Synthesis and Evaluation of Novel Ligustrazine Derivatives as Multi-Targeted Inhibitors for the Treatment of Alzheimer’s Disease

A series of novel ligustrazine derivatives 8a–r were designed, synthesized, and evaluated as multi-targeted inhibitors for anti-Alzheimer’s disease (AD) drug discovery. The results showed that most of them exhibited a potent ability to inhibit both ChEs, with a high selectivity towards AChE. In particular, compounds 8q and 8r had the greatest inhibitory abilities for AChE, with IC(50) values of 1.39 and 0.25 nM, respectively, and the highest selectivity towards AChE (for 8q, IC(50) BuChE/IC(50) AChE = 2.91 × 10(6); for 8r, IC(50) BuChE/IC(50) AChE = 1.32 × 10(7)). Of note, 8q and 8r also presented potent inhibitory activities against Aβ aggregation, with IC(50) values of 17.36 µM and 49.14 µM, respectively. Further cellular experiments demonstrated that the potent compounds 8q and 8r had no obvious cytotoxicity in either HepG2 cells or SH-SY5Y cells, even at a high concentration of 500 μM. Besides, a combined Lineweaver-Burk plot and molecular docking study revealed that these compounds might act as mixed-type inhibitors to exhibit such effects via selectively targeting both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChEs. Taken together, these results suggested that further development of these compounds should be of great interest.