Antimicrobial peptides: The natural proteins and the future application for treatment of infectious diseases

Abstract

Infectious diseases caused by microorganisms are involved in life-threatening worldwide. Of these, bacteria is the major cause of morbidity and mortality. During the decade, an increasing of the prevalence of antibiotic resistance pathogens has been reported. The resistant ability of microorganisms is studied and defined to be associated with over-used drugs, inappropriate treatment and prolonged therapy of infected patients. Although new antibiotics are continuously discovered, global trends of multi-drug resistant infection still remained. Antimicrobial peptides (AMPs) are small cationic peptides which produced by broad range of organisms from invertebrate to vertebrate. Due to the fact that AMPs have high positive charge, they prefer to react with the negatively charge of microbial membrane and represent antimicrobial activity against gram-positive and gram-negative bacteria, virus, fungi as well as parasites. Modes of AMPs action are explained and models of microbial membrane disruption by AMPs are illustrated. Five potent AMPs consisting of cathelicidin, defensins, histatins, protegrins and magainins are selectively reviewed. Cathelicidins, defensins and histatins are human short polypeptides that mostly found in various kinds of cells, tissues and body fluids whereas protegrins and magainins are synthesized in porcine leukocytes and skin of Xenopus laevis, an African clawed frog, respectively. In vitro and in vivo antimicrobial activities testing of these peptides are overviewed. Others actions of these peptides such as endotoxin neutralization, immunomodulatory activities, angiogenesis and wound healing are included. In addition, the application in clinical trials and trends of AMPs research are discussed. Bull Chiang Mai Assoc Med Sci 2013; 46(1): 1-19