Characterization, bioactivity evaluation and rational modification of bioactive peptides from frog skin secretion

Abstract

In recent years, due to the misuse of antibiotics, the development of multi-drug resistant bacteria have been very rapid and has had a very significant impact on the course of human disease. Therefore, the search for a substance to replace traditional antibiotics has become one of the most important research nowadays. Antimicrobial peptides, due to their unique physicochemical properties, have shown good application prospects. In the present study, the activity and toxicity of the skin secretions of Phyllomedusinae frog species were investigated. The antimicrobial peptide QUB-3163 was extracted from the skin secretion of Phyllomedusa bicolor using the ‘shotgun cloning’ technique, and then its activity and modifications were investigated. At the same time, the activity, toxicity and mechanism of action of antimicrobial peptides of the same family were also studied to find out the commonality and differences in their activities. Subsequently, Dermatoxin-J1 was modified and the modified antimicrobial peptide was studied. It was found that peptide 21-4 showed good antimicrobial activity and low cytotoxicity, and Dermatoxin-J1 also showed relatively good antimicrobial activity, but there was still room for improvement in terms of cytotoxicity. In the subsequent modifications, it was also shown that charge and hydrophobicity had different effects on both activity and toxicity, respectively. In addition, the antimicrobial peptides were less likely to cause bacterial resistance than antibiotics, and showed better activity against pathogens that were already multi-drug resistant. Therefore, antimicrobial peptides have a very good development prospect.

Thesis is embargoed until 31 July 2030.

Date of Award	Jul 2025
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Tianbao Chen (Supervisor), Mei Zhou (Supervisor) & Lei Wang (Supervisor)