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

Commun Biol. 2021 May 14;4(1):573. doi: 10.1038/s42003-021-02061-w.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood-Brain Barrier / drug effects*
  • Butyrylcholinesterase / chemistry*
  • Butyrylcholinesterase / metabolism*
  • Cholinesterase Inhibitors / pharmacology*
  • Enzyme Activation
  • Humans
  • Male
  • Mice
  • Mice, Inbred ICR
  • Nerve Agents / toxicity*
  • Oximes / pharmacology*

Substances

  • Cholinesterase Inhibitors
  • Nerve Agents
  • Oximes
  • BCHE protein, human
  • Butyrylcholinesterase