Syntheses and antimicrobial activities of ogipeptin derivatives

Abstract Novel cyclic peptide derivatives based on ogipeptins A, B, C, and D were synthesized. Starting with a mixture of ogipeptins A–D, a practical four-step synthetic procedure was followed to prepare novel derivatives with various kinds of acyl side chains. Among the 45 new synthetic derivatives identified, the antibacterial activities of compounds 8-3 and 8-38 were comparable with those of ogipeptin A. In in vitro nephrotoxicity screening using LLC-PK1 cells, compounds 8-3 and 8-38 showed significantly lower cytotoxicity (LD20 > 480 μM) than colistin (LD20 = 44.2 μM).