Development of protease resistant and non-cytotoxic Jelleine analogs with enhanced broad spectrum antimicrobial efficacy

Short systemic half- life of Antimicrobial Peptides (AMP) is one of the major bottlenecks that limits their successful commercialization as therapeutics. In this work, we have designed analogs of the natural AMP Jelleine, obtained from royal jelly of apis mellifera. Among the designed peptides, J3 and J4 were the most potent with broad spectrum activities against a varied class of ESKAPE pathogens and fungus C. albicans. All the developed peptides were more effective against Gram-negative bacteria in comparison to the Gram-positive pathogens, and were especially effective against P. aeruginosa and C. albicans. J3 and J4 were completely trypsin resistant and serum stable, while retaining the non-cytotoxicity of the parent Jelleine, Jc. The designed peptides were membranolytic in their mode of action. CD and MD simulations in the presence of bilayers, established that J3 and J4 were non-structured even upon membrane binding and suggested that biological properties of the AMPs were innocent of any specific secondary structural requirements. Enhancement of charge to increase the antimicrobial potency, controlling the hydrophobic-hydrophilic balance to maintain non-cytotoxicity and induction of unnatural amino acid residues to impart protease resistance, remains some of the fundamental principles in the design of more effective antimicrobial therapeutics of the future, which may help combat the quickly rising menace of antimicrobial resistance in the microbes.