Identification and bioactivity assessment of an antimicrobial peptide from the defensive skin secretion of the northern leopard frog, Rana pipiens

Abstract

In response to the growing threat of bacterial resistance, antimicrobial peptides (AMPs) have emerged due to their broad-spectrum activity and low probability of resistance generation. In many ways, antimicrobial peptides have advantages that are difficult to match with antibiotics, and so research into them continues to intensify.

In the present work, a novel AMP belonging to the Brevinin family was isolated from the skin secretions of Rana pipiens. After cDNA library construction and gene sequencing of mRNA from skin secretions, a sequence of a mature peptide was identified. After synthesis, identification and purification steps, the peptide sequence was tested for biological activity, including antibacterial, anticancer and haemolytic.

As a result of the above experimental steps, the sequence of the mature peptide was identified as: FLPIIAGVAAKVFPKIFCTISKKC. The peptide sequence was identified as a known antimicrobial peptide named Brevinin-1Pk. In bioactivity assays, this peptide was found to be significantly inhibitory to Gram-positive and Gram-negative bacteria and yeast (Staphylococcus aureus and Escherichia coli and Candida albicans, respectively.) at concentrations of 2 µM, 16 µM and 32 µM respectively, and anticancer activity was found at 100 µM with an IC50 of 2.822 * 10-5 M. At the same time, this peptide performed poorly in the haemolytic assay, showing significant haemolysis at a concentration of only 32 µM.

Based on the experimental results, Brevinin-1Pk has been shown to have potential as a clinical antibacterial agent. The haemolytic activity of Brevinin-1Pk is one to two orders of magnitude higher than that of antimicrobial drugs already in clinical use, and therefore it should probably be used as a topical agent for clinical purposes.

Thesis embargoed until 31 December 2026.

Date of Award	Dec 2021
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Mei Zhou (Supervisor), Lei Wang (Supervisor) & Tianbao Chen (Supervisor)