New potent and selective αvβ integrin ligands: Macrocyclic peptides containing RGD motif synthesized by sortase A-mediated ligation.

Three 14-mer macrocyclic peptides 1-3 containing mono-, di- and tri-RGD structure motif were designed and synthesized by sortase A-mediated ligation in good yields. The results of in intro cell-based biological assays indicated that linear peptide 5 and macrocyclic peptide 1, containing di-RGD and mono-RGD motif respectively, showed remarkable potency and selectivity to αβ integrin.