Synthesis and anticholinesterase activity of 4-aryl-4-oxo-N-phenyl-2-aminylbutyramides, novel class of reversible, moderately potent cholinesterase inhibitors, are reported. Simple substituent variation on aroyl moiety changes anti-AChE activity for two orders of magnitude; also substitution and type of hetero(ali)cycle in position 2 of butanoic moiety govern AChE/BChE selectivity. The most potent compounds showed mixed-type inhibition, indicating their binding to free enzyme and enzyme-substrate complex. Alignment-independent 3D QSAR study on reported compounds, and compounds having similar potencies obtained from the literature, confirmed that alkyl substitution on aroyl moiety of molecules is requisite for inhibition activity. The presence of hydrophobic moiety at close distance from hydrogen bond acceptor has favorable influence on inhibition potency. Docking studies show that compounds probably bind in the middle of the AChE active site gorge, but are buried deeper inside BChE active site gorge, as a consequence of larger BChE gorge void.
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