Identification and functional study of the bioactive peptide QUB-2417 from the skin secretion of the tree frog, Phyllomedusa bicolor

Abstract

With the rising of antibiotic resistance, it is urgent to search for new antimicrobials, and many scholars have focused on AMPs. Generally, it is difficult for pathogenic microorganisms to develop resistance to AMPs because of their action mechanism. In this thesis, an AMP was identified from the skin secretion of Phyllomedusa bicolor, a tree frog from the Amazon rainforest, and was named QUB-2417. The peptide sequence was acquired by molecular cloning through constructing a cDNA library with isolated mRNA from skin secretion. Then the peptide was chemically synthesised by Solid Phase Peptide Synthesis, purified by RP-HPLC, and then analysed by MALDI-TOF MS to identify the peptide. In the antimicrobial assay, QUB-2417 exhibited potent and broad-spectrum antibacterial activity. Its MICs against S. aureus, E. coli and C. albicans were 4, 16 and 16 μM, respectively. In the MTT assay, QUB-2417 exhibited bioactivity against lung cancer cell line NCI-H838 at the highest test concentration (10-4 M) and the value of IC50 was 35.3 µM. In the haemolysis bioassay, QUB-2417 exhibited about 30% haemolytic effect at the highest test concentration (128 μM) and the value of HC50 was 690 µM. Hence, the peptide deserves serious attention as a potential therapeutic due to its potent relevant bioactivity and is expected to be optimised as a good drug candidate.

Thesis embargoed until 31 December 2026.

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