Discovery of benzyloxy benzamide derivatives as potent neuroprotective agents against ischemic stroke

Aberrant activation of N-methyl-d-aspartate receptors (NMDAR) and the resulting neuronal nitric oxide synthase (nNOS) excessive activation play crucial pathogenic roles in neuronal damage caused by stroke. Disrupting postsynaptic density protein 95 (PSD95)-nNOS protein-protein interaction (PPI) has been proposed as a potential therapeutic strategy for ischemic stroke without incurring the unwanted side effects of direct NMDAR antagonism. Based on a specific PSD95-nNOS PPI inhibitor (SCR4026), we conducted a detailed study on structure-activity relationship (SAR) to discover a series of novel benzyloxy benzamide derivatives. Here, our efforts resulted in the best 29 (LY836) with improved neuroprotective activities in primary cortical neurons from glutamate-induced damage and drug-like properties. Whereafter, co-immunoprecipitation experiment demonstrated that 29 significantly blocked PSD95-nNOS association in cultured cortical neurons. Furthermore, 29 displayed good pharmacokinetic properties (T_1/2 = 4.26 and 4.08 h after oral and intravenous administration, respectively) and exhibited powerful therapeutic effects in rats subjected to middle cerebral artery occlusion (MCAO) by reducing infarct size and neurological deficit score. These findings suggested that compound 29 may be a promising neuroprotection agent for the treatment of ischemic stroke.