New Safe Method for Preparation of Sarin-Exposed Human Erythrocytes Acetylcholinesterase Using Non-Toxic and Stable Sarin Analogue Isopropyl p -Nitrophenyl Methylphosphonate and its Application to Evaluation of Nerve Agent Antidotes

Introduction A non-toxic and stable sarin analogue, isopropyl p -nitrophenyl methylphosphonate (INMP), was synthesized for safe preparation of sarin-exposed acetylcholinesterase (AChE). Results and Discussion This agent was stable for years, able to be handled in an ordinary laboratory without special care, and its 50% inhibitory concentration (IC 50 ) on 0.04 U/ml human erythrocytes AChE was 15 nM. This reagent was thought to be especially useful since it enables experiments that require sarin-inhibited AChE, such as the development of antidotes for sarin, in a usual laboratory. To demonstrate the usefulness of this method, 40 known and novel pyridinealdoxime methiodide (PAM)-type oxime antidotes were synthesized, and their reactivation activities to INMP-exposed AChE and structure–activities correlation were studied. Conclusion Among the antidotes tested in this experiment except for 2-PAM, the compound found to have the highest reactivation activity, was the novel hydrophobic 2-PAM-type compound, 2-[(hydroxyimino)methyl]-1-[4-( tert -butyl)benzyl] pyridinium bromide.