Phenylimino-2H-chromen-3-carboxamide derivatives as novel small molecule inhibitors of β-secretase (BACE1).

The inhibition of β secretase (BACE1) is potentially important approach to treatment of Alzheimer disease (AD). A novel series of 4-bromophenyl piperazine derivatives coupled to the phenylimino-2H-chromen-3-carboxamide scaffold were investigated as BACE1 inhibitors in this study. Docking study suggested that the phenyl-imino group of the scaffold establishes favorable π-π stacking interaction with side chain of Phe108 of flap pocket. Some of the docking proposed derivatives were synthesized and evaluated for BACE1 inhibitory activity using a FRET-based assay. High BACE1 inhibitory activities were observed from derivatives containing fused heteroaromtic groups attached through the aliphatic linkage to the N4-piperazine moiety, which may be attributed to the engagement of effective interactions with S1-S'1 sub-pocket residues. Of the most potent compounds, 9e displayed an IC50 value for BACE1 of 98 nM. Some of these derivatives demonstrated good inhibitory activity on Aβ production in N2a-APPswe cells at 5 and 10 μM. These compounds might be considered as promising BACE1 inhibitory agents that could lower Aβ production in AD.