Reactivators of phosphylated central acetylcholinesterase (AChE) – ReCNS-AChE

Poisoning by organophosphorus nerve agents (OPNAs) and pesticides is a serious public and military health issue with over 260 000 fatalities annually worldwide. The acute toxicity of OPNAs results from the irreversible inhibition of acetylcholinesterase (AChE), which regulates cholinergic transmission in the peripheral and in the central nervous system (CNS) by hydrolyzing acetylcholine. Conventional emergency treatment of OPNA poisoning consists of rapid administration of pyridinium oxime antidotes for reactivation of AChE and neuroprotection. However, the reactivation of central AChE is still inefficient due to the fact that positively charged pyridiniums do not cross, or only very poorly (<10%, for pralidoxime), the brain blood barrier (BBB). Moreover pyridinium(s) oximes are highly hepatocytotoxic and exhibit a quite narrow spectrum of reactivation. Despite decades of research in this field, there are no efficient and general broad-spectrum reactivators for organophosphorus-inhibited AChE. As a consequence, remediation of both acute and chronic intoxications of civilian and military populations by organophosphorus nerve agents continues to be a challenge of paramount importance. There is a great need for safe, non-invasive and effective methods to facilitate the entry of new broad-spectrum reactivators into the CNS for reactivating central AChE and treat OPNAs poisoning. In continuation of DetoxNeuro ANR-06-BLAN-0163, ReAChE ANR-09-BLAN-192, the aims of our innovative and ambitious ReCNS-AChE ASTRID dual fundamental research program are to develop novel bi- and trifunctional hybrid reactivators that will concomitantly modulate the BBB permeability, by the use of drug carrier molecules such as glucose, ascorbic acid and nucleoside, penetrate the BBB and reactivate phosphylated AChE in the CNS. These unique dual and synergistic effects will be optimized by the rational design and synthesis (Partners 1 and 2) of a new class of central multifunctional reactivators that are highly water soluble, uncharged and non hepatocytotoxic. By means of molecular docking and theoretical calculations (Partners 3 and 4), the best candidates will be selected over libraries of potential hybrids and synthesized using straightforward and convergent pathways based of click chemistry. It is emphasized that the Carrier-Mediated Transport (CMT) that is widely expressed at the BBB level will trigger the transport of our multifunctional reactivators into the brain and reactivate central AChE. The planned in vitro, kinetic parameters determination, as well as in vivo biological evaluations on mice model will allow us to assess the BBB permeability, the performance and the overall reactivation efficiency of our new molecules (Partner 4). We also plan to use X-ray sources of a completely new kind, so called X-ray free electron lasers (XFEL) to study AChE/reactivators complex to shed light on the structural dynamics and mechanistic parameters that govern reactivation of AChE (Partners 3 and 4). Thus, the bioconjugaison of AChE reactivators to the above mentioned endogenous “nutriments-drug” able to be CMT transported represents an emerging novel trend in biotherapeutics and remediation for OPs poisoning and thus, for the reactivation of phosphylated AChE in the CNS.