Discovery and Evaluation of N -Arylindole-Based GluN2B-NMDAR Antagonists with Reduced Cardiotoxicity for the Treatment of Ischemic Stroke

GluN2B-NMDARs are promising targets for ischemic stroke therapy, but antagonist development has been limited by poor selectivity and cardiotoxicity. We report NFI23, a novel N-arylindole derivative, as a selective GluN2B-NMDAR antagonist. NFI23 showed potent neuroprotection against NMDA-induced cytotoxicity. Molecular docking revealed its binding to the Ifenprodil site, partial overlap with EVT-101, and unique interactions. NFI23 reduced Ca2+ influx, ROS generation, and neuronal apoptosis, while preserving mitochondrial membrane potential and restoring p-ERK1/2 expression. Competitive binding assays confirmed its low nanomolar affinity. In vitro metabolism indicated high plasma stability and low drug interaction risk, while in vivo pharmacokinetics demonstrated favorable absorption and brain penetration. In a rat MCAO model, NFI23 provided marked neuroprotection. Molecular dynamics simulations confirmed stable receptor binding. Notably, NFI23 exhibited negligible hERG channel inhibition and excellent selectivity over other subtypes and σ1/σ2 receptors, supporting it as a promising and safer therapeutic candidate for ischemic stroke.