The effect of three newly developed bispyridinium non-oxime compounds (MB408, MB442, and MB444) on the therapeutic efficacy of a standard antidotal treatment (atropine in combination with the oxime HI-6 or obidoxime) of acute poisoning by two nerve agents (sarin and cyclosarin) in mice was studied. The therapeutic efficacy of atropine in combination with an oxime with or without one of the bispyridinium non-oximes was evaluated by determination of the 24 h LD50 values of the nerve agents studied and by measurement of the survival time after supralethal poisoning. Addition of all tested non-oximes increased the therapeutic efficacy of atropine in combination with an oxime against sarin poisoning; however, the differences were not significant. The non-oximes also positively influenced the number of surviving mice 6 h after supralethal poisoning with sarin. In the case of cyclosarin, they were also slightly beneficial in the treatment of acute poisoning. The higher dose of MB444 was able to significantly increase the therapeutic efficacy of standard antidotal treatment of poisoning with cyclosarin. The benefit of each bispyridinium non-oxime compound itself was obviously dose-dependent. In summary, the addition of MB compounds to the standard antidotal treatment of acute nerve agent poisoning was beneficial for the antidotal treatment of sarin or cyclosarin poisoning, although their benefit at 24 h after poisoning was not significant, with the exception of the higher dose of MB444 against cyclosarin.

• Klíčová slova
• Atropine, Cyclosarin, Mice, Non-oxime bispyridinium compounds, Oximes, Sarin,
• MeSH
• atropin farmakologie   MeSH
• časové faktory MeSH
• kombinovaná farmakoterapie MeSH
• LD50 MeSH
• modely nemocí na zvířatech MeSH
• myši MeSH
• obidoxim chlorid farmakologie   MeSH
• organofosforové sloučeniny * MeSH
• otrava organofosfáty farmakoterapie   MeSH
• oximy farmakologie   MeSH
• pyridinové sloučeniny farmakologie   MeSH
• sarin * MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• asoxime chloride MeSH Prohlížeč
• atropin MeSH
• cyclohexyl methylphosphonofluoridate MeSH Prohlížeč
• MB408 MeSH Prohlížeč
• MB442 MeSH Prohlížeč
• MB444 MeSH Prohlížeč
• obidoxim chlorid MeSH
• organofosforové sloučeniny * MeSH
• oximy MeSH
• pyridinové sloučeniny MeSH
• sarin * MeSH

Mono-quaternary pyridinium oximes derived from K-oximes K027, K048 and K203 were designed, synthesized and evaluated for the reactivation of organophosphate-inhibited cholinesterases. The incorporation of the halogen atoms to the structure decreased the pKa value of the oxime group resulting in an increased formation of oximate necessary for reactivation. The stability and pKa values were found to be similar to analogous bis-quaternary compounds. Some mono-quaternary oximes resulted as relatively strong inhibitors of human acetylcholinesterase. Nevertheless, the reactivation ability of mono-quaternary oximes for organophosphate-inhibited cholinesterases was lower compared to their bis-quaternary analogues. These results were further confirmed by the determination of reactivation kinetics, when in some cases novel compounds showed improvement reactivation compared to the tested standards, but no improvement to bis-quaternary K-oximes. A computational study investigated reactivation process for K027, and its two analogues for VX-inhibited AChE. This study revealed slight differences between reactivation of mono-quaternary and bis-quaternary oximes. Abbreviations: 2-PAM, pralidoxime; AChE, acetylcholinesterase; ACN, acetonitrile; ATCI, acetylcholine iodide; BChE, butyrylcholinesterase; BTCI, butyrylcholine iodide; Bu3SnSnBu3, bis(tributyltin) Et2O, diethyl ether; ChEs, cholinesterases; CNS, central nervous system; DAD, diode array detector; DIBAL-H, diisobutylaluminium hydride; DMF, dimethylformamide; DMSO, dimethyl sulfoxide; DTNB, 5,5́-dithiobis-2-nitrobenzoic acid; Et3N, triethylamine; EtOAc, ethyl acetate; EWG, electron withdrawing group; HI-6, asoxime; hrAChE, human recombinant acetylcholinesterase; hrBChE, human recombinant butyrylcholinesterase; hrChEs, human recombinant cholinesterases; HPLC, high-performance liquid chromatography; HRMS, high-resolution mass spectrometry; KD, dissociation constant; kr, first-order reactivation rate constant; kr2, second-order reactivation rate constant; LüH-6, obidoxime; MeOH, methanol; MM, molecular mechanics; MMC-4, methoxime; m.p., melting point; NCIs, non-covalent interactions; NEDPA, 4-nitrophenyl ethyl dimethylphosphoramidate; NEMP, 4-nitrophenyl ethyl methylphosphonate; NIMP, isopropyl methylphosphonate; NMR, nuclear magnetic resonance spectroscopy; OPs, organophosphates; PBS, phosphate-buffered saline; Pd(dppf)Cl2.CH2Cl2, [1,1'-Bis(diphenylphosphino)ferrocene]dichloropalladium(II) in complex with dichloromethane; pKa, negative decimal logarithm of the dissociation constant; POX, paraoxon; PPh3, triphenylphosphine; QM, quantum mechanics; rt, room temperature; SN2, bimolecular nucleophilic substitution; SNAc, nucleophilic acyl substitution; THF, tetrahydrofuran; TMC-4, trimedoxime; TNB, 5-thio-2-nitrobenzoic acid; UHPLC, ultra high-performance liquid chromatography; UV, ultraviolet; UV-VIS, ultraviolet-visible.

• Klíčová slova
• Cholinesterase, Inhibition, Organophosphate, Oxime, Reactivation,
• MeSH
• acetylcholinesterasa * metabolismus   MeSH
• butyrylcholinesterasa metabolismus   MeSH
• cholinesterasové inhibitory * farmakologie   chemie   chemická syntéza   MeSH
• halogenace MeSH
• kinetika MeSH
• lidé MeSH
• molekulární struktura MeSH
• oximy * chemie   farmakologie   chemická syntéza   MeSH
• pyridinové sloučeniny chemie   farmakologie   chemická syntéza   MeSH
• reaktivátory cholinesterázy farmakologie   chemie   chemická syntéza   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetylcholinesterasa * MeSH
• butyrylcholinesterasa MeSH
• cholinesterasové inhibitory * MeSH
• oximy * MeSH
• pyridinové sloučeniny MeSH
• reaktivátory cholinesterázy MeSH

Oxidative stress status and morphological injuries in the brain of Wistar rats induced by repeated application of selected acetylcholinesterase reactivators - asoxime, obidoxime, K027, K048, K074, and K075 were evaluated. Each oxime in a dose of 0.1 of LD50/kg im was given 2x/week for 4 weeks. Markers of lipid peroxidation (malondialdehyde, MDA), and protein oxidation (advanced oxidation protein products, AOPP), as well as the activity of antioxidant enzymes (catalase, CAT, superoxide dismutase, SOD, glutathione reductase, GR, and glutathione peroxidase, GPx), were estimated in the brain tissue homogenates on day 35 of the study. Brain alterations were carefully quantified by semiquantitative grading scales - brain damage score (BDS). Oxidative stress parameters, MDA and AOPP were significantly highest in the asoxime-, obidoxime- and K075-treated groups (p < 0.001). The activity of SOD and CAT was significantly elevated in the obidoxime-, K048-, and K075-treated groups (p < 0.001). Besides, GR was markedly decreased in the obidoxime- and K074-treated groups (p < 0.01), while treatment with K048, K074 and K075 induced extremely high elevation in GPx levels (p < 0.001). In the same groups of rats, brain alterations associated with polymorphonuclear cell infiltrate were significantly more severe than those observed in animals receiving only asoxime or K027 (p < 0.001). The presented results confirmed that treatment with different oximes significantly improved the oxidative status and attenuated signs of inflammation in rats' brains. Presented results, together with our previously published data can help to predict likely adverse systemic toxic effects, and target organ systems, which are crucial for establishing risk categories, as well as in dose selection of K-oximes as drug candidates.

• Klíčová slova
• Brain, Oxidative stress, Oximes, Pathohistology, Subacute toxicity,
• MeSH
• acetylcholinesterasa metabolismus   MeSH
• krysa rodu Rattus MeSH
• mozek MeSH
• obidoxim chlorid * farmakologie   MeSH
• oxidační stres MeSH
• oximy * farmakologie   MeSH
• potkani Wistar MeSH
• produkty pokročilé oxidace proteinů metabolismus   farmakologie   MeSH
• superoxiddismutasa metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• obidoxim chlorid * MeSH
• oximy * MeSH
• produkty pokročilé oxidace proteinů MeSH
• superoxiddismutasa 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.

• Klíčová slova
• butyrylcholinesterase, docking, mechanistic studies and chemometrics, neurotoxic agents, 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
• Názvy látek
• butyrylcholinesterasa MeSH
• cholinesterasové inhibitory MeSH
• cyclohexyl methylphosphonofluoridate MeSH Prohlížeč
• organofosforové sloučeniny MeSH
• oximy MeSH
• reaktivátory cholinesterázy MeSH
• sarin MeSH

The neuroprotective effects of newly developed oximes (K156, K203) and currently available oximes (obidoxime, HI-6) in combination with atropine in rats poisoned with cyclosarin were studied. The cyclosarin-induced neurotoxicity was monitored using a functional observational battery 24 hours after cyclosarin challenge. The results indicate that a newly developed oxime K156 is able to counteract slightly cyclosarin-induced neurotoxicity while another newly developed oxime K203 is completely ineffective in reducing cyclosarin-induced neurotoxic signs and symptoms. The neuroprotective efficacy of K156 is comparable with commonly used obidoxime and oxime HI-6. Thus, none of the newly developed oximes achieves better neuroprotective efficacy than both commonly used oximes. They are therefore not suitable replacements for antidotal treatment of acute poisonings with cyclosarin.

• MeSH
• chemické bojové látky toxicita   MeSH
• krysa rodu Rattus MeSH
• neurotoxické syndromy prevence a kontrola   MeSH
• organofosforové sloučeniny toxicita   MeSH
• oximy chemie   terapeutické užití   MeSH
• potkani Wistar MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• chemické bojové látky MeSH
• cyclohexyl methylphosphonofluoridate MeSH Prohlížeč
• organofosforové sloučeniny MeSH
• oximy MeSH

BACKGROUND: Oximes are used in addition to atropine to treat organophosphate poisoning. However, the efficiency of oximes is still a matter of debate. In vitro experiments suggested than new oximes are more potent than the commercial oximes. However, the antidotal activity of new oximes has not been assessed in vivo. METHODS: The aim of this work was to assess the safety and efficiency of new oximes compared to pralidoxime in a rat model of diethyl paraoxon-induced non-lethal respiratory toxicity. RESULTS: Safety study of oximes showed no adverse effects on ventilation in rats. KO-33, KO-48, KO-74 oximes did not exhibit significant antidotal effect in vivo. In contrast, KO-27 and BI-6 showed evidence of antidotal activity by normalization of respiratory frequency and respiratory times. KO-27 became inefficient only during the last 30 min of the study. In contrast, pralidoxime demonstrated to be inefficient at 30 min post injection. Inversely, the antidotal activity of BI-6 occurred lately, within the last 90 min post injection. CONCLUSION: This study showed respiratory safety of new oximes. Regarding, the efficiency, KO-27 revealed to be a rapid acting antidote toward diethylparaoxon-induced respiratory toxicity, meanwhile BI-6 was a late-acting antidote. Simultaneous administration of these two oximes might result in a complete and prolonged antidotal efficiency.

• Klíčová slova
• BI-6, KO-27, diethyl-paraoxon, oximes, plethysmography, pralidoxime, rats, ventilatory effects,
• MeSH
• antidota farmakologie   MeSH
• bezpečnost MeSH
• cholinesterasové inhibitory toxicita   MeSH
• dýchání účinky léků   MeSH
• krysa rodu Rattus MeSH
• otrava organofosfáty farmakoterapie   etiologie   MeSH
• oximy farmakologie   MeSH
• paraoxon toxicita   MeSH
• potkani Sprague-Dawley MeSH
• větrání metody   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antidota MeSH
• cholinesterasové inhibitory MeSH
• oximy MeSH
• paraoxon MeSH

Tabun is one of the most dangerous nerve agents because it has deleterious effects like inhibition of the essential enzymes acetylcholinesterase (AChE) and butyrylcholinesterase. Some oximes such HI6 as 2-PAM are nucleophiles that are capable to reactivate inhibited human AChE under some conditions. Zwitterionic and cationic species have the best chance of productive action on inhibited AChE. However uncharged oximes can give important interaction information. In order to investigate the interaction and behavior of cationic and uncharged oximes, we performed molecular docking simulations and molecular dynamics and calculated binding energies of complexes of these compounds with human AChE. The uncharged oximes of larger structure were more susceptible to the influence of the substituents on the phosphorus atom and presented low binding energies. In contrast, HI 6 and 2-PAM showed high binding energy values with great contribution of the amino acid Asp74, demonstrating the importance of the quaternary nitrogen to the affinity and interaction of the oximes/AChE tabun-inhibited complexes.

• Klíčová slova
• acetylcholinesterase, chemical defense, tabun, uncharged oximes,
• MeSH
• acetylcholinesterasa chemie   MeSH
• cholinesterasové inhibitory chemie   MeSH
• lidé MeSH
• organofosfáty chemie   MeSH
• oximy chemie   MeSH
• pralidoximové sloučeniny chemie   MeSH
• reaktivátory cholinesterázy chemie   MeSH
• simulace molekulového dockingu metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• cholinesterasové inhibitory MeSH
• organofosfáty MeSH
• oximy MeSH
• pralidoxime MeSH Prohlížeč
• pralidoximové sloučeniny MeSH
• reaktivátory cholinesterázy MeSH
• tabun MeSH Prohlížeč

The reactivating and therapeutic efficacy of a new acetylcholinesterase reactivator, designated BI-6(1-/2-hydroxyiminomethylpyridinium/-4-/carbamoylpyridinium+ ++/-2-butene dibromide), against the organophosphate soman was compared with oximes at present used (pralidoxime, obidoxime, methoxime) and H oximes (HI-6, HLö-7) using in vitro and in vivo methods. H oximes HI-6 and HLö-7 seem to be the most efficacious acetylcholinesterase reactivators against soman according to the evaluation of their reactivating and therapeutic efficacy in vitro as well as in vivo. The new oxime BI-6 is not as effective as the H oximes against soman, nevertheless it is significantly more effective against soman than the currently available oximes, pralidoxime, obidoxime and methoxime, which failed to protect rats poisoned with supralethal doses of soman. Our results confirm that the reactivating efficacy of oximes evaluated by the methods in vitro closely correlates not only with the potency of oximes in vivo in reactivating soman-inhibited acetylcholinesterase but also with the ability to protect rats poisoned with supralethal doses of soman.

• MeSH
• cholinesterasové inhibitory otrava   MeSH
• krysa rodu Rattus MeSH
• oximy terapeutické užití   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny farmakologie   terapeutické užití   MeSH
• reaktivátory cholinesterázy terapeutické užití   MeSH
• soman otrava   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• BI 6 MeSH Prohlížeč
• cholinesterasové inhibitory MeSH
• oximy MeSH
• pyridinové sloučeniny MeSH
• reaktivátory cholinesterázy MeSH
• soman MeSH

The cholinesterase-inhibiting organophosphorus compounds referred to as nerve agents (soman, sarin, tabun, GF agent, and VX) are particularly toxic and are considered to be among the most dangerous chemical warfare agents. Included in antidotal medical countermeasures are oximes to reactivate the inhibited cholinesterase. Much experimental work has been done to better understand the properties of the oxime antidotal candidates including the currently available pralidoxime and obidoxime, the H oximes HI-6 and Hlö-7, and methoxime. There is no single, broad-spectrum oxime suitablefor the antidotal treatment of poisoning with all organophosphorus agents. If more than one oxime is available, the choice depends primarily on the identity of the responsible organophosphorus compound. The H oximes appear to be very promising antidotes against nerve agents because they are able to protect experimental animals from toxic effects and improve survival of animals poisoned with supralethal doses. They appear more effective against nerve agent poisoning than the currently used oximes pralidoxime and obidoxime, especially in the case of soman poisoning. On the other hand, pralidoxime and especially obidoxime seem sufficiently effective to treat poisonings with organophosphorus insecticides that have relatively less toxicity than nerve agents.

• MeSH
• antidota škodlivé účinky   chemie   farmakokinetika   terapeutické užití   MeSH
• chemické bojové látky chemie   otrava   MeSH
• lidé MeSH
• organofosforové sloučeniny chemie   MeSH
• otrava organofosfáty * MeSH
• otrava farmakoterapie   MeSH
• oximy škodlivé účinky   chemie   farmakokinetika   terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• antidota MeSH
• chemické bojové látky MeSH
• organofosforové sloučeniny MeSH
• oximy MeSH

The potency of newly developed oximes (K074, K075) and commonly used oximes (obidoxime, HI-6) to reactivate nerve agent-inhibited acetylcholinesterase was evaluated in rats poisoned with soman, tabun or cyclosarin at a lethal dose corresponding to their LD(50) value. In vivo determined percentage of reactivation of soman-inhibited blood and brain acetylcholinesterase in poisoned rats showed that only the oxime HI-6 was able to reactivate soman-inhibited acetylcholinesterase in the peripheral (blood) as well as central (brain) compartment. In vivo determined percentage of reactivation of tabun-inhibited blood and brain acetylcholinesterase in poisoned rats showed that obidoxime is the most efficacious reactivator of tabun-inhibited acetylcholinesterase among studied oximes in the peripheral compartment (blood) while K074 seems to be the most efficacious reactivator of tabun-inhibited acetylcholinesterase among studied oximes in the central compartment (brain). In vivo determined percentage of reactivation of cyclosarin-inhibited blood and brain acetylcholinesterase in poisoned rats showed that HI-6 is the most efficacious reactivator of cyclosarin-inhibited acetylcholinesterase among studied oximes. Due to their reactivating effects, both newly developed K oximes can be considered to be promising oximes for the antidotal treatment of acute tabun poisonings while the oxime HI-6 is still the most promising oxime for the treatment of acute soman and cyclosarin poisonings.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• chemické bojové látky otrava   MeSH
• enzymové reaktivátory farmakologie   MeSH
• krysa rodu Rattus MeSH
• organofosfáty MeSH
• organofosforové sloučeniny MeSH
• otrava organofosfáty * MeSH
• oximy farmakologie   MeSH
• potkani Wistar MeSH
• soman otrava   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• chemické bojové látky MeSH
• cyclohexyl methylphosphonofluoridate MeSH Prohlížeč
• enzymové reaktivátory MeSH
• organofosfáty MeSH
• organofosforové sloučeniny MeSH
• oximy MeSH
• soman MeSH
• tabun MeSH Prohlížeč