Hydrocarbon Stapling Enables Improvement of Antimicrobial Activity and Proteolytic Stability of Host-Defense Peptide Ocellatin-3N.

Ocellatin-3N is a cationic, amphiphilic host-defense peptide with 19 residues, which is isolated from the Caribbean frog Leptodactylus nesiotus. Its analogue Oce-3N-0 shows potent inhibitory activity against both Gram-negative and Gram-positive pathogens, and has great potential as a broad-spectrum antimicrobial agent. However, the application of Oce-3N-0 as an antimicrobial agent is limited due to its both unstable structure and susceptibility to degradation by proteases. In this research, a series of hydrocarbon-stable analogs of Oce-3N-0 are synthesized and evaluated for their chemical and biological properties to improve potential application of Oce-3N-0 in the field of antimicrobial drug development. Some analogs show remarkable improvement not only in protease resistance but also in antimicrobial activity when compared to the parent peptide. In particular, the stapled peptide Oce-3N-5 shows promising prospects for novel antimicrobial drug development. This study can provide a reference for the development of antimicrobial drugs.