Molecular cloning, peptide synthesis and functional characterization of a bioactive peptide from the skin secretion of the waxy monkey tree frog, Phyllomedusa sauvagii

Abstract

The skin of amphibians is rich in a variety of bioactive substances, including antimicrobial peptides (AMPs). Unlike traditional antibiotics, which typically target specific bacterial processes such as enzyme activity or protein synthesis, antimicrobial peptides (AMPs) exert their antibacterial effects primarily through mechanisms like membrane disruption or damage. AMPs have attracted increasing attention due to their potent antibacterial activity and lower potential to induce resistance. In this study, a peptide named QUB-2683 was identified from a cDNA library derived from the skin secretions of the wax monkey tree frog, Phyllomedusa sauvagii, by a "shotgun" cloning strategy. The peptide was chemically synthesised by solid-phase peptide synthesis, and the bioactivity and cytotoxicity of the synthetic peptide were further evaluated by antimicrobial assays, MTT assays and haemolysis assays. The results showed that QUB-2683 had potent antibacterial activity against a gram-negative bacterium, E. coli and a gram-positive bacterium, S. aureus, but was less active against the yeast, C. albicans with minimum inhibitory concentrations of 2 µM, 1 µM, and 64 µM, respectively. In addition, QUB-2683 showed anticancer activity against the human non-small cell lung cancer at 12.5μM and low haemolysis at 16 μM. These findings suggest that QUB-2683 is a promising candidate for developing new antibacterial and anticancer therapies. Furthermore, this study highlights the potential of amphibian skin secretions as a source for discovering peptides with significant applications in drug development.

Thesis is embargoed until 31 December 2029.

Date of Award	Dec 2024
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Lei Wang (Supervisor), Tianbao Chen (Supervisor) & Mei Zhou (Supervisor)