Lysine-Tethered Stable Bicyclic Cationic Antimicrobial Peptide Combats Bacterial Infection in Vivo
Tong He, Lei Xu, Yuchen Hu, Xiaomin Tang, Rui Qu, Xuejun Zhao, Hao Bai, Lixian Li, Wanyi Chen, Guangli Luo, Gang Fu, Wei Wang, Xuefeng Xia, Jinqiang Zhang
Abstract
Antimicrobial peptides (AMPs) have attracted great attention as next generation antibiotics for the treatment of multidrug-resistant (MDR) bacterial infections. Poor proteolytic stability has however undermined clinical applications of AMPs. A novel peptide cyclization approach is described to enhance the in vivo antibacterial activity of AMPs. Bicyclic antimicrobial peptides were synthesized by cross-linking the ε-amino groups of three lysine residues with a 1,3,5-trimethylene benzene spacer. In a proof of principal study, four bicyclic peptides were synthesized from the cationic AMP OH-CM6. One bicyclic peptide retained strong antimicrobial activity and low toxicity but exhibited a prolonged half-life in serum. Antibacterial activity was consequently improved in vivo without renal or hepato-toxicity. The novel peptide cyclization approach represents an important tool for enhancing AMP proteolytic stability for improved treatment of bacterial infection.