Molecular cloning and functional evaluation of an antimicrobial peptide, QUB 1985, from the skin secretions of Phyllomedusa bicolor

Abstract

Antimicrobial peptides (AMPs), which are the first line of defence against invasive microorganisms, are secreted from the skin secretions of amphibians and have numerous significant bioactivities. In this thesis, the skin secretions of the South American, Giant Leaf Frog, Phyllomedusa bicolor, were used to identify QUB-1985, peptide that is a member of the plasticin family of the phylloseptins superfamily. Molecular cloning was used to create a cDNA library using extracted mRNA from frog skin secretions to obtain the peptide sequence. By using a solid phase peptide synthesiser, reversed-phase high performance liquid chromatography was used to purify the peptide, and MALDI-TOF MS was used to confirm its identity. Biological assays were used to test QUB-1985, and the results indicated strong antimicrobial activity against S. aureus, E. coli, and C. albicans, with MIC values of 8, 16, and 32 μM, respectively. Against the human lung cancer cell line, H838, it exhibited strong anticancer activity, particularly at concentrations of 6.25 to 12.5 μM. Additionally, at 32 μM, it demonstrated 15% haemolysis, indicating haemolytic activity. Due to its high bioactivity, the peptide merits significant attention as a possible therapeutic and is anticipated to be optimised to be an interesting drug candidate.

Thesis embargoed until 31 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)