Oxime reactivators of acetylcholinesterase (AChE) are used as causal antidotes for intended and unintended poisoning by organophosphate nerve agents and pesticides. Despite all efforts to develop new AChE reactivators, none of these drug candidates replaced conventional clinically used oximes. In addition to the therapeutic efficacy, determining the safety profile is crucial in preclinical drug evaluation. The exact mechanism of oxime toxicity and the structure-toxicity relationship are subjects of ongoing research, with oxidative stress proposed as a possible mechanism. In the present study, we investigated four promising bispyridinium oxime AChE reactivators, K048, K074, K075, and K203, and their ability to induce oxidative stress in vitro. Cultured human hepatoma cells were exposed to oximes at concentrations corresponding to their IC50 values determined by the MTT assay after 24 h. Their potency to generate reactive oxygen species, interfere with the thiol antioxidant system, and induce lipid peroxidation was evaluated at 1, 4, and 24 h of exposure. Reactivators without a double bond in the four-carbon linker, K048 and K074, showed a greater potential to induce oxidative stress compared with K075 and K203, which contain a double bond. Unlike oximes with a three-carbon-long linker, the number of aldoxime groups attached to the pyridinium moieties does not determine the oxidative stress induction for K048, K074, K075, and K203 oximes. In conclusion, our results emphasize that the structure of oximes plays a critical role in inducing oxidative stress, and this relationship does not correlate with their cytotoxicity expressed as the IC50 value. However, it is important to note that oxidative stress cannot be disregarded as a potential contributor to the side effects associated with oximes.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• antidota farmakologie   MeSH
• buňky Hep G2 MeSH
• cholinesterasové inhibitory toxicita   MeSH
• lidé MeSH
• organofosfáty toxicita   MeSH
• oxidační stres MeSH
• oximy farmakologie   chemie   MeSH
• pyridinové sloučeniny farmakologie   chemie   MeSH
• reaktivátory cholinesterasy * farmakologie   chemie   MeSH
• uhlík MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• antidota MeSH
• cholinesterasové inhibitory MeSH
• organofosfáty MeSH
• oximy MeSH
• pyridinové sloučeniny MeSH
• reaktivátory cholinesterasy * MeSH
• uhlík MeSH

To date, the only treatments developed for poisoning by organophosphorus compounds, the most toxic chemical weapons of mass destruction, have exhibited limited efficacy and versatility. The available causal antidotes are based on reactivation of the enzyme acetylcholinesterase (AChE), which is rapidly and pseudo-irreversibly inhibited by these agents. In this study, we developed a novel series of monoquaternary reactivators combining permanently charged moieties tethered to position 6- of 3-hydroxypyridine-2-aldoxime reactivating subunit. Highlighted representatives (21, 24, and 27; also coded as K1371, K1374, and K1375, respectively) that contained 1-phenylisoquinolinium, 7-amino-1-phenylisoquinolinium and 4-carbamoylpyridinium moieties as peripheral anionic site ligands, respectively, showed efficacy superior or comparable to that of the clinically used standards. More importantly, these reactivators exhibited wide-spectrum efficacy and were minutely investigated via determination of their reactivation kinetics in parallel with molecular dynamics simulations to study their mechanisms of reactivation of the tabun-inhibited AChE conjugate. To further confirm the potential applicability of these candidates, a mouse in vivo assay was conducted. While K1375 had the lowest acute toxicity and the most suitable pharmacokinetic profile, the oxime K1374 with delayed elimination half-life was the most effective in ameliorating the signs of tabun toxicity. Moreover, both in vitro and in vivo, the versatility of the agents was substantially superior to that of clinically used standards. Their high efficacy and broad-spectrum capability make K1374 and K1375 promising candidates that should be further investigated for their potential as nerve agents and insecticide antidotes.

• Klíčová slova
• Acetylcholinesterase, Butyrylcholinesterase, Insecticides, Nerve agents, Organophosphates, Organophosphorus compounds, Oxime reactivator,
• MeSH
• acetylcholinesterasa účinky léků   metabolismus   MeSH
• antidota chemická syntéza   chemie   farmakologie   MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• oximy chemická syntéza   chemie   farmakologie   MeSH
• reaktivátory cholinesterasy chemická syntéza   chemie   farmakologie   MeSH
• simulace molekulární dynamiky MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• antidota MeSH
• oximy MeSH
• reaktivátory cholinesterasy MeSH

Certain AChE reactivators, asoxime, obidoxime, K027, K048, and K075, when taken in overdoses and sometimes even when introduced within therapeutic ranges, may injure the different organs. As a continuation of previously published data, in this study, Wistar rats have sacrificed 24 hrs and 7 days after single im application of 0.1LD50, 0.5LD50 and 1.0LD50 of each reactivator, and examinated tissue samples were obtained for pathohistological and semiquantitative analysis. A severity of tissue alteration, expressed as different tissue damage scores were evaluated. Morphological structure of examinated tissues treated with of 0.1LD50 of all reactivators was comparable with the control group of rats. Moderate injuries were seen in visceral tissues treated with 0.5LD50 of asoxime, obidoxime and K027. Acute damages were enlarged after treatment with 0.5LD50 and 1.0LD50 of all reactivators during the next 7 days. The most prominent changes were seen in rats treated with 1.0LD50 of K048 and K075 (P < 0.001 vs. control and asoxime-treated group). All reactivators given by a single, high, unitary dose regimen, have an adverse effect not only on the main visceral tissue, but on the whole rat as well, but the exact mechanism of cellular injury remains to be confirmed in further investigation.

• MeSH
• biopsie MeSH
• chemické bojové látky škodlivé účinky   chemie   toxicita   MeSH
• histocytochemie MeSH
• krysa rodu Rattus MeSH
• LD50 MeSH
• molekulární struktura MeSH
• orgánová specificita MeSH
• oximy aplikace a dávkování   škodlivé účinky   chemie   toxicita   MeSH
• plíce účinky léků   metabolismus   patologie   MeSH
• vnitřnosti účinky léků   patologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• žaludek účinky léků   patologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chemické bojové látky MeSH
• oximy MeSH

Therapeutic application of newly developed oximes is limited due to their adverse effects on different tissues. Within this article, it has been investigated which morphological changes could be observed in Wistar rats after the treatment with increasing doses of selected acetyl cholinesterase reactivators - asoxime, obidoxime, K027, K048, and K075. Subsequently, heart, diaphragm and musculus popliteus were obtained for pathohistological and semiquantitative analysis 24 hrs and 7 days after im administration of a single dose of 0.1 LD50, 0.5 LD50, and 1.0 LD50 of each oxime. Different muscle damage score was based on an estimation scale from 0 (no damage) to 5 (strong damage). In rats treated with 0.1 LD50 of each oxime, muscle fibres did not show any change. The intensive degeneration was found in all muscles after treatment with 0.5 LD50 of asoxime and obidoxime, respectively. Acute toxic muscle injury was developed within 7 days following treatment with 0.5 LD50 and 1.0 LD50 of each oxime, with the highest values in K048 and K075 group (P < 0.001 vs. control and asoxime), respectively. The early muscle alterations observed in our study seem to contribute to the pathogenesis of the oxime-induced toxic muscle injury, which probably manifests as necrosis and/or inflammation.

• MeSH
• bránice účinky léků   zranění   MeSH
• kosterní svaly účinky léků   zranění   MeSH
• krysa rodu Rattus MeSH
• myozitida chemicky indukované   MeSH
• nekróza MeSH
• oximy toxicita   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny toxicita   MeSH
• srdce účinky léků   MeSH
• svaly účinky léků   patologie   MeSH
• testy akutní toxicity 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
• Názvy látek
• 1-(4-hydroxyiminomethylpyridinium)-3-(carbamoylpyridinium) propane dibromide MeSH Prohlížeč
• 1-(4-hydroxyiminomethylpyridinium)-4-(4-carbamoylpyridinium)butane MeSH Prohlížeč
• K075 compound MeSH Prohlížeč
• oximy MeSH
• pyridinové sloučeniny MeSH

The toxic effect of organophosphates is attributed to irreversible inhibition of acetylcholinesterase (AChE; EC 3.1.1.7), the enzyme that hydrolyses the neurotransmitter acetylcholine. Inhibition potency in vivo of one of the most toxic nerve agents--Russian VX (RVX;N,N-diethyl-2-[methyl-(2-methylpropoxy)phosphoryl]sulfanylethanamine) (1 x LD(50) dose administered intramuscularly, i.m.) was studied in rats. AChE in blood was inhibited by 50%, 3 min after i.m. RVX. Butylcholinesterase (BChE; EC 3.1.1.8) in plasma was inhibited less rapidly and only by 10-20%, 20 min after RVX. AChE and BChE activities in diaphragm were reduced only 35% and 15% at 30 min. While AChE and BChE activities were reduced only about 20% and 15%, respectively, the decline in activity was rapid, occurring within 3 min. These findings indicate that RVX most potently inhibits ChE outside the central nervous system.

• MeSH
• acetylcholinesterasa krev   MeSH
• bránice účinky léků   enzymologie   MeSH
• časové faktory MeSH
• chování zvířat účinky léků   MeSH
• játra účinky léků   enzymologie   MeSH
• krysa rodu Rattus MeSH
• LD50 MeSH
• mozek účinky léků   enzymologie   MeSH
• organothiofosforové sloučeniny toxicita   MeSH
• potkani Wistar MeSH
• tkáňová distribuce účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acetylcholinesterasa MeSH
• organothiofosforové sloučeniny MeSH
• S-(N,N-diethylaminoethyl) isobutyl methylphosphothiolate MeSH Prohlížeč

Seven new oxime-based acetylcholinesterase reactivators were compared with three currently available ones (obidoxime, trimedoxime, HI-6) for their ability to lessen cholinesterase inhibition in blood and brain of cyclosarin-treated rats. Oximes were given at doses of 5% their LD(50) along with 21 mg/kg atropine five min before the LD(50) of cyclosarin (120 ug/kg) was administered. Blood and brain samples were collected 30 minutes later. The greatest difference between acetylcholinesterase inhibition in blood of cyclosarin-treated rats was found after administration of HI-6 (40%), compared to 22% for trimedoxime and 6% for obidoxime. Only two of the seven newly synthesized oximes had any effect (K203 at 7%, K156 at 5%). Effective oximes against cyclosarin-inhibited plasma butyrylcholinesterase were HI-6 (42%), trimedoxime (11%), and K156 (4%). The oximes were less effective in brain than in blood, with reactivation values for HI-6 30% against acetylcholinesterase and 10% against butyrylcholinesterase. Values for newly synthesized oximes were less than 10% for K206, K269 and K203.

• Klíčová slova
• acetylcholinesterase, butyrylcholinesterase, cyclosarin, oximes, reactivators,
• MeSH
• acetylcholinesterasa krev   metabolismus   MeSH
• atropin farmakologie   MeSH
• krysa rodu Rattus MeSH
• mozek účinky léků   enzymologie   MeSH
• organofosforové sloučeniny toxicita   MeSH
• oximy chemie   farmakologie   MeSH
• potkani Wistar MeSH
• reaktivátory cholinesterasy chemie   farmakologie   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
• Názvy látek
• acetylcholinesterasa MeSH
• atropin MeSH
• cyclohexyl methylphosphonofluoridate MeSH Prohlížeč
• organofosforové sloučeniny MeSH
• oximy MeSH
• reaktivátory cholinesterasy MeSH

The therapeutical efficacies of eleven oxime-based acetylcholinesterase reactivators were compared in an in vivo (rat model) study of treatment of intoxication caused by tabun. In this group there were some currently available oximes (obidoxime, trimedoxime and HI-6) and the rest were newly synthesized compounds. The best reactivation efficacy for acetylcholinesterase in blood (expressed as percent of reactivation) among the currently available oximes was observed after administration of trimedoxime (16%) and of the newly synthesized K127 (22432) (25%). The reactivation of butyrylcholinesterase in plasma was also studied; the best reactivators were trimedoxime, K117 (22435), and K127 (22432), with overall reactivation efficacies of approximately 30%. Partial protection of brain ChE against tabun inhibition was observed after administration of trimedoxime (acetylcholinesterase 20%; butyrylcholinesterase 30%) and obidoxime (acetylcholinesterase 12%; butyrylcholinesterase 16%).

• Klíčová slova
• Acetylcholinesterase, butyrylcholinesterase, oximes, pretreatment, reactivators,
• Publikační typ
• časopisecké články MeSH

In this work, two oximes for the treatment of tabun-inhibited acetylcholinesterase (AChE; EC 3.1.1.7), K074 (1,4-bis(4-hydroxyiminomethylpyridinium)butane dibromide) and K075 ((E)-1,4-bis(4-hydroxyiminomethylpyridinium)but-2-en dibromide), were tested in vitro as reactivators of AChE. Comparison was made with currently used AChE reactivators (pralidoxime, HI-6, methoxime and obidoxime). Human brain homogenate was taken as an appropriate source of the cholinesterases. As resulted, oxime K074 appears to be the most potent reactivator of tabun-inhibited AChE, with reactivation potency comparable to that of obidoxime. A second AChE reactivator, K075, does not attain as great a reactivation potency as K074, although its maximal reactivation (17%) was achieved at relevant concentrations for humans.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• aktivace enzymů účinky léků   MeSH
• butany chemie   farmakologie   MeSH
• cholinesterasové inhibitory toxicita   MeSH
• lidé MeSH
• nucleus caudatus účinky léků   enzymologie   MeSH
• obidoxim chlorid chemie   farmakologie   MeSH
• organofosfáty toxicita   MeSH
• oximy chemie   farmakologie   MeSH
• pralidoximové sloučeniny chemie   farmakologie   MeSH
• pyridinové sloučeniny chemie   farmakologie   MeSH
• reaktivátory cholinesterasy chemie   farmakologie   MeSH
• techniky in vitro MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 1,4-bis(4-hydroxyiminomethylpyridinium)butane dibromide MeSH Prohlížeč
• acetylcholinesterasa MeSH
• asoxime chloride MeSH Prohlížeč
• butany MeSH
• cholinesterasové inhibitory MeSH
• K075 compound MeSH Prohlížeč
• N,N'-monomethylenebis(pyridiniumaldoxime) MeSH Prohlížeč
• obidoxim chlorid MeSH
• organofosfáty MeSH
• oximy MeSH
• pralidoxime MeSH Prohlížeč
• pralidoximové sloučeniny MeSH
• pyridinové sloučeniny MeSH
• reaktivátory cholinesterasy MeSH
• tabun MeSH Prohlížeč