Antimicrobial Peptides against Microbial Biofilms: their Structures and Modes of Action

The formation of biofilms contributes significantly to bacterial resistance to antibiotics, innate host defences and in persistent infections. In this era of multidrugresistant bacterial infections, the discovery of novel antibacterial agents is required to treat infections that kill these organisms via novel mechanisms of action. Antimicrobial peptides, also known as host-defence peptides are short polypeptides (<40 amino acids) and are an integral part of the innate immune system that protects a host from bacterial infection. This chapter discusses the potential of anti-microbial peptides as an antiinfective agent, its advantages, disadvantages, their structures and mechanisms of action. A perception of the bacteriostatic and bactericidal mechanism of antimicrobial peptides is required to facilitate the rational design of novel antimicrobial agents. Thus a deeper understanding of the mechanism of natural AMPs will also aid in developing new antibacterial agents. Furthermore, the chapter also considers the possibility of the use of synthetic antimicrobial peptides containing both natural and unnatural amino acids as anti-infective agents. Apart from the antibacterial property, AMPs are also being used as drug delivery vectors to transport the cell impermeable drugs to the cell interior. The diversity and broad spectrum antimicrobial activity of AMPs along with its multidimensional properties could be exploited as a potential and promising drug candidate.

Keywords: Antimicrobial peptides, Human β-defensin, Indolicidin, Synthetic peptide, biofilms, host defences, host-defence peptides, unnatural amino acids, β- peptides.