Reactivators of Tabun-Inhibited Acetylcholinesterase: Structure-Biological Activity Relationship

Acetylcholinesterase (AChE; EC 3.1.1.7) reactivators (called oximes) are important group of drugs used as antidotes in the treatment of intoxications with highly toxic organophosphorus compounds such as pesticides (paraoxon, chlorpyrifos etc.) and nerve agents (sarin, tabun etc.). After the sarin terroristic attack in Tokyo subway, their development employed many scientists from both - military and civilian sectors. Due to the rapid synthesis and evaluation of the biological activity of many new structurally different potential antidotes in our laboratories, we would like to discuss relationship between the structure of currently available AChE reactivators and their biological activity.

There is a wide range of organophosphorus nerve agents and pesticides and, therefore, our article was focused on reactivators of tabun-inhibited AChE only. This agent was chosen for its poor ability of currently commercially available oximes to reactivate AChE inhibited by this nerve agent.

Presented results arised from our in vitro studies comprising more than one hundred structurally different AChE reactivators, which were published during last five years. In this article, the main structural requirements (presence of the quaternary nitrogens; choice, presence, and position of the nucleophilic group; length, shape, and rigidity of the connection chain) influencing reactivation potency of currently available oximes is discussed.

Keywords: nerve agent, acetylcholinesterase, AChE, butyrylcholinesterase, BuChE, pesticide, antidote, organophosphorus compound, oxime, reactivator, in vitro, in vivo, structure-activity relationship