Acetylcholinesterase (AChE) is the key enzyme responsible for deactivating the ACh neurotransmitter. Irreversible or prolonged inhibition of AChE, therefore, elevates synaptic ACh leading to serious central and peripheral adverse effects which fall under the cholinergic syndrome spectra. To combat the toxic effects of some AChEI, such as organophosphorus (OP) nerve agents, many compounds with reactivator effects have been developed. Within the most outstanding reactivators, the substances denominated oximes stand out, showing good performance for reactivating AChE and restoring the normal synaptic acetylcholine (ACh) levels. This review was developed with the purpose of covering the new advances in AChE reactivation. Over the past years, researchers worldwide have made efforts to identify and develop novel active molecules. These researches have been moving farther into the search for novel agents that possess better effectiveness of reactivation and broad-spectrum reactivation against diverse OP agents. In addition, the discovery of ways to restore AChE in the aged form is also of great importance. This review will allow us to evaluate the major advances made in the discovery of new acetylcholinesterase reactivators by reviewing all patents published between 2016 and 2019. This is an important step in continuing this remarkable research so that new studies can begin.

• Keywords
• acetylcholinesterase, new trends in reactivators, organophosphorus compounds, reactivation process, therapeutic potential,
• MeSH
• Acetylcholinesterase metabolism   MeSH
• GPI-Linked Proteins metabolism   MeSH
• Humans MeSH
• Oximes chemistry   therapeutic use   MeSH
• Patents as Topic MeSH
• Cholinesterase Reactivators * chemistry   therapeutic use   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• ACHE protein, human MeSH Browser
• GPI-Linked Proteins MeSH
• Oximes MeSH
• Cholinesterase Reactivators * MeSH

The present work aimed to compare the small, neutral and monoaromatic oxime, isatin-3-oxime (isatin-O), to the commercial ones, pralidoxime (2-PAM) and obidoxime, in a search for a new potential reactivator for acetylcholinesterase (AChE) inhibited by the pesticide paraoxon (AChE/POX) as well as a novel potential scaffold for further synthetic modifications. The multicriteria decision methods (MCDM) allowed the identification of the best docking poses of those molecules inside AChE/POX for further molecular dynamic (MD) studies, while Ellman's modified method enabled in vitro inhibition and reactivation assays. In corroboration with the theoretical studies, our experimental results showed that isatin-O have a reactivation potential capable of overcoming 2-PAM at the initial moments of the assay. Despite not achieving better results than obidoxime, this molecule is promising for being an active neutral oxime with capacity of crossing the blood⁻brain barrier (BBB), to reactivate AChE/POX inside the central and peripheral nervous systems. Moreover, the fact that isatin-O can also act as anticonvulsant makes this molecule a possible multipotent reactivator. Besides, the MCDM method showed to be an accurate method for the selection of the best docking poses generated in the docking studies.

• Keywords
• Ellman’s method, TOPSIS-AHP, acetylcholinesterase, molecular modeling, multicriteria decision making, neutral oxime,
• MeSH
• Cholinesterase Inhibitors pharmacology   MeSH
• Erythrocytes drug effects   enzymology   MeSH
• Models, Molecular * MeSH
• Molecular Structure MeSH
• Oximes chemistry   pharmacology   MeSH
• Paraoxon chemistry   pharmacology   MeSH
• Cholinesterase Reactivators chemistry   pharmacology   MeSH
• Molecular Dynamics Simulation MeSH
• Molecular Docking Simulation MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cholinesterase Inhibitors MeSH
• Oximes MeSH
• Paraoxon MeSH
• Cholinesterase Reactivators MeSH

BACKGROUND: The aim of our study was to compare the ability of two combinations of oximes (HI-6 + trimedoxime and HI-6 + K203) with atropine to counteract acute sarin-induced brain damage with the efficacy of antidotal treatment involving single oxime (HI-6) and atropin using in vivo methods. METHODS: Brain damage and neuroprotective effects of antidotal treatment were evaluated in rats poisoned with sarin at a sublethal dose (108 μg/kg i.m.; 90% LD50) using histopathological, Fluoro-Jade B and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis 24 h after sarin administration. RESULTS: Both combinations of oximes reduce the number of rats that died before the end of experiment compared to non-treated sarin poisoning and sarin poisoning treated with HI-6 and atropine. In the case of treatment of sarin poisoning with HI-6 in combination with K203, all rats survived till the end of experiment. HI-6 with atropine was able to reduce sarin-induced brain damage, however, both combinations were slightly more effective. CONCLUSIONS: The oxime HI-6 in combination with K203 and atropine seems to be the most effective. Thus, both tested oxime combinations bring a small benefit in elimination of acute sarin-induced brain damage compared to single oxime antidotal therapy.

• Keywords
• FluoraJadeB, HI-6, Histopathology, K203, Rats, Sarin, TUNEL, Trimedoxime,
• MeSH
• Antidotes therapeutic use   MeSH
• Drug Therapy, Combination MeSH
• Neurotoxicity Syndromes drug therapy   MeSH
• Oximes therapeutic use   MeSH
• Rats, Wistar MeSH
• Sarin poisoning   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Antidotes MeSH
• Oximes MeSH
• Sarin 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.

• Keywords
• acetylcholinesterase, antidote, butyrylcholinesterase, organophosphate, oxime, paraoxon,
• MeSH
• Acetylcholinesterase chemistry   MeSH
• Antidotes chemical synthesis   pharmacology   MeSH
• Butyrylcholinesterase chemistry   MeSH
• Cholinesterase Inhibitors chemistry   MeSH
• Enzyme Assays MeSH
• Erythrocytes drug effects   enzymology   MeSH
• Insecticides antagonists & inhibitors   chemistry   toxicity   MeSH
• Protein Interaction Domains and Motifs MeSH
• Humans MeSH
• Obidoxime Chloride chemistry   pharmacology   MeSH
• Oximes chemical synthesis   pharmacology   MeSH
• Paraoxon antagonists & inhibitors   chemistry   toxicity   MeSH
• Cholinesterase Reactivators chemical synthesis   pharmacology   MeSH
• Protein Structure, Secondary MeSH
• Molecular Docking Simulation MeSH
• Thermodynamics MeSH
• Protein Binding MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Antidotes MeSH
• Butyrylcholinesterase MeSH
• Cholinesterase Inhibitors MeSH
• Insecticides MeSH
• Obidoxime Chloride MeSH
• Oximes MeSH
• Paraoxon MeSH
• Cholinesterase Reactivators MeSH