new compounds were tested in vitro on a model of tabun- and paraoxon-inhibited AChE. Monooxime reactivators were not able to exceed the best known compounds for tabun poisoning, but some of them did show reactivation comparable with known compounds for paraoxon poisoning. However, extensive differences were found by a SAR study for various substitutions on the non-oxime part of the reactivator molecule.
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Affiliation(s)
- Kamil Musilek
- Department of Pharmaceutical Chemistry and Drug Control, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 500 05, Hradec Kralove, Czech Republic
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Reiner E, Radić Z, Simeon-Rudolf V. Mechanisms of Organophosphate Toxicity and Detoxication with Emphasis on Studies in Croatia. Arh Hig Rada Toksikol 2007; 58:329-38. [PMID: 17913688 DOI: 10.2478/v10004-007-0026-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mechanisms of Organophosphate Toxicity and Detoxication with Emphasis on Studies in CroatiaThis review comprises studies on the mechanisms of toxicity and detoxication of organophosphorus (OP) compounds done in Croatia in different research areas. One area is the synthesis of antidotes against OP poisoning and their in vivo testing in experimental animals. In vitro studies included in this review focus on the mechanisms of reversible inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), protection of cholinesterases from inhibition by OPs, and reactivation of phosphylated cholinesterases. The third area comprises distribution profiles of BChE and paraoxonase (PON) phenotypes in selected population groups and the detection of OPs and metabolites in humans. Finally, methods are described for the detection of OP compounds in human blood and other media by means of cholinesterase inhibition.
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Affiliation(s)
- Elsa Reiner
- Institute for Medical Research and Occupational Health, Zagreb, Croatia.
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Targeted synthesis of 1-(4-hydroxyiminomethylpyridinium)-3-pyridiniumpropane dibromide--a new nerve agent reactivator. Molecules 2007; 12:1964-72. [PMID: 17960099 DOI: 10.3390/12081964] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 08/14/2007] [Accepted: 08/14/2007] [Indexed: 11/17/2022] Open
Abstract
Preparation of 1-(4-hydroxy-iminomethylpyridinium)-3-pyridiniumpropane dibromide is described. This compound represents a new acetylcholinesterase (AChE) reactivator, which has no substituents on the second pyridinium ring as found in other commonly used AChE reactivators. The reactivation ability of this reactivator was tested on tabun- and cyclosarin-inhibited AChE. According to the results obtained, the new compound (without substitution and with decreased molecule size) showed increased reactivation potency in case of cyclosarin inhibited AChE. A potent oxime for treatment of tabun and cyclosarin-caused intoxications was thus obtained via slight modification of the reactivator structure (compared to trimedoxime and K027).
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Sinko G, Calić M, Bosak A, Kovarik Z. Limitation of the Ellman method: cholinesterase activity measurement in the presence of oximes. Anal Biochem 2007; 370:223-7. [PMID: 17716616 DOI: 10.1016/j.ab.2007.07.023] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Revised: 06/14/2007] [Accepted: 07/16/2007] [Indexed: 11/28/2022]
Abstract
The Ellman method for assaying thiols is widely used for cholinesterase activity measurement. Cholinesterase activity is measured indirectly by quantifying the concentration of 5-thio-2-nitrobenzoic acid (TNB) ion formed in the reaction between the thiol reagent 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) and thiocholine, a product of substrate (i.e., acetylthiocholine [ATCh]) hydrolysis by the cholinesterase. Oximes, reactivators of inhibited cholinesterase, are nucleophiles that also react with ATCh (oximolysis), producing thiocholine and (indirectly) TNB ion. The aim of this study was to characterize ATCh oximolysis. Therefore, we measured the oximolysis between oximes (K027 and HI-6) and ATCh in the presence of DTNB at different pH values, taking into account the final concentration of a product that is thiocholine. To confirm oximate ion involvement in the nucleophilic attack, we also determined the reaction rate between the oximes and ATCh, without DTNB, at different pH values by measuring the decrease in oximate ion absorption over time. The oximate ion of K027 reacted 14 times faster with ATCh (306M(-1)min(-1)) than the oximate ion of HI-6 (22M(-1)min(-1)). However, the rate constants obtained with the Ellman method were 84M(-1)min(-1) for K027 and 22M(-1)min(-1) for HI-6. Our results confirmed that the rate obtained with K027 using the Ellman method is actually the rate of the Ellman reaction itself. This suggests that the Ellman method cannot be used uncritically to evaluate oxime reaction with choline esters, in particular when oximolysis is faster than the Ellman reaction itself at a given pH.
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Affiliation(s)
- Goran Sinko
- Institute for Medical Research and Occupational Health, HR-10001 Zagreb, Croatia.
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35
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Kovarik Z, Calić M, Sinko G, Bosak A. Structure-Activity Approach in the Reactivation of Tabun-Phosphorylated Human Acetylcholinesterase with Bispyridinium para-Aldoximes. Arh Hig Rada Toksikol 2007; 58:201-9. [PMID: 17562604 DOI: 10.2478/v10004-007-0013-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Structure-Activity Approach in the Reactivation of Tabun-Phosphorylated Human Acetylcholinesterase with Bispyridinium para-AldoximesWe investigated interactions of bispyridinium para-aldoximes N,N'-(propano)bis(4-hydroxyiminomethyl) pyridinium bromide (TMB-4), N,N'-(ethano)bis(4-hydroxyiminomethyl)pyridinium methanosulphonate (DMB-4), and N,N'-(methano)bis(4-hydroxyiminomethyl)pyridinium chloride (MMB-4) with human erythrocyte acetylcholinesterase phosphorylated by tabun. We analysed aldoxime conformations to determine the flexibility of aldoxime as an important feature for binding to the acetylcholinesterase active site. Tabun-inhibited human erythrocyte acetylcholinesterase was completely reactivated only by the most flexible bispyridinium aldoxime - TMB-4 with a propylene chain between two rings. Shorter linkers than propylene (methylene or ethylene) as in MMB-4 and DMB-4 did not allow appropriate orientation in the active site, and MMB-4 and DMB-4 were not efficient reactivators of tabun-phosphorylated acetylcholinesterase. Since aldoximes are also reversible inhibitors of native acetylcholinesterase, we determined dissociation constants and their protective index against acetylcholinesterase inactivation by tabun.
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Affiliation(s)
- Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia.
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