Identification and functional evaluation of a bioactive peptide QUB-2669 from the skin secretion of the American bullfrog Lithobates catesbeiana

Due to the prevalence of antimicrobial resistance, researching potential antibiotic substitutes against the multi-drug resistant bacteria has become a global concern. Amphibian skin, secreting many bioactive peptides, is a rich source of novel antimicrobial peptides. In this thesis, QUB-2669, derived from the skin secretion of the American bullfrog, Lithobates catesbeiana, was identified as a member of the ranatuerin-1 family. During the process of peptide synthesis, the methionine residue, containing a sulphur, was accidentally oxidised, therefore, another peptide named MetO-QUB-2669 was obtained. QUB-2669 presented moderate antimicrobial activities against Escherichia coli (minimum inhibitory concentration (MIC) was 32 μM) and Candida albicans (MIC was 64 μM), but was not sensitive against the Gram-positive bacterium Staphylococcus aureus (MIC was 128 μM). Apart from these, QUB-2669 showed slight antiproliferative effects against the cancer cell line NCI H838 at a concentration of 10-4 M. Besides, the haemolytic activity of QUB-2669 was lower than 20 % at the concentration range from 1 μM to 16 μM. Compared with QUB-2669, MetO-QUB-2669 showed lower antimicrobial, antiproliferative and haemolytic activities. Hence, QUB-2669 could be further modified by reducing the haemolytic ability and increasing the antimicrobial activities to become a potential candidate against microbial infections.<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

• Tu, Jingyu

Advisors dc:contributor.advisor

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

• Antimicrobial resistance
• amphibian skin
• bioactive peptides
• ranatuerin-1 family
• oxidised methionine

Language dc:language

eng

Identifier

oai:pure.qub.ac.uk/portal:studenttheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177

OAI identifier oai:identifier

oai:pure.qub.ac.uk/portal:studenttheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177