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1.
Sci Rep ; 10(1): 15834, 2020 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-32985607

RESUMO

Whether central apnoea or hypopnoea can be induced by organophosphorus poisoning remains unknown to date. By using the acute brainstem slice method and multi-electrode array system, we established a paraoxon (a typical acetylcholinesterase inhibitor) poisoning model to investigate the time-dependent changes in respiratory burst amplitudes of the pre-Bötzinger complex (respiratory rhythm generator). We then determined whether pralidoxime or atropine, which are antidotes of paraoxon, could counteract the effects of paraoxon. Herein, we showed that paraoxon significantly decreased the respiratory burst amplitude of the pre-Bötzinger complex (p < 0.05). Moreover, pralidoxime and atropine could suppress the decrease in amplitude by paraoxon (p < 0.05). Paraoxon directly impaired the pre-Bötzinger complex, and the findings implied that this impairment caused central apnoea or hypopnoea. Pralidoxime and atropine could therapeutically attenuate the impairment. This study is the first to prove the usefulness of the multi-electrode array method for electrophysiological and toxicological studies in the mammalian brainstem.


Assuntos
Intoxicação por Organofosfatos/complicações , Apneia do Sono Tipo Central/induzido quimicamente , Animais , Atropina/uso terapêutico , Encéfalo/efeitos dos fármacos , Paraoxon/antagonistas & inibidores , Paraoxon/toxicidade , Compostos de Pralidoxima/uso terapêutico , Ratos , Explosão Respiratória/efeitos dos fármacos
2.
Eur J Med Chem ; 185: 111787, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31675511

RESUMO

New uncharged conjugates of 6-methyluracil derivatives with imidazole-2-aldoxime and 1,2,4-triazole-3-hydroxamic acid units were synthesized and studied as reactivators of organophosphate-inhibited cholinesterase. Using paraoxon (POX) as a model organophosphate, it was shown that 6-methyluracil derivatives linked with hydroxamic acid are able to reactivate POX-inhibited human acetylcholinesterase (AChE) in vitro. The reactivating efficacy of one compound (5b) is lower than that of pyridinium-2-aldoxime (2-PAM). Meanwhile, unlike 2-PAM, in vivo study showed that the lead compound 5b is able: (1) to reactivate POX-inhibited AChE in the brain; (2) to decrease death of neurons and, (3) to prevent memory impairment in rat model of POX-induced neurodegeneration.


Assuntos
Acetilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Ácidos Hidroxâmicos/farmacologia , Paraoxon/antagonistas & inibidores , Uracila/análogos & derivados , Animais , Encéfalo/enzimologia , Relação Dose-Resposta a Droga , Humanos , Ácidos Hidroxâmicos/química , Ligantes , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos , Simulação de Acoplamento Molecular , Estrutura Molecular , Paraoxon/farmacologia , Paraoxon/toxicidade , Teoria Quântica , Ratos , Ratos Wistar , Relação Estrutura-Atividade , Uracila/síntese química , Uracila/química , Uracila/farmacologia
3.
Chem Biol Interact ; 310: 108735, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31276662

RESUMO

Organophosphates (OPs) irreversibly inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. The reactivation of these inhibited enzymes is paramount for their normal function. Present study evaluates reactivation potency of two newly developed oximes, K456 and K733, against paraoxon (POX)-inhibited human-RBC-AChE and human-plasma-BChE in comparison to reported reactivator, pralidoxime (2-PAM). In vitro studies showed higher intrinsic toxicities of both oximes than 2-PAM for AChE. No substantial reactivation of hBChE was noted by tested concentration. Contrary to 2-PAM, the in silico study predicted lower binding free energies for both oximes. However, the detailed interaction study revealed inability of oximes to interact with catalytic anionic site of AChE and hBChE in contrast to 2-PAM. Both in vitro and in silico studies conclude that K456 and K733 are unlikely to be used as reactivators of paraoxon-inhibited AChE or BChE.


Assuntos
Inibidores da Colinesterase/farmacologia , Reativadores da Colinesterase/farmacologia , Oximas/farmacologia , Paraoxon/antagonistas & inibidores , Compostos de Piridínio/farmacologia , Acetilcolinesterase/química , Butirilcolinesterase/química , Eritrócitos/enzimologia , Humanos , Paraoxon/farmacologia
4.
Chem Biol Interact ; 297: 67-79, 2019 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-30393113

RESUMO

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.


Assuntos
Acetilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Reativadores da Colinesterase/farmacologia , Oximas/farmacologia , Paraoxon/antagonistas & inibidores , Animais , Biocatálise , Reativadores da Colinesterase/síntese química , Reativadores da Colinesterase/química , Relação Dose-Resposta a Droga , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Cinética , Estrutura Molecular , Oximas/síntese química , Oximas/química , Paraoxon/farmacologia , Pele/efeitos dos fármacos , Pele/metabolismo , Relação Estrutura-Atividade , Suínos , Temperatura
5.
Colloids Surf B Biointerfaces ; 171: 358-367, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30059851

RESUMO

New mixed cationic liposomes based on L-α-phosphatidylcholine and dihexadecylmethylhydroxyethylammonium bromide (DHDHAB) were designed to overcome the BBB crossing by using the intranasal route. Synthesis and self-assembly of DHDHAB were performed. A low critical association concentration (0.01 mM), good solubilization properties toward hydrophobic dye Orange OT and antimicrobial activity against gram-positive bacteria Staphylococcus aureus (MIC=7.8 µg mL-1) and Bacillus cereus (MIC=7.8 µg mL-1), low hemolytic activities against human red blood cells (less than 10%) were achieved. Conditions for preparation of cationic vesicles and mixed liposomes with excellent colloidal stability at room temperature were determined. The intranasal administration of rhodamine B-loaded cationic liposomes was shown to increase bioavailability into the brain in comparison to the intravenous injection. The cholinesterase reactivator, 2-PAM, was used as model drug for the loading in cationic liposomes. 2-PAM-loaded cationic liposomes displayed high encapsulation efficiency (∼ 90%) and hydrodynamic diameter close to 100 nm. Intranasally administered 2-PAM-loaded cationic liposomes were effective against paraoxon-induced acetylcholinesterase inhibition in the brain. 2-PAM-loaded liposomes reactivated 12 ± 1% of brain acetylcholinesterase. This promising result opens the possibility to use marketed positively charged oximes in medical countermeasures against organophosphorus poisoning for reactivation of central acetylcholinesterase by implementing a non-invasive approach, via the "nose-brain" pathway.


Assuntos
Antibacterianos/farmacologia , Encéfalo/efeitos dos fármacos , Reativadores da Colinesterase/farmacologia , Sistemas de Liberação de Medicamentos , Compostos de Pralidoxima/farmacologia , Compostos de Amônio Quaternário/farmacologia , Acetilcolinesterase/metabolismo , Administração Intranasal , Antibacterianos/administração & dosagem , Antibacterianos/síntese química , Antibacterianos/química , Bacillus cereus/efeitos dos fármacos , Encéfalo/metabolismo , Cátions/química , Reativadores da Colinesterase/administração & dosagem , Reativadores da Colinesterase/química , Lipossomos/química , Paraoxon/antagonistas & inibidores , Paraoxon/farmacologia , Tamanho da Partícula , Compostos de Pralidoxima/administração & dosagem , Compostos de Pralidoxima/química , Compostos de Amônio Quaternário/síntese química , Compostos de Amônio Quaternário/química , Rodaminas/administração & dosagem , Rodaminas/química , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície
6.
Molecules ; 23(5)2018 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-29735900

RESUMO

Nerve agents and oxon forms of organophosphorus pesticides act as strong irreversible inhibitors of two cholinesterases in the human body: acetylcholinesterase (AChE; EC 3.1.1.7) and butyrylcholinesterase (BChE; EC 3.1.1.8), and are therefore highly toxic compounds. For the recovery of inhibited AChE, antidotes from the group of pyridinium or bispyridinium aldoxime reactivators (pralidoxime, obidoxime, HI-6) are used in combination with anticholinergics and anticonvulsives. Therapeutic efficacy of reactivators (called "oximes") depends on their chemical structure and also the type of organophosphorus inhibitor. Three novel oximes (K131, K142, K153) with an oxime group in position four of the pyridinium ring were designed and then tested for their potency to reactivate human (Homo sapiens sapiens) AChE (HssACHE) and BChE (HssBChE) inhibited by the pesticide paraoxon (diethyl 4-nitrophenyl phosphate). According to the obtained results, none of the prepared oximes were able to satisfactorily reactivate paraoxon-inhibited cholinesterases. On the contrary, extraordinary activity of obidoxime in the case of paraoxon-inhibited HssAChE reactivation was confirmed. Additional docking studies pointed to possible explanations for these results.


Assuntos
Acetilcolinesterase/química , Antídotos/síntese química , Butirilcolinesterase/química , Inibidores da Colinesterase/química , Reativadores da Colinesterase/síntese química , Inseticidas/antagonistas & inibidores , Oximas/síntese química , Paraoxon/antagonistas & inibidores , Antídotos/farmacologia , Reativadores da Colinesterase/farmacologia , Ensaios Enzimáticos , Eritrócitos/efeitos dos fármacos , Eritrócitos/enzimologia , Humanos , Inseticidas/química , Inseticidas/toxicidade , Simulação de Acoplamento Molecular , Cloreto de Obidoxima/química , Cloreto de Obidoxima/farmacologia , Oximas/farmacologia , Paraoxon/química , Paraoxon/toxicidade , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Estrutura Secundária de Proteína , Relação Estrutura-Atividade , Termodinâmica
7.
Toxicol Lett ; 293: 229-234, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29129799

RESUMO

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.


Assuntos
Acetamidas/uso terapêutico , Inibidores da Colinesterase/toxicidade , Reativadores da Colinesterase/uso terapêutico , Inseticidas/toxicidade , Oximas/uso terapêutico , Paraoxon/antagonistas & inibidores , Paraoxon/toxicidade , Acetamidas/farmacocinética , Acetilcolinesterase/metabolismo , Aerossóis , Animais , Butirilcolinesterase/metabolismo , Substâncias para a Guerra Química/intoxicação , Inibidores da Colinesterase/farmacocinética , Reativadores da Colinesterase/farmacocinética , Feminino , Exposição por Inalação , Inseticidas/farmacocinética , Macaca mulatta , Intoxicação por Organofosfatos/tratamento farmacológico , Oximas/farmacocinética , Paraoxon/farmacocinética
8.
J Control Release ; 247: 175-181, 2017 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-28043864

RESUMO

A simple and highly efficient catalytic scavenger of poisonous organophosphorus compounds, based on organophosphorus hydrolase (OPH, EC 3.1.8.1), is produced in aqueous solution by electrostatic coupling of the hexahistidine tagged OPH (His6-OPH) and poly(ethylene glycol)-b-poly(l-glutamic acid) diblock copolymer. The resulting polyion complex, termed nano-OPH, has a spherical morphology and a diameter from 25nm to 100nm. Incorporation of His6-OPH in nano-OPH preserves catalytic activity and increases stability of the enzyme allowing its storage in aqueous solution for over a year. It also decreases the immune and inflammatory responses to His6-OPH in vivo as determined by anti-OPH IgG and cytokines formation in Sprague Dawley rats and Balb/c mice, respectively. The nano-OPH pharmacokinetic parameters are improved compared to the naked enzyme suggesting longer blood circulation after intravenous (iv) administrations in rats. Moreover, nano-OPH is bioavailable after intramuscular (im), intraperitoneal (ip) and even transbuccal (tb) administration, and has shown ability to protect animals from exposure to a pesticide, paraoxon and a warfare agent, VX. In particular, a complete protection against the lethal doses of paraoxon was observed with nano-OPH administered iv and ip as much as 17h, im 5.5h and tb 2h before the intoxication. Further evaluation of nano-OPH as a catalytic bioscavenger countermeasure against organophosphorus chemical warfare agents and pesticides is warranted.


Assuntos
Arildialquilfosfatase/uso terapêutico , Inseticidas/toxicidade , Neurotoxinas/toxicidade , Intoxicação por Organofosfatos/prevenção & controle , Paraoxon/toxicidade , Animais , Arildialquilfosfatase/administração & dosagem , Arildialquilfosfatase/química , Arildialquilfosfatase/farmacocinética , Feminino , Inseticidas/antagonistas & inibidores , Masculino , Camundongos Endogâmicos BALB C , Neurotoxinas/antagonistas & inibidores , Compostos Organofosforados/antagonistas & inibidores , Compostos Organofosforados/toxicidade , Paraoxon/antagonistas & inibidores , Ratos Sprague-Dawley
9.
Bioorg Med Chem Lett ; 24(19): 4743-4748, 2014 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-25190468

RESUMO

The search of proficient oximes as reactivators of irreversibly inhibited-AChE by organophosphate poisoning necessitates an appropriate assessment of their physicochemical properties and reactivation kinetics. Therefore, herein acid dissociation constant; pKa, lipophilicity; logP, polar surface area, hydrogen bond donor and acceptor counts of structurally different oximes (two tertiary oximes and thirteen pyridinium aldoxime derivatives) have been evaluated. The experimentally obtained data for pKa has been comparatively analyzed by using non-linear regression. Further the tested oximes were screened through in vitro reactivation kinetics against paraoxon-inhibited AChE. The pKa values of all the examined oximes were within the range of 7.50-9.53. pKa values of uncharged and mono-pyridinium oximes were in good correlation with their reactivation potency. The high negative logP values of pyridinium oxime reactivators indicate their high hydrophilic character; hence oximes with improved lipophilicity should be designed for the development of novel and more potent antidotes. Propane and butane linked oximes were superior reactivators than xylene linked bis-oxime reactivators. It is concluded from the present study that pKa value is not only ruled by the position of oximino functionality in the pyridinium ring, but also by the position of linker. Although, pyridinium oximes are proved to be better reactivators but their lipophilicity has to be improved.


Assuntos
Reativadores da Colinesterase/farmacologia , Oximas/farmacologia , Paraoxon/antagonistas & inibidores , Acetilcolinesterase/metabolismo , Físico-Química , Reativadores da Colinesterase/química , Relação Dose-Resposta a Droga , Humanos , Cinética , Estrutura Molecular , Oximas/química , Relação Estrutura-Atividade
10.
CNS Neurol Disord Drug Targets ; 11(8): 1052-60, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23244429

RESUMO

Prophylactic administration of reversible acetylcholinesterase (AChE) inhibitors can protect against the lethal effects of organophosphorus compounds (OPCs). The usefulness of pyridostigmine, the only compound approved by the Food and Drug Administration (FDA) for such pretreatment, has been questioned. In search for more efficacious alternatives, we have examined in vivo the efficacy of a group of ten compounds with known anti-AChE activity (pyridostigmine, metoclopramide, tiapride, ranitidine, physostigmine, tacrine, amiloride, methylene blue, 7- methoxytacrine and K-27) to reduce mortality induced by the OPC methyl-paraoxon. AChE inhibitors were given intraperitoneally in equitoxic dosage (25% of LD01) 30 min before OPC exposure. Protection was quantified in rats by determining the relative risk of death (RR) by Cox analysis, with RR=1 for animals given only methyl-paraoxon, but no pretreatment. Only physostigmine (RR=0.39), K-27 (RR=0.40) and tacrine (RR=0.48) significantly (p≤ 0.05) reduced methylparaoxon- induced mortality, when given prophylactically. Pretreatment with pyridostigmine, ranitidine, tiapride, amiloride, metoclopramide and methylene blue did not significantly protect against the lethal effects of methyl-paraoxon. 7-methoxytacrine (7-MEOTA) significantly (p≤ 0.05) increased the relative risk of methyl-paraoxon-induced death (RR=1.31). These results indicate that pretreatment with pyridostigmine cannot be considered a broad-spectrum approach against OPC exposure. K-27 may be a suitable alternative if passage into the brain is contraindicated.


Assuntos
Inibidores da Colinesterase/administração & dosagem , Fármacos Neuroprotetores/administração & dosagem , Organofosfatos/toxicidade , Paraoxon/análogos & derivados , Animais , Dose Letal Mediana , Masculino , Mortalidade/tendências , Organofosfatos/administração & dosagem , Organofosfatos/antagonistas & inibidores , Paraoxon/administração & dosagem , Paraoxon/antagonistas & inibidores , Paraoxon/toxicidade , Ratos , Ratos Wistar , Fatores de Tempo
11.
Brain Behav Immun ; 26(1): 159-69, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21925261

RESUMO

Accidental organophosphate poisoning resulting from environmental or occupational exposure, as well as the deliberate use of nerve agents on the battlefield or by terrorists, remain major threats for multi-casualty events, with no effective therapies yet available. Even transient exposure to organophosphorous compounds may lead to brain damage associated with microglial activation and to long-lasting neurological and psychological deficits. Regulation of the microglial response by adaptive immunity was previously shown to reduce the consequences of acute insult to the central nervous system (CNS). Here, we tested whether an immunization-based treatment that affects the properties of T regulatory cells (Tregs) can reduce brain damage following organophosphate intoxication, as a supplement to the standard antidotal protocol. Rats were intoxicated by acute exposure to the nerve agent soman, or the organophosphate pesticide, paraoxon, and after 24 h were treated with the immunomodulator, poly-YE. A single injection of poly-YE resulted in a significant increase in neuronal survival and tissue preservation. The beneficial effect of poly-YE treatment was associated with specific recruitment of CD4(+) T cells into the brain, reduced microglial activation, and an increase in the levels of brain derived neurotrophic factor (BDNF) in the piriform cortex. These results suggest therapeutic intervention with poly-YE as an immunomodulatory supplementary approach against consequences of organophosphate-induced brain damage.


Assuntos
Encefalopatias/induzido quimicamente , Encefalopatias/tratamento farmacológico , Substâncias para a Guerra Química/toxicidade , Inibidores da Colinesterase/toxicidade , Fatores Imunológicos/farmacologia , Fármacos Neuroprotetores/farmacologia , Compostos Organofosforados/toxicidade , Peptídeos/farmacologia , Animais , Encéfalo/patologia , Encefalopatias/patologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Linfócitos T CD4-Positivos/efeitos dos fármacos , Proliferação de Células , Citometria de Fluxo , Processamento de Imagem Assistida por Computador , Imuno-Histoquímica , Imageamento por Ressonância Magnética , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Atividade Motora/efeitos dos fármacos , Paraoxon/antagonistas & inibidores , Paraoxon/toxicidade , Ratos , Ratos Sprague-Dawley , Soman/antagonistas & inibidores , Soman/toxicidade , Linfócitos T/efeitos dos fármacos
12.
Am J Emerg Med ; 30(6): 901-7, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21871755

RESUMO

OBJECTIVE: The composite effects of organophosphorus (OP)-cholinesterase (ChE) inhibitors and oximes on the actions of nondepolarizing neuromuscular blockers in acute OP-ChE inhibitor intoxication have not been evaluated in detail. We investigated the effects of paraoxon (Pox) (an OP-ChE inhibitor) and pralidoxime (PAM) (an oxime) on the nondepolarizing neuromuscular blocking action of rocuronium. METHODS: Isometric twitch tensions of rat left phrenic nerve-hemidiaphragm preparations elicited by indirect (phrenic nerve) supramaximal stimulation at 0.1 Hz were evaluated. Analysis of variance with post hoc testing was used for statistical comparison, and P < .05 was accepted as significant. RESULTS: Rocuronium reduced the indirectly elicited twitch tensions in normal (50% inhibitory concentration [IC(50)], 9.84 [9.64-10.04] µM, mean [95% confidence interval]) and all pretreated diaphragms (P < .01, n = 6) in a concentration-dependent fashion. Paraoxon caused a rightward shift in the rocuronium concentration-twitch tension curve (IC(50), 15.48 [15.24-15.72] µM). The rightward shift was completely inhibited by previous copretreatment (IC(50), 9.98 [9.77-10.20] µM) and partially inhibited by simultaneous copretreatment (IC(50), 11.68 [11.45-11.91] µM) with PAM but was not inhibited by subsequent copretreatment (IC(50), 13.69 [13.39-13.99] µM) with PAM (P < .01, n = 6). Atropine did not influence the rightward shift (P < .01, n = 6). DISCUSSION: Paraoxon depressed rocuronium-induced neuromuscular block by inhibiting ChEs, and the action of Pox was inhibited by PAM. Pralidoxime acts more intensely when applied earlier. The time-dependent effect of PAM indicates that the preceding presence of PAM in proximity to ChEs before Pox is necessary for definite suppression of the Pox-induced ChE inhibition.


Assuntos
Androstanóis/antagonistas & inibidores , Inibidores da Colinesterase/farmacologia , Reativadores da Colinesterase/farmacologia , Fármacos Neuromusculares não Despolarizantes/antagonistas & inibidores , Paraoxon/farmacologia , Compostos de Pralidoxima/farmacologia , Androstanóis/farmacologia , Animais , Diafragma/efeitos dos fármacos , Diafragma/fisiologia , Relação Dose-Resposta a Droga , Interações Medicamentosas , Masculino , Fármacos Neuromusculares não Despolarizantes/farmacologia , Paraoxon/antagonistas & inibidores , Nervo Frênico/efeitos dos fármacos , Nervo Frênico/fisiologia , Ratos , Ratos Wistar , Rocurônio , Fatores de Tempo
13.
Toxicol In Vitro ; 25(1): 301-7, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20888407

RESUMO

Although organophosphate (OP)-induced acetylcholinesterase (AChE) inhibition is the critical mechanism causing toxicities that follow exposure, other biochemical events, including oxidative stress, have been reported to contribute to OP toxicity. Fullerenes are carbon spheres with antioxidant activity. Thus, we hypothesized that fullerenes could counteract the effects of OP compounds and tested this hypothesis using two in vitro test systems, hen brain and human neuroblastoma SH-SY5Y cells. Cells were incubated with eight different derivatized fullerene compounds before challenge with paraoxon (0=control, 5×10(-8), 10(-7), 2×10(-7) or 5×10(-7) M) or diisopropylphosphorofluoridate (DFP, 0=control, 5×10(-6), 10(-5), 2×10(-5), and 5×10(-5) M) and measurement of AChE activities. Activities of brain and SH-SY5Y AChE with OP compounds alone ranged from 55-83% lower than non-treated controls after paraoxon and from 60-92% lower than non-treated controls after DFP. Most incubations containing 1 and 10 µM fullerene derivatives brought AChE activity closer to untreated controls, with improvements in AChE activity often >20%. Using dissipation of superoxide anion radicals as an indicator (xanthine oxidation as a positive control), all fullerene derivatives demonstrated significant antioxidant capability in neuroblastoma cells at 1 µM concentrations. No fullerene derivative at 1 µM significantly affected neuroblastoma cell viability, when determined using either Alamar Blue dye retention or a luminescent assay for ATP production. These studies suggest that derivatized fullerene nanomaterials have potential capability to ameliorate OP-induced AChE inhibition resulting in toxicities.


Assuntos
Acetilcolinesterase/metabolismo , Antioxidantes/farmacologia , Inibidores da Colinesterase , Reativadores da Colinesterase/farmacologia , Fulerenos/farmacologia , Organofosfatos/antagonistas & inibidores , Animais , Antioxidantes/química , Antioxidantes/toxicidade , Encéfalo/citologia , Encéfalo/enzimologia , Encéfalo/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Galinhas , Inibidores da Colinesterase/toxicidade , Reativadores da Colinesterase/química , Reativadores da Colinesterase/toxicidade , Embrião de Mamíferos , Fulerenos/química , Fulerenos/toxicidade , Humanos , Isoflurofato/antagonistas & inibidores , Isoflurofato/toxicidade , Camundongos , Neuroblastoma , Neurônios/enzimologia , Neurônios/metabolismo , Organofosfatos/toxicidade , Paraoxon/antagonistas & inibidores , Paraoxon/toxicidade , Superóxidos/metabolismo
14.
Bioorg Med Chem ; 16(17): 8218-23, 2008 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-18676153

RESUMO

Acetylcholinesterase reactivators are crucial antidotes for the treatment of organophosphate intoxication. Eighteen monoquaternary reactivators of acetylcholinesterase with modified side chain were developed in an effort to extend the properties of pralidoxime. The known reactivators (pralidoxime, HI-6, obidoxime, trimedoxime, methoxime) and the prepared compounds were tested in vitro on a model of tabun- and paraoxon-inhibited AChE. Monoquaternary reactivators were not able to exceed the best known compounds for tabun poisoning, but some of them did show reactivation better or comparable with pralidoxime for paraoxon poisoning. However, extensive differences were found by a SAR study for various side chains on the non-oxime part of the reactivator molecule.


Assuntos
Acetilcolinesterase/efeitos dos fármacos , Ativadores de Enzimas/farmacologia , Modelos Biológicos , Organofosfatos/antagonistas & inibidores , Paraoxon/antagonistas & inibidores , Compostos de Piridínio/farmacologia , Acetilcolinesterase/química , Animais , Encéfalo/enzimologia , Inibidores da Colinesterase/farmacologia , Relação Dose-Resposta a Droga , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Ativação Enzimática/efeitos dos fármacos , Ativadores de Enzimas/síntese química , Ativadores de Enzimas/química , Estrutura Molecular , Organofosfatos/farmacologia , Paraoxon/farmacologia , Compostos de Piridínio/síntese química , Compostos de Piridínio/química , Ratos , Estereoisomerismo , Relação Estrutura-Atividade
15.
Bioorg Med Chem ; 15(21): 6733-41, 2007 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-17764957

RESUMO

Acetylcholinesterase reactivators are crucial antidotes for the treatment of organophosphate intoxication. Fifteen new monooxime reactivators of acetylcholinesterase with a (E)-but-2-ene linker were developed in an effort to extend the properties of K-oxime (E)-1-(4-carbamoylpyridinium)-4-(4-hydroxyiminomethylpyridinium)-but-2-ene dibromide (K203). The known reactivators (pralidoxime, HI-6, obidoxime, K075, K203) and the new compounds were tested in vitro on a model of tabun- and paraoxon-inhibited AChE. Monooxime reactivators were not able to exceed the best known compounds for tabun poisoning, but some of them did show reactivation comparable with known compounds for paraoxon poisoning. However, extensive differences were found by a SAR study for various substitutions on the non-oxime part of the reactivator molecule.


Assuntos
Acetilcolinesterase/efeitos dos fármacos , Antídotos/química , Antídotos/farmacologia , Reativadores da Colinesterase/química , Reativadores da Colinesterase/farmacologia , Oximas/química , Oximas/farmacologia , Animais , Antídotos/síntese química , Inibidores da Colinesterase/intoxicação , Reativadores da Colinesterase/síntese química , Desenho de Fármacos , Organofosfatos/antagonistas & inibidores , Organofosfatos/farmacologia , Oximas/síntese química , Paraoxon/antagonistas & inibidores , Paraoxon/farmacologia , Ratos , Relação Estrutura-Atividade
16.
Bioorg Med Chem Lett ; 17(11): 3172-6, 2007 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-17383875

RESUMO

Six novel AChE reactivators with a (Z)-but-2-ene linker were synthesized using the known synthetic pathways. Their ability to reactivate AChE, which had been previously inhibited by nerve agent tabun or pesticide paraoxon, was tested in vitro and compared to pralidoxime, HI-6, obidoxime, and K075. The novel synthesized compounds were found to be ineffective against GA-inhibited AChE but the ability of (Z)-1,4-bis(4-hydroxyiminomethylpyridinium)-but-2-ene dibromide to reactivate paraoxon-inhibited AChE was comparable with that of oxime K075. Notably, the oxime group in position four substantially increased the ability of the novel compounds to reactivate paraoxon-inhibited AChE.


Assuntos
Inibidores da Colinesterase/farmacologia , Reativadores da Colinesterase/química , Reativadores da Colinesterase/farmacologia , Organofosfatos/antagonistas & inibidores , Oximas/química , Oximas/farmacologia , Paraoxon/antagonistas & inibidores , Compostos de Piridínio/química , Compostos de Piridínio/farmacologia , Acetilcolinesterase/efeitos dos fármacos , Butanos/farmacologia , Reativadores da Colinesterase/síntese química , Humanos , Organofosfatos/farmacologia , Oximas/síntese química , Paraoxon/farmacologia , Compostos de Piridínio/síntese química
17.
Bioorg Med Chem Lett ; 15(19): 4304-7, 2005 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-16046128

RESUMO

A squaric monoester monoamide motif was employed as an effective reactive immunogen for the discovery of monoclonal antibodies with reactive residue(s) in their combining sites. Two antibodies, 2D4 and 3C8, were uncovered that enhance paraoxon hydrolysis over background. Kinetic analysis of these antibodies was performed and interestingly both undergo a single turnover event due to covalent modification within the antibody combining site. Because antibodies 2D4 and 3C8 result in covalent attachment and thus inactivation of paraoxon, they could be useful probes for investigating paraoxon intoxication.


Assuntos
Anticorpos Catalíticos/farmacologia , Ciclobutanos/imunologia , Haptenos/química , Paraoxon/imunologia , Vacinação , Amidas , Animais , Anticorpos Catalíticos/biossíntese , Sítios de Ligação de Anticorpos , Ciclobutanos/administração & dosagem , Ciclobutanos/síntese química , Ésteres , Haptenos/administração & dosagem , Haptenos/imunologia , Hidrólise , Cinética , Camundongos , Camundongos Endogâmicos BALB C , Paraoxon/antagonistas & inibidores , Paraoxon/química , Praguicidas/antagonistas & inibidores , Praguicidas/química , Praguicidas/imunologia , Relação Estrutura-Atividade
18.
Toxicol Sci ; 78(2): 241-7, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-14976354

RESUMO

The effect of the organophosphorous insecticide paraoxon on the integrity of the blood-brain barrier (BBB) and permeability of pyridostigmine (PYR), a peripheral inhibitor of cholinesterase activity, was examined in Long Evans rats. The integrity of the BBB was examined by measuring the number of capillaries leaking horseradish peroxidase, which was injected into the heart. Treatment with paraoxon at 100 microg/kg, intramuscularly, resulted in a 3- to 4-fold increase in the number of leaky capillaries in young rats (25 to 30 days old) but not in older rats (90 days old). Interestingly, young rats treated with PYR (30 mg/kg, po) 50 min before treatment with paraoxon showed an inhibited effect of paraoxon on the BBB. Furthermore, no increase in the degree of inhibition of acetylcholinesterase activity was observed in young rats treated with PYR before paraoxon compared with young rats treated with paraoxon alone. Cholinergic toxicity, as assessed by changes in behavior, was not observed in young rats treated with paraoxon alone; but, slight signs of cholinergic toxicity were observed in rats treated with PYR. Young rats treated with both PYR and paraoxon did not exhibit more extensive signs of toxicity than rats treated with paraoxon alone or PYR alone. The results indicate that treatment with paraoxon can compromise BBB permeability at dosages that do not induce cholinergic toxicity, but only in young rats. Also, PYR pre-exposure appears to protect the BBB from the paraoxon-induced alterations.


Assuntos
Comportamento Animal/efeitos dos fármacos , Barreira Hematoencefálica/efeitos dos fármacos , Inibidores da Colinesterase/farmacologia , Inseticidas/toxicidade , Paraoxon/toxicidade , Brometo de Piridostigmina/farmacologia , Fatores Etários , Animais , Barreira Hematoencefálica/metabolismo , Encéfalo/enzimologia , Encéfalo/metabolismo , Capilares/efeitos dos fármacos , Capilares/enzimologia , Capilares/fisiopatologia , Inibidores da Colinesterase/metabolismo , Colinesterases/análise , Colinesterases/metabolismo , Interações Medicamentosas , Peroxidase do Rábano Silvestre/administração & dosagem , Peroxidase do Rábano Silvestre/análise , Humanos , Masculino , Paraoxon/antagonistas & inibidores , Síndrome do Golfo Pérsico/etiologia , Síndrome do Golfo Pérsico/metabolismo , Brometo de Piridostigmina/metabolismo , Ratos , Ratos Long-Evans
19.
Toxicol Appl Pharmacol ; 156(1): 56-63, 1999 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-10101099

RESUMO

This investigation effort is focused on increasing organophosphate (OP) degradation by phosphotriesterase to antagonize OP intoxication. For these studies, sterically stabilized liposomes encapsulating recombinant phosphotriesterase were employed. This enzyme was obtained from Flavobacterium sp. and was expressed in Escherichia coli. It has a broad substrate specificity, which includes parathion, paraoxon, soman, sarin, diisopropylfluorophosphate, and other organophosphorous compounds. Paraoxon is rapidly hydrolyzed by phosphotriesterase to the less toxic 4-nitrophenol and diethylphosphate. This enzyme was isolated and purified over 1600-fold and subsequently encapsulated within sterically stabilized liposomes (SL). The properties of this encapsulated phosphotriesterase were investigated. When these liposomes containing phosphotriesterase were incubated with paraoxon, it readily degraded the paraoxon. Hydrolysis of paraoxon did not occur when these sterically stabilized liposomes contained no phosphotriesterase. These sterically stabilized liposomes (SL) containing phosphotriesterases (SL)* were employed as a carrier model to antagonize the toxic effects of paraoxon by hydrolyzing it to the less toxic 4-nitrophenol and diethylphosphate. This enzyme-SL complex (SL)* was administered intravenously to mice either alone or in combination with pralidoxime (2-PAM) and/or atropine intraperitoneally. These results indicate that this carrier model system provides a striking enhanced protective effects against the lethal effects of paraoxon. Moreover when these carrier liposomes were administered with 2-PAM and/or atropine, a dramatic enhanced protection was observed.


Assuntos
Esterases/administração & dosagem , Inseticidas/intoxicação , Paraoxon/intoxicação , Animais , Arildialquilfosfatase , Portadores de Fármacos , Ponto Isoelétrico , Lipossomos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Paraoxon/antagonistas & inibidores , Compostos de Pralidoxima/farmacologia , Proteínas Recombinantes/administração & dosagem
20.
Neurotoxicology ; 19(6): 833-8, 1998 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9863772

RESUMO

Acute organophosphorus anticholinesterase poisoning induces a necrotizing end-plate myopathy in rats and patients. Acetylcholine (ACh) excess leads to prolonged synaptic currents and increased influx of cations including calcium through the postsynaptic ACh receptor channels with prolonged muscle membrane depolarization, excess calcium influx into the sarcoplasm, and ultimately muscle fiber necrosis. Quinoline derivatives such as quinidine induce or worsen pre- and postsynaptic disorders of neuromuscular transmission in humans, and are beneficial in patients suffering from a rare congenital myasthenic syndrome called the slow channel congenital myasthenic syndrome. These drugs correct the prolonged opening times of the mutated acetylcholine receptor channels in this myasthenic syndrome. We treated paraoxon-poisoned rats with 4 x 10 or 4 x 50 mg/kg of quinidine and assessed the severity of the necrotizing myopathy in gastrocnemius and diaphragm muscle biopsies. Fasciculations were decreased and the necrotizing myopathy was prevented in most treated rats, with absence of necrotic muscle fibers in most animals in the high-dose group. Survival was not different from untreated poisoned animals. A number of physiological mechanisms, including blocking of presynaptic voltage-gated sodium or calcium channels or inhibition of the postsynaptic ACh receptors channels may have contributed to the attenuation of the myonecrosis. The optimal dose and the drug of choice amongst the clinically available quinoline derivatives remains to be determined.


Assuntos
Inibidores da Colinesterase/intoxicação , Inseticidas/intoxicação , Doenças Musculares/prevenção & controle , Paraoxon/intoxicação , Quinidina/uso terapêutico , Animais , Biópsia , Inseticidas/antagonistas & inibidores , Masculino , Fibras Musculares Esqueléticas/patologia , Doenças Musculares/induzido quimicamente , Doenças Musculares/patologia , Necrose , Paraoxon/antagonistas & inibidores , Ratos , Ratos Wistar
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