Multifunctional Donepezil Analogues as Cholinesterase and BACE1 Inhibitors.

A series of 22 donepezil analogues were synthesized through alkylation/benzylation and compared to donepezil and its 6--desmethyl adduct. All the compounds were found to be potent inhibitors of both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), two enzymes responsible for the hydrolysis of the neurotransmitter acetylcholine in Alzheimer's disease patient brains. Many of them displayed lower inhibitory concentrations of AChE (IC = 0.016 ± 0.001 µM to 0.23 ± 0.03 µM) and BChE (IC = 0.11 ± 0.01 µM to 1.3 ± 0.2 µM) than donepezil. One of the better compounds was tested against AChE and was found to be even more active than donepezil and inhibited AChE better than AChE. The analogues with the aromatic substituents were generally more potent than the ones with aliphatic substituents. Five of the analogues also inhibited the action of β-secretase (BACE1) enzyme.