Development of multi-targets antidotes against organophosphorus nerve agents – Multidote

Since the September 11, 2001, terrorist attacks in the United States, and more recently the use of chemical weapons, including the nerve agent sarin, against rebels in the Syrian civil war, the specter of a chemical threat using organophosphorus nerve agents (OPNA) against civilian populations has renewed research interest in the development of new antidotes. In the battlefields or terrorist attacks, conventional emergency treatment of OPNA poisoning consists of rapid administration of pyridinium oxime for reactivation of acetylcholinesterase (AChE) and diazepam and atropine for the neuroprotection. Currently, the French Army is equipped with an autoinjector containing 2-PAM as the reactivator component, atropine and avizafone. However, the current treatment does not limit the nicotinic effects leading to the death of the intoxicated person (by paralysis of the respiratory muscles). Based on the results of the previous projects (REI-DGA-2009-34-0023, ANR ReAChE ANR-09-BLAN-192, thesis DGA),this project aims at developing original multi-target antidotes against NOP poisoning by reactivating hAChE, and by simultaneously blocking nicotinic acetylcholine receptors (nAChRs) so as to limit peripheral nicotinic effects (ie paralysis of respiratory muscles) and the muscarinic receptors (mAChRs) responsible for adverse effects (eg bronchial hypersecretions,). The multidisciplinary integrated approach (organic chemistry, computational chemistry (molecular docking), enzymology, structural biology and neuropharmacology) will be a major asset for the success of this project. The docking studies and molecular dynamics carried out on OPNA-inhibited AChE, on nAChRs and mAChRs will allow validating the structural modifications of compounds developed in the previous projects. This structural modification will allow improving the anti-nicotinic and anti-muscarinic properties of the compounds. The synthesized multi-target antidotes will be tested in vitro for the reactivation of OPNA-inhibited hAChE. Electrophysiological and binding tests on nAChRs and mAChRs receptors will validate in vitro the specificity and activity of these antidotes (antagonists / agonists, allosteric modulators). Pharmacokinetics profiles of the best candidates will be realized as well as its protective index determination. X-ray crystallography studies as well as original investigations on microcrystals of AChE/reactivators complex will allow us to shed light on the structural dynamic and mechanistic parameters that govern reactivation of AChE at a molecular level.