Non-quaternary oximes detoxify nerve agents and reactivate nerve agent-inhibited human butyrylcholinesterase

Abstract

Government-sanctioned use of nerve agents (NA) has escalated dramatically in recent years. Oxime reactivators of organophosphate (OP)-inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) serve as antidotes toward poisoning by OPNAs. The oximes used as therapeutics are quaternary compounds that cannot penetrate the blood–brain barrier (BBB). There remains an urgent need for the development of next generation OPNA therapeutics. We have developed two high-throughput screening (HTS) assays using a fluorogenic NA surrogate, O-ethyl methylphosphonyl O-4-methyl-3-cyano-coumarin (EMP-MeCyC). EMP-MeCyC detoxification and EMP-BChE reactivation screening campaigns of ~155,000 small molecules resulted in the identification of 33 nucleophile candidates, including non-quaternary oximes. Four of the oximes were reactivators of both Sarin- and VX-inhibited BChE and directly detoxified Sarin. One oxime also detoxified VX. The novel reactivators included a non-quaternary pyridine amidoxime, benzamidoxime, benzaldoxime and a piperidyl-ketoxime. The VX-inhibited BChE reactivation reaction rates by these novel molecules were similar to those observed with known bis-quaternary reactivators and faster than mono-quaternary pyridinium oximes. Notably, we discovered the first ketoxime reactivator of OP-ChEs and detoxifier of OPNAs. Preliminary toxicological studies demonstrated that the newly discovered non-quaternary oximes were relatively non-toxic in mice. The discovery of unique non-quaternary oximes opens the door to the design of novel therapeutics and decontamination agents following OPNA exposure.

Optical imaging probes for selective detection of butyrylcholinesterase

“…[30][31][32] Additionally, BChE enzyme inhibited by OPs can be reactivated with numerous oximes. 20,21,[33][34][35] Frequently encountered nerve agents including V-type (VX, VM, VE, VG), G-type (soman, sarin, tabun, cyclosarin), and neurotoxic pesticides including aldicarb, carbofuran, and dichlorvos were depicted in Fig. 1A.…”

Retrospective detection for V-type OPNAs exposure via phosphonylation and disulfide adducts in albumin

“…Protein adducts, recognized as important targets for retrospective detection of OPNAs exposure, form via covalent bonding of the phosphorus atom in organophosphorus to active amino acids from the proteins 16 – 18 . Based on the principle of convenient sampling, butyrylcholinesterase (BChE) with high reactivity and albumin with high concentration in blood and easy covalent binding with OPNAs are the research focus of target proteins in the field 19 – 23 . However, OPNAs-BChE adducts face many disadvantages, such as complicated purification and easy aging.…”