Biological activity, physicochemical properties and toxicity studies of an antimicrobial peptide, QUB-2577, discovered from the skin secretion of Rana Pipiens

Abstract

Because of the different environments in which they live around the globe, plants and animals of all kinds secrete a chemical substance called host defence peptides within their own bodies in order to protect their own health while remaining as free as possible from external interference. In particular, peptides found in frog skin secretions or other amphibian skin secretions are short amino acid chains and are known for their high target specificity and low side effects. Over the past five decades, a large number of studies have revealed the broad-spectrum antimicrobial activity of these peptides and the promise of alternatives to antibiotics, discoveries that will not only aid in the development of novel drugs but also deepen our understanding of physiological and pathological processes.

In this research, bioactive peptides were extracted and identified from the skin secretions of Rana pipiens using a genomic shotgun cloning method. The mRNA from the secretion was isolated to construct a cDNA library via reverse transcription. Molecular cloning techniques were employed to amplify and sequence the targeted cDNA. This study successfully identified a peptide, named QUB-2577. Various assays, including antimicrobial, haemolytic toxicity, and antiproliferative tests, were conducted to assess the biological properties of QUB-2577. The findings indicate that QUB-2577 exhibits potent antimicrobial and antiproliferative effects, with a MIC value of 2 micromoles and an MBC of 4 micromoles against S. aureus. The MIC for E. coli was also 2 micromoles, and the MBC was 4 micromoles. Against C. albicans, the MIC was 8 micromoles and MBC was 16 micromoles. Meanwhile, a good antiproliferative effect was shown with the IC50 value of 7.26 micromoles. However, the peptide presents haemolytic toxicity with about 20% haemolysis at 16 micromoles.

Thesis is embargoed until 31st December 2029.

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