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

7-methoxytacrine-4-pyridinealdoxime (7-MEOTA-4-PA, named hybrid 5C) is a compound formerly synthesized and evaluated in vitro, together with 4-pyridine aldoxime (4-PA) and commercial reactivators of acetylcholinesterase (AChE). This compound was designed with the purpose of being a prophylactic reactivator, capable of interacting with different subdomains of the active site of AChE. To investigate these interactions, theoretical results from docking were first compared with experimental data of hybrid 5C, 4-PA, and two commercial oximes, on the reactivation of human AChE (HssAChE) inhibited by VX. Then, further docking studies, molecular dynamics simulations, and molecular mechanics Poisson-Boltzmann surface area calculations, were carried out to investigate reactivation performances, considering the near attack conformation (NAC) approach, prior to the nucleophilic substitution mechanism. Our results helped to elucidate the interactions of such molecules with the different subdomains of the active site of HssAChE. Additionally, NAC poses of each oxime were suggested for further theoretical studies on the reactivation reaction.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• cholinesterasové inhibitory chemická syntéza   chemie   farmakologie   MeSH
• lidé MeSH
• molekulární modely MeSH
• molekulární struktura MeSH
• obidoxim chlorid chemie   farmakologie   MeSH
• organothiofosforové sloučeniny chemie   farmakologie   MeSH
• oximy chemie   farmakologie   MeSH
• pralidoximové sloučeniny chemie   farmakologie   MeSH
• pyridiny chemie   farmakologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Organophosphates, useful agents as pesticides, also represent a serious danger due to their high acute toxicity. There is indication that oximes, when administered before organophosphate exposure, can protect from these toxic effects. We have tested at equitoxic dosage (25% of LD01 ) the prophylactic efficacy of five experimental (K-48, K-53, K-74, K-75, K-203) and two established oximes (pralidoxime and obidoxime) to protect from mortality induced by the organophosphate paraoxon. Mortalities were quantified by Cox analysis and compared with those observed after pretreatment with a strong acetylcholinesterase inhibitor (10-methylacridine) and after the FDA-approved pretreatment compound pyridostigmine. All nine tested substances statistically significantly reduced paraoxon-induced mortality. Best protection was conferred by the experimental oxime K-48, reducing the relative risk of death (RR) to 0.10, which was statistically significantly superior to pyridostigmine (RR = 0.31). The other oximes reduced the RR to 0.13 (obidoxime), 0.20 (K-203), 0.21 (K-74), 0.24 (K-75) and 0.26 (pralidoxime), which were significantly more efficacious than 10-methylacridine (RR = 0.65). These data support the hypothesis that protective efficacy is not primarily due to cholinesterase inhibition and indicate that the tested experimental oximes may be considered promising alternatives to the established pretreatment compound pyridostigmine.

• MeSH
• analýza přežití MeSH
• LD50 MeSH
• obidoxim chlorid aplikace a dávkování   farmakologie   MeSH
• ochranné látky aplikace a dávkování   farmakologie   MeSH
• paraoxon chemie   toxicita   MeSH
• potkani Wistar MeSH
• pralidoximové sloučeniny aplikace a dávkování   farmakologie   MeSH
• proporcionální rizikové modely MeSH
• reaktivátory cholinesterázy aplikace a dávkování   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

K-oximes were developed as modern drug candidates acting as AChE reactivators. In this study, it has been investigated which interspecies and intergender differences changes could be observed in Wistar rats and Swiss mice, both genders, after the treatment with increasing doses of selected acetylcholinesterase reactivators - asoxime, obidoxime, K027, K048, and K075. After the 24 h, a number of died animals was counted and the median lethal dose (LD50) for each oxime was calculated. By using the intramuscular route of administration, asoxime and K027 had the least toxicity in female rats (640.21 mg/kg and 686.08 mg/kg), and in female mice (565.75 mg/kg and 565.74 mg/kg), respectively. Moreover, asoxime and K027 showed 3, 4 or 8 times less acute toxicity in comparison to K048, obidoxime and K075, respectively. Beyond, K075 had the greatest toxicity in male rats (81.53 mg/kg), and in male mice (57.34 mg/kg), respectively. Our results can help to predict likely adverse toxic effects, target organ systems and possible outcome in the event of massive human overexposure, and in establishing risk categories or in dose selection for the initial repeated dose toxicity tests to be conducted for each oxime.

• MeSH
• acetylcholinesterasa chemie   metabolismus   MeSH
• krysa rodu rattus MeSH
• LD50 MeSH
• myši MeSH
• obidoxim chlorid toxicita   MeSH
• oximy toxicita   MeSH
• potkani Wistar MeSH
• prekurzory léčiv toxicita   MeSH
• reaktivátory cholinesterázy chemie   metabolismus   toxicita   MeSH
• testy akutní toxicity metody   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články 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 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.

• 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

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.

• MeSH
• acetylcholinesterasa chemie   MeSH
• antidota chemická syntéza   farmakologie   MeSH
• butyrylcholinesterasa chemie   MeSH
• cholinesterasové inhibitory chemie   MeSH
• enzymatické testy MeSH
• erytrocyty účinky léků   enzymologie   MeSH
• insekticidy antagonisté a inhibitory   chemie   toxicita   MeSH
• interakční proteinové domény a motivy MeSH
• lidé MeSH
• obidoxim chlorid chemie   farmakologie   MeSH
• oximy chemická syntéza   farmakologie   MeSH
• paraoxon antagonisté a inhibitory   chemie   toxicita   MeSH
• reaktivátory cholinesterázy chemická syntéza   farmakologie   MeSH
• sekundární struktura proteinů MeSH
• simulace molekulového dockingu MeSH
• termodynamika MeSH
• vazba proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Our research team will synthesise both priority compounds K203 and K027 (and reference asoxim and obidoxim) in sufficient volumes and supreme purity. Pharmacokinetics studies will set perspective therapeutic regimes (doses and rate of administration) and absorption gastrointestinal window. Bioavailability studies will determine biodistribution and effect / toxic exposition ratio in particular physiological systems. Investigation of motor functions of the upper gastrointestinal tract enables to evaluate possible therapeutic effect (against organophosphates poisoning) and possible side effects of acetylcholinesterase modulators to the gastrointestinal tract. The research team will use oesophageal impedance, pH-metry, high resolution manometry and electrogastrography. This is a priority and high impact society project.

Řešitelský kolektiv bude syntetizovat obě originální látky K203 a K027 (a referenční asoxim, obidoxim) v dostatečném množství pro experimentální použití u prasat (celkem 14 skupin po 6 zvířatech). Pro ověření čistoty těchto látek bude užito standardních analytických technik. Etapa farmakokinetiky stanoví perspektivní terapeutické režimy (velikosti dávek a frekvence jejich podávání); absorpční gastrointest. okno v případě perorálního podání (s cílem optimalizovat aplikovatelné lékové formy). Etapa biodistribuční určí mechanismy depotizace a účinnostní / toxické expozice v jednotlivých fyziologických systémech (se zvláštním zřetelem k hematoencefalické bariéře). Vyšetření motorických funkcí gastrointestinálního traktu bude hodnotit terapeutický efekt (proti toxickým účinkům organofosforových sloučenin na jícen a žaludek) a možné nežádoucí vedlejší účinky modulátorů acetylcholinesterasy na trávicí trakt. Budou použity metody impedance, pH-metrie, manometrie s vysokým rozlišením a elektrogastrografie.

• MeSH
• acetylcholinesterasa MeSH
• diagnostické techniky gastrointestinální MeSH
• farmakokinetika MeSH
• gastrointestinální motilita MeSH
• modely u zvířat MeSH
• obidoxim chlorid farmakokinetika   chemická syntéza   MeSH
• prasata MeSH
• reaktivátory cholinesterázy MeSH

• Konspekt
• Farmacie. Farmakologie
• NLK Obory
• farmacie a farmakologie
• gastroenterologie
• biochemie
• NLK Publikační typ
• závěrečné zprávy o řešení grantu IGA MZ ČR

The ability of two novel bispyridinium oximes K727 and K733 and currently available oximes (HI-6, obidoxime) to reactivate sarin-inhibited acetylcholinesterase and to reduce acute toxicity of sarin was evaluated. To investigate the reactivating efficacy of the oximes, the rats were administered intramuscularly with atropine and oximes in equitoxic doses corresponding to 5% of their LD50 values at 1 min after the intramuscular administration of sarin at a dose of 24 µg/kg (LD50). The activity of acetylcholinesterase was measured at 60 min after sarin poisoning. The LD50 value of sarin in non-treated and treated mice was assessed using probit-logarithmical analysis of death occurring within 24 h after intramuscular administration of sarin at five different doses. In vivo determined percentage of reactivation of sarin-inhibited rat blood, diaphragm and brain acetylcholinesterase showed that the potency of both novel oximes K727 and K733 to reactivate sarin-inhibited acetylcholinesterase roughly corresponds to the reactivating efficacy of obidoxime. On the other hand, the oxime HI-6 was found to be the most efficient reactivator of sarin-inhibited acetylcholinesterase. While the oxime HI-6 was able to reduce the acute toxicity of sarin >3 times, both novel oximes and obidoxime decreased the acute toxicity of sarin <2 times. Based on the results, we can conclude that the reactivating and therapeutic efficacy of both novel oximes K727 and K733 is significantly lower compared to the oxime HI-6 and, therefore, they are not suitable for the replacement of the oxime HI-6 for the antidotal treatment of acute sarin poisoning.

• MeSH
• acetylcholinesterasa krev   chemie   metabolismus   MeSH
• antagonisté muskarinových receptorů terapeutické užití   MeSH
• antidota terapeutické užití   MeSH
• atropin terapeutické užití   MeSH
• bránice účinky léků   enzymologie   MeSH
• cholinesterasové inhibitory aplikace a dávkování   chemie   toxicita   MeSH
• kombinovaná farmakoterapie MeSH
• mozek účinky léků   enzymologie   MeSH
• myši MeSH
• neurony účinky léků   enzymologie   MeSH
• neurotoxické syndromy krev   farmakoterapie   etiologie   metabolismus   MeSH
• obidoxim chlorid terapeutické užití   MeSH
• outbrední kmeny zvířat MeSH
• oximy terapeutické užití   MeSH
• potkani Wistar MeSH
• proteiny nervové tkáně agonisté   antagonisté a inhibitory   metabolismus   MeSH
• pyridinové sloučeniny terapeutické užití   MeSH
• reaktivátory cholinesterázy terapeutické užití   MeSH
• sarin aplikace a dávkování   antagonisté a inhibitory   toxicita   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

Obidoxime, a weak acetylcholine-esterase (AChE) inhibitor, exerts muscarinic receptor antagonism with a significant muscarinic M2 receptor selective profile. The current examinations aimed to determine the functional significance of muscarinic M2 receptors in the state of AChE inhibition, elucidating muscarinic M2 and M3 receptor interaction. In the in vitro examinations, methacholine evoked concentration-dependent bladder contractile and atrial frequency inhibitory responses. Although atropine abolished both, methoctramine (1 μmol/L) only affected the cholinergic response in the atrial preparations. However, in the presence of methoctramine, physostigmine, an AChE inhibitor, increased the basal tension of the bladder strip preparations (+68%), as well as the contractile responses to low concentrations of methacholine (< 5 μmol/L; +90-290%). In contrast to physostigmine, obidoxime alone raised the basal tension (+58%) and the responses to low concentrations of methacholine (< 5 μmol/L; +80-450%). Physostigmine concentration-dependently increased methacholine-evoked responses, similarly to obidoxime at low concentrations. However, at large concentrations (> 5 μmol/L), obidoxime, because of its unselective muscarinic receptor antagonism, inhibited the methacholine bladder responses. In conclusion, the current results show that muscarinic M2 receptors inhibit muscarinic M3 receptor-evoked contractile responses to low concentrations of acetylcholine in the synaptic cleft. The muscarinic M2 and M3 receptor crosstalk could be a counteracting mechanism in the treatment of AChE inhibition when using reactivators, such as obidoxime.

• MeSH
• antagonisté muskarinových receptorů farmakologie   MeSH
• atropin farmakologie   MeSH
• cholinesterasové inhibitory farmakologie   MeSH
• diaminy farmakologie   MeSH
• fysostigmin farmakologie   MeSH
• interakce mezi receptory a ligandy MeSH
• krysa rodu rattus MeSH
• methacholinchlorid farmakologie   MeSH
• močový měchýř účinky léků   enzymologie   metabolismus   MeSH
• obidoxim chlorid farmakologie   MeSH
• receptor muskarinový M2 antagonisté a inhibitory   MeSH
• receptor muskarinový M3 antagonisté a inhibitory   MeSH
• srdeční síně účinky léků   enzymologie   metabolismus   MeSH
• svalová kontrakce účinky léků   MeSH
• techniky in vitro MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH