Identification and functional study of a bioactive peptide QUB-2007 from the skin secretion of the bicolour tree-frog Phyllomedusa bicolor

Antimicrobial peptides secreted in amphibian skin secretions have many important bioactivities and act as the first line of defence against invading microorganisms. In this thesis, QUB-2007, a peptide belonging to the Phylloseptin family of the Dermaseptin superfamily, was derived from the skin secretion of Phyllomedusa bicolor. The peptide sequence was obtained by molecular cloning through constructing a cDNA library with isolated mRNA from frog skin secretion. The peptide was synthesised by solid phase peptide synthesis, purified using reversed-phase high performance liquid chromatography and structurally-confirmed by MALDI-TOF MS. In broth microdilution assays, QUB-2007 showed antimicrobial activities against the Gram-negative bacterium, Escherichia coli (E. coli ATCC CRM 8739), and the yeast, Candida albicans (C. albicans ATCC CRM 10231) at concentration of 32 μM, and the Gram-positive bacterium, Staphylococcus aureus (S. aureus ATCC CRM6538) at a concentration of 8 μM. In terms of MTT anticancer cell proliferation assays, QUB-2007 was shown to have anticancer activities against HCI-H838 lung cancer cells at a concentration of 10-4 M. With regard to haemolysis, QUB-2007 was haemolytic at concentrations of 32 μM could be 15%.<br/><br/>In conclusion, QUB-2007 has potential to be a drug, but its haemolytic activity is a big obstacle. It can be achieved by modifying the peptide, such as in changing certain amino acid sequences to change its cationicity, hydrophobicity and amphipathicity.<br/><br/><i>Thesis embargoed until 31 December 2026</i>.

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

2021

Author dc:creator

• Xu, Zixin

Advisors dc:contributor.advisor

• Zhou, Mei
• Wang, Lei
• Chen, Tianbao

• Antimicrobial peptides
• antimicrobial activity
• anti-proliferation activity
• haemolytic activity
• non-small lung cancer cell
• phylloseptin

Language dc:language

eng

Identifier

oai:pure.qub.ac.uk/portal:studenttheses/cd4e451d-40cb-4057-845b-a86a2e81ac42

OAI identifier oai:identifier

oai:pure.qub.ac.uk/portal:studenttheses/cd4e451d-40cb-4057-845b-a86a2e81ac42