Identification and evaluation of a bioactive peptide, QUB-3195, from the skin secretion of Phyllomedusa sauvagei

Abstract

Antimicrobial resistance has emerged as a greater hazard to public health than other issues throughout the past several years and antimicrobial peptides have been identified as viable therapeutics against drug-resistant bacteria due to their broad-spectrum action and low propensity to induce drug resistance. Peptides secreted from amphibian skins have a great range of bioactive functions and thus there has been a growing interest in peptides as clinical therapeutic agents. The Dermaseptin peptides are a superfamily of antimicrobial peptides. They have a variety of low-cytotoxic antimicrobial and anticancer properties.In this study, QUB-3195, a novel Dermaseptin peptide, was isolated from the skin secretion of Phyllomedusa sauvagei. A cDNA library was constructed by using the isolation mRNA from frog skin secretion and ‘shotgun’ cloning, through the use of which the mature peptide sequence was deduced. The purified peptide was obtained by reversed-phase high performance liquid chromatography. In this research, QUB-3195 was found to exhibit a wide range of antimicrobial activity against tested Gram-negative bacteria, Gram-positive bacteria, and yeast. The MIC and MBC values for both tested bacteria were determined to be 1 μM.For the yeast strain, the MIC and MBC were both 16 μM. In addition, QUB-3195 inhibited a human lung cancer cell line (H838). The half minimal inhibitory concentration (IC50, µM) of QUB-3195 was 39.9 µM. However, the peptide showed a weak inhibitory function of haemolysis activity with a HC50 value of 287.7 µM. In summary, due to its strong antibacterial and anticancer properties, QUB-3195 is a good option for developing novel medications for use in clinical settings. Also, with further modifications and experiments, QUB-3195 may be found to have better antimicrobial and anticancer functions in future studies.

Thesis is embargoed until 31st 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)