Structural modifications of 4-aryl-4-oxo-2-aminylbutanamides and their acetyl- and butyrylcholinesterase inhibitory activity. Investigation of AChE-ligand interactions by docking calculations and molecular dynamics simulations.

Congeneric set of thirty-eight 4-aryl-4-oxo-2-(N-aryl/cycloalkyl)butanamides has been designed, synthesized and evaluated for acetyl- and butyrylcholinesterase inhibitory activity. Structural variations included cycloalkylamino group attached to C2 position of butanoyl moiety, and variation of amido moiety of molecules. Twelve compounds, mostly piperidino and imidazolo derivatives, inhibited AChE in low micromolar range, and were inactive toward BChE. Several N-methylpiperazino derivatives showed inhibition of BChE in low micromolar or submicromolar concentrations, and were inactive toward AChE. Therefore, the nature of the cycloalkylamino moiety governs the AChE/BChE selectivity profile of compounds. The most active AChE inhibitor showed mixed-type inhibition modality, indicating its binding to free enzyme and to enzyme-substrate complex. Thorough docking calculations of the seven most potent AChE inhibitors from the set, showed that the hydrogen bond can be formed between amide -NH- moiety of compounds and -OH group of Tyr 124. The 10 ns unconstrained molecular dynamic simulation of the AChE-compound 18 complex shows that this interaction is the most persistent. This is, probably, the major anchoring point for the binding.