New Heterostilbene and Triazole Oximes as Potential CNS-Active and Cholinesterase-Targeted Therapeutics

Abstract

New furan, thiophene and triazole oximes were synthesized through several-step reaction paths to investigate their potential for development of central nervous systems (CNS)-active and cholinesterase-targeted therapeutics in organophosphorus compound (OP) poisonings. Acute OP poisoning is still a challenge in treating patients despite the development of a large number of oxime compounds that should have the capacity to reactivate acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The activity of these two enzymes, crucial for neurotransmission, are blocked by the OP, which has the consequence of disturbing normal cholinergic nerve signal transduction in the peripheral and CNS, leading to cholinergic crisis. Oximes in use have one or two pyridinium rings and cross the brain–blood barrier poorly due to the quaternary nitrogen. Following our recent study on 2-thienostilbene oximes, in this paper we described the synthesis of 63 heterostilbene derivatives out of which 26 oximes were tested as inhibitors and reactivators of AChE and BChE inhibited by OP nerve agents – sarin and cyclosarin. While the majority of oximes were potent inhibitors of both enzymes in micromolar range, we identified several oximes as BChE or AChE selective inhibitors with a potential for drug development. Moreover, even oximes were poor reactivators of AChE, four heterocyclic derivatives reactivated the cyclosarin-inhibited BChE up to 70%, and cis,trans-5 [2-((Z)-2-(5-((E)-(hydroxyimino)methyl)thiophen-2-yl)vinyl)benzonitrile] had comparable reactivation efficacy to the standard oxime HI-6. In silico analysis and molecular docking studies connected the kinetic data to the structural features of these oximes, and confirmed their productive interactions with the active site of the cyclosarin-inhibited BChE. Based on inhibition and reactivation and their ADMET properties regarding lipophilicity, CNS activity, and hepatotoxicity, these compounds could be considered for further development of CNS-active reactivators in OP poisoning as well as cholinesterase-targeted therapeutics in neurodegenerative diseases like Alzheimer’s and Parkinson’s.