Ionic and Non-Ionic Counterparts Based on Bis(Uracilyl)Alkane Moiety with Highest Selectivity Towards Acetylcholinesterase for Protection Against Organophosphate Poisoning and Treating Alzheimer’s Disease

A series of bisuracils, in which uracil and 3,6-dimethyluracil moieties were bridged with a polymethylene spacer, and the uracil moiety contained a pentamethylene radical with ionic and non-ionic aminobenzyl groups, were synthesised. These bisuracils have been identified as cholinesterase inhibitors with exceptional selectivity for acetylcholinesterase (AChE) over butyrylcholinesterase (BuChE). These bisuracils, which have been identified as highly effective AChE inhibitors, demonstrated activity at nano- and sub-nanomolar concentrations, with exceptional selectivity for AChE over BuChE. In kinetic studies of lead bisuracils <b>2b</b> and <b>3c</b>, both compounds exhibited mixed-type inhibition against AChE and BuChE. Additionally, molecular dynamic simulations demonstrated robust and stable interactions of <b>2b</b> and <b>3c</b> with the binding sites of their target. Bisuracil <b>2b</b> showed significant potential for protection of AChE from irreversible inhibition by paraoxon; the most effective dose of 0.01 mg/kg was shown to reduce mortality in paraoxon-poisoned mice. Bisuracil <b>3c</b> effectively inhibited brain AChE activity, reversing scopolamine-induced amnesia in mice at a dose of 5 mg/kg, which indicates its potential for cognitive enhancement. These findings position ionic bisuracils as promising prophylactics against organophosphate poisoning and non-ionic bisuracils as viable candidates for Alzheimer's disease therapeutics.