The design of MB327, a bispyridinium compound that ameliorates the nicotinic effects of acute organophosphorus nerve agent (NA) intoxication, followed an observation made by the German pharmacologist Klaus Schoene in the 1970s, who noted therapeutic activity in bispyridinium molecules missing the usual oxime group, CHNOH. Some of these compounds protected mice against soman. One structurally related to obidoxime called HY10 had this action. Its oxime moieties were capped by tert-butyl groups: CH=NOtBu. We modified HY10 by changing the bridge between the pyridinium units from a dimethylene ether to a trimethylene group (CH2OCH2 → CH2CH2CH2) and prepared a novel relative of trimedoxime, called LB1, whose synthesis and stereochemistry are described. Unlike obidoxime or trimedoxime, LB1 because of its capped oxime groups, cannot directly reactivate NA inhibited acetylcholinesterase. Its antidotal activity in mice is now reported. The therapeutic efficacy of LB1, atropine alone, atropine with LB1, atropine with an oxime (HI-6, obidoxime or trimedoxime), and atropine with an oxime and LB1, was studied by determining the LD50 values of the NAs soman, sarin, or tabun in mice treated with these compounds or mixtures. LB1 exceeded MB327 in toxicity and its activity was insufficient for a useful addition to the current standard antidotal treatment (protective ratio data are compared to those of MB327). Although this study produced largely negative biological results, the therapeutically beneficial mechanism of the effective bispyridinium non-oxime analogues is unclear, and has been demonstrated only in vivo. The present study points out directions in structural optimisation unlikely to yield the desired therapeutic outcomes and provides a literature review that could promote creative thinking for the design of widely-desirable non-oxime therapeutics for anticholinesterase inhibitors.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• antidota * chemická syntéza   chemie   farmakologie   terapeutické užití   MeSH
• atropin terapeutické užití   farmakologie   MeSH
• cholinesterasové inhibitory toxicita   MeSH
• myši MeSH
• nervová bojová látka * toxicita   MeSH
• organofosforové sloučeniny * toxicita   MeSH
• oximy chemie   MeSH
• pyridinové sloučeniny * chemická syntéza   chemie   terapeutické užití   farmakologie   MeSH
• soman toxicita   MeSH
• trimedoxim chemie   chemická syntéza   farmakologie   terapeutické užití   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

A-series agent A-234 belongs to a new generation of nerve agents. The poisoning of a former Russian spy Sergei Skripal and his daughter in Salisbury, England, in March 2018 led to the inclusion of A-234 and other A-series agents into the Chemical Weapons Convention. Even though five years have already passed, there is still very little information on its chemical properties, biological activities, and treatment options with established antidotes. In this article, we first assessed A-234 stability in neutral pH for subsequent experiments. Then, we determined its inhibitory potential towards human recombinant acetylcholinesterase (HssAChE; EC 3.1.1.7) and butyrylcholinesterase (HssBChE; EC 3.1.1.8), the ability of HI-6, obidoxime, pralidoxime, methoxime, and trimedoxime to reactivate inhibited cholinesterases (ChEs), its toxicity in rats and therapeutic effects of different antidotal approaches. Finally, we utilized molecular dynamics to explain our findings. The results of spontaneous A-234 hydrolysis showed a slow process with a reaction rate displaying a triphasic course during the first 72 h (the residual concentration 86.2%). A-234 was found to be a potent inhibitor of both human ChEs (HssAChE IC50 = 0.101 ± 0.003 μM and HssBChE IC50 = 0.036 ± 0.002 μM), whereas the five marketed oximes have negligible reactivation ability toward A-234-inhibited HssAChE and HssBChE. The acute toxicity of A-234 is comparable to that of VX and in the context of therapy, atropine and diazepam effectively mitigate A-234 lethality. Even though oxime administration may induce minor improvements, selected oximes (HI-6 and methoxime) do not reactivate ChEs in vivo. Molecular dynamics implies that all marketed oximes are weak nucleophiles, which may explain the failure to reactivate the A-234 phosphorus-serine oxygen bond characterized by low partial charge, in particular, HI-6 and trimedoxime oxime oxygen may not be able to effectively approach the A-234 phosphorus, while pralidoxime displayed low interaction energy. This study is the first to provide essential experimental preclinical data on the A-234 compound.

• MeSH
• acetylcholinesterasa MeSH
• antidota farmakologie   MeSH
• butyrylcholinesterasa MeSH
• cholinesterasové inhibitory toxicita   MeSH
• fosfor MeSH
• krysa rodu rattus MeSH
• kyslík MeSH
• lidé MeSH
• oximy farmakologie   MeSH
• pralidoximové sloučeniny * MeSH
• pyridinové sloučeniny farmakologie   MeSH
• reaktivátory cholinesterasy * farmakologie   MeSH
• taurin analogy a deriváty   MeSH
• trimedoxim farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The nerve agents of the A-series are relatively recent chemical weapons with no antidote available yet. Once inside the human body, those chemicals act similarly to the classic nerve agents, by binding to the catalytic residue Serine 203 (Ser203) of human acetylcholinesterase (HssAChE) and thus preventing the proper function of this enzyme. However, there is no experimental evidence yet if the current antidotes for intoxication by nerve agents are also capable of restoring AChE inhibited by the nerve agents of the A-series. In order to launch some light on this issue, we used computational techniques (molecular docking, molecular dynamics and MM-PBSA interaction energy calculations) to assess the performances of the four currently available commercial oximes (2-PAM, HI-6, obidoxime and trimedoxime) when in contact with HssAChE inhibited by the agent A-242. Based on the near-attack conformation (NAC) criterion, our results suggest that the commercial oximes would have limited efficacy to reactivate the enzyme since they are not able to properly approach the adduct Ser203-A-242. Among those oximes, trimedoxime seems to be the most promising, since it showed lower values of energy in the MM-PBSA calculations, a higher stability inside the catalytic anionic center (CAS) of HssAChE, and was able to adopt a position closer to the NAC that could enable the reactivation mechanism.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• antidota farmakologie   MeSH
• cholinesterasové inhibitory chemie   toxicita   MeSH
• lidé MeSH
• nervová bojová látka * toxicita   MeSH
• organofosfáty MeSH
• oximy chemie   farmakologie   MeSH
• pyridinové sloučeniny farmakologie   MeSH
• reaktivátory cholinesterasy * farmakologie   MeSH
• simulace molekulového dockingu MeSH
• trimedoxim farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Organophosphorus (OP) compounds are used as both chemical weapons and pesticides. However, these agents are very dangerous and toxic to humans, animals, and the environment. Thus, investigations with reactivators have been deeply developed in order to design new antidotes with better efficiency, as well as a greater spectrum of action in the acetylcholinesterase (AChE) reactivation process. With that in mind, in this work, we investigated the behavior of trimedoxime toward the Mus musculus acetylcholinesterase (MmAChE) inhibited by a range of nerve agents, such as chemical weapons. From experimental assays, reactivation percentages were obtained for the reactivation of different AChE-OP complexes. On the other hand, theoretical calculations were performed to assess the differences in interaction modes and the reactivity of trimedoxime within the AChE active site. Comparing theoretical and experimental data, it is possible to notice that the oxime, in most cases, showed better reactivation percentages at higher concentrations, with the best result for the reactivation of the AChE-VX adduct. From this work, it was revealed that the mechanistic process contributes most to the oxime efficiency than the interaction in the site. In this way, this study is important to better understand the reactivation process through trimedoxime, contributing to the proposal of novel antidotes.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• antidota farmakologie   MeSH
• cholinesterasové inhibitory metabolismus   farmakologie   MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• myši MeSH
• nervová bojová látka chemie   MeSH
• organofosforové sloučeniny chemie   MeSH
• oximy chemie   MeSH
• reaktivátory cholinesterasy chemie   farmakologie   MeSH
• trimedoxim farmakologie   terapeutické užití   MeSH
• výpočetní biologie metody   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

For over 60 years, researchers across the world have sought to deal with poisoning by nerve agents, the most toxic and lethal chemical weapons. To date, there is no efficient causal antidote with sufficient effect. Every trialed compound fails to fulfil one or more criteria (e.g. reactivation potency, broad reactivation profile). In this recent contribution, we focused our attention to one of the promising compounds, namely the bis-pyridinium reactivator K203. The oxime K203 is very often cited as the best reactivator against tabun poisoning. Herein, we provide all the available literature data in comprehensive and critical review to address whether K203 could be considered as a new drug candidate against organophosphorus poisoning with the stress on tabun. We describe its development from the historical point of view and review all available in vitro as well as in vivo data to date. K203 is easily accessible by a relatively simple two-step synthesis. It is well accommodated in the enzyme active gorge of acetylcholinesterase providing suitable interactions for reactivation, as shown by molecular docking simulations. According to a literature survey, in vitro data for tabun-inhibited AChE are extraordinary. However, in vivo efficiency remains unconvincing. The K203 toxicity profile did not show any perturbations compared to clinically used standards; on the other hand versatility of K203 does not exceed currently available oximes. In summary, K203 does not seem to address current issues associated with the organophosphorus poisoning, especially the broad profile against all nerve agents. However, its reviewed efficacy entitles K203 to be considered as a backup or tentative replacement for obidoxime and trimedoxime, currently only available anti-tabun drugs.

• MeSH
• acetylcholinesterasa MeSH
• antidota farmakologie   terapeutické užití   MeSH
• nervová bojová látka otrava   MeSH
• obidoxim chlorid MeSH
• organofosfáty toxicita   MeSH
• otrava organofosfáty farmakoterapie   MeSH
• oximy terapeutické užití   MeSH
• pyridinové sloučeniny terapeutické užití   MeSH
• simulace molekulového dockingu MeSH
• trimedoxim MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Beside the key inhibition of acetylcholinesterase (AChE), involvement of oxidative stress in organophosphate (OP)-induced toxicity has been supported by experimental and human studies. On the other hand, according to our best knowledge, possible antioxidant properties of oximes, the only causal antidotes to OP-inhibited AChE, have been examined only by a few studies. Thus, we have determined the effect of four conventional (obidoxime, trimedoxime, pralidoxime, asoxime) and two promising experimental oximes (K027, K203) on dichlorvos (DDVP)-induced oxidative changes in vivo. Wistar rats (5/group) were treated with oxime (5% LD50 i.m) immediately after DDVP challenge (75% LD50 s.c). Oxidative stress biomarkers were determined in plasma and brain 60 min after the treatment: prooxidative-superoxide anion (O2·-) and total oxidative status (TOS); antioxidative-superoxide dismutase (SOD), total thiol (SH) groups, total antioxidant status (TAS) and paraoxonase (PON1); tissue oxidative stress burden-prooxidative-antioxidative balance (PAB) and oxidative stress index (OSI); oxidative tissue damage-malondialdehyde (MDA) and advanced oxidation protein products (AOPP). All oximes were able to attenuate DDVP-induced oxidative stress in rat plasma and brain. Changes of determined parameters in brain were not as prominent as it was seen in plasma. Based on OSI, better abilities of oxime K027, K203 and obidoxime to maintain DDVP-induced oxidative stress in rat brain were shown as compared to trimedoxime, pralidoxime and asoxime. Oximes can influence the complex in vivo redox processes that might contribute to their overall therapeutic efficacy. Further research is needed to understand the underlying molecular mechanisms involved in this phenomenon.

• MeSH
• aryldialkylfosfatasa krev   MeSH
• biologické markery krev   MeSH
• cholinesterasové inhibitory farmakologie   MeSH
• dichlorvos toxicita   MeSH
• krysa rodu rattus MeSH
• malondialdehyd krev   MeSH
• mozek účinky léků   MeSH
• obidoxim chlorid farmakologie   MeSH
• otrava organofosfáty farmakoterapie   MeSH
• oxidační stres účinky léků   MeSH
• oximy farmakologie   MeSH
• pralidoximové sloučeniny MeSH
• pyridinové sloučeniny farmakologie   MeSH
• superoxiddismutasa krev   MeSH
• trimedoxim farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The ability of two newly developed oximes (K305, K307) to protect tabun-poisoned rats from tabun-induced inhibition of brain acetylcholinesterase, acute neurotoxic signs and symptoms and brain damage was compared with that of the oxime K203 and trimedoxime. The reactivating and neuroprotective effects of the oximes studied combined with atropine on rats poisoned with tabun at a sublethal dose were evaluated. The reactivating efficacy of a newly developed oxime K305 is lower compared to the reactivating efficacy of the oxime K203 and trimedoxime while the ability of the oxime K307 to reactivate tabun-inhibited acetylcholinesterase (AChE) in the brain roughly corresponds to the reactivating efficacy of the oxime K203 and it is slightly lower compared to trimedoxime. In addition, only one newly developed oxime (K307) combined with atropine was able to markedly decrease tabun-induced neurotoxicity although it did not eliminate all tabun-induced acute neurotoxic signs and symptoms. These results correspond to the histopathological evaluation of tabun-induced brain damage. Therefore, the newly developed oximes are not suitable for the replacement of commonly used oximes (especially trimedoxime) in the treatment of acute tabun poisonings.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• atropin terapeutické užití   MeSH
• chemické bojové látky otrava   MeSH
• lidé MeSH
• mozek účinky léků   enzymologie   MeSH
• neuroprotektivní látky terapeutické užití   MeSH
• neurotoxické syndromy farmakoterapie   MeSH
• organofosfáty toxicita   MeSH
• otrava organofosfáty farmakoterapie   MeSH
• oximy terapeutické užití   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny terapeutické užití   MeSH
• reaktivátory cholinesterasy terapeutické užití   MeSH
• trimedoxim terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

The reactivating and therapeutic efficacy of two newly developed oximes (K305, K307) was compared with the oxime K203 and trimedoxime using in vivo methods The study determining percentage of reactivation of tabun-inhibited acetylcholinesterase in the peripheral as well as central nervous system (diaphragm, brain) in tabun-poisoned rats showed that the reactivating efficacy of both newly developed oximes is lower compared to the reactivating efficacy of the oxime K203 and trimedoxime. The therapeutic efficacy of all oximes studied roughly corresponds to their reactivating efficacy. While the ability of the oxime K305 to reduce acute toxicity of tabun in mice is approaching to the therapeutic efficacy of trimedoxime, the ability of another novel bispyridinium oxime K307 to reduce acute toxicity of tabun is significantly lower compared to trimedoxime and the oxime K203. Thus, the reactivating and therapeutic efficacy of both examined newly developed oximes does not prevail the effectiveness of the oxime K203 and trimedoxime and, therefore, they are not suitable for their replacement of commonly used oximes for the treatment of acute tabun poisoning.

• MeSH
• acetylcholinesterasa účinky léků   MeSH
• antidota aplikace a dávkování   farmakologie   toxicita   MeSH
• atropin aplikace a dávkování   farmakologie   toxicita   MeSH
• bránice enzymologie   MeSH
• modely u zvířat MeSH
• mozek enzymologie   účinky léků   MeSH
• mutantní kmeny myší MeSH
• nervová bojová látka farmakologie   chemie   toxicita   MeSH
• organofosfáty farmakologie   toxicita   MeSH
• oximy * farmakologie   chemie   klasifikace   MeSH
• potkani Wistar MeSH
• reaktivátory cholinesterasy aplikace a dávkování   farmakologie   toxicita   MeSH
• trimedoxim farmakologie   chemie   klasifikace   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH

The ability of two newly developed bispyridinium oximes (K920, K923) to reduce tabun-induced acute neurotoxic signs and symptoms was compared with the oxime K203 and trimedoxime using a functional observational battery (FOB). The neuroprotective effects of the oximes studied combined with atropine on rats poisoned with tabun at a sublethal dose (130 μg/kg i.m.; 80% of LD50 value) were evaluated. Tabun-induced neurotoxicity was monitored by FOB at 2 h after tabun administration. The results indicate that all tested oximes combined with atropine enable tabun-poisoned rats to survive till the end of experiment while one non-treated tabun-poisoned rat died within 2 h. Both newly developed oximes (K920, K923) combined with atropine were able to markedly decrease tabun-induced neurotoxicity in the case of sublethal poisoning although they did not eliminate all tabun-induced acute neurotoxic signs and symptoms. Their ability to decrease tabun-induced acute neurotoxicity did not prevail the neuroprotective efficacy of trimedoxime and the oxime K203. Therefore, the newly developed oximes are not suitable for the replacement of currently available oximes (especially trimedoxime) in the treatment of acute tabun poisonings.

• MeSH
• molekulární struktura MeSH
• neuroprotektivní látky chemie   terapeutické užití   MeSH
• neurotoxické syndromy etiologie   prevence a kontrola   MeSH
• organofosfáty toxicita   MeSH
• oximy chemie   terapeutické užití   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny chemie   terapeutické užití   MeSH
• reaktivátory cholinesterasy chemie   terapeutické užití   MeSH
• trimedoxim chemie   terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

The reactivating and therapeutic efficacy of three original bispyridinium oximes (K727, K733 and K203) and one currently available oxime (trimedoxime) was evaluated in tabun-poisoned rats and mice. The oxime-induced reactivation of tabun-inhibited acetylcholinesterase was measured in diaphragm and brain of tabun-poisoned rats. The results showed that the reactivating efficacy of two recently developed oximes (K727 and K733) does not achieve the level of the reactivation of tabun-inhibited acetylcholinesterase induced by oxime K203 and trimedoxime. While all oximes studied were able to increase the activity of tabun-inhibited acetylcholinesterase in diaphragm, oxime K733 was not able to reactivate tabun-inhibited acetylcholinesterase in the brain. The therapeutic efficacy of all oximes studied roughly corresponds to their reactivating efficacy. While both recently developed oximes were able to reduce acute toxicity of tabun less than 1.5-fold, another original oxime K203 and commonly used trimedoxime reduced the acute toxicity of tabun almost two times. In conclusion, the reactivating and therapeutic potency of both newly developed oximes does not prevail the effectiveness of oxime K203 and trimedoxime, and therefore, they are not suitable for their replacement of commonly used oximes for the antidotal treatment of acute tabun poisoning.

• MeSH
• antidota terapeutické užití   MeSH
• atropin farmakologie   MeSH
• chemické bojové látky toxicita   MeSH
• cholinesterasové inhibitory toxicita   MeSH
• injekce intramuskulární MeSH
• krysa rodu rattus MeSH
• LD50 MeSH
• myši MeSH
• organofosfáty toxicita   MeSH
• oximy terapeutické užití   MeSH
• parasympatolytika farmakologie   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny terapeutické užití   MeSH
• reaktivátory cholinesterasy terapeutické užití   MeSH
• trimedoxim terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH