Design, synthesis and evaluation of novel 1-phenyl-pyrrolo[1,2-b]isoquinolin-3-one derivatives as antagonists for the glycine binding site of the NMDA receptor

A new series of 1-phenyl-pyrrolo[1,2-b]isoquinolin-3-one derivatives were designed, synthesized and demonstrated to act as antagonists for the glycine binding site of the NMDA receptor. These new derivatives protected PC12 cells against NMDA-induced injury and cell apoptosis in vitro, among which compound 13b exhibited excellent cytoneuroprotective potency and shown a dose-dependent prevention. The increased intracellular Ca2+ influx caused by NMDA in PC12 cells was reversed when pretreated with compound 13b. Furthermore, the interaction between compound 13b and the glycine binding site of the NMDA receptor was validated via MST assay. It was observed that the stereochemistry of compound 13b did not influence the binding affinity, which was consistent with the neuroprotective result. Molecular docking study confirmed the observed activity of compound 13b by virtue of their Pi-stacking, cation-Pi, H-bonding and Pi-electron interactions with the key amino acids in the glycine binding pocket. These results confirm the potential of 1-phenyl-pyrrolo[1,2-b]isoquinolin-3-one derivatives as neuroprotective agents targeting the glycine binding site of the NMDA receptor.