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
Butyryl cholinesterase (BChE) has been seen as a key enzyme in the search for new strategies in the treatment of poisoning by organophosphates (OPs), since human BChE (HssBChE), complexed with the appropriate oxime, can be a suitable scavenger and deactivator for OPs in the blood stream. However, the efficacy of HssBChE is limited by its strict stoichiometric scavenging, slow reactivation, and propensity for aging. The improvement of the reactivation rate by new and more efficient oximes could contribute to mitigate this problem and increase the HssBChE efficiency as scavenger. Several oximes have been synthesized and tested with this goal, some with promising results, but the mechanistic aspects of the reactivation reaction are not fully understood yet. In order to better investigate this mechanism, docking and mixed quantum and molecular mechanics combined with principal components analysis were performed here to evaluate the capacity of reactivation and determine the preferred route for the reactivation reaction of two new oximes on HssBChE inhibited by the neurotoxic agents cyclosarin and sarin. Plots of potential energies were calculated and all the transition states of the reactional mechanism were determined. Our results showed a good correlation with experimental data and pointed to the most efficient oxime with both OPs. The protocol used could be a suitable tool for a preliminary evaluation of the HssBChE reactivation rates by new oximes.
- MeSH
- butyrylcholinesterasa chemie MeSH
- chemické modely MeSH
- cholinesterasové inhibitory chemie farmakologie MeSH
- lidé MeSH
- molekulární modely MeSH
- organofosforové sloučeniny chemie farmakologie MeSH
- oximy chemie farmakologie MeSH
- reaktivátory cholinesterázy chemie farmakologie MeSH
- sarin chemie farmakologie MeSH
- vazba proteinů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
In the present work, we performed docking and molecular dynamics simulations studies on two groups of long-tailored oximes designed as peripheral site binders of acetylcholinesterase (AChE) and potential penetrators on the blood brain barrier. Our studies permitted to determine how the tails anchor in the peripheral site of sarin-inhibited human AChE, and which aminoacids are important to their stabilization. Also the energy values obtained in the docking studies corroborated quite well with the experimental results obtained before for these oximes.
- MeSH
- acetylcholinesterasa chemie metabolismus MeSH
- lidé MeSH
- ligandy MeSH
- molekulární konformace MeSH
- oximy chemie farmakologie MeSH
- sarin chemie farmakologie MeSH
- simulace molekulární dynamiky * MeSH
- simulace molekulového dockingu * MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- vodíková vazba MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The cholinesterase biosensors are analytical devices suitable for assay of cholinesterase inhibitors in the course of suppression of the biorecognition element activity. Both acetylcholinesterase and butyrylcholinesterase are used for their assay. The biosensors can be used for assay of organophosphorus and carbamate pesticides, nerve agents, drugs in Alzheimer´s disease and myasthenia treatment. The review summarizes the knowledge of cholinesterases, their immobilization and inhibitors as well as shows examples of their activities.
- MeSH
- acetylcholinesterasa MeSH
- Alzheimerova nemoc MeSH
- biosenzitivní techniky * metody využití MeSH
- butyrylcholinesterasa MeSH
- cholinesterasové inhibitory * MeSH
- dichlorvos * analýza normy MeSH
- karbamáty * farmakologie MeSH
- lidé MeSH
- organofluorofosfonáty * farmakologie MeSH
- reaktivátory cholinesterázy analýza MeSH
- sarin farmakologie MeSH
- Check Tag
- lidé MeSH
The reactivation of organophosphorus compound (OP)-inhibited acetylcholinesterase (AChE) by oximes is inadequate in case of different OP nerve agents. This fact led to the synthesis of numerous novel oximes by different research groups in order to identify more effective reactivators. In the present study, we investigated the reactivation kinetics of a homologous series of bispyridinium bis-oximes bearing a (E)-but-2-ene linker with tabun-, sarin-, and cyclosarin-inhibited human AChE. In part, marked differences in affinity and reactivity of the investigated oximes toward OP-inhibited human AChE were recorded. These properties depended on the position of the oxime groups and the inhibitor. None of the tested oximes was equally effective against all used OPs. In addition, the data indicate that a (E)-but-2-ene linker decreased in most cases the reactivating potency in comparison to oximes bearing an oxybismethylene linker, e.g., obidoxime and HI-6. The results of this study give further insight into structural requirements for oxime reactivators, underline the necessity to investigate the kinetic interactions of oximes and AChE with structurally different OP inhibitors, and point to the difficulty to develop an oxime reactivator which is efficient against a broad spectrum of OPs.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- alkeny chemie MeSH
- cholinesterasové inhibitory farmakologie chemie MeSH
- erytrocytární membrána enzymologie účinky léků MeSH
- GPI-vázané proteiny MeSH
- kinetika MeSH
- lidé MeSH
- molekulární struktura MeSH
- organofosfáty * antagonisté a inhibitory farmakologie MeSH
- organofosforové sloučeniny antagonisté a inhibitory farmakologie MeSH
- oximy farmakokinetika chemie MeSH
- pyridinové sloučeniny farmakologie chemie MeSH
- reaktivátory cholinesterázy farmakologie chemie MeSH
- sarin antagonisté a inhibitory farmakologie MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
Background. Cholinesterases are a group of serine hydrolases that split the neurotransmitter acetylcholine (ACh) and terminate its action. Of the two types, butyrylcholinesterase and acetylcholinesterase (AChE), AChE plays the key role in ending cholinergic neurotransmission. Cholinesterase inhibitors are substances, either natural or man-made that interfere with the break-down of ACh and prolong its action. Hence their relevance to toxicology and pharmacology. Methods and Results. The present review summarizes current knowledge of the cholinesterases and their inhibition. Particular attention is paid to the toxicology and pharmacology of cholinesterase-related inhibitors such as nerve agents (e.g. sarin, soman, tabun, VX), pesticides (e.g. paraoxon, parathion, malathion, malaoxon, carbofuran), selected plants and fungal secondary metabolites (e.g. aflatoxins), drugs for Alzheimer’s disease (e.g. huperzine, metrifonate, tacrine, donepezil) and Myasthenia gravis (e.g. pyridostigmine) treatment and other compounds (propidium, ethidium, decamethonium). Conclusions. The crucial role of the cholinesterases in neural transmission makes them a primary target of a large number of cholinesterase-inhibiting drugs and toxins. In pharmacology, this has relevance to the treatment of neurodegenerative disorders.
- MeSH
- acetylcholinesterasa farmakologie metabolismus MeSH
- Alzheimerova nemoc enzymologie farmakoterapie metabolismus MeSH
- butyrylcholinesterasa farmakologie metabolismus MeSH
- cholinesterasové inhibitory farmakologie terapeutické užití toxicita MeSH
- cholinesterasy farmakologie metabolismus MeSH
- molekulární struktura MeSH
- myasthenia gravis enzymologie farmakoterapie metabolismus MeSH
- organofosforové sloučeniny toxicita MeSH
- sarin farmakologie toxicita MeSH
- vazebná místa účinky léků MeSH
- vztahy mezi strukturou a aktivitou MeSH
The potency of currently used oximes to reactivate sarin-inhibited acetylcholinesterase (AChE) in various parts of pig brain and whole pig brain was evaluated using in vitro methods. Significant differences in reactivation potency among all tested oximes were observed. At concentrations (10(-4) M) corresponding to recommended doses in vivo, the oxime HI-6 seems to be a more efficacious reactivator of sarin-inhibited AChE in whole pig brain as well as in cerebral hemispheres and cerebellum compared with the other oximes studied. Nevertheless, there are not any differences in the potency of oximes tested to reactivate sarin-inhibited AChE in medulla oblongata. Thus, the oxime HI-6 appears to be the most promising oxime among currently available oximes for the antidotal treatment of acute sarin poisoning, although it is not more efficacious than other currently used oximes in medulla oblongata, whose function is necessary for the vital functions of respiration and circulation.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory farmakologie MeSH
- kinetika MeSH
- mozek enzymologie účinky léků MeSH
- obidoxim chlorid farmakologie MeSH
- pralidoximové sloučeniny farmakologie MeSH
- prasata MeSH
- pyridinové sloučeniny farmakologie MeSH
- reaktivátory cholinesterázy farmakologie MeSH
- sarin farmakologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
In vitro as well as in vivo evaluation of the reactivating efficacy of various oximes against nerve agent-inhibited acetylcholinesterase has been usually done with the help of animal experiments. Nevertheless, previously published data indicate that the reactivation potency of oximes may be different in human and animal species, which may hamper the extrapolation of animal data to human data. Therefore, to better evaluate the efficacy of various oximes (pralidoxime, obidoxime, HI-6, K033) to reactivate brain acetylcholinesterase inhibited by sarin by in vitro methods, human, rat and pig brain acetylcholinesterase were used to calculate kinetic parameters for the reactivation. Our results show differences among the species, depending on the type of oxime, and indicate that data from animal experiments needs to be carefully evaluated before extrapolation to humans.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory farmakologie MeSH
- druhová specificita MeSH
- financování organizované MeSH
- kinetika MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- mozek enzymologie účinky léků MeSH
- obidoxim chlorid metabolismus MeSH
- oximy farmakologie metabolismus MeSH
- pralidoximové sloučeniny farmakologie MeSH
- prasata MeSH
- pyridinové sloučeniny farmakologie metabolismus MeSH
- reaktivátory cholinesterázy farmakologie MeSH
- sarin farmakologie MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
The aim of this work was the comparison of reactivation potency of four oxime acetylcholinesterase (AChE) reactivators (pralidoxime, HI-6, K027 and K033) on three resources of the enzyme (human, pig and rat brain homogenate) inhibited by nerve agent sarin. The results demonstrate remarkable differences in the reactivation of inhibited brain AChE, depending on the oxime and species.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory farmakologie MeSH
- financování organizované MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- mozek enzymologie účinky léků MeSH
- oximy farmakologie MeSH
- prasata MeSH
- sarin farmakologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
