The fluorinated bis-pyridinium oximes were designed and synthesized with the aim of increasing their nucleophilicity and potential to reactivate phosphorylated human recombinant acetylcholinesterase (AChE) and human purified plasmatic butyrylcholinesterase (BChE) in relation to chlorinated and non-halogenated oxime analogues. Compared to non-halogenated oximes, halogenated oximes showed lower pKa of the oxime group (fluorinated < chlorinated < non-halogenated) along with higher level of oximate anion formation at the physiological pH, and had a higher binding affinity of both AChE and BChE. The stability tests showed that the fluorinated oximes were stable in water, while in buffered environment di-fluorinated oximes were prone to rapid degradation, which was reflected in their lower reactivation ability. Mono-fluorinated oximes showed comparable reactivation to non-halogenated (except asoxime) and mono-chlorinated oximes in case of AChE inhibited by sarin, cyclosarin, VX, and tabun, but were less efficient than di-chlorinated ones. The same trend was observed in the reactivation of inhibited BChE. The advantage of halogen substituents in the stabilization of oxime in a position optimal for in-line nucleophilic attack were confirmed by extensive molecular modelling of pre-reactivation complexes between the analogue oximes and phosphorylated AChE and BChE. Halogen substitution was shown to provide oximes with additional beneficial properties, e.g., fluorinated oximes gained antioxidative capacity, and moreover, halogens themselves did not increase cytotoxicity of oximes. Finally, the in vivo administration of highly efficient reactivator and the most promising analogue, 3,5-di-chloro-bispyridinium oxime with trimethylene linker, provided significant protection of mice exposed to sarin and cyclosarin.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- butyrylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory chemie MeSH
- halogeny MeSH
- myši MeSH
- nervová bojová látka * farmakologie MeSH
- organofosforové sloučeniny MeSH
- oximy chemie MeSH
- reaktivátory cholinesterasy * chemie MeSH
- sarin chemie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Oxime-based molecules are used for the treatment of patients to reactivate acetylcholinesterase (AChE) function after organophosphate intoxication. However, their efficacy is limited by low penetration through the blood-brain barrier and fast elimination. In this work, the cucurbit[7]uril (CB[7]) carrier was used for the encapsulation of the clinical agent asoxime to enhance brain bioavailability and the treatment window. We present a pharmacokinetic study of asoxime and the asoxime-CB[7] complex in an in vivo mouse model. Ultrahigh-performance liquid chromatography with electrospray ionization-mass spectrometry detection was developed to determine asoxime and CB[7] in biological fluids and tissues after thorough optimization of chromatographic conditions. The dihydroxypropane-silica stationary phase using hydrophilic interaction liquid chromatography conditions provided the best chromatographic performance. The final method was validated and applied for the pharmacokinetic study of mouse plasma, urine, bile, liver, kidney, and brain samples at different times after administration of asoxime and the asoxime-CB[7] complex. The results showed a greater than 3-fold increase in the area under the curve (AUC) in the brain for asoxime administered as a complex with CB[7] relative to that for the administration of asoxime alone. The effectiveness of the treatment strategy was evaluated using a reactivation study and a functional observatory battery. Protection of brain AChE activity is crucial for saving human lives or reducing the consequences of poisoning. The asoxime administered as a complex increased the brain activity by approximately 30% compared to that with atropine alone. CB[7] coadministration improved the AChE activity by 11%, which agrees with the higher asoxime AUC assessed in the pharmacokinetic study.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory aplikace a dávkování toxicita MeSH
- enzymatické testy MeSH
- hematoencefalická bariéra metabolismus MeSH
- hmotnostní spektrometrie MeSH
- hydrofobní a hydrofilní interakce MeSH
- imidazoly chemie MeSH
- lidé MeSH
- modely nemocí na zvířatech MeSH
- myši MeSH
- nosiče léků chemie MeSH
- otrava organofosfáty farmakoterapie MeSH
- oximy aplikace a dávkování farmakokinetika MeSH
- plocha pod křivkou MeSH
- přemostěné cyklické sloučeniny chemie MeSH
- pyridinové sloučeniny aplikace a dávkování farmakokinetika MeSH
- reaktivátory cholinesterasy aplikace a dávkování farmakokinetika MeSH
- sarin aplikace a dávkování toxicita MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Poisoning with organophosphorus compounds used as pesticides or misused as chemical weapons remains a serious threat to human health and life. Their toxic effects result from irreversible blockade of the enzymes acetylcholinesterase and butyrylcholinesterase, which causes overstimulation of the cholinergic system and often leads to serious injury or death. Treatment of organophosphorus poisoning involves, among other strategies, the administration of oxime compounds. Oximes reactivate cholinesterases by breaking the covalent bond between the serine residue from the enzyme active site and the phosphorus atom of the organophosphorus compound. Although the general mechanism of reactivation has been known for years, the exact molecular aspects determining the efficiency and selectivity of individual oximes are still not clear. This hinders the development of new active compounds. In our research, using relatively simple and widely available molecular docking methods, we investigated the reactivation of acetyl- and butyrylcholinesterase blocked by sarin and tabun. For the selected oximes, their binding modes at each step of the reactivation process were identified. Amino acids essential for effective reactivation and those responsible for the selectivity of individual oximes against inhibited acetyl- and butyrylcholinesterase were identified. This research broadens the knowledge about cholinesterase reactivation and demonstrates the usefulness of molecular docking in the study of this process. The presented observations and methods can be used in the future to support the search for new effective reactivators.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- aktivace enzymů MeSH
- butyrylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory farmakologie MeSH
- fosfor chemie MeSH
- katalytická doména MeSH
- konformace proteinů MeSH
- kvantová teorie MeSH
- lidé MeSH
- ligandy MeSH
- molekulární modely MeSH
- myši MeSH
- organofosfáty chemie MeSH
- oximy chemie MeSH
- proteosyntéza MeSH
- reaktivátory cholinesterasy farmakologie MeSH
- sarin chemie MeSH
- shluková analýza MeSH
- simulace molekulového dockingu * MeSH
- vazba proteinů MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Therapeutic efficacy of antidotal treatment of acute poisoning by nerve agents is generally assessed by the evaluation of LD50 values of nerve agents over 24 h following poisoning without or with a single administration of antidotal treatment. In this study, LD50 values of four nerve agents (sarin, soman, tabun and cyclosarin) for non-treated and treated poisoning were evaluated in mice for two experimental end points - 6 h and 24 h. While the efficacy of atropine or oxime-based antidotal treatment was the same regardless of the experimental end point, the therapeutic efficacy of all three newly developed bispyridinium non-oxime compounds (MB408, MB442, and MB444) was mostly slightly higher at the 6 h end point compared to the 24 h end point, although the therapeutic efficacy of MB compounds was not superior to oxime-based antidotal treatment. These results contrast with a study in guinea-pigs using a structurally-related compound, MB327, which showed a striking increase in protection at 6 h compared to 24 h. It is suggested that the disparity may be due to pharmacokinetic differences between the two animal species.
- MeSH
- antidota farmakologie MeSH
- časové faktory MeSH
- chemické bojové látky toxicita MeSH
- LD50 MeSH
- myši MeSH
- nikotinoví antagonisté farmakologie MeSH
- organofosfáty toxicita MeSH
- organofosforové sloučeniny toxicita MeSH
- otrava organofosfáty farmakoterapie etiologie MeSH
- oximy farmakologie MeSH
- pyridinové sloučeniny farmakologie MeSH
- reaktivátory cholinesterasy farmakologie MeSH
- sarin toxicita MeSH
- soman toxicita MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
The enantiomers of racemic 2-hydroxyimino-N-(azidophenylpropyl)acetamide-derived triple-binding oxime reactivators were separated, and tested for inhibition and reactivation of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibited with tabun (GA), cyclosarin (GF), sarin (GB), and VX. Both enzymes showed the greatest affinity toward the methylimidazole derivative (III) of 2-hydroxyimino-N-(azidophenylpropyl)acetamide (I). The crystal structure was determined for the complex of oxime III within human BChE, confirming that all three binding groups interacted with active site residues. In the case of BChE inhibited by GF, oximes I (kr = 207 M-1 min-1) and III (kr = 213 M-1 min-1) showed better reactivation efficiency than the reference oxime 2-PAM. Finally, the key mechanistic steps in the reactivation of GF-inhibited BChE with oxime III were modeled using the PM7R6 method, stressing the importance of proton transfer from Nε of His438 to Oγ of Ser203 for achieving successful reactivation.
- MeSH
- acetylcholinesterasa chemie metabolismus MeSH
- aktivace enzymů účinky léků MeSH
- butyrylcholinesterasa chemie metabolismus MeSH
- cholinesterasové inhibitory farmakologie MeSH
- katalytická doména MeSH
- kinetika MeSH
- krystalografie rentgenová MeSH
- lidé MeSH
- organofosfáty farmakologie MeSH
- organofosforové sloučeniny farmakologie MeSH
- oximy chemie izolace a purifikace metabolismus farmakologie MeSH
- sarin farmakologie MeSH
- stereoizomerie MeSH
- techniky in vitro MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Organophosphorus compounds have been widely employed to the development of warfare nerve agents and pesticides, resulting in a huge number of people intoxicated annually, being a serious problem of public health. Efforts worldwide have been done in order to design new technologies that are capable of combating or even reversing the poisoning caused by these OP nerve agents. In this line, the bioremediation arises as a promising and efficient alternative for this purpose. As an example of degrading enzymes, there is the organophosphate-degrading (OpdA) enzyme from Agrobacterium radiobacter, which has been quite investigated experimentally due to its high performance in the degradation of neurotoxic nerve agents. This work aims to look into the structural and electronic details that govern the interaction modes of these compounds in the OpdA active site, with the posterior hydrolysis reaction prediction. Our findings have brought about data about the OpdA performance towards different nerve agents, and among them, we may realize that the degradation efficiency strongly depends on the nerve agent structure and its stereochemistry, being in this case the compound Tabun the one more effectively hydrolyzed. By means of the chemical bonds (AIM) and orbitals (FERMO) analysis, it is suggested that the initial reactivity of the OP nerve agents in the OpdA active site does not necessarily dictate the reactivity and interaction modes over the reaction coordinate.
- MeSH
- Agrobacterium tumefaciens enzymologie MeSH
- bakteriální proteiny chemie metabolismus MeSH
- biodegradace * MeSH
- biokatalýza MeSH
- fosfatasy chemie metabolismus MeSH
- katalytická doména MeSH
- kvantová teorie MeSH
- lidé MeSH
- nervová bojová látka chemie metabolismus MeSH
- sarin chemie metabolismus MeSH
- simulace molekulového dockingu MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The potency of three nerve agents (sarin, soman, tabun) to induce oxidative damage of DNA in lymphocytes, liver and brain during lethal or sublethal poisoning was investigated. The single strand breaks or oxidative base DNA damage was evaluated with the help of Comet assay and a specific enzyme able to detect oxidative bases of DNA (endonuclease III). While sarin and soman administered at sublethal doses corresponding to 50% of their LD50 values were not able to induce oxidative damage of DNA, their lethal dose (LD50) induced the significant increase of the number of oxidative bases in DNA of hepatocytes. In addition, tabun administered at lethal dose (LD50) induced significant increase of the number of single strand breaks and oxidative bases of DNA in glial cells isolated from pontomedullar brain region. Thus, some nerve agents were able to induce oxidative damage in the peripheral as well as central compartment but only in the case of severe poisoning caused by lethal doses of nerve agents. This non-cholinergic effect of nerve agents has probably consequences with nerve agents-induced hypoxic status during acute cholinergic crisis and it can contribute to their long-term toxic effects.
Bispyridinium oximes with one (K865, K866, K867) or two (K868, K869, K870) ortho-positioned chlorine moiety, analogous to previously known K027, K048 and K203 oximes, and potent reactivators of human acetylcholinesterase (AChE) inhibited by nerve agents, were tested in the reactivation of human butyrylcholinesterase (BChE) inhibited by sarin, cyclosarin, VX, and tabun. A previously highlighted AChE reactivator, dichlorinated bispyridinium oxime with propyl linker (K868), was tested in more detail for reactivation of four nerve agent-BChE conjugates. Its BChE reactivation potency was showed to be promising when compared to the standard oximes used in medical practice, asoxime (HI-6) and pralidoxime (2-PAM), especially in case of sarin and tabun. This finding could be used in the pseudo-catalytic scavenging of the most nerve agents due to its cumulative capacity to reactivate both AChE and BChE.
- MeSH
- aktivace enzymů účinky léků MeSH
- butyrylcholinesterasa chemie metabolismus MeSH
- cholinesterasové inhibitory chemie metabolismus MeSH
- halogenace MeSH
- kinetika MeSH
- lidé MeSH
- nervová bojová látka chemie metabolismus MeSH
- oximy chemie metabolismus farmakologie MeSH
- pyridinové sloučeniny chemie MeSH
- sarin chemie metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Organophosphorus compounds (OP) nerve agents are among the most toxic chemical substances known. Their toxicity is due to their ability to bind to acetylcholinesterase. Currently, some enzymes, such as phosphotriesterase, human serum paraoxonase 1 and diisopropyl fluorophosphatase, capable of degrading OP, have been characterized. Regarding the importance of bioremediation methods for detoxication of OP, this work aims to study the interaction modes between the human human deoxyuridine triphosphate nucleotidohydrolase (dUTPase) and Sarin and VX, considering their Rp and Sp enantiomers, to evaluate the asymmetric catalysis of those compounds. In previous work, this enzyme has shown good potential to degrade phosphotriesters, and based on this characteristic, we have applied the human dUTPase to the OP degradation. Molecular docking, chemometrics and mixed quantum and molecular mechanics calculations have been employed, showing a good interaction between dUTPase and OP. Two possible reaction mechanisms were tested, and according to our theoretical results, the catalytic degradation of OP by dUTPase can take place via both mechanisms, beyond being stereoselective, that is, dUTPase cleaves one enantiomer preferentially in relation to other. Chemometric techniques provided excellent assistance for performing this theoretical investigation. The dUTPase study shows importance by the fact of it being a human enzyme. Communicated by Ramaswamy H. Sarma.
- MeSH
- analýza hlavních komponent MeSH
- biodegradace MeSH
- katalytická doména MeSH
- kvantová teorie * MeSH
- lidé MeSH
- nervová bojová látka chemie metabolismus MeSH
- organofosforové sloučeniny chemie metabolismus MeSH
- organothiofosforové sloučeniny chemie metabolismus MeSH
- pyrofosfatasy metabolismus MeSH
- sarin chemie metabolismus MeSH
- simulace molekulového dockingu * MeSH
- vodíková vazba MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The oximes 4-carbamoyl-1-[({2-[(E)-(hydroxyimino) methyl] pyridinium-1-yl} methoxy) methyl] pyridinium (known as HI-6) and 3-carbamoyl-1-[({2-[(E)-(hydroxyimino) methyl] pyridinium-1-yl} methoxy) methyl] pyridinium (known as HS-6) are isomers differing from each other only by the position of the carbamoyl group on the pyridine ring. However, this slight difference was verified to be responsible for big differences in the percentual of reactivation of acetylcholinesterase (AChE) inhibited by the nerve agents tabun, sarin, cyclosarin, and VX. In order to try to find out the reason for this, a computational study involving molecular docking, molecular dynamics, and binding energies calculations, was performed on the binding modes of HI-6 and HS-6 on human AChE (HssAChE) inhibited by those nerve agents.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- chemické bojové látky chemie MeSH
- cholinesterasové inhibitory chemie MeSH
- lidé MeSH
- nervová bojová látka chemie MeSH
- organofosfáty chemie MeSH
- organofosforové sloučeniny chemie MeSH
- organothiofosforové sloučeniny chemie MeSH
- oximy metabolismus MeSH
- pralidoximové sloučeniny metabolismus MeSH
- pyridinové sloučeniny metabolismus MeSH
- sarin chemie MeSH
- simulace molekulární dynamiky MeSH
- simulace molekulového dockingu MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
