Design, synthesis, and biological activity of human glutaminyl cyclase inhibitors against Alzheimer’s disease

Human glutaminyl cyclase (hQC) has emerged as a critical target in Alzheimer’s disease (AD) due to its role in generating pyroglutamate-modified amyloid β (pE-Aβ). In this study, 13 compounds were designed as target compounds by fragment-based drug design (FBDD) and molecular docking, and subsequently assessed for drug-like properties and predicted inhibitory activities through ADMET analysis and Uni-QSAR modeling. Target compounds were synthesized via systematic multi-step approaches, with acceptable yields. The in vitro hQC enzyme inhibition assay revealed that all target compounds exhibited superior inhibitory activity compared to the reference compound PBD150 (140.50 $\pm$ 0.93 nM), with compounds A3 (3.36 $\pm$ 0.90 nM), A4 (3.20 $\pm$ 1.15 nM), B1 (3.99 $\pm$ 0.99 nM), and B2 (3.64 $\pm$ 0.98 nM) standing out for further investigation. Further, molecular dynamics (MD) simulations were conducted on compounds A3, A4, B1, and B2, revealing the stability and binding interactions of the compounds within the hQC active site over a 200 ns simulation period. Then, the results of binding free energy calculations validated the superior binding affinities of compounds A3, A4, B1, and B2 than PBD150. These findings highlight A3, A4, B1, and B2 as promising hQC inhibitors, offering insights for AD drug development.