Antimicrobial Peptides: Principal Defense Constituents of Silk Worms - A Review

Abstract

Insect has a highly developed innate immune system consisting of cellular and humoral responses. Antimicrobial peptides (AMPs) are the important components of the insect’s humoral defense system and were first purified from the giant silk moth, Hyalophora cecropia L (Boman et al., 1980). For a variety of infections, they serve as the initial line of defense. AMPS are low molecular weight peptides and generally cationic in nature. Off late, the resistance of the pathogenic microbes towards established antibiotics have become a serious threat to global health. Over the years, an array of AMPs from natural sources has served as potent candidate against various infective agents viz. bacteria, fungi and viruses. These insect peptides not only exhibit antibacterial action by rupturing the microbial membrane but also prevent the development of drug resistance by microbes. Studies have shown AMPS to have synergistic effects with traditional antibiotics, providing an opportunity for combined therapy. Defensin, cecropins, drosocin, attacins, diptericins, ponericins, metchnikowins and melittin are a few classes of AMPs from insects that are currently isolated. However, the possibility of discovering new AMPs cannot be fully ruled out. Currently, 33 peptides are undergoing clinical trials, and 43% of the 77 AMPs are still in the preclinical stage (Makwana et al., 2023). Daptomycin and ovitavancin are two antibacterial lipopeptides that Food and Drug Administration has recently approved that are used for skin infection caused by bacteria. The present paper is an attempt to provide a comprehensive insight on antimicrobial peptides isolated from silk worm with reference to their structures, functions and possible mechanism of action.