Molecular cloning, synthesis and bioactivity evaluation of a peptide from the skin secretion of the Australian tree frog, Litoria cearulea

Abstract

Natural products, derived from plants, animals and minerals, have long been used in traditional medicines for the treatment of human diseases and play an important role in the modern pharmaceutical industry. Among these natural products, amphibian skin secretions serve as valuable sources for researching new medicines due to their rich variety of bioactive compounds. In this study, a bioactive peptide, namely QUB-2309, was characterised from the skin secretion of the Australian tree frog, Litoria caerulea, and its precursor cDNA sequence was obtained by 'shotgun' cloning. Subsequently, the peptide was synthesised by solid-phase peptide synthesis. The synthetic peptide was purified by reverse-phase high-performance liquid chromatography and identified by MOLDI-TOF mass spectrometry. To assess the antibacterial activity, anticancer activity and haemolytic activity of the peptide, MIC/MBC assays, MTT assay and haemolysis assay were performed. QUB-2309 demonstrated statistically significant inhibitory activity against human lung cancer cell line NCI-H838 staring from a concentration of 10-5 M. However, no antimicrobial activity was detected against the tested strains, including Escherichia coli, Staphylococcus aureus and Candida albicans, at the highest tested concentration. Additionally, QUB-2309 has no detectable haemolytic activity even at a concentration of 512 μM. The lack of hemolytic activity suggests that QUB-2309 may have a favourable safety profile, making it a promising candidate for further development as a therapeutic agent.

Thesis is embargoed until 31 December 2028.

Date of Award	Dec 2023
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Mei Zhou (Supervisor), Tianbao Chen (Supervisor) & Xiaoling Chen (Supervisor)