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
Organophosphorus nerve agents pose a global threat to both military personnel and civilian population, because of their high acute toxicity and insufficient medical countermeasures. Commonly used drugs could ameliorate the intoxication and overall medical outcomes. In this study, we tested the drugs able to alleviate the symptoms of Alzheimer's disease (donepezil, huperzine A, memantine) or Parkinson's disease (procyclidine). They were administered to mice before soman intoxication in terms of their: i) protection potential against soman toxicity and ii) influence on post-exposure therapy consisting of atropine and asoxime (also known as oxime HI-6). Their pretreatment effect was not significant, when administered alone, but in combination (acetylcholinesterase inhibitor such as denepezil or huperzine A with NMDA antagonist such as memantine or procyclidine) they lowered the soman toxicity more than twice. These combinations also positively influenced the efficacy of post-exposure treatment in a similar fashion; the combinations increased the therapeutic effectiveness of antidotal treatment. In conclusion, the most effective combination - huperzine A and procyclidine - lowered the toxicity three times and improved the post-exposure therapy efficacy more than six times. These results are unprecedented in the published literature.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- antidota terapeutické užití MeSH
- atropin terapeutické užití farmakologie MeSH
- cholinesterasové inhibitory toxicita MeSH
- jedy * MeSH
- memantin terapeutické užití MeSH
- míra přežití MeSH
- myši MeSH
- oximy terapeutické užití farmakologie MeSH
- procyklidin farmakologie MeSH
- pyridinové sloučeniny farmakologie MeSH
- receptory N-methyl-D-aspartátu MeSH
- soman * toxicita MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Nerve agents pose a real threat to both the military and civil populations, but the current treatment of the poisoning is unsatisfactory. Thus, we studied the efficacy of prophylactic use of memantine alone or in combination with clinically used reversible acetylcholinesterase inhibitors (pyridostigmine, donepezil, rivastigmine) against soman. In addition, we tested their influence on post-exposure therapy consisting of atropine and asoxime. Pyridostigmine alone failed to decrease the acute toxicity of soman. But all clinically used acetylcholinesterase inhibitors administered alone reduced the acute toxicity, with donepezil showing the best efficacy. The combination of memantine with reversible acetylcholinesterase inhibitors attenuated soman acute toxicity significantly. The pretreatment administered alone or in combinations influenced the efficacy of post-exposure treatment in a similar fashion: (i) pyridostigmine or memantine alone did not affect the antidotal treatment, (ii) centrally acting reversible acetylcholinesterase inhibitors alone increased the antidotal treatment slightly, (iii) combination of memantine with reversible acetylcholinesterase inhibitors increased the antidotal treatment more markedly. In conclusion, memantine alone failed to decrease the acute toxicity of soman or increase post-exposure antidotal treatment efficacy. The combination of memantine with donepezil significantly increased post-exposure effectiveness (together 5.12, pretreatment alone 1.72). Both drugs, when applied together, mitigate soman toxicity and boost post-exposure treatment.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- antiparkinsonika aplikace a dávkování MeSH
- cholinesterasové inhibitory aplikace a dávkování toxicita MeSH
- donepezil aplikace a dávkování MeSH
- dopaminové látky aplikace a dávkování MeSH
- kombinovaná farmakoterapie MeSH
- memantin aplikace a dávkování MeSH
- myši MeSH
- preexpoziční profylaxe metody MeSH
- soman toxicita MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Therapeutic efficacy of antidotal treatment of acute poisoning by nerve agents is generally assessed by the evaluation of LD50 values of nerve agents over 24 h following poisoning without or with a single administration of antidotal treatment. In this study, LD50 values of four nerve agents (sarin, soman, tabun and cyclosarin) for non-treated and treated poisoning were evaluated in mice for two experimental end points - 6 h and 24 h. While the efficacy of atropine or oxime-based antidotal treatment was the same regardless of the experimental end point, the therapeutic efficacy of all three newly developed bispyridinium non-oxime compounds (MB408, MB442, and MB444) was mostly slightly higher at the 6 h end point compared to the 24 h end point, although the therapeutic efficacy of MB compounds was not superior to oxime-based antidotal treatment. These results contrast with a study in guinea-pigs using a structurally-related compound, MB327, which showed a striking increase in protection at 6 h compared to 24 h. It is suggested that the disparity may be due to pharmacokinetic differences between the two animal species.
- MeSH
- antidota farmakologie MeSH
- časové faktory MeSH
- chemické bojové látky toxicita MeSH
- LD50 MeSH
- myši MeSH
- nikotinoví antagonisté farmakologie MeSH
- organofosfáty toxicita MeSH
- organofosforové sloučeniny toxicita MeSH
- otrava organofosfáty farmakoterapie etiologie MeSH
- oximy farmakologie MeSH
- pyridinové sloučeniny farmakologie MeSH
- reaktivátory cholinesterasy farmakologie MeSH
- sarin toxicita MeSH
- soman toxicita MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
The potency of three nerve agents (sarin, soman, tabun) to induce oxidative damage of DNA in lymphocytes, liver and brain during lethal or sublethal poisoning was investigated. The single strand breaks or oxidative base DNA damage was evaluated with the help of Comet assay and a specific enzyme able to detect oxidative bases of DNA (endonuclease III). While sarin and soman administered at sublethal doses corresponding to 50% of their LD50 values were not able to induce oxidative damage of DNA, their lethal dose (LD50) induced the significant increase of the number of oxidative bases in DNA of hepatocytes. In addition, tabun administered at lethal dose (LD50) induced significant increase of the number of single strand breaks and oxidative bases of DNA in glial cells isolated from pontomedullar brain region. Thus, some nerve agents were able to induce oxidative damage in the peripheral as well as central compartment but only in the case of severe poisoning caused by lethal doses of nerve agents. This non-cholinergic effect of nerve agents has probably consequences with nerve agents-induced hypoxic status during acute cholinergic crisis and it can contribute to their long-term toxic effects.
The influence of three newly developed bispyridinium antinicotinic compounds (the non-oximes MB408, MB442 and MB444) on the therapeutic efficacy of a standard antidotal treatment (atropine in combination with an oxime) of acute poisoning by the organophosphorus nerve agents tabun and soman was studied in mice. 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 LD50 values of the nerve agents and measurement of the survival time after supralethal poisoning. Addition of all the tested non-oximes increased significantly the therapeutic efficacy of atropine in combination with an oxime against tabun poisoning. They also positively influenced the number of surviving mice 6 hr after supralethal poisoning with tabun. However, they were only slightly effective for the treatment of soman poisoning. The benefit of the tested bispyridinium non-oximes was dose-dependent. To conclude, the addition of bispyridinium non-oximes to the standard antidotal treatment of acute poisoning with tabun was beneficial regardless of the chosen non-oxime, but only slightly beneficial in the case of soman poisoning.
- MeSH
- antidota chemická syntéza farmakologie terapeutické užití MeSH
- atropin farmakologie MeSH
- kombinovaná farmakoterapie MeSH
- LD50 MeSH
- lidé MeSH
- modely nemocí na zvířatech MeSH
- myši MeSH
- nervová bojová látka otrava MeSH
- nikotinoví agonisté chemická syntéza farmakologie MeSH
- organofosfáty toxicita MeSH
- otrava organofosfáty farmakoterapie etiologie MeSH
- oximy farmakologie MeSH
- preklinické hodnocení léčiv MeSH
- pyridinové sloučeniny chemická syntéza farmakologie terapeutické užití MeSH
- soman otrava MeSH
- synergismus léků MeSH
- výsledek terapie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The potency of one reversible inhibitor of acetylcholinesterase (6-chlorotacrine), one reactivator of acetycholinesterase (K027) and their combination to increase the resistance of mice against soman and the efficacy of antidotal treatment of soman-poisoned mice was evaluated. While 6-chlorotacrine was able to markedly protect mice against acute toxicity of soman and the pharmacological pretreatment with 6-chlorotacrine increased the efficacy of antidotal treatment (the oxime HI-6 in combination with atropine) of soman-poisoned mice more than two times, the bispyridinium oxime K027 did not protect mice from acute toxicity of soman, however, the pharmacological pretreatment with this compound was able to markedly increase the efficacy of antidotal treatment of soman-poisoned mice. On the other hand, the combination of both modulators of acetylcholinesterase did not increase the prophylactic efficacy of 6-chlorotacrine alone. These findings demonstrate that pharmacological pretreatment of somanpoisoned mice can be promising and useful in the case of administration of 6-chlorotacrine while the administration of the oxime K027 did not bring any additional benefit when combined with 6- chlorotacrine.
- MeSH
- antidota MeSH
- atropin aplikace a dávkování farmakologie MeSH
- cholinesterasové inhibitory toxicita MeSH
- kombinovaná farmakoterapie MeSH
- modely u zvířat MeSH
- myši MeSH
- oximy aplikace a dávkování farmakologie MeSH
- reaktivátory cholinesterasy farmakologie MeSH
- rezistence k insekticidům účinky léků MeSH
- soman aplikace a dávkování toxicita MeSH
- synergismus léků MeSH
- takrin analogy a deriváty aplikace a dávkování farmakologie metabolismus MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- Publikační typ
- práce podpořená grantem MeSH
Organophosphorus compounds (OP) are part of a group of compounds that may be hazardous to health. They are called neurotoxic agents because of their action on the nervous system, inhibiting the acetylcholinesterase (AChE) enzyme and resulting in a cholinergic crisis. Their high toxicity and rapid action lead to irreversible damage to the nervous system, drawing attention to developing new treatment methods. The diisopropyl fluorophosphatase (DFPase) enzyme has been considered as a potent biocatalyst for the hydrolysis of toxic OP and has potential for bioremediation of this kind of intoxication. In order to investigate the degradation process of the nerve agents Tabun, Cyclosarin and Soman through the wild-type DFPase, and taking into account their stereochemistry, theoretical studies were carried out. The intermolecular interaction energy and other parameters obtained from the molecular docking calculations were used to construct a data matrix, which were posteriorly treated by statistical analyzes of chemometrics, using the PCA (Principal Components Analysis) multivariate analysis. The analyzed parameters seem to be quite important for the reaction mechanisms simulation (QM/MM). Our findings showed that the wild-type DFPase enzyme is stereoselective in hydrolysis, showing promising results for the catalytic degradation of the neurotoxic agents under study, with the degradation mechanism performed through two proposed pathways.
Background: Intoxication by nerve agents could be prevented by using small acetylcholinesterase inhibitors (eg, pyridostigmine) for potentially exposed personnel. However, the serious side effects of currently used drugs led to research of novel potent molecules for prophylaxis of organophosphorus intoxication. Methods: The molecular design, molecular docking, chemical synthesis, in vitro methods (enzyme inhibition, cytotoxicity, and nicotinic receptors modulation), and in vivo methods (acute toxicity and prophylactic effect) were used to study bispyridinium, bisquinolinium, bisisoquinolinium, and pyridinium-quinolinium/isoquinolinium molecules presented in this study. Results: The studied molecules showed non-competitive inhibitory ability towards human acetylcholinesterase in vitro that was further confirmed by molecular modelling studies. Several compounds were selected for further studies. First, their cytotoxicity, nicotinic receptors modulation, and acute toxicity (lethal dose for 50% of laboratory animals [LD50]; mice and rats) were tested to evaluate their safety with promising results. Furthermore, their blood levels were measured to select the appropriate time for prophylactic administration. Finally, the protective ratio of selected compounds against soman-induced toxicity was determined when selected compounds were found similarly potent or only slightly better to standard pyridostigmine. Conclusion: The presented small bisquaternary molecules did not show overall benefit in prophylaxis of soman-induced in vivo toxicity.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- buněčné linie MeSH
- cholinesterasové inhibitory chemie farmakologie MeSH
- HeLa buňky MeSH
- knihovny malých molekul chemie farmakologie MeSH
- lidé MeSH
- molekulární modely MeSH
- molekulární struktura MeSH
- nervová bojová látka škodlivé účinky MeSH
- soman škodlivé účinky MeSH
- viabilita buněk účinky léků MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
x
- Klíčová slova
- VX agent, tabun,
- MeSH
- acetylcholinesterasa MeSH
- biosenzitivní techniky MeSH
- chemické bojové látky * analýza MeSH
- kolorimetrie MeSH
- kyselina dithionitrobenzoová * MeSH
- neuronové sítě * MeSH
- organofosfáty analýza MeSH
- organothiofosforové sloučeniny analýza MeSH
- reaktivátory cholinesterasy MeSH
- sarin analýza MeSH
- soman analýza MeSH
