Six novel brominated bis-pyridinium oximes were designed and synthesized to increase their nucleophilicity and reactivation ability of phosphorylated acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Their pKa was valuably found lower to parent non-halogenated oximes. Stability tests showed that novel brominated oximes were stable in water, but the stability of di-brominated oximes was decreased in buffer solution and their degradation products were prepared and characterized. The reactivation screening of brominated oximes was tested on AChE and BChE inhibited by organophosphorus surrogates. Two mono-brominated oximes reactivated AChE comparably to non-halogenated analogues, which was further confirmed by reactivation kinetics. The acute toxicity of two selected brominated oximes was similar to commercially available oxime reactivators and the most promising brominated oxime was tested in vivo on sarin- and VX-poisoned rats. This brominated oxime showed interesting CNS distribution and significant reactivation effectiveness in blood. The same oxime resulted with the best protective index for VX-poisoned rats.

• Keywords
• Cholinesterase, Nerve agent, Nucleophile, Organophosphate, Oxime, Reactivation,
• MeSH
• Acetylcholinesterase * metabolism   drug effects   MeSH
• Butyrylcholinesterase * metabolism   MeSH
• Chemical Warfare Agents toxicity   MeSH
• Cholinesterase Inhibitors * toxicity   pharmacology   MeSH
• Halogenation MeSH
• Rats MeSH
• Nerve Agents * toxicity   MeSH
• Organothiophosphorus Compounds * toxicity   MeSH
• Oximes * pharmacology   chemistry   MeSH
• Rats, Wistar MeSH
• Pyridinium Compounds pharmacology   MeSH
• Cholinesterase Reactivators * pharmacology   chemistry   MeSH
• Sarin * toxicity   MeSH
• Drug Stability MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acetylcholinesterase * MeSH
• Butyrylcholinesterase * MeSH
• Chemical Warfare Agents MeSH
• Cholinesterase Inhibitors * MeSH
• Nerve Agents * MeSH
• Organothiophosphorus Compounds * MeSH
• Oximes * MeSH
• Pyridinium Compounds MeSH
• Cholinesterase Reactivators * MeSH
• Sarin * MeSH
• VX MeSH Browser

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.

• Keywords
• Acetylcholinesterase, Butyrylcholinesterase, Insecticides, Nerve agents, Organophosphates, Organophosphorus compounds, Oxime reactivator,
• MeSH
• Acetylcholinesterase drug effects   metabolism   MeSH
• Antidotes chemical synthesis   chemistry   pharmacology   MeSH
• Mice, Inbred BALB C MeSH
• Mice MeSH
• Oximes chemical synthesis   chemistry   pharmacology   MeSH
• Cholinesterase Reactivators chemical synthesis   chemistry   pharmacology   MeSH
• Molecular Dynamics Simulation MeSH
• Structure-Activity Relationship MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Antidotes MeSH
• Oximes MeSH
• Cholinesterase Reactivators MeSH

Antidotes against organophosphates often possess physicochemical properties that mitigate their passage across the blood-brain barrier. Cucurbit[7]urils may be successfully used as a drug delivery system for bisquaternary oximes and improve central nervous system targeting. The main aim of these studies was to elucidate the relationship between cucurbit[7]uril, oxime K027, atropine, and paraoxon to define potential risks or advantages of this delivery system in a complex in vivo system. For this reason, in silico (molecular docking combined with umbrella sampling simulation) and in vivo (UHPLC-pharmacokinetics, toxicokinetics; acetylcholinesterase reactivation and functional observatory battery) methods were used. Based on our results, cucurbit[7]urils affect multiple factors in organophosphates poisoning and its therapy by (i) scavenging paraoxon and preventing free fraction of this toxin from entering the brain, (ii) enhancing the availability of atropine in the central nervous system and by (iii) increasing oxime passage into the brain. In conclusion, using cucurbit[7]urils with oximes might positively impact the overall treatment effectiveness and the benefits can outweigh the potential risks.

• Keywords
• CB7, K027, acetylcholinesterase, antidote, cucurbit[7]uril, cucurbiturils, in vivo, mouse, paraoxon, pesticide,
• MeSH
• Atropine chemistry   MeSH
• Blood-Brain Barrier MeSH
• Imidazoles chemistry   MeSH
• Mice MeSH
• Oximes chemistry   MeSH
• Paraoxon chemistry   toxicity   MeSH
• Computer Simulation MeSH
• Bridged-Ring Compounds chemistry   MeSH
• Pyridinium Compounds chemistry   MeSH
• Cholinesterase Reactivators chemistry   toxicity   MeSH
• Molecular Docking Simulation MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• 1-(4-hydroxyiminomethylpyridinium)-3-(carbamoylpyridinium) propane dibromide MeSH Browser
• Atropine MeSH
• cucurbit(7)uril MeSH Browser
• Imidazoles MeSH
• Oximes MeSH
• Paraoxon MeSH
• Bridged-Ring Compounds MeSH
• Pyridinium Compounds MeSH
• Cholinesterase Reactivators MeSH

Current palliative pharmacotherapy of Alzheimer's disease based on the cholinergic hypothesis led to the development of four cholinesterase inhibitors. These compounds can bring prolongation of the symptom-free period in some patients. This is the first report directly comparing donepezil and rivastigmine plasma and brain levels in in-vivo study. Donepezil and rivastigmine were applied i.m. to rats; the dose was calculated from clinical recommendations. The samples were analysed on an Agilent 1260 Series LC with UV/VIS detector. An analytical column (Waters Spherisorb S5 W (250 mm × 4.6 i.d.; 5 μm particle size)) with guard column (Waters Spherisorb S5 W (30 mm × 4.6 mm i.d.)) was used. The mobile phase contained acetonitrile and 50 mM sodium dihydrogen phosphate (17:83; v/v); pH 3.1. The LLOQ in rat plasma was 0.5 ng/mL for donepezil and 0.8 ng/mL for rivastigmine, and the LLOQ in rat brain was 1.0 ng/mL for donepezil and 1.1 ng/mL for rivastigmine. Both compounds showed ability to target the central nervous system, with brain concentrations exceeding those in plasma. Maximum brain concentration after i.m. administration was reached in the 36 (8.34 ± 0.34 ng/mL) and 17 minute (6.18 ± 0.40 ng/mL), respectively for donepezil and rivastigmine. The differences in brain profile can be most easily expressed by plasma/brain AUCtotal ratios: donepezil ratio in the brain was nine-times higher than in plasma and rivastigmine ratio was less than two-times higher than in plasma.

• Keywords
• Acetylcholinesterase inhibitors, Alzheimer’s disease, Donepezil, HPLC, Rivastigmine,
• Publication type
• Journal Article MeSH

UNLABELLED: Inhibitors of acetylcholinesterase (AChE) may be used in the treatment of various cholinergic deficits, among them being myasthenia gravis (MG). This paper describes the first in vivo data for promising small quaternary inhibitors (K298 and K524): acute toxicity study, cholinesterase inhibition, absorption, and blood-brain barrier penetration. The newly prepared AChE inhibitors (bis-quinolinium and quinolinium compounds) possess a positive charge in the molecule which ensures that anti-AChE action is restricted to peripheral effect. HPLC-MS was used for determination of real plasma and brain concentration in the pharmacokinetic part of the study, and standard non-compartmental analysis was performed. The maximum plasma concentrations were attained at 30 min (K298; 928.76 ± 115.20 ng/ml) and 39 min (K524; 812.40 ± 54.96 ng/ml) after i.m. APPLICATION: Both compounds are in fact able to target the central nervous system. It seems that the difference in the CNS distribution profile depends on an active efflux system. The K524 brain concentration was actively decreased to below an effective level; in contrast, K298 progressively accumulated in brain tissue. Peripheral AChE inhibitors are still first-line treatment in the mild forms of MG. Commonly prescribed carbamates have many severe side effects related to AChE carbamylation. The search for new treatment strategies is still important. Unlike carbamates, these new compounds target AChE via apparent π-π or π-cationic interaction aside at the AChE catalytic site.

• Keywords
• Acetylcholinesterase, Blood–brain barrier, Myasthenia gravis, Preclinical study, Small quaternary inhibitors,
• MeSH
• Quinolinium Compounds administration & dosage   blood   pharmacokinetics   toxicity   MeSH
• Cholinesterase Inhibitors administration & dosage   blood   pharmacokinetics   toxicity   MeSH
• Cholinesterases blood   MeSH
• Blood-Brain Barrier drug effects   metabolism   MeSH
• Rats MeSH
• Lethal Dose 50 MeSH
• Brain Chemistry drug effects   MeSH
• Brain drug effects   metabolism   MeSH
• Rats, Wistar MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Quinolinium Compounds MeSH
• Cholinesterase Inhibitors MeSH
• Cholinesterases MeSH