Discovery of Stable and Permeable N‑Methylated Cyclic Peptides to Block the Endocytosis of GluA2 AMPAR for Ischemic Stroke Therapy

The membrane-permeable peptide Tat-GluA2-3Y exhibits therapeutic potential by competitively binding BRAG2 to disrupt GluA2 endocytosis. However, their poor in vivo stability has become a barrier to clinical application. To address this limitation, we systematically designed a series of N-methylated cyclic peptides derived from GluA2-3Y and identified the optimal peptide, c10c-G1V3, which exhibited high binding affinity for BRAG2 (Kd = 7.37 μM) and potent neuroprotective activity in both the OGD-induced cell model (cell viability: 85.97%) and the Glu-induced cell model (cell viability: 76.34%) at 10 μM. Mechanistically, c10c-G1V3 markedly attenuated Glu-induced intracellular reactive oxygen species accumulation. Notably, it displayed superior plasma stability and favorable in vivo pharmacokinetic properties compared to Tat-GluA2-3Y. In SD rat tMCAO models, 8 mg/kg c10c-G1V3 reduced infarct volume comparably to that of Tat-GluA2-3Y. Collectively, these findings establish c10c-G1V3 as a promising candidate for the development of novel therapeutics against an ischemic stroke.