No abstract

The emergence of antibiotic-resistant bacteria has become a major challenge in current clinical treatment. As essential natural molecules involved in innate immunity, antimicrobial peptides (AMPs) have the potential to break the limits of antibiotic resistance. While AMPs are widely presented in various organisms on this planet, the marine environment is unique in generating a large number of AMPs that exhibit characteristic structures and functions. This review summarizes the structures and mechanisms of action of AMPs derived from invertebrates, fish, amphibians, reptiles, and mammals in the ocean. The comparison of AMPs from organisms in different habitats demonstrates the preference of Arg (arginine) and Leu (leucine) in marine AMPs, which might be associated with the adaptation to the unique features of bacterial membranes in marine environments. In addition, the potential and applications of marine AMPs for the development of novel antibiotics are also described. These summaries are expected to provide a reference for the development and utilization of marine resources in drug development or aquiculture.

The abuse of antibiotics and lack of new antibacterial drugs has led to the emergence of superbugs that raise fears of untreatable infections. The Cathelicidin family of antimicrobial peptide (AMP) with varying antibacterial activities and safety is considered to be a promising alternative to conventional antibiotics. In this study, we investigated a novel Cathelicidin peptide named Hydrostatin-AMP2 from the sea snake Hydrophis cyanocinctus. The peptide was identified based on gene functional annotation of the H. cyanocinctus genome and bioinformatic prediction. Hydrostatin-AMP2 showed excellent antimicrobial activity against both Gram-positive and Gram-negative bacteria, including standard and clinical Ampicillin-resistant strains. The results of the bacterial killing kinetic assay demonstrated that Hydrostatin-AMP2 had faster antimicrobial action than Ampicillin. Meanwhile, Hydrostatin-AMP2 exhibited significant anti-biofilm activity including inhibition and eradication. It also showed a low propensity to induce resistance as well as low cytotoxicity and hemolytic activity. Notably, Hydrostatin-AMP2 apparently decreased the production of pro-inflammatory cytokines in the LPS-induced RAW264.7 cell model. To sum up, these findings indicate that Hydrostatin-AMP2 is a potential peptide candidate for the development of new-generation antimicrobial drugs fighting against antibiotic-resistant bacterial infections.