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Wong PT, Bhattacharjee S, Cannon J, Tang S, Yang K, Bowden S, Varnau V, O'Konek JJ, Choi SK. Reactivity and mechanism of α-nucleophile scaffolds as catalytic organophosphate scavengers. Org Biomol Chem 2019; 17:3951-3963. [PMID: 30942252 DOI: 10.1039/c9ob00503j] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Despite their unique benefits imparted by their structure and reactivity, certain α-nucleophile molecules remain underexplored as chemical inactivators for the topical decontamination of reactive organophosphates (OPs). Here, we present a library of thirty α-nucleophile scaffolds, each designed with either a pyridinium aldoxime (PAM) or hydroxamic acid (HA) α-nucleophile core tethered to a polar or charged scaffold for optimized physicochemical properties and reactivity. These library compounds were screened for their abilities to catalyze the hydrolysis of a model OP, paraoxon (POX), in kinetic assays. These screening experiments led to the identification of multiple lead compounds with the ability to inactivate POX two- to four-times more rapidly than Dekon 139-the active ingredient currently used for skin decontamination of OPs. Our mechanistic studies, performed under variable pH and temperature conditions suggested that the differences in the reactivity and activation energy of these compounds are fundamentally attributable to the core nucleophilicity and pKa. Following their screening and mechanistic studies, select lead compounds were further evaluated and demonstrated greater efficacy than Dekon 139 in the topical decontamination of POX in an ex vivo porcine skin model. In addition to OP reactivity, several compounds in the PAM class displayed a dual mode of activity, as they retained the ability to reactivate POX-inhibited acetylcholine esterase (AChE). In summary, this report describes a rationale for the hydrophilic scaffold design of α-nucleophiles, and it offers advanced insights into their chemical reactivity, mechanism, and practical utility as OP decontaminants.
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Affiliation(s)
- Pamela T Wong
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
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2
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Bharate SB, Chao CK, Thompson CM. Comparison of the reactivation rates of acetylcholinesterase modified by structurally different organophosphates using novel pyridinium oximes. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2019; 71:103218. [PMID: 31302432 PMCID: PMC6736693 DOI: 10.1016/j.etap.2019.103218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 03/27/2019] [Accepted: 06/24/2019] [Indexed: 06/10/2023]
Abstract
A novel panel of oximes were synthesized, which have displayed varying degree of reactivation ability towards different organophosphorus (OP) modified cholinesterases. In the present article, we report a comparative reactivation profile of a series of quaternary pyridinium-oximes for electric eel acetylcholinesterase (EEAChE) inhibited by the organophosphorus (OP) inhibitors methyl paraoxon (MePOX), ethyl paraoxon (POX; paraoxon) and diisopropyl fluorophosphate (DFP) that are distinguishable as dimethoxyphosphoryl, diethoxyphosphoryl and diisopropoxyphosphoryl AChE-OP-adducts. Most of the 59-oximes tested led to faster and more extensive reactivation of MePOX- and POX-inhibited EEAChE as compared to DFP-modified EEAChE. All were effective reactivators of three OP-modified EEAChE conjugates showing 18-21% reactivation for DFP-inhibited AChE and ≥45% reactivation for MePOX- and POX-inhibited EEAChE. Oximes 7 and 8 showed kr values better than pralidoxime (1) for DFP-inhibited EEAChE. Reactivation rates determined at different inhibition times showed no significant change in kr values during 0-90 min incubation with three OPs. However, a 34-72% decrease in kr for MePOX and POX and > 95% decrease in kr for DFP-inhibited EEAChE was observed after 24 h of OP-exposure (aging).
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Affiliation(s)
- Sandip B Bharate
- The Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT, 59812, USA; Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India.
| | - Chih-Kai Chao
- The Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT, 59812, USA
| | - Charles M Thompson
- The Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT, 59812, USA.
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3
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Repsold BP, Malan SF, Joubert J, Oliver DW. Multi-targeted directed ligands for Alzheimer's disease: design of novel lead coumarin conjugates. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2018; 29:231-255. [PMID: 29390885 DOI: 10.1080/1062936x.2018.1423641] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/01/2018] [Indexed: 06/07/2023]
Abstract
Alzheimer's Disease (AD) is a neurodegenerative disease characterized by central nervous system insults with progressive cognitive (memory, attention) and non-cognitive (anxiety, depression) impairments. Pathophysiological events affect predominantly cholinergic neuronal loss and dysfunctions of the dopaminergic system. The aim of the current study was to design multi-targeted directed lead structures based on the coumarin scaffold with inhibitory properties at two key enzymes in disease relevant systems, i.e. acetylcholinesterase (AChE) and monoamine oxidase B (MAO-B). Conventional and microwave synthetic methods were utilized to synthesize coumarin scaffold-based novel morpholino, piperidino, thiophene and erucic acid conjugates. Biological assays indicated that the coumarin-morpholine ether conjugate BPR 10 was the most potent hMAO-B inhibitor. The coumarin-piperidine conjugates BPR 13 and BPR 12 were the most potent inhibitors of eeAChE at 100 μM and 1 μM, respectively. Molecular modelling studies were conducted with Accelrys® Discovery Studio® V3.1.1 utilising the published hMAO-B (2V61) and hAChE (4EY7) crystal structures. Compound BPR 10 occupies both the entrance and substrate cavities of the active site of MAO-B. BPR 13 resides in both the peripheral anionic site (PAS) and the catalytic anionic site (CAS) of hAChE. This study demonstrated that the coumarin scaffold serves as a promising pharmacophore for MTDLs design.
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Affiliation(s)
- B P Repsold
- a Pharmaceutical Chemistry, School of Pharmacy , North-West University , Potchefstroom , South Africa
| | - S F Malan
- b Pharmaceutical Chemistry, School of Pharmacy , University of the Western Cape , Bellville , South Africa
| | - J Joubert
- b Pharmaceutical Chemistry, School of Pharmacy , University of the Western Cape , Bellville , South Africa
| | - D W Oliver
- a Pharmaceutical Chemistry, School of Pharmacy , North-West University , Potchefstroom , South Africa
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Hosseini SA, Moghimi A, Iman M, Ebrahimi F. Docking Studies, Synthesis, and In-vitro Evaluation of Novel Oximes Based on Nitrones as Reactivators of Inhibited Acetylcholinesterase. IRANIAN JOURNAL OF PHARMACEUTICAL RESEARCH : IJPR 2017; 16:880-892. [PMID: 29201079 PMCID: PMC5610744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Acetylcholinesterase has important role in synaptic cleft. It breaks down the acetylcholineat cholinergic synapsesand terminates the cholinergic effects. Some chemical agents like organophosphorus compounds (OPCs) including nerve agents and pesticides react with acetylcholinesteraseirreversibly. They inhibit normal biological enzyme action and result in accumulation of acetylcholineand show toxic effects andcholinergic symptoms. The process of Acetylcholinesterase (AChE) inhibition can be reversed by a nucleophilic agent to dephosphorylate and reactivate the enzyme. In this study, design and docking studies of 15 novel nitrone based onoximes as reactivators were performed by using AutoDock program. Then, more effective reactivatorsoximes in terms of binding energy and orientation within the active site were synthesized and evaluated in-vitro on human AChE (hAChE) inhibited by paraoxon and compared to standard hAChE reactivators (2-PAM and obidoxime). Our results used to design new derivatives of Oxim with better efficacy than 2-PAM and obidoxime. Syntheses of some selected bis-pyridiniumoximes based on the nitrones are underway.
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Affiliation(s)
- Seyed Ayoub Hosseini
- Department of Chemistry, Faculty of Science, Imam Hossein University, Tehran, Iran.
| | - Abolghasem Moghimi
- Department of Chemistry, Faculty of Science, Imam Hossein University, Tehran, Iran.
| | - Maryam Iman
- Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
- Department of Pharmaceutics, Faculty of pharmacy, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | - Firoz Ebrahimi
- Department of Biology, Faculty of Science, Imam Hossein University, Tehran, Iran.
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5
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Chao CK, Ahmed SK, Gerdes JM, Thompson CM. Novel Organophosphate Ligand O-(2-Fluoroethyl)-O-(p-Nitrophenyl)Methylphosphonate: Synthesis, Hydrolytic Stability and Analysis of the Inhibition and Reactivation of Cholinesterases. Chem Res Toxicol 2016; 29:1810-1817. [PMID: 27551891 PMCID: PMC5575788 DOI: 10.1021/acs.chemrestox.6b00160] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The organophosphate O-(2-fluoroethyl)-O-(p-nitrophenyl) methyphosphonate 1 is the first-in-class, fluorine-18 radiolabeled organophosphate inhibitor ([18F]1) of acetylcholinesterase (AChE). In rats, [18F]1 localizes in AChE rich regions of the brain and other tissues where it likely exists as the (CH3)(18FCH2CH2O)P(O)-AChE adduct (ChE-1). Characterization of this adduct would define the inhibition mechanism and subsequent postinhibitory pathways and reactivation rates. To validate this adduct, the stability (hydrolysis) of 1 and ChE-1 reactivation rates were determined. Base hydrolysis of 1 yields p-nitrophenol and (CH3) (FCH2CH2O)P(O)OH with pseudo first order rate constants (kobsd) at pH 7.4 (PBS) of 3.25 × 10-4 min-1 (t1/2 = 35.5 h) at 25 °C and 8.70 × 10-4 min-1 (t1/2 = 13.3 h) at 37 °C. Compound 1 was a potent inhibitor of human acetylcholinesterase (HuAChE; ki = 7.5 × 105 M-1 min-1), electric eel acetylcholinesterase (EEAChE) (ki = 3.0 × 106 M-1 min-1), and human serum butyrylcholinesterase (HuBChE; 1.95 × 105 M-1 min-1). Spontaneous and oxime-mediated reactivation rates for the (CH3) (FCH2CH2O)P(O)-serine ChE adducts using 2-PAM (10 μM) were (a) HuAChE 8.8 × 10-5 min-1 (t1/2 = 131.2 h) and 2.41 × 10-2 min-1 (t1/2 = 0.48 h), (b) EEAChE 9.32 × 10-3 min-1 (t1/2 = 1.24 h) and 3.33 × 10-2 min-1 (t1/2 = 0.35 h), and (c) HuBChE 1.16 × 10-4 min-1 (t1/2 = 99.6 h) and 4.19 × 10-2 min-1 (t1/2 = 0.27 h). All ChE-1 adducts undergo rapid and near complete restoration of enzyme activity following addition of 2-PAM (30 min), and no aging was observed for either reactivation process. The fast reactivation rates and absence of aging of ChE-1 adducts are explained on the basis of the electron-withdrawing fluorine group that favors the nucleophilic reactivation processes but disfavors cation-based dealkylation aging mechanisms. Therefore, the likely fate of radiolabeled compound 1 in vivo is the formation of (CH3)(FCH2CH2O)P(O)-serine adducts and monoacid (CH3)(FCH2CH2O)P(O)OH from hydrolysis and reactivation.
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Affiliation(s)
- Chih-Kai Chao
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana 59812, United States
| | - S. Kaleem Ahmed
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana 59812, United States
- Center for Neuromolecular Research, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama 35205, United States
| | - John M. Gerdes
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana 59812, United States
- Center for Neuromolecular Research, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama 35205, United States
| | - Charles M. Thompson
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana 59812, United States
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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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7
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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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8
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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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9
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Pooja P, Aggarwal S, Tiwari AK, Kumar V, Pratap R, Singh G, Mishra AK. Novel pyridinium oximes: synthesis, molecular docking and in vitro reactivation studies. RSC Adv 2015. [DOI: 10.1039/c4ra14696d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A computational approach has been attempted for the screening of 4-pyridoxinium (4P) ring based reactivators for paraoxon inhibited AChE.
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Affiliation(s)
- Pooja Pooja
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
- Department of Chemistry
| | - S. Aggarwal
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
- Department of Chemistry
| | - A. K. Tiwari
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
| | - V. Kumar
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
| | - R. Pratap
- Department of Chemistry
- University of Delhi
- Delhi-110054
- India
| | - G. Singh
- Department of Chemistry
- University of Delhi
- Delhi-110054
- India
| | - A. K. Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Delhi-110054
- India
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10
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Karade HN, Valiveti AK, Acharya J, Kaushik MP. Synthesis and in vitro evaluation of bis-quaternary 2-(hydroxyimino)-N-(pyridin-3-yl)acetamide derivatives as reactivators against sarin and VX inhibited human acetylcholinesterase (hAChE). Bioorg Med Chem 2014; 22:2684-91. [DOI: 10.1016/j.bmc.2014.03.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 03/13/2014] [Accepted: 03/14/2014] [Indexed: 10/25/2022]
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11
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da Cunha Xavier Soares SF, Vieira AA, Delfino RT, Figueroa-Villar JD. NMR determination of Electrophorus electricus acetylcholinesterase inhibition and reactivation by neutral oximes. Bioorg Med Chem 2013; 21:5923-30. [DOI: 10.1016/j.bmc.2013.05.063] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/21/2013] [Accepted: 05/29/2013] [Indexed: 12/20/2022]
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12
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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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13
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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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14
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Bharate SB, Thompson CM. Antimicrobial, antimalarial, and antileishmanial activities of mono- and bis-quaternary pyridinium compounds. Chem Biol Drug Des 2010; 76:546-51. [PMID: 21040494 DOI: 10.1111/j.1747-0285.2010.01035.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pyridinium-based oxime compounds have been utilized worldwide as antidotes following exposure to anticholinesterase agents. In the event of combined chemical and biological incident, it is of vital importance to know the ability of antidotes to provide additional protection against biological threats. This paper reports results of in vitro antimicrobial and antiprotozoal activities of a series of quaternary pyridinium oximes against a number of lower pathogenicity BSL-1 and 2 agents. In general, our compound panel had little to no antimicrobial action except for thiophene- and benzothiophene-substituted monoquaternary pyridinium compounds 21 and 24 that showed moderate antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus with IC(50) values ranging from 12.2 to 17.7 μg/mL. Compounds 21 and 24 also exhibited antileishmanial activity against Leishmania donovani with IC(50) values of 19 and 18 μg/mL, respectively. Another monoquaternary pyridinium compound with a bromobutyl side chain 17 showed antimalarial activity against both a chloroquine sensitive and resistant strains of Plasmodium falciparum with IC(50) values of 3.7 and 4.0 μg/mL, respectively. None of the bisquaternary pyridinium compounds showed antimicrobial or antiprotozoal activity. None of the compounds showed cytotoxic effects toward mammalian kidney fibroblasts. Results of this study indicate that the pyridinium compounds, some of which are already in use as antidotes, do not have significant antimicrobial and antiprotozoal activities and cannot be relied upon for additional protection in the event of combined chemical-biological incident.
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Affiliation(s)
- Sandip B Bharate
- NIH COBRE Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
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15
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Bharate SB, Guo L, Reeves TE, Cerasoli DM, Thompson CM. Bisquaternary pyridinium oximes: Comparison of in vitro reactivation potency of compounds bearing aliphatic linkers and heteroaromatic linkers for paraoxon-inhibited electric eel and recombinant human acetylcholinesterase. Bioorg Med Chem 2010; 18:787-94. [PMID: 20005727 PMCID: PMC2818686 DOI: 10.1016/j.bmc.2009.11.052] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2009] [Revised: 11/18/2009] [Accepted: 11/21/2009] [Indexed: 11/26/2022]
Abstract
Oxime reactivators are the drugs of choice for the post-treatment of OP (organophosphorus) intoxication and used widely for mechanistic and kinetic studies of OP-inhibited cholinesterases. The purpose of the present study was to evaluate new oxime compounds to reactivate acetylcholinesterase (AChE) inhibited by the OP paraoxon. Several new bisquaternary pyridinium oximes with heterocyclic linkers along with some known bisquaternary pyridinium oximes bearing aliphatic linkers were synthesized and evaluated for their in vitro reactivation potency against paraoxon-inhibited electric eel acetylcholinesterase (EeAChE) and recombinant human acetylcholinesterase (rHuAChE). Results herein indicate that most of the compounds are better reactivators of EeAChE than of rHuAChE. The reactivation potency of two different classes of compounds with varying linker chains was compared and observed that the structure of the connecting chain is an important factor for the activity of the reactivators. At a higher concentration (10(-3)M), compounds bearing aliphatic linker showed better reactivation than compounds with heterocyclic linkers. Interestingly, oximes with a heterocyclic linker inhibited AChE at higher concentration (10(-3)M), whereas their ability to reactivate was increased at lower concentrations (10(-4)M and 10(-5)M). Compounds bearing either a thiophene linker 26, 46 or a furan linker 31 showed 59%, 49% and 52% reactivation of EeAChE, respectively, at 10(-5)M. These compounds showed 14%, 6% and 15% reactivation of rHuAChE at 10(-4)M. Amongst newly synthesized analogs with heterocyclic linkers (26-35 and 45-46), compound 31, bearing furan linker chain, was found to be the most effective reactivator with a k(r) 0.042min(-1), which is better than obidoxime (3) for paraoxon-inhibited EeAChE. Compound 31 showed a k(r) 0.0041min(-1) that is near equal to pralidoxime (1) for paraoxon-inhibited rHuAChE.
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Affiliation(s)
- Sandip B. Bharate
- NIH COBRE Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Lilu Guo
- ATERIS Technologies LLC, 901 N Orange Street, Missoula, MT 59802, USA
| | - Tony E. Reeves
- USAMRICD, Research Division, Physiology and Immunology Branch, 3100 Ricketts Point Road, APG, MD 21010, USA
| | - Douglas M. Cerasoli
- USAMRICD, Research Division, Physiology and Immunology Branch, 3100 Ricketts Point Road, APG, MD 21010, USA
| | - Charles M. Thompson
- NIH COBRE Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
- ATERIS Technologies LLC, 901 N Orange Street, Missoula, MT 59802, USA
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16
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Novel bisquaternary oximes--reactivation of acetylcholinesterase and butyrylcholinesterase inhibited by paraoxon. Molecules 2009; 14:4915-21. [PMID: 20032868 PMCID: PMC6255039 DOI: 10.3390/molecules14124915] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 11/24/2009] [Accepted: 11/27/2009] [Indexed: 11/17/2022] Open
Abstract
Four novel bisquaternary aldoxime cholinesterase reactivators differing in their chemical structure were prepared. Afterwards, their biological activity was evaluated for their ability to reactivate acetylcholinesterase (AChE; EC 3.1.1.7) and butyrylcholinesterase (BuChE; EC 3.1.1.8) inhibited by paraoxon. Their reactivation activity was compared with standard reactivators--pralidoxime, obidoxime and HI-6--which are clinically used at present. As it resulted, none of the prepared compounds surpassed obidoxime, which is considered to be the most potent compound if used for reactivation of AChE inhibited by paraoxon. In case of BuChE reactivation, two compounds (K053 and K068) achieved similar results as obidoxime.
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