The discovery and functional study of an antimicrobial peptide QUB-1955 from the skin secretion of the northern orange-legged leaf frog, phyllomedusa hypochondrialis

Due to the increasing resistance of bacteria to conventional antibiotics, new antimicrobial drugs need to be discovered urgently. Natural active substances extracted from skin secretions of anurans have attracted much interest in recent years. Among them, anti-bacterial peptides with broad-spectrum antibacterial activity have become promising drug candidates for the development of new antibiotics. <br/><br/>In this research, a bioactive peptide which belongs to the phylloseptin family, named QUB- 1955, was isolated from Phyllomedusa hypochondrialis skin secretions. Initially, the mature peptide was identified from the cloned biosynthetic precursor encoding cDNA. Sufficient QUB-1955 was produced by solid-phase peptide synthesis and then, reverse phase high performance liquid chromatography (RP-HPLC) and matrix-assisted, laser desorption, ionisation, time-of-flight mass spectrometry (MALDI-TOF MS) were used to purify and confirm the structure of QUB-1955 for subsequent biological activity experiments (antimicrobial assays, anti-cancer cell assays and haemolysis assay). <br/><br/>In the order of potency, QUB-1955 had relatively potent antibacterial activity against Gram- positive bacteria (S. aureus), while it was weak against Gram-negative bacteria (E. coli), and had no activity against yeast (C. albicans). When incubated with cancer cell lines, QUB-1955 had no obvious anti-cancer cell activity against colorectal cancer cells and brain cancer cells at the concentrations tested. It did not induce haemolysis at the MIC for S. aureus. These data provide evidence that QUB-1955 could be further evaluated and manipulated as a possible lead compound for a new anti-bacterial drug against Gram-positive bacteria.

Name dc:type.qualificationname

Master of Philosophy

Level dc:type.qualificationlevel

Masters Thesis

Grantor dc:publisher.institution

Queen's University Belfast

Year dc:date.issued

2020

Author dc:creator

• Shao, Yanghui

Advisors dc:contributor.advisor

• Zhou, Mei
• Wang, Lei

Language dc:language

eng

Identifier

oai:pure.qub.ac.uk/portal:studenttheses/d2c627af-0454-4aa9-a729-d875eff9de4c

OAI identifier oai:identifier

oai:pure.qub.ac.uk/portal:studenttheses/d2c627af-0454-4aa9-a729-d875eff9de4c