Synthesis of Some Analogues of Polymyxin E1 Antibiotic Using Automated Solid Phase Peptide Synthesis Assisted With Microwave Irradiation

Abstract

Five analogues of Polymyxin E1 antibiotic were synthesized via Fmoc- solid phase peptide synthesis (SPPS) strategy using Biotage® Initiator+Alstra™ microwave peptide synthesizer. The aim of this work is to study the importance of the cyclization conditions of the lactam ring on the purity and yield of the final compounds. For this purpose, replacing L-Thr10 with L-Asp allowed the application of different cyclization methodologies. In all analogues, the Dab5,8,9 residues were replaced with Arg, while the Dab4 residue involved in lactam cyclization was replaced with Lys. Modification of the linear tripeptide tail was applied to two of the analogues. The obtained compounds were characterized with different spectroscopic techniques and will be tested for their antimicrobial activity.