Design, synthesis, and stability evaluation of semaglutide-derived lactam-stapled peptide scaffolds for GLP-1R targeting

Glucagon-like peptide-1 receptor (GLP-1R) ligands including semaglutide play an important role in drug discovery. Herein, a short semaglutide-derived GLP-1R-engaging segment was used as the basis for scaffold construction, and conformational restabilisation was introduced through lactam stapling and bulky aromatic non-natural amino acid substitution. A total of 108 stapled peptide candidates were designed by structure-guided modelling and virtual screening. Among them, 35 peptides were synthesised and characterised. Most stapled analogues showed improved serum and proteolytic stability relative to semaglutide, and 11CP-17B, 11CP-17N, and 11CP-19N showed the most favourable stability profiles. Molecular dynamics simulations and MM-GBSA analysis were consistent with receptor-compatible poses and favourable predicted interaction patterns for these representative analogues. Collectively, these results define a practical strategy for constructing stabilised semaglutide-derived peptide scaffolds and provide a basis for subsequent functional optimisation of GLP-1R-targeting peptides.