Probing the activity of a non-oxime reactivator for acetylcholinesterase inhibited by organophosphorus nerve agents

Chem Biol Interact. 2016 Nov 25;259(Pt B):133-141. doi: 10.1016/j.cbi.2016.04.002. Epub 2016 Apr 7.

Abstract

Currently fielded treatments for nerve agent intoxication include atropine, an acetylcholine receptor antagonist, and pralidoxime (2PAM), a small molecule reactivator of acetylcholinesterase (AChE). 2PAM reactivates nerve agent-inhibited AChE via direct nucleophilic attack by the oxime moiety on the phosphorus center of the bound nerve agent. Due to a permanently charged pyridinium motif, 2PAM is not thought to cross the blood brain barrier and therefore cannot act directly in the neuronal junctions of the brain. In this study, ADOC, a non-permanently charged, non-oxime molecule initially identified using pesticide-inhibited AChE, was characterized in vitro against nerve agent-inhibited recombinant human AChE. The inhibitory and reactivation potentials of ADOC were determined with native AChE and AChE inhibited with tabun, sarin, soman, cyclosarin, VX, or VR and then compared to those of 2PAM. Several structural analogs of ADOC were used to probe the reactivation mechanism of the molecule. Finally, guinea pigs were used to examine the protective efficacy of the compound after exposure to sarin. The results of both in vitro and in vivo testing will be useful in the design of future small molecule reactivators.

Keywords: Acetylcholinesterase; Guinea pig; Organophosphorus nerve agent; Oxime; Pralidoxime; Reactivator.

MeSH terms

  • Acetylcholinesterase / chemistry
  • Acetylcholinesterase / genetics
  • Acetylcholinesterase / metabolism*
  • Animals
  • Cholinesterase Reactivators / chemistry
  • Cholinesterase Reactivators / metabolism*
  • Cholinesterase Reactivators / therapeutic use
  • Erythrocytes / enzymology
  • Guinea Pigs
  • Half-Life
  • Humans
  • Kinetics
  • Male
  • Nerve Agents / chemistry
  • Nerve Agents / metabolism*
  • Nerve Agents / poisoning
  • Organophosphate Poisoning / drug therapy
  • Organophosphates / chemistry
  • Organophosphates / metabolism
  • Oximes / chemistry*
  • Phenols / chemistry
  • Phenols / metabolism*
  • Phenols / therapeutic use
  • Pralidoxime Compounds / chemistry
  • Pralidoxime Compounds / metabolism*
  • Pralidoxime Compounds / therapeutic use
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Sarin / chemistry
  • Sarin / metabolism
  • Soman / chemistry
  • Soman / metabolism
  • Structure-Activity Relationship

Substances

  • 4-amino-2-((diethylamino)methyl)phenol
  • Cholinesterase Reactivators
  • Nerve Agents
  • Organophosphates
  • Oximes
  • Phenols
  • Pralidoxime Compounds
  • Recombinant Proteins
  • Soman
  • Sarin
  • Acetylcholinesterase
  • pralidoxime
  • tabun