Synthesis of cyclic peptide antibiotics and related compounds

Abstract

Since the discovery of the antibiotics, countless of human lives have been saved. The human lifespan has been increased on average by 23 years since this founding. Unfortunately, the appearance of multidrug resistant bacteria seems to be foreshadowing the dawn of the post antibiotic era. With an urgent sanitary dilemma, the necessity of the development of new antibiotics active against multidrug resistant bacteria have been declared. The WHO (World Health Organization) have outlined the growing concern on Gram-negative bacteria, which have proven to be the most resistant to current antibiotic. In this project, an analogue of a polymyxin family member called macolacin, which is active against a certain resistance shown by Gram-negative bacteria, is being synthesized and tested through the minimum inhibitory concentration. The polymyxin family is a group of a pentacationic cyclic lipo-decapeptides with substantial activity against Gram-negative bacteria being already used as a last resort drug. Unfortunately, a severe nephrotoxicity was detected in previous studies4 and the analogue synthesized is meant to keep the activity while diminishing its toxicity through a disulfide bond. In addition, a 14 amino acids cyclic peptide developed by Polyphor called murepavadin which is extremely active against P. aeruginosa but with some nephrotoxicity will be synthesized. The peptides are being synthesized through solid phase peptide synthesis with the Fmoc/tBu orthogonal strategy being used. Both peptides being synthesized are being characterized through HPLC-MS.