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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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Rosenberg YJ, Garcia K, Diener J, Sullivan D, Donahue S, Mao L, Lees J, Jiang X, Urban LA, Momper JD, Ho KY, Taylor P. A single post-exposure oxime RS194B treatment rapidly reactivates acetylcholinesterase and reverses acute symptoms in macaques exposed to diethylphosphorothioate parathion and chlorpyrifos insecticides. J Neurochem 2024; 168:370-380. [PMID: 36786545 DOI: 10.1111/jnc.15777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/20/2023] [Accepted: 01/28/2023] [Indexed: 02/15/2023]
Abstract
Millions of individuals globally suffer from inadvertent, occupational or self-harm exposures from organophosphate (OP) insecticides, significantly impacting human health. Similar to nerve agents, insecticides are neurotoxins that target and inhibit acetylcholinesterase (AChE) in central and peripheral synapses in the cholinergic nervous system. Post-exposure therapeutic countermeasures generally include administration of atropine with an oxime to reactivate the OP-inhibited AChE. However, animal model studies and recent clinical trials using insecticide-poisoned individuals have shown minimal clinical benefits of the currently approved oximes and their efficacy as antidotes has been debated. Currently used oximes either reactivate poorly, do not readily cross the blood-brain barrier (BBB), or are rapidly cleared from the circulation and must be repeatedly administered. Zwitterionic oximes of unbranched and simplified structure, for example RS194B, have been developed that efficiently cross the BBB resulting in reactivation of OP-inhibited AChE and dramatic reversal of severe clinical symptoms in mice and macaques exposed to OP insecticides or nerve agents. Thus, a single IM injection of RS194B has been shown to rapidly restore blood AChE and butyrylcholinesterase (BChE) activity, reverse cholinergic symptoms, and prevent death in macaques following lethal inhaled sarin and paraoxon exposure. The present macaque studies extend these findings and assess the ability of post-exposure RS194B treatment to counteract oral poisoning by highly toxic diethylphosphorothioate insecticides such as parathion and chlorpyrifos. These OPs require conversion by P450 in the liver of the inactive thions to the active toxic oxon forms, and once again demonstrated RS194B efficacy to reactivate and alleviate clinical symptoms within 60 mins of a single IM administration. Furthermore, when delivered orally, the Tmax of RS194B at 1-2 h was in the same range as those administered IM but were maintained in the circulation for longer periods greatly facilitating the use of RS194B as a non-invasive treatment, especially in isolated rural settings.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Jeremiah D Momper
- Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
| | - Kwok-Yiu Ho
- Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
| | - Palmer Taylor
- Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
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3
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Thakur A, Patwa J, Pant S, Jeet Singh Flora S, Sharma A. Synthesis and evaluation of small organic molecule as reactivator of organophosphorus inhibited acetylcholinesterase. Drug Chem Toxicol 2024; 47:26-41. [PMID: 36514993 DOI: 10.1080/01480545.2022.2150210] [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: 08/07/2022] [Revised: 11/08/2022] [Accepted: 11/16/2022] [Indexed: 12/15/2022]
Abstract
A series of uncharged salicylaldehyde oximes were synthesized and evaluated for the reactivation of organophosphorus (OP) nerve agents simulants Diethylchlorophosphonate (DCP) & Diethylcyanophosphonate (DCNP) and pesticides (paraoxon & malaoxon) inhibited electric eel Acetylcholinesterase (AChE). The computational software Swiss ADME and molinspiration were used to unfold the probability of drug-likeness properties of the oximes derivatives. Substituted aromatic oximes with diethylamino or bromo group with free hydroxyl group ortho to oxime moiety were found efficient to regenerate the enzymatic activity in in-vitro AChE assay. The alkylation of the ortho hydroxyl group of derivatives led to the loss of reactivation potential. The derivatives with a hydroxyl group and without oxime group and vice versa did not show significant reactivation potency against tested OP toxicants. Further, we also evaluated the reactivation potential of these selected molecules on the rat brain homogenate against different OPs inhibited ChE and found maximum reactivation potency of oxime 2e. The in-vitro results were further validated by molecular docking and dynamic studies which showed that the hydroxyl group interacted with serine amino acids in the catalytic anionic site of AChE enzyme and was stable up to 200 ns consequently providing proper orientation to oxime moiety for reactivating the OP inhibited enzyme. It has thus been proved by the structure-activity relationship of oximes derivatives that hydroxyl group ortho to oxime is essential for reactivating OP inhibited electric eel AChE. Amongst the twenty-one oximes derivatives, 2e was found to be most active in regenerating the paraoxon, malaoxon, DCP and DCNP inhibited AChE enzyme.
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Affiliation(s)
- Ashima Thakur
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - Jayant Patwa
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - Suyash Pant
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Kolkata, India
| | - Swaran Jeet Singh Flora
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - Abha Sharma
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Raebareli, India
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4
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Nomura K, Narimatsu E, Oke Y, Oku Y. The lesion site of organophosphorus-induced central apnea and the effects of antidotes. Sci Rep 2023; 13:20419. [PMID: 37990100 PMCID: PMC10663552 DOI: 10.1038/s41598-023-47745-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 11/17/2023] [Indexed: 11/23/2023] Open
Abstract
Organophosphorus poisoning kills individuals by causing central apnea; however, the underlying cause of death remains unclear. Following findings that the pre-Bötzinger complex impairment alone does not account for central apnea, we analyzed the effect of paraoxon on the brainstem-spinal cord preparation, spanning the lower medulla oblongata to phrenic nucleus. Respiratory bursts were recorded by connecting electrodes to the ventral 4th cervical nerve root of excised brainstem-spinal cord preparations obtained from 6-day-old Sprague-Dawley rats. We observed changes in respiratory bursts when paraoxon, neostigmine, atropine, and 2-pyridine aldoxime methiodide were administered via bath application. The percentage of burst extinction in the paraoxon-poisoning group was 50% compared with 0% and 18.2% in the atropine and 2-pyridine aldoxime methiodide treatment groups, respectively. Both treatments notably mitigated the paraoxon-induced reduction in respiratory bursts. In the neostigmine group, similar to paraoxon, bursts stopped in 66.7% of cases but were fully reversed by atropine. This indicates that the primary cause of central apnea is muscarinic receptor-mediated in response to acetylcholine excess. Paraoxon-induced central apnea is hypothesized to result from neural abnormalities within the inferior medulla oblongata to the phrenic nucleus, excluding pre-Bötzinger complex. These antidotes antagonize central apnea, suggesting that they may be beneficial therapeutic agents.
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Affiliation(s)
- Kazuhito Nomura
- Department of Physiology, Hyogo Medical University, 1-1, Mukogawa-Cho, Nishinomiya-Shi, Hyogo-Ken, 663-8501, Japan.
- Department of Emergency Medicine, Sapporo Medical University, Sapporo-Shi, 064-8543, Japan.
| | - Eichi Narimatsu
- Department of Emergency Medicine, Sapporo Medical University, Sapporo-Shi, 064-8543, Japan
| | - Yoshihiko Oke
- Department of Physiology, Hyogo Medical University, 1-1, Mukogawa-Cho, Nishinomiya-Shi, Hyogo-Ken, 663-8501, Japan
| | - Yoshitaka Oku
- Department of Physiology, Hyogo Medical University, 1-1, Mukogawa-Cho, Nishinomiya-Shi, Hyogo-Ken, 663-8501, Japan
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5
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Kapitanov IV, Špulák M, Pour M, Soukup O, Marek J, Jun D, Novak M, Diz de Almeida JSF, França TCC, Gathergood N, Kuča K, Karpichev Y. Sustainable ionic liquids-based molecular platforms for designing acetylcholinesterase reactivators. Chem Biol Interact 2023; 385:110735. [PMID: 37802409 DOI: 10.1016/j.cbi.2023.110735] [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: 07/19/2023] [Revised: 09/09/2023] [Accepted: 09/25/2023] [Indexed: 10/10/2023]
Abstract
We report a green chemistry approach for preparation of oxime-functionalized ILs as AChE reactivators: amide/ester linked IL, l-alanine, and l-phenylalanine derived salts bearing pyridinium aldoxime moiety. The reactivation capacities of the novel oximes were evaluated towards AChE inhibited by typical toxic organophosphates, sarin (GB), VX, and paraoxon (PON). The studied compounds are mostly non-toxic up to the highest concentrations screened (2 mM) towards Gram-negative and Gram-positive bacteria cell lines and both filamentous fungi and yeasts in the in vitro screening experiments as well as towards the eukaryotic cell (CHO-K1 cell line). Introduction of the oxime moiety in initially biodegradable structure decreases its ability to biodegradation. The compound 3d was shown to reveal remarkable activity against the AChE inhibited by VX, exceeding conventional reactivators 2-PAM and obidoxime. The regularities on antidotal activity, cell viability, plasma stability, biodegradability as well as molecular docking study of the newly synthesized oximes will be used for further improvement of their structures.
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Affiliation(s)
- Illia V Kapitanov
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia Tee 15, 12618 Tallinn, Estonia
| | - Marcel Špulák
- Department of Organic and Bioorganic Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 500 05 Hradec Kralove, Czech Republic
| | - Milan Pour
- Department of Organic and Bioorganic Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 500 05 Hradec Kralove, Czech Republic
| | - Ondřej Soukup
- Biomedical Research Center, University Hospital Hradec Kralove, Sokolska 581, 500 05 Hradec Kralove, Czech Republic; Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defense, Trebesska 1575, 500 01 Hradec Kralove, Czech Republic
| | - Jan Marek
- Biomedical Research Center, University Hospital Hradec Kralove, Sokolska 581, 500 05 Hradec Kralove, Czech Republic; Department of Epidemiology, Faculty of Military Health Sciences, University of Defense, Trebesska 1575, 500 01 Hradec Kralove, Czech Republic
| | - Daniel Jun
- Department of Epidemiology, Faculty of Military Health Sciences, University of Defense, Trebesska 1575, 500 01 Hradec Kralove, Czech Republic
| | - Martin Novak
- Biomedical Research Center, University Hospital Hradec Kralove, Sokolska 581, 500 05 Hradec Kralove, Czech Republic
| | - Joyce S F Diz de Almeida
- Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense (LMCBD), Military Institute of Engineering, Rio de Janeiro, RJ, Brazil
| | - Tanos C C França
- Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense (LMCBD), Military Institute of Engineering, Rio de Janeiro, RJ, Brazil; Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanskeho 62, 500 03 Hradec Kralove, Czech Republic
| | - Nicholas Gathergood
- School of Chemistry, College of Science, University of Lincoln, Lincoln LN6 7TS, UK
| | - Kamil Kuča
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanskeho 62, 500 03 Hradec Kralove, Czech Republic.
| | - Yevgen Karpichev
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia Tee 15, 12618 Tallinn, Estonia.
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6
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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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7
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Countermeasures in organophosphorus intoxication: pitfalls and prospects. Trends Pharmacol Sci 2022; 43:593-606. [DOI: 10.1016/j.tips.2022.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/14/2022] [Accepted: 04/17/2022] [Indexed: 11/24/2022]
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8
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Cannon J, Tang S, Yang K, Harrison R, Choi SK. Dual acting oximes designed for therapeutic decontamination of reactive organophosphates via catalytic inactivation and acetylcholinesterase reactivation. RSC Med Chem 2021; 12:1592-1603. [PMID: 34671741 DOI: 10.1039/d1md00194a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 08/04/2021] [Indexed: 01/24/2023] Open
Abstract
A conventional approach in the therapeutic decontamination of reactive organophosphate (OP) relies on chemical OP degradation by oxime compounds. However, their efficacy is limited due to their lack of activity in the reactivation of acetylcholinesterase (AChE), the primary target of OP. Here, we describe a set of α-nucleophile oxime derivatives which are newly identified for such dual modes of action. Thus, we prepared a 9-member oxime library, each composed of an OP-reactive oxime core linked to an amine-terminated scaffold, which varied through an N-alkyl functionalization. This library was screened by enzyme assays performed with human and electric eel subtypes of OP-inactivated AChE, which led to identifying three oxime leads that displayed significant enhancements in reactivation activity comparable to 2-PAM. They were able to reactivate both enzymes inactivated by three OP types including paraoxon, chlorpyrifos and malaoxon, suggesting their broad spectrum of OP susceptibility. All compounds in the library were able to retain catalytic reactivity in paraoxon inactivation by rates increased up to 5 or 8-fold relative to diacetylmonoxime (DAM) under controlled conditions at pH (8.0, 10.5) and temperature (17, 37 °C). Finally, selected lead compounds displayed superb efficacy in paraoxon decontamination on porcine skin in vitro. In summary, we addressed an unmet need in therapeutic OP decontamination by designing and validating a series of congeneric oximes that display dual modes of action.
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Affiliation(s)
- Jayme Cannon
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School Ann Arbor Michigan 48109 USA .,Department of Internal Medicine, University of Michigan Medical School Ann Arbor Michigan 48109 USA
| | - Shengzhuang Tang
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School Ann Arbor Michigan 48109 USA .,Department of Internal Medicine, University of Michigan Medical School Ann Arbor Michigan 48109 USA
| | - Kelly Yang
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School Ann Arbor Michigan 48109 USA
| | - Racquel Harrison
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School Ann Arbor Michigan 48109 USA
| | - Seok Ki Choi
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School Ann Arbor Michigan 48109 USA .,Department of Internal Medicine, University of Michigan Medical School Ann Arbor Michigan 48109 USA
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9
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Choi SK. Nanomaterial-Enabled Sensors and Therapeutic Platforms for Reactive Organophosphates. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:224. [PMID: 33467113 PMCID: PMC7830340 DOI: 10.3390/nano11010224] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 12/29/2020] [Accepted: 01/14/2021] [Indexed: 01/15/2023]
Abstract
Unintended exposure to harmful reactive organophosphates (OP), which comprise a group of nerve agents and agricultural pesticides, continues to pose a serious threat to human health and ecosystems due to their toxicity and prolonged stability. This underscores an unmet need for developing technologies that will allow sensitive OP detection, rapid decontamination and effective treatment of OP intoxication. Here, this article aims to review the status and prospect of emerging nanotechnologies and multifunctional nanomaterials that have shown considerable potential in advancing detection methods and treatment modalities. It begins with a brief introduction to OP types and their biochemical basis of toxicity followed by nanomaterial applications in two topical areas of primary interest. One topic relates to nanomaterial-based sensors which are applicable for OP detection and quantitative analysis by electrochemical, fluorescent, luminescent and spectrophotometric methods. The other topic is directed on nanotherapeutic platforms developed as OP remedies, which comprise nanocarriers for antidote drug delivery and nanoscavengers for OP inactivation and decontamination. In summary, this article addresses OP-responsive nanomaterials, their design concepts and growing impact on advancing our capability in the development of OP sensors, decontaminants and therapies.
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Affiliation(s)
- Seok Ki Choi
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, USA;
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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10
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Hrvat NM, Kovarik Z. Counteracting poisoning with chemical warfare nerve agents. Arh Hig Rada Toksikol 2020; 71:266-284. [PMID: 33410774 PMCID: PMC7968514 DOI: 10.2478/aiht-2020-71-3459] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/01/2020] [Accepted: 11/01/2020] [Indexed: 12/14/2022] Open
Abstract
Phosphylation of the pivotal enzyme acetylcholinesterase (AChE) by nerve agents (NAs) leads to irreversible inhibition of the enzyme and accumulation of neurotransmitter acetylcholine, which induces cholinergic crisis, that is, overstimulation of muscarinic and nicotinic membrane receptors in the central and peripheral nervous system. In severe cases, subsequent desensitisation of the receptors results in hypoxia, vasodepression, and respiratory arrest, followed by death. Prompt action is therefore critical to improve the chances of victim's survival and recovery. Standard therapy of NA poisoning generally involves administration of anticholinergic atropine and an oxime reactivator of phosphylated AChE. Anticholinesterase compounds or NA bioscavengers can also be applied to preserve native AChE from inhibition. With this review of 70 years of research we aim to present current and potential approaches to counteracting NA poisoning.
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Affiliation(s)
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Zagreb, Croatia
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11
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Thakur A, Patil P, Sharma A, Flora S. Advances in the Development of Reactivators for the Treatment of Organophosphorus Inhibited Cholinesterase. CURR ORG CHEM 2020. [DOI: 10.2174/1385272824999201020203544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Organophosphorus Compounds (OPCs) are used as pesticides to control pest, as
chemical weapons in military conflict and unfortunately in the terrorist attack. These compounds
are irreversible inhibitors of acetylcholinesterase, resulting in the accumulation of
acetylcholine that leads to severe health complications which may be ended with the death of
the victim. Current antidotes used for reactivation of organophosphorus inhibited acetylcholinesterase
(OP-AChE) are not able to cross the blood-brain barrier efficiently, therefore being
incapable to reactivate OP-AChE of the central nervous system. Due to limitations with
current antidotes, there is an urgent need for new effective antidotes that could be included in
the treatment regimen of OP poisoning. In this direction, comprehensive work has been done
to improve the permeability of existing antidotes using a variety of strategies that include
synthesis of oxime bonded to peripheral site binding moiety via an alkyl, aryl, or heteroatom-containing linker, synthesis
of sugar oximes, and prodrug of 2-PAM, incorporating fluorine and chlorine in the structure of charged oximes.
Other classes of compounds such as the mannich base, N-substituted hydroxyimino acetamide, alkylating
agents, have been investigated for reactivation of OP-AChE. This review comprises the development of various
classes of reactivators with the aim of either enhancing blood-brain permeability of existing antidotes or discovering
a new class of reactivators.
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Affiliation(s)
- Ashima Thakur
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - Pooja Patil
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - Abha Sharma
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - S.J.S. Flora
- Pharmacology & Toxicology, National Institute of Pharmaceutical Education and Research, Raebareli, India
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12
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Rosenberg Y, Saxena A. Acetylcholinesterase inhibition resulting from exposure to inhaled OP can be prevented by pretreatment with BChE in both macaques and minipigs. Neuropharmacology 2020; 174:108150. [PMID: 32442543 PMCID: PMC7365266 DOI: 10.1016/j.neuropharm.2020.108150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/05/2020] [Accepted: 05/14/2020] [Indexed: 10/24/2022]
Abstract
More frequent and widespread nerve agent attacks highlight the need for efficacious pre- and post-exposure organophosphate (OP) counter-measures to protect military and civilian populations. Because of critical targeting of acetylcholinesterase (AChE) in the CNS by OPs, a pre-treatment candidate for preventing/reducing poisoning will be a broadly acting molecule that scavenges OPs in blood before they reach their physiological targets. Prophylactic human butyrylcholinesterase (HuBChE), the leading pretreatment candidate, has been shown to protect against multiple LD50's of nerve agents in rodents, macaques, and minipigs. This review describes the development of a HuBChE bioscavenger pretreatment from early proof-of-concept studies to pre-clinical studies with the native injectable enzyme and the development of aerosolized forms of recombinant enzyme, which can be delivered by inhalation nebulizer devices, to effect protection against inhaled OP nerve agents and insecticides. Early animal studies utilized parenteral exposure. However, lungs are the portal of entry for most volatile OP vapors and represent the major means of OP intoxication. In this regard, pretreat-ment with 7.5 mg/kg of HuBChE by IM injection protected minipigs against lethal sarin vapor and prevented AChE inhibition in the blood. This is similar to the five-day protection in macaques by an aerosolized rHuBChE using a nebulizer against aerosolized paraoxon (estimated to be an 8 mg/kg estimated human dose). Importantly, lethal inhaled doses of OP may be smaller relative to the same dose delivered by injection, thus reducing the protective HuBChE dose, while a combination of HuBChE and post-exposure oxime may prolong protection.
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Affiliation(s)
| | - Ashima Saxena
- U.S. Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
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Wong PT, Tang S, Cannon J, Yang K, Harrison R, Ruge M, O'Konek JJ, Choi SK. Shielded α-Nucleophile Nanoreactor for Topical Decontamination of Reactive Organophosphate. ACS APPLIED MATERIALS & INTERFACES 2020; 12:33500-33515. [PMID: 32603588 DOI: 10.1021/acsami.0c08946] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Here, we describe a nanoscale reactor strategy with a topical application in the therapeutic decontamination of reactive organophosphates (OPs) as chemical threat agents. It involves functionalization of poly(amidoamine) dendrimer through a combination of its partial PEG shielding and exhaustive conjugation with an OP-reactive α-nucleophile moiety at its peripheral branches. We prepared a 16-member library composed of two α-nucleophile classes (oxime, hydroxamic acid), each varying in its reactor valency (43-176 reactive units per nanoparticle), and linker framework for α-nucleophile tethering. Their mechanism for OP inactivation occurred via nucleophilic catalysis as verified against P-O and P-S bonded OPs including paraoxon-ethyl (POX), malaoxon, and omethoate by 1H NMR spectroscopy. Screening their reactivity for POX inactivation was performed under pH- and temperature-controlled conditions, which resulted in identifying 13 conjugates, each showing shorter POX half-life up to 2 times as compared to a reference Dekon 139 at pH 10.5, 37 °C. Of these, 10 conjugates were further confirmed for greater efficacy in POX decontamination experiments performed in two skin models, porcine skin and an artificial human microtissue. Finally, a few lead conjugates were selected and demonstrated for their biocompatibility in vitro as evident with lack of skin absorption, no inhibition of acetylcholinesterase (AChE), and no cytotoxicity in human neuroblastoma cells. In summary, this study presents a novel nanoreactor library, its screening methods, and identification of potent lead conjugates with potential for therapeutic OP decontamination.
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14
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Faiz Norrrahim MN, Idayu Abdul Razak MA, Ahmad Shah NA, Kasim H, Wan Yusoff WY, Halim NA, Mohd Nor SA, Jamal SH, Ong KK, Zin Wan Yunus WM, Knight VF, Mohd Kasim NA. Recent developments on oximes to improve the blood brain barrier penetration for the treatment of organophosphorus poisoning: a review. RSC Adv 2020; 10:4465-4489. [PMID: 35495228 PMCID: PMC9049292 DOI: 10.1039/c9ra08599h] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 12/16/2019] [Indexed: 11/25/2022] Open
Abstract
Organophosphorus (OP) compounds are highly toxic synthetic compounds which have been used as pesticides and developed as warfare nerve agents. They represent a threat to both military and civilian populations. OP pesticides affect the nervous system and are thought to have caused at least 5 million deaths since their discovery in the 1930s. At present the treatment of OP nerve agent poisoning commonly involves the use of parenteral oximes. However, the blood brain barrier (BBB) remains a challenge in the delivery of oximes to the central nervous system (CNS). This is because almost all macromolecule drugs (including oximes) fail to pass through the BBB to reach the CNS structures. The presence of a permanent cationic charge in oximes has made these compounds inefficient in crossing the BBB. Thus, oximes are unable to reactivate acetylcholinesterase (AChE) in the CNS. Using current structural and mechanistic understanding of the BBB under both physiological and pathological conditions, it becomes possible to design delivery systems for oximes and other drugs that are able to cross the BBB effectively. This review summarises the recent strategies in the development of oximes which are capable of crossing the BBB to treat OP poisoning. Several new developments using oximes are reviewed along with their advantages and disadvantages. This review could be beneficial for future directions in the development of oxime and other drug delivery systems into the CNS. Organophosphorus (OP) compounds are highly toxic synthetic compounds which have been used as pesticides and developed as warfare nerve agents.![]()
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15
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Maček Hrvat N, Kalisiak J, Šinko G, Radić Z, Sharpless KB, Taylor P, Kovarik Z. Evaluation of high-affinity phenyltetrahydroisoquinoline aldoximes, linked through anti-triazoles, as reactivators of phosphylated cholinesterases. Toxicol Lett 2019; 321:83-89. [PMID: 31863869 DOI: 10.1016/j.toxlet.2019.12.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/06/2019] [Accepted: 12/13/2019] [Indexed: 01/22/2023]
Abstract
Acetylcholinesterase (AChE) is a pivotal enzyme in neurotransmission. Its inhibition leads to cholinergic crises and could ultimately result in death. A related enzyme, butyrylcholinesterase (BChE), may act in the CNS as a co-regulator in terminating nerve impulses and is a natural plasma scavenger upon exposure to organophosphate (OP) nerve agents that irreversibly inhibit both enzymes. With the aim of improving reactivation of cholinesterases phosphylated by nerve agents sarin, VX, cyclosarin, and tabun, ten phenyltetrahydroisoquinoline (PIQ) aldoximes were synthesized by Huisgen 1,3 dipolar cycloaddition between alkyne- and azide-building blocks. The PIQ moiety may serve as a peripheral site anchor positioning the aldoxime moiety at the AChE active site. In terms of evaluated dissociation inhibition constants, the aldoximes could be characterized as high-affinity ligands. Nevertheless, high binding affinity of these oximes to AChE or its phosphylated conjugates did not assure rapid and selective AChE reactivation. Rather, potential reactivators of phosphylated BChE, with its enlarged acyl pocket, were identified, especially in case of cyclosarin, where the reactivation rates of the lead reactivator was 100- and 6-times that of 2-PAM and HI-6, respectively. Nevertheless, the return of the enzyme activity was affected by the nerve agent conjugated to catalytic serine, which highlights the lack of the universality of reactivators with respect to both the target enzyme and OP structure.
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Affiliation(s)
- Nikolina Maček Hrvat
- Institute for Medical Research and Occupational Health, HR-10000 Zagreb, Croatia
| | - Jarosław Kalisiak
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Goran Šinko
- Institute for Medical Research and Occupational Health, HR-10000 Zagreb, Croatia
| | - Zoran Radić
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093-0650, United States
| | - K Barry Sharpless
- Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Palmer Taylor
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093-0650, United States
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, HR-10000 Zagreb, Croatia.
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16
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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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17
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Król T, Trybus W, Trybus E, Kopacz-Bednarska A, Kowalczyk M, Brytan M, Paluch M, Antkowiak B, Saracyn M, Król G, Ciechanowska M. Assessment of exogenous melatonin action on mouse liver cells after exposure to soman. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2018; 64:147-154. [PMID: 30391876 DOI: 10.1016/j.etap.2018.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 10/26/2018] [Indexed: 06/08/2023]
Abstract
Melatonin is a hormone with many different biological activities and therefore seems to be an important factor reducing the harmful effects caused by toxic organophosphorus compounds. In this study, we attempted to evaluate the protective effect of melatonin on liver cells of mice challenged with chemical warfare agent-soman. The study was conducted at the level of ultrastructural and biochemical changes (analysis of the activity of model lysosomal enzymes and assessment of the level of lipid peroxidation). Significant biochemical and ultrastructural changes were found in the studied mouse hepatocytes after administration of soman alone, and soman in combination with melatonin, and the scope of the disclosed changes was dependent on the time of action of the examined factors. Melatonin has shown protective action, shielding liver cells from toxic effects of soman, which may result from its antioxidant properties and stimulation of the lysosomal compartment, the system coordinating the isolation and removal of cell-threatening processes.
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Affiliation(s)
- Teodora Król
- Department of Cell Biology and Electron Microscopy, Institute of Biology, The Jan Kochanowski University, Kielce, Poland.
| | - Wojciech Trybus
- Department of Cell Biology and Electron Microscopy, Institute of Biology, The Jan Kochanowski University, Kielce, Poland
| | - Ewa Trybus
- Department of Cell Biology and Electron Microscopy, Institute of Biology, The Jan Kochanowski University, Kielce, Poland
| | - Anna Kopacz-Bednarska
- Department of Cell Biology and Electron Microscopy, Institute of Biology, The Jan Kochanowski University, Kielce, Poland
| | - Marek Kowalczyk
- Department of Pharmacology and Toxicology, Military Institute of Hygiene and Epidemiology, Warsaw, Poland; Józef Piłsudski University of Physical Education in Warsaw, Warsaw, Poland
| | - Marek Brytan
- Department of Pharmacology and Toxicology, Military Institute of Hygiene and Epidemiology, Warsaw, Poland
| | - Małgorzata Paluch
- Department of Pharmacology and Toxicology, Military Institute of Hygiene and Epidemiology, Warsaw, Poland
| | - Bożena Antkowiak
- Department of Pharmacology and Toxicology, Military Institute of Hygiene and Epidemiology, Warsaw, Poland
| | | | - Grzegorz Król
- Faculty of Management, University of Warsaw, Szturmowa 1/3, 02-678, Warsaw, Poland
| | - Magdalena Ciechanowska
- Department of Pharmacology and Toxicology, Military Institute of Hygiene and Epidemiology, Warsaw, Poland
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18
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Tang S, Wong PT, Cannon J, Yang K, Bowden S, Bhattacharjee S, O'Konek JJ, Choi SK. Hydrophilic scaffolds of oxime as the potent catalytic inactivator of reactive organophosphate. Chem Biol Interact 2018; 297:67-79. [PMID: 30393113 DOI: 10.1016/j.cbi.2018.10.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/12/2018] [Accepted: 10/24/2018] [Indexed: 12/22/2022]
Abstract
Despite its efficacy as a skin decontaminant of reactive organophosphates (OP), Dekon 139-a potassium salt of 2,3-butanedione monooxime (DAM)-is associated with adverse events related to percutaneous absorption largely due to its small size and lipophilicity. In order to address this physicochemical issue, we synthesized and evaluated the activity of a focused library of 14 hydrophilic oxime compounds, each designed with either a DAM or monoisonitrosoacetone (MINA) oxime tethered to a polar or charged scaffold in order to optimize the size, hydrophilicity, and oxime acidity. High-throughput colorimetric assays were performed with paraoxon (POX) as a model OP to determine the kinetics of POX inactivation by these compounds under various pH and temperature conditions. This primary screening led to the identification of 6 lead compounds, predominantly in the MINA series, which displayed superb catalytic activity by reducing the POX half-life (t1/2) by 2-3 fold relative to Dekon 139. Our mechanistic studies show that POX inactivation by the oxime compounds occurred faster at a higher temperature and in a pH-dependent manner in which the negatively charged oximate species is ≥ 10-fold more effective than the neutral oxime species. Lastly, using one of the lead compounds, we demonstrated its promising efficacy for POX decontamination in porcine skin ex vivo, and showed its potent ability to protect acetylcholine esterase (AChE) through POX inactivation. In summary, we report the rational design and chemical biological validation of novel hydrophilic oximes which address an unmet need in therapeutic OP decontamination.
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Affiliation(s)
- Shengzhuang Tang
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Pamela T Wong
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Jayme Cannon
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Kelly Yang
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Sierra Bowden
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Somnath Bhattacharjee
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Jessica J O'Konek
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Seok Ki Choi
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, United States.
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19
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Costanzi S, Machado JH, Mitchell M. Nerve Agents: What They Are, How They Work, How to Counter Them. ACS Chem Neurosci 2018; 9:873-885. [PMID: 29664277 DOI: 10.1021/acschemneuro.8b00148] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Nerve agents are organophosphorus chemical warfare agents that exert their action through the irreversible inhibition of acetylcholinesterase, with a consequent overstimulation of cholinergic transmission followed by its shutdown. Beyond warfare, they have notoriously been employed in acts of terrorism as well as high profile assassinations. After a brief historical introduction on the development and deployment of nerve agents, this review provides a survey of their chemistry, the way they affect cholinergic transmission, the available treatment options, and the current directions for their improvement. As the review illustrates, despite their merits, the currently available treatment options present several shortcomings. Current research directions involve the search for improved antidotes, antagonists of the nicotinic receptors, small-molecule pretreatment options, as well as bioscavengers as macromolecular pretreatment options. These efforts are making good progress in many different directions and, hopefully, will lead to a lower target susceptibility, thus reducing the appeal of nerve agents as chemical weapons.
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Affiliation(s)
| | - John-Hanson Machado
- Department of Chemistry, The George Washington University, 800 22nd Street NW, Washington, DC 20052, United States
- Computational Biology Institute, The George Washington University, 45085 University Drive Suite 305, Ashburn, Virginia 20147, United States
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20
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Katz FS, Pecic S, Schneider L, Zhu Z, Hastings-Robinson A, Luzac M, Macdonald J, Landry DW, Stojanovic MN. New therapeutic approaches and novel alternatives for organophosphate toxicity. Toxicol Lett 2018; 291:1-10. [PMID: 29614332 DOI: 10.1016/j.toxlet.2018.03.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/18/2018] [Accepted: 03/26/2018] [Indexed: 10/17/2022]
Abstract
Organophosphate compounds (OPCs) are commonly used as pesticides and were developed as nerve agents for chemical warfare. Exposure to OPCs results in toxicity due to their covalent binding and inhibition of acetylcholinesterase (AChE). Treatment for toxicity due to OPC exposure has been largely focused on the reactivation of AChE by oxime-based compounds via direct nucleophilic attack on the phosphorous center. However, due to the disadvantages to existing oxime-based reactivators for treatment of OPC poisoning, we considered non-oxime mechanisms of reactivation. A high throughput screen of compound libraries was performed to discover previously unidentified reactivation compounds, followed by studies on their analogs. In the process, we discovered multiple non-oxime classes of compounds, the most robust of which we have already reported [1]. Herein, we report other classes of compounds we identified in our screen that are efficient at reactivation. During biochemical characterization, we also found some compounds with other activities that may inspire novel therapeutic approaches to OPC toxicity. Specifically, we found compounds that [1] increase the rate of substrate hydrolysis by AChE and, [2] protect the enzyme from inhibition by OPC. Further, we discovered that a subset of reactivator compounds recover activity from both AChE and the related enzyme butyrylcholinesterase (BuChE). We now report these compounds, their activities and discuss how each relates to therapeutic approaches that would provide alternatives to traditional oxime-based reactivation.
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Affiliation(s)
- Francine S Katz
- Department of Medicine, Columbia University, 630 W 168th Street, BB8-444, New York, NY, 10032, USA.
| | - Stevan Pecic
- Department of Medicine, Columbia University, 630 W 168th Street, BB8-444, New York, NY, 10032, USA.
| | - Laura Schneider
- Department of Medicine, Columbia University, 630 W 168th Street, BB8-444, New York, NY, 10032, USA
| | - Zhengxiang Zhu
- Department of Medicine, Columbia University, 630 W 168th Street, BB8-444, New York, NY, 10032, USA
| | - Ashley Hastings-Robinson
- Department of Medicine, Columbia University, 630 W 168th Street, BB8-444, New York, NY, 10032, USA
| | - Michal Luzac
- Department of Medicine, Columbia University, 630 W 168th Street, BB8-444, New York, NY, 10032, USA
| | - Joanne Macdonald
- Genecology Research Centre, Inflammation and Healing Research Cluster, School of Science and Engineering, University of the Sunshine Coast, 90 Sippy Downs Drive Sippy Downs, QLD 4556, Australia
| | - Donald W Landry
- Department of Medicine, Columbia University, 630 W 168th Street, BB8-444, New York, NY, 10032, USA
| | - Milan N Stojanovic
- Department of Medicine, Columbia University, 630 W 168th Street, BB8-444, New York, NY, 10032, USA
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21
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Post-exposure treatment with the oxime RS194B rapidly reactivates and reverses advanced symptoms of lethal inhaled paraoxon in macaques. Toxicol Lett 2017; 293:229-234. [PMID: 29129799 DOI: 10.1016/j.toxlet.2017.10.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/18/2017] [Accepted: 10/29/2017] [Indexed: 01/02/2023]
Abstract
Fatalities from organophosphate (OP) insecticide result from both occupational and deliberate exposure; significantly impacting human health. Like nerve agents, insecticides are neurotoxins which target and inhibit acetylcholinesterases (AChE) in central and peripheral synapses in the cholinergic nervous system. Post-exposure therapeutic countermeasures generally include administration of atropine with a pyridinium aldoxime e.g. pralidoxime, to reactivate the OP-inhibited AChE. However, commonly used oximes inefficiently cross the bloodbrain barrier and are rapidly cleared and their benefit is debated. Recent findings have demonstrated the ability of a novel zwitterionic, centrally acting, brain penetrating oxime (RS194B) to reverse severe symptoms and rapidly reactivate sarin-inhibited AChE in macaques, but it has not been tested following OP pesticide poisoning. In the present study, the symptoms following a lethal dose of inhaled paraoxon (100ug/kg), were shown to mimic those in insecticide poisoned individuals and were also rapidly reversed in macaques by post-exposure IM administration of 80mg/kg of RS194B. This occurred with a concomitant reactivation of AChE to 40-100% in<1hr and BChE (40% in 8h). These findings will be used to develop a macaque model with RS194B as a post-exposure treatment for insecticide poisoning and generate efficacy data for approval under the FDA Animal rule.
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22
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Malfatti MA, Enright HA, Be NA, Kuhn EA, Hok S, McNerney MW, Lao V, Nguyen TH, Lightstone FC, Carpenter TS, Bennion BJ, Valdez CA. The biodistribution and pharmacokinetics of the oxime acetylcholinesterase reactivator RS194B in guinea pigs. Chem Biol Interact 2017; 277:159-167. [PMID: 28941624 DOI: 10.1016/j.cbi.2017.09.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 09/13/2017] [Accepted: 09/19/2017] [Indexed: 01/09/2023]
Abstract
Organophosphorus-based (OP) nerve agents represent some of the most toxic substances known to mankind. The current standard of care for exposure has changed very little in the past decades, and relies on a combination of atropine to block receptor activity and oxime-type acetylcholinesterase (AChE) reactivators to reverse the OP binding to AChE. Although these oximes can block the effects of nerve agents, their overall efficacy is reduced by their limited capacity to cross the blood-brain barrier (BBB). RS194B, a new oxime developed by Radic et al. (J. Biol. Chem., 2012) has shown promise for enhanced ability to cross the BBB. To fully assess the potential of this compound as an effective treatment for nerve agent poisoning, a comprehensive evaluation of its pharmacokinetic (PK) and biodistribution profiles was performed using both intravenous and intramuscular exposure routes. The ultra-sensitive technique of accelerator mass spectrometry was used to quantify the compound's PK profile, tissue distribution, and brain/plasma ratio at four dose concentrations in guinea pigs. PK analysis revealed a rapid distribution of the oxime with a plasma t1/2 of ∼1 h. Kidney and liver had the highest concentrations per gram of tissue followed by lung, spleen, heart and brain for all dose concentrations tested. The Cmax in the brain ranged between 0.03 and 0.18% of the administered dose, and the brain-to-plasma ratio ranged from 0.04 at the 10 mg/kg dose to 0.18 at the 200 mg/kg dose demonstrating dose dependent differences in brain and plasma concentrations. In vitro studies show that both passive diffusion and active transport contribute little to RS194B traversal of the BBB. These results indicate that biodistribution is widespread, but very low quantities accumulate in the guinea pig brain, indicating this compound may not be suitable as a centrally active reactivator.
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Affiliation(s)
- Michael A Malfatti
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
| | - Heather A Enright
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Nicholas A Be
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Edward A Kuhn
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Saphon Hok
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Forensic Science Center, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - M Windy McNerney
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; War Related Illness and Injury Study Center, Veterans Affairs, Palo Alto, CA 94304, USA
| | - Victoria Lao
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Tuan H Nguyen
- Global Security Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Felice C Lightstone
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Timothy S Carpenter
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Brian J Bennion
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Carlos A Valdez
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Forensic Science Center, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
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23
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Rosenberg YJ, Mao L, Jiang X, Lees J, Zhang L, Radic Z, Taylor P. Post-exposure treatment with the oxime RS194B rapidly reverses early and advanced symptoms in macaques exposed to sarin vapor. Chem Biol Interact 2017; 274:50-57. [PMID: 28693885 PMCID: PMC5586507 DOI: 10.1016/j.cbi.2017.07.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 07/03/2017] [Accepted: 07/06/2017] [Indexed: 01/04/2023]
Abstract
Organophosphate (OP) nerve agents and pesticides trigger a common mechanism of neurotoxicity resulting from critical targeting and inhibition of acetylcholinesterases (AChE) in central and peripheral synapses in the cholinergic nervous system. Therapeutic countermeasures have thus focused on either administering an oxime post-exposure, that can rapidly reactivate OP-inhibited AChE, or by preventing OP poisoning through administering pre-exposure treatments that scavenge OPs before they inhibit their physiological AChE targets. While several pyridinium aldoxime antidotes are currently approved, their utility is impaired due to their inability to cross the blood-brain barrier (BBB) efficiently. The present study utilized a macaque (Ma) model to demonstrate the efficacy of a novel zwitterionic and centrally acting oxime RS194B to reactivate sarin- and paraoxon-inhibited macaque AChE and butyrylcholinesterase (BChE) in vitro and to further assess the capacity of RS194B to effect a reversal of clinical symptoms following sarin inhalation in vivo. In vitro, oxime reactivation of MaAChE and MaBChE was shown to be comparable to their human orthologs, while the macaque studies indicated that IM administration of 62.5 mg/kg of RS194B and 0.28 mg/kg atropine after continuous exposure to 49.6 μg/kg sarin vapor, rapidly reactivated the inhibited AChE and BChE in blood and reversed both early and advanced clinical symptoms of sarin-induced toxicity following pulmonary exposure within 1 h. The rapid cessation of autonomic and central symptoms, including convulsions, observed in macaques bodes well for the use of RS194B as an intra- or post-exposure human treatment and validates the macaque model in generating efficacy and toxicology data required for approval under the FDA Animal rule.
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Affiliation(s)
| | | | | | | | - Limin Zhang
- Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla 92093-0650, USA.
| | - Zoran Radic
- Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla 92093-0650, USA.
| | - Palmer Taylor
- Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla 92093-0650, USA.
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Wei Z, Liu YQ, Wang SZ, Yao L, Nie HF, Wang YA, Liu XY, Zheng ZB, Li S. Conjugates of salicylaldoximes and peripheral site ligands: Novel efficient nonquaternary reactivators for nerve agent-inhibited acetylcholinesterase. Bioorg Med Chem 2017; 25:4497-4505. [DOI: 10.1016/j.bmc.2017.06.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 06/13/2017] [Accepted: 06/25/2017] [Indexed: 10/19/2022]
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Buchwald P, Bodor N. Brain-Targeting Chemical Delivery Systems and Their Cyclodextrin-Based Formulations in Light of the Contributions of Marcus E. Brewster. J Pharm Sci 2016; 105:2589-2600. [DOI: 10.1016/j.xphs.2016.04.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/07/2016] [Accepted: 04/07/2016] [Indexed: 11/29/2022]
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Chambers JE, Meek EC, Bennett JP, Bennett WS, Chambers HW, Leach CA, Pringle RB, Wills RW. Novel substituted phenoxyalkyl pyridinium oximes enhance survival and attenuate seizure-like behavior of rats receiving lethal levels of nerve agent surrogates. Toxicology 2015; 339:51-57. [PMID: 26705700 DOI: 10.1016/j.tox.2015.12.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/03/2015] [Accepted: 12/11/2015] [Indexed: 11/16/2022]
Abstract
Novel substituted phenoxyalkyl pyridinium oximes, previously shown to reactivate brain cholinesterase in rats treated with high sublethal dosages of surrogates of sarin and VX, were tested for their ability to prevent mortality from lethal doses of these two surrogates. Rats were treated subcutaneously with 0.6mg/kg nitrophenyl isopropyl methylphosphonate (NIMP; sarin surrogate) or 0.65mg/kg nitrophenyl ethyl methylphosphonate (NEMP; VX surrogate), dosages that were lethal within 24h to all tested rats when they received only 0.65mg/kg atropine at the time of initiation of seizure-like behavior (about 30min). If 146mmol/kg 2-PAM (human equivalent dosage) was also administered, 40% and 33% survival was obtained with NIMP and NEMP, respectively, while the novel Oximes 1 and 20 provided 65% and 55% survival for NIMP and 75 and 65% for NEMP, respectively. In addition, both novel oximes resulted in a highly significant decrease in time to cessation of seizure-like behavior compared to 2-PAM during the first 8h of observation. Brain cholinesterase inhibition was slightly less in novel oxime treated rats compared to 2-PAM in the 24h survivors. The lethality data indicate that 24h survival is improved by two of the novel oximes compared to 2-PAM. The cessation of seizure-like behavior data strongly suggest that these novel oximes are able to penetrate the blood-brain barrier and can combat the hypercholinergic activity that results in seizures. Therefore this oxime platform has exceptional promise as therapy that could both prevent nerve agent-induced lethality and attenuate nerve agent-induced seizures.
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Affiliation(s)
- Janice E Chambers
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762, USA.
| | - Edward C Meek
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762, USA.
| | - Joshua P Bennett
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762, USA.
| | - W Shane Bennett
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762, USA.
| | - Howard W Chambers
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, P.O. Box 9775, Mississippi State, MS 39762, USA.
| | - C Andrew Leach
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762, USA.
| | - Ronald B Pringle
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762, USA.
| | - Robert W Wills
- Department of Pathobiology/Population Medicine, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762, USA.
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Legler PM, Soojhawon I, Millard CB. A conformational change in the peripheral anionic site of Torpedo californica acetylcholinesterase induced by a bis-imidazolium oxime. ACTA ACUST UNITED AC 2015; 71:1788-98. [PMID: 26327369 DOI: 10.1107/s1399004715011281] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/09/2015] [Indexed: 08/30/2023]
Abstract
As part of ongoing efforts to design improved nerve agent antidotes, two X-ray crystal structures of Torpedo californica acetylcholinesterase (TcAChE) bound to the bis-pyridinium oxime, Ortho-7, or its experimental bis-imidazolium analogue, 2BIM-7, were determined. Bis-oximes contain two oxime groups connected by a hydrophobic linker. One oxime group of Ortho-7 binds at the entrance to the active-site gorge near Trp279, and the second binds at the bottom near Trp84 and Phe330. In the Ortho-7-TcAChE complex the oxime at the bottom of the gorge was directed towards the nucleophilic Ser200. In contrast, the oxime group of 2BIM-7 was rotated away from Ser200 and the oxime at the entrance induced a significant conformational change in the peripheral anionic site (PAS) residue Trp279. The conformational change alters the surface of the PAS and positions the imidazolium oxime of 2BIM-7 further from Ser200. The relatively weaker binding and poorer reactivation of VX-inhibited, tabun-inhibited or sarin-inhibited human acetylcholinesterase by 2BIM-7 compared with Ortho-7 may in part be owing to the unproductively bound states caught in crystallo. Overall, the reactivation efficiency of 2BIM-7 was comparable to that of 2-pyridine aldoxime methyl chloride (2-PAM), but unlike 2-PAM the bis-imidazolium oxime lacks a fixed charge, which may affect its membrane permeability.
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Affiliation(s)
- Patricia M Legler
- CBMSE, U.S. Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375, USA
| | - Iswarduth Soojhawon
- Bacterial Diseases, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Charles B Millard
- Division of Biochemistry, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
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Schmidt HR, Radić Z, Taylor P, Fradinger EA. Quaternary and tertiary aldoxime antidotes for organophosphate exposure in a zebrafish model system. Toxicol Appl Pharmacol 2015; 284:197-203. [DOI: 10.1016/j.taap.2015.02.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 01/28/2015] [Accepted: 02/05/2015] [Indexed: 11/29/2022]
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Bhattacharjee AK, Marek E, Le HT, Ratcliffe R, DeMar JC, Pervitsky D, Gordon RK. Discovery of non-oxime reactivators using an in silico pharmacophore model of reactivators for DFP-inhibited acetylcholinesterase. Eur J Med Chem 2015; 90:209-20. [DOI: 10.1016/j.ejmech.2014.11.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 11/03/2014] [Accepted: 11/05/2014] [Indexed: 10/24/2022]
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Kalász H, Nurulain SM, Veress G, Antus S, Darvas F, Adeghate E, Adem A, Hashemi F, Tekes K. Mini review on blood-brain barrier penetration of pyridinium aldoximes. J Appl Toxicol 2014; 35:116-23. [PMID: 25291712 DOI: 10.1002/jat.3048] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/14/2014] [Accepted: 06/16/2014] [Indexed: 01/27/2023]
Abstract
This paper reviews the blood-brain barrier (BBB) penetration of newly developed pyridinium aldoximes. Pyridinium aldoximes are highly charged hydrophilic compounds used in the treatment of subjects exposed to organophosphonates because they are effective as acetylcholinesterase reactivators. Pyridinium aldoximes have antidotal effects against poisoning with cholinesterase inhibitors, a frequent problem affecting people working with organophosphate-based insecticides and pesticides. Toxic organophosphonate products such as sarin and tabun can be used by terrorists as chemical warfare agents. This poses a severe challenge to all innocent and peace-loving people worldwide. This review gives a brief summary of BBB transporters and description of the current in vitro and in vivo methods for the characterization of BBB penetration of established and novel pyridinium aldoximes. The authors provide a putative mechanism of penetration, outline some future ways of formulation and discuss the possible advantages and disadvantages of increasing BBB penetration.
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Affiliation(s)
- H Kalász
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, 1089, Budapest, Nagyvárad tér 4, Hungary; Department of Pharmacology and Therapeutics, CMHS, United Arab Emirates University, Al Ain, P.O.Box 17666, United Arab Emirates
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McHardy SF, Bohmann JA, Corbett MR, Campos B, Tidwell MW, Thompson PM, Bemben CJ, Menchaca TA, Reeves TE, Cantrell WR, Bauta WE, Lopez A, Maxwell DM, Brecht KM, Sweeney RE, McDonough J. Design, synthesis, and characterization of novel, nonquaternary reactivators of GF-inhibited human acetylcholinesterase. Bioorg Med Chem Lett 2014; 24:1711-4. [DOI: 10.1016/j.bmcl.2014.02.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/13/2014] [Accepted: 02/18/2014] [Indexed: 10/25/2022]
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Okolotowicz KJ, Dwyer M, Smith E, Cashman JR. Preclinical studies of noncharged oxime reactivators for organophosphate exposure. J Biochem Mol Toxicol 2013; 28:23-31. [PMID: 23943350 DOI: 10.1002/jbt.21519] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 07/09/2013] [Accepted: 07/20/2013] [Indexed: 11/07/2022]
Abstract
A countermeasure that protects the brain from organophosphate toxicity is an unmet need. Few small molecule reactivators that can cross the blood brain barrier and reactivate brain acetyl cholinesterases have been reported. Herein, we describe preclinical investigations of a new class of amidine-oxime reactivator of cholinesterases with improved potency and blood brain barrier permeability. (Z)-N-((E)-1-(Dimethylamino)-2-(hydroxyimino)ethylidene)butan-1-aminium chloride, 1, is zwitterionic at physiological pH but possesses increased oxime nucleophilicity because of the adjacent amidine functionality. The amidine-oximes reported herein were observed to be nontoxic (up to 200 mg/kg in vivo) and are chemically and metabolically stable. The results presented herein show that uncharged amidine-oxime reactivators such as 1 can penetrate the blood brain barrier in animals and protect from the toxicity of nerve agent model compounds.
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Renou J, Mercey G, Verdelet T, Păunescu E, Gillon E, Arboléas M, Loiodice M, Kliachyna M, Baati R, Nachon F, Jean L, Renard PY. Syntheses and in vitro evaluations of uncharged reactivators for human acetylcholinesterase inhibited by organophosphorus nerve agents. Chem Biol Interact 2013; 203:81-4. [DOI: 10.1016/j.cbi.2012.09.023] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/31/2012] [Accepted: 09/18/2012] [Indexed: 12/01/2022]
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Bhonsle JB, Causey R, Oyler BL, Bartolucci C, Lamba D, Pesaresi A, Bhamare NK, Soojhawon I, Garcia GE. Evaluation and computational characterization of the facilitated transport of Glc carbon C-1 oxime reactivators across a blood brain barrier model. Chem Biol Interact 2012; 203:129-34. [PMID: 23073172 DOI: 10.1016/j.cbi.2012.09.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 09/04/2012] [Accepted: 09/25/2012] [Indexed: 10/27/2022]
Abstract
We are evaluating a facilitative transport strategy to move oximes across the blood brain barrier (BBB) to reactivate inhibited brain acetylcholinesterase (AChE). We selected glucose (Glc) transporters (GLUT) for this purpose as these transporters are highly represented in the BBB. Glc conjugates have successfully moved drugs across the BBB and previous work has shown that Glc-oximes (sugar-oximes, SOxs) can reduce the organophosphonate induced hypothermia response. We previously evaluated the reactivation potential of Glc carbon C-1 SOxs. Here we report the reactivation parameters for VX- and GB-inhibited human (Hu) AChE of the best SOx (13c) and our findings that the kinetics are similar to those of the parent oxime. Although crystals of Torpedo californica AChE were produced, neither soaked or co-crystallized experiments were successful at concentrations below 20mM 13c, and higher concentrations cracked the crystals. 13c was non-toxic to neuroblastoma and kidney cell lines at 12-18 mM, allowing high concentrations to be used in a BBB kidney cell model. The transfer of 13c from the donor side was asymmetric with the greatest loss of 13c from the apical- or luminal-treated side. There was no apparent transfer from the basolateral side. The 13cP(app) results indicate a 'low' transport efficiency; however, mass accounting revealed only a 20% recovery from the apical dose in which high concentrations were found in the cell lysate fraction. Molecular modeling of 13c through the GLUT-1 channel demonstrated that transport of 13c was more restricted than Glc. Selected sites were compared and the 13c binding energies were greater than two times those of Glc.
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Affiliation(s)
- Jayendra B Bhonsle
- Astha Drug Discovery & Research, 5284 Randolph Road #262, Rockville, MD 20852, USA
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de Araujo Furtado M, Rossetti F, Chanda S, Yourick D. Exposure to nerve agents: from status epilepticus to neuroinflammation, brain damage, neurogenesis and epilepsy. Neurotoxicology 2012; 33:1476-1490. [PMID: 23000013 DOI: 10.1016/j.neuro.2012.09.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Revised: 07/25/2012] [Accepted: 09/03/2012] [Indexed: 12/17/2022]
Abstract
Epilepsy is a common neurological disorder characterized by an initial injury due to stroke, traumatic brain injury, brain infection, or febrile seizures causing status epilepticus (SE). This phenomenon precedes recurrent (secondary) seizures, the latent period (period without seizures) and downstream appearance of spontaneous recurrent seizures (SRS). Epilepsy inducers include the organophosphorous (OP) compounds modified as chemical warfare nerve agents, such as soman. SE induced by soman is a result of cholinergic system hyperactivity caused by the irreversible inhibition of acetylcholinesterase, and the subsequent increase in the amount of the neurotransmitter acetylcholine at central and peripheral sites. SE leads to profound, permanent, complex and widespread brain damage and associated cognitive and behavioral deficits, accompanied by impaired neurogenesis. Several anticonvulsant and neuroprotective strategies have been studied in order to avoid the epileptogenesis which occurs after SE caused by soman exposure. In recent studies, we showed that SRS occur post-soman exposure and neuropathology can be reduced with diazepam (DZP) and valproic acid (VPA) when administered in combination treatment. These effects are accompanied by neurogenesis seen 15 days post-exposure in the hippocampal dentate gyrus (DG). This review discusses several findings about epilepsy induced by soman exposure such as behavioral changes, EEG anomalies, neuropathology, neuroinflammation, neurogenesis, possible circuitry changes and current strategies for treatment. The soman seizure model is an important model of temporal lobe epilepsy (TLE) and comparable in certain respects with well studied models in the literature such as pilocarpine and kainic acid. All these models together allow for a greater understanding of the different mechanisms of seizure induction, propagation and options for treatment. These studies are very necessary for current military and civilian treatment regimens, against OP nerve agent exposure, which fail to prevent SE resulting in severe neuropathology and epilepsy.
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Affiliation(s)
- Marcio de Araujo Furtado
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Franco Rossetti
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Soma Chanda
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Debra Yourick
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States.
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Radić Z, Sit RK, Garcia E, Zhang L, Berend S, Kovarik Z, Amitai G, Fokin VV, Barry Sharpless K, Taylor P. Mechanism of interaction of novel uncharged, centrally active reactivators with OP-hAChE conjugates. Chem Biol Interact 2012; 203:67-71. [PMID: 22975155 DOI: 10.1016/j.cbi.2012.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 08/20/2012] [Accepted: 08/21/2012] [Indexed: 10/27/2022]
Abstract
A library of more than 200 novel uncharged oxime reactivators was used to select and refine lead reactivators of human acetylcholinesterase (hAChE) covalently conjugated with sarin, cyclosarin, VX, paraoxon and tabun. N-substituted 2-hydroxyiminoacetamido alkylamines were identified as best reactivators and reactivation kinetics of the lead oximes, RS41A and RS194B, were analyzed in detail. Compared to reference pyridinium reactivators, 2PAM and MMB4, molecular recognition of RS41A reflected in its Kox constant was compromised by an order of magnitude on average for different OP-hAChE conjugates, without significant differences in the first order maximal phosphorylation rate constant k(2). Systematic structural modifications of the RS41A lead resulted in several-fold improvement with reactivator, RS194B. Kinetic analysis indicated K(ox) reduction for RS194B as the main kinetic constant leading to efficient reactivation. Subtle structural modifications of RS194B were used to identify essential determinants for efficient reactivation. Computational molecular modeling of RS41A and RS194B interactions with VX inhibited hAChE, bound reversibly in Michaelis type complex and covalently in the pentacoordinate reaction intermediate suggests that the faster reactivation reaction is a consequence of a tighter RS194B interactions with hAChE peripheral site (PAS) residues, in particular with D74, resulting in lower interaction energies for formation of both the binding and reactivation states. Desirable in vitro reactivation properties of RS194B, when coupled with its in vivo pharmacokinetics and disposition in the body, reveal the potential of this oxime design as promising centrally and peripherally active antidotes for OP toxicity.
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Affiliation(s)
- Zoran Radić
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093-0650, USA.
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Mercey G, Verdelet T, Renou J, Kliachyna M, Baati R, Nachon F, Jean L, Renard PY. Reactivators of acetylcholinesterase inhibited by organophosphorus nerve agents. Acc Chem Res 2012; 45:756-66. [PMID: 22360473 DOI: 10.1021/ar2002864] [Citation(s) in RCA: 245] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Since the September 11, 2001, terrorist attacks in the United States, the specter of a chemical threat against civilian populations has renewed research interest in chemical warfare agents, their mechanisms of action, and treatments that reverse their effects. In this Account, we focus specifically on organophosphorus nerve agents (OPNAs). Although some OPNAs are used as pest control, the most toxic chemicals in this class are used as chemical warfare agents in armed conflicts. The acute toxicity of OPNAs results from the irreversible inhibition of acetylcholinesterase (AChE, EC 3.1.1.7) via the formation of a covalent P-O bond at the serine hydroxyl group in the enzyme active site. AChE breaks down the neurotransmitter acetylcholine at neuronal synapses and neuromuscular junctions. The irreversible inhibition of AChE causes the neurotransmitter to accumulate in the synaptic cleft, leading to overstimulation of cholinergic receptors, seizures, respiratory arrest, and death. The current treatment for OPNA poisoning combines an antimuscarinic drug (e.g., atropine), an anticonvulsant drug (e.g., diazepam), and an AChE reactivator of the pyridinium aldoxime family (pralidoxime, trimedoxime, obidoxime, HI-6, HLö-7). Because of their high nucleophilicity, oximes can displace the phosphyl group from the catalytic serine, thus restoring the enzyme's catalytic activity. During 50 years of research in the reactivator field, researchers have synthesized and tested numerous structural modifications of monopyridinium oximes and bispyridinium oximes. In the past decade, medicinal chemists have focused their research on the more efficient bispyridinium reactivators, but all known reactivators have several drawbacks. First, due to their permanent positive charge, they do not cross the blood-brain barrier (BBB) efficiently and do not readily reactivate AChE in the central nervous system. Second, no single oxime is efficient against a wide variety of OPNAs. Third, oximes cannot reactivate "aged" AChE. This Account summarizes recent strategies for the development of AChE reactivators capable of crossing the BBB. The use of nanoparticulate transport and inhibition of P-glycoprotein efflux pumps improves BBB transport of these AChE reactivators. Chemical modifications that increased the lipophilicity of the pyridinium aldoximes, the addition of a fluorine atom and the replacement of a pyridyl ring with a dihydropyridyl moiety, enhances BBB permeability. The glycosylation of pyridine aldoximes facilitates increased BBB penetration via the GLUT-1 transport system. The development of novel uncharged reactivators that can move efficiently across the BBB represents one of the most promising of these new strategies.
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Affiliation(s)
- Guillaume Mercey
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
| | - Tristan Verdelet
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
| | - Julien Renou
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
| | - Maria Kliachyna
- Faculté de Pharmacie, Université de Strasbourg, CNRS UMR 7199, Laboratoire des Systèmes Chimiques Fonctionnels, 74 route du Rhin, BP 60024, 67401 Illkirch, France
| | - Rachid Baati
- Faculté de Pharmacie, Université de Strasbourg, CNRS UMR 7199, Laboratoire des Systèmes Chimiques Fonctionnels, 74 route du Rhin, BP 60024, 67401 Illkirch, France
| | - Florian Nachon
- Département de Toxicologie, Institut de Recherche Biomédicale des Armées, 24 Avenue des Maquis du Grésivaudan, BP87, 38702 La Tronche, France
| | - Ludovic Jean
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
| | - Pierre-Yves Renard
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
- Institut Universitaire de France, 103 Boulevard Saint Michel, 75005 Paris, France
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Discovery of non-oxime reactivators using an in silico pharmacophore model of oxime reactivators of OP-inhibited acetylcholinesterase. Eur J Med Chem 2012; 49:229-38. [DOI: 10.1016/j.ejmech.2012.01.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 12/26/2011] [Accepted: 01/07/2012] [Indexed: 11/30/2022]
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Radić Z, Sit RK, Kovarik Z, Berend S, Garcia E, Zhang L, Amitai G, Green C, Radić B, Fokin VV, Sharpless KB, Taylor P. Refinement of structural leads for centrally acting oxime reactivators of phosphylated cholinesterases. J Biol Chem 2012; 287:11798-809. [PMID: 22343626 DOI: 10.1074/jbc.m111.333732] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We present a systematic structural optimization of uncharged but ionizable N-substituted 2-hydroxyiminoacetamido alkylamine reactivators of phosphylated human acetylcholinesterase (hAChE) intended to catalyze the hydrolysis of organophosphate (OP)-inhibited hAChE in the CNS. Starting with the initial lead oxime RS41A identified in our earlier study and extending to the azepine analog RS194B, reactivation rates for OP-hAChE conjugates formed by sarin, cyclosarin, VX, paraoxon, and tabun are enhanced severalfold in vitro. To analyze the mechanism of intrinsic reactivation of the OP-AChE conjugate and penetration of the blood-brain barrier, the pH dependence of the oxime and amine ionizing groups of the compounds and their nucleophilic potential were examined by UV-visible spectroscopy, (1)H NMR, and oximolysis rates for acetylthiocholine and phosphoester hydrolysis. Oximolysis rates were compared in solution and on AChE conjugates and analyzed in terms of the ionization states for reactivation of the OP-conjugated AChE. In addition, toxicity and pharmacokinetic studies in mice show significantly improved CNS penetration and retention for RS194B when compared with RS41A. The enhanced intrinsic reactivity against the OP-AChE target combined with favorable pharmacokinetic properties resulted in great improvement of antidotal properties of RS194B compared with RS41A and the standard peripherally active oxime, 2-pyridinealdoxime methiodide. Improvement was particularly noticeable when pretreatment of mice with RS194B before OP exposure was combined with RS194B reactivation therapy after the OP insult.
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Affiliation(s)
- Zoran Radić
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California 92093, USA
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Kalisiak J, Ralph EC, Cashman JR. Nonquaternary reactivators for organophosphate-inhibited cholinesterases. J Med Chem 2011; 55:465-74. [PMID: 22206546 DOI: 10.1021/jm201364d] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new class of amidine-oxime reactivators of organophosphate (OP)-inhibited cholinesterases (ChE) was synthesized and tested in vitro and in vivo. Compared with 2-PAM, the most promising cyclic amidine-oxime (i.e., 12e) showed comparable or greater reactivation of OP-inactivated AChE and OP-inactivated BChE. To the best of our knowledge, this is the first report of a nonquaternary oxime that has, comparable to 2-PAM, in vitro potency for reactivation of Sarin (GB)-inhibited AChE and BChE. Amidine-oximes were tested in vitro, and reactivation rates for OP-inactivated butyrylcholinesterase (BChE) were greater than those for 2-PAM or MINA. Amidine-oxime reactivation rates for OP-inactivated acetylcholinesterase (AChE) were lower compared to 2-PAM but greater compared with MINA. Amidine-oximes were tested in vivo for protection against the toxicity of nerve agent model compounds. (i.e., a model of Sarin). Post-treatment (i.e., 5 min after OP exposure, i.p,) with amidine oximes 7a-c and 12a, 12c, 12e, 12f, and 15b (145 μmol/kg, i.p.) protected 100% of the mice challenged with the sarin model compound. Even at 25% of the initial dose of amidine-oxime (i.e., a dose of 36 μmol/kg, i.p.), 7b and 12e protected 100% of the animals challenged with the sarin nerve agent model compound that caused lethality in 6/11 animals without amidine-oxime.
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Affiliation(s)
- Jarosław Kalisiak
- Human BioMolecular Research Institute, 5310 Eastgate Mall, San Diego, California 92121, United States
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Khan FA, Campbell AJ, Hoyt B, Herdman C, Ku T, Thangavelu S, Gordon RK. Oxidative mechanisms for the biotransformation of 1-methyl-1,6-dihydropyridine-2-carbaldoxime to pralidoxime chloride. Life Sci 2011; 89:911-7. [PMID: 21989207 DOI: 10.1016/j.lfs.2011.09.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 08/02/2011] [Accepted: 09/13/2011] [Indexed: 01/02/2023]
Abstract
AIMS Due to pralidoxime chloride's (2-PAM) positive charge, it's penetration through the blood brain barrier (BBB) and reactivation of organophosphate (OP) inhibited central nervous system (CNS) acetylcholinesterase (AChE) is poor. The results of CNS inhibited AChE are seizures. Pro-2-PAM (1-methyl-1,6-dihydropyridine-2-carbaldoxime), a pro-drug of 2-PAM, due to higher hydrophobicity, penetrates the BBB better but must be oxidized to 2-PAM, the active form of the oxime to reactivate CNS AChE in order to abrogate seizures. In this study, we characterize the in vivo mechanism of pro-2-PAM oxidation. MAIN METHODS A high pressure liquid chromatography (HPLC) assay was developed to quantify the conversion of pro-2-PAM to 2-PAM. NADPH oxidase activity was measured by a photo-luminescence assay using lucigenin substrate. Upon analysis, the rate of NADPH induced oxidation suggested that an alternate mechanism may be involved. Therefore, various enzyme co-factors of oxidation-reduction enzyme systems were evaluated, including nicotinamide adenine dinucleotide (NAD), nicotinamide adenine dinucleotide phosphate (NADP), flavin adenine dinucleotide (FAD), riboflavin 5'-phosphate (FMN), and riboflavin. Next, a spectrophotometric assay was developed to measure the conversion of pro-2-PAM to 2-PAM in the presence of riboflavin. KEY FINDINGS In guinea pig brain homogenate, diphenyleneiodonium (DPI), a specific NADPH oxidase inhibitor, reduced pro-2-PAM to 2-PAM conversion to less than 25%. In contrast, riboflavin, FAD, and FMN rapidly oxidized all pro-2-PAM to 2-PAM in an in vitro assay. Riboflavin oxidized pro-2-PAM reactivated diisopropylfluorophosphate (DFP) inhibited AChE. SIGNIFICANCE The present study shows that pro-2-PAM was rapidly oxidized by riboflavin to 2-PAM, which reactivated organophosphate (OP)-inhibited AChE.
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Affiliation(s)
- Farhat A Khan
- Department of Regulated Laboratories, Division of Regulated Activities, Silver Spring, MD 20910, United States.
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Masson P. Evolution of and perspectives on therapeutic approaches to nerve agent poisoning. Toxicol Lett 2011; 206:5-13. [PMID: 21524695 DOI: 10.1016/j.toxlet.2011.04.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 04/08/2011] [Indexed: 01/18/2023]
Abstract
After more than 70 years of considerable efforts, research on medical defense against nerve agents has come to a standstill. Major progress in medical countermeasures was achieved between the 50s and 70s with the development of anticholinergic drugs and carbamate-based pretreatment, the introduction of pyridinium oximes as antidotes, and benzodiazepines in emergency treatments. These drugs ensure good protection of the peripheral nervous system and mitigate the acute effects of exposure to lethal doses of nerve agents. However, pyridostigmine and cholinesterase reactivators currently used in the armed forces do not protect/reactivate central acetylcholinesterases. Moreover, other drugs used are not sufficiently effective in protecting the central nervous system against seizures, irreversible brain damages and long-term sequelae of nerve agent poisoning.New developments of medical counter-measures focus on: (a) detoxification of organophosphorus molecules before they react with acetylcholinesterase and other physiological targets by administration of stoichiometric or catalytic scavengers; (b) protection and reactivation of central acetylcholinesterases, and (c) improvement of neuroprotection following delayed therapy.Future developments will aim at treatment of acute and long-term effects of low level exposure to nerve agents, research on alternative routes for optimizing drug delivery, and therapies. Though gene therapy for in situ generation of bioscavengers, and cell therapy based on neural progenitor engraftment for neuronal regeneration have been successfully explored, more studies are needed before practical medical applications can be made of these new approaches.
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Affiliation(s)
- Patrick Masson
- IRBA-CRSSA, Toxicology Dept., 38702 La Tronche Cedex, France.
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Kalisiak J, Ralph EC, Zhang J, Cashman JR. Amidine-oximes: reactivators for organophosphate exposure. J Med Chem 2011; 54:3319-30. [PMID: 21438612 DOI: 10.1021/jm200054r] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new class of amidine-oxime reactivators of organophosphate (OP)-inhibited cholinesterases (ChE) were designed, synthesized, and tested. These compounds represent a novel group of oximes with enhanced capabilities of crossing the blood-brain barrier. Lack of brain penetration is a major limitation for currently used oximes as antidotes of OP poisoning. The concept described herein relies on a combination of an amidine residue and oxime functionality whereby the amidine increases the binding affinity to the ChE and the oxime is responsible for reactivation. Amidine-oximes were tested in vitro and reactivation rates for OP-BuChE were greater than pralidoxime (2-PAM) or monoisonitrosoacetone (MINA). Amidine-oxime reactivation rates for OP-AChE were lower compared to 2-PAM but greater compared with MINA. After pretreatment for 30 min with oximes 15c and 15d (145 μmol/kg, ip) mice were challenged with a soman model compound. In addition, 15d was tested in a post-treatment experiment (145 μmol/kg, ip, administration 5 min after sarin model compound exposure). In both cases, amidine-oximes afforded 100% 24 h survival in an animal model of OP exposure.
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Affiliation(s)
- Jarosław Kalisiak
- Human BioMolecular Research Institute, 5310 Eastgate Mall, San Diego, California 92121, United States.
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Sit RK, Radić Z, Gerardi V, Zhang L, Garcia E, Katalinić M, Amitai G, Kovarik Z, Fokin VV, Sharpless KB, Taylor P. New structural scaffolds for centrally acting oxime reactivators of phosphylated cholinesterases. J Biol Chem 2011; 286:19422-30. [PMID: 21464125 DOI: 10.1074/jbc.m111.230656] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We describe here the synthesis and activity of a new series of oxime reactivators of cholinesterases (ChEs) that contain tertiary amine or imidazole protonatable functional groups. Equilibration between the neutral and protonated species at physiological pH enables the reactivators to cross the blood-brain barrier and distribute in the CNS aqueous space as dictated by interstitial and cellular pH values. Our structure-activity analysis of 134 novel compounds considers primarily imidazole aldoximes and N-substituted 2-hydroxyiminoacetamides. Reactivation capacities of novel oximes are rank ordered by their relative reactivation rate constants at 0.67 mm compared with 2-pyridinealdoxime methiodide for reactivation of four organophosphate (sarin, cyclosarin, VX, and paraoxon) conjugates of human acetylcholinesterase (hAChE). Rank order of the rates differs for reactivation of human butyrylcholinesterase (hBChE) conjugates. The 10 best reactivating oximes, predominantly hydroxyimino acetamide derivatives (for hAChE) and imidazole-containing aldoximes (for hBChE) also exhibited reasonable activity in the reactivation of tabun conjugates. Reactivation kinetics of the lead hydroxyimino acetamide reactivator of hAChE, when analyzed in terms of apparent affinity (1/K(ox)) and maximum reactivation rate (k(2)), is superior to the reference uncharged reactivators monoisonitrosoacetone and 2,3-butanedione monoxime and shows potential for further refinement. The disparate pH dependences for reactivation of ChE and the general base-catalyzed oximolysis of acetylthiocholine reveal that distinct reactivator ionization states are involved in the reactivation of ChE conjugates and in conferring nucleophilic reactivity of the oxime group.
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Affiliation(s)
- Rakesh K Sit
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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Inhibition of blood and tissue cholinesterases by soman in guinea pigs in vivo. J Appl Biomed 2011. [DOI: 10.2478/v10136-009-0030-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Prokai-Tatrai K, Szarka S, Nguyen V, Sahyouni F, Walker C, White S, Talamantes T, Prokai L. "All in the mind"? Brain-targeting chemical delivery system of 17β-estradiol (Estredox) produces significant uterotrophic side effect. ACTA ACUST UNITED AC 2011; Suppl 7. [PMID: 24380028 DOI: 10.4172/2153-2435.s7-002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Here we revisit the peculiarly named redox chemical delivery system concept. This unique prodrug approach has long been claimed to be capable of targeting 17β-estradiol (E2), which has numerous beneficial central effects, into the brain without detrimental peripheral hormonal exposure. Using a well-established protocol to monitor E2's antidepressant-like effect, we show that the administration of this chemical delivery system incorporated into hydroxypropyl-β-cyclodextrin (i.e., Estredox), indeed, triggers a transient antidepressant-like behavior in ovariectomized mice. At the same time, even an acute dose of the carefully purified chemical delivery system produces significant circulating E2 levels and uterotrophic side effects for several days after drug administration. For the first time, we also unequivocally show by liquid chromatography coupled with tandem mass spectrometry that the uterus of the Estredox-treated animals contains a large quantity of E2 compared to that of the control group. These thus far unexposed yet consequential peripheral side effects brought about by Estredox call for a thorough and unbiased reassessment of the extent of brain-targeting of the hormone via the chemical delivery system approach.
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Affiliation(s)
- Katalin Prokai-Tatrai
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States ; Department of Pharmaceutical Sciences, University of North Texas System College of Pharmacy, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States
| | - Szabolcs Szarka
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States
| | - Vien Nguyen
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States
| | - Fatima Sahyouni
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States
| | - Cary Walker
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States
| | - Shastazia White
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States
| | - Tatjana Talamantes
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States
| | - Laszlo Prokai
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, United States
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Shih TM, Guarisco JA, Myers TM, Kan RK, McDonough JH. The oxime pro-2-PAM provides minimal protection against the CNS effects of the nerve agents sarin, cyclosarin, and VX in guinea pigs. Toxicol Mech Methods 2010; 21:53-62. [DOI: 10.3109/15376516.2010.529190] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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