Bioactivity analysis of a novel peptide, QUB-3368, identified from the skin secretion of the torrent frog, (Amolops hainanensis)

Abstract

Antimicrobial peptides (AMPs) are a group of biological molecules with great potential as novel therapeutics for bacterial infections. AMPs are naturally occurring peptides that exhibit potent killing or inhibition of a broad range of microorganisms, including bacteria, fungi and viruses. In this study, a peptide, namely QUB-3368, was identified from the skin secretion of the Chinese torrent frog, Amolops hainanesis, and its bioactivity was evaluated by a series of bioassays. The peptide encoding cDNA was initially cloned by “shotgun” cloning and the full length of the mature peptide sequence was obtained. Subsequently, the peptide was synthesised through solid-phase peptide synthesis (SPPS) and purified by reverse-phase high-performance liquid chromatography (HPLC). After that, the purified peptide was confirmed using a MALDI-TOF mass spectrometer. Three bioassays, including antimicrobial assay, MTT assay and haemolysis assay, were performed. It was found that peptide QUB-3368 showed significant inhibitory and killing effects against a gram-negative bacterium, E. coli (ATCC® CRM 8739TM) (MIC/MBC=2 µM), and a gram-positive bacterium S. aureus (ATCC® CRM 6538TM) (MIC/MBC=32 µM). However, the peptide displayed a weak activity against C. albicans (ATCC® CRM 10231TM) with an MIC of 256 µM. QUB-3368 also demonstrated a significant inhibitory effect on the proliferation of NCI-H838 non-small cell lung cancer cell line in a concentration-dependent manner with an IC50 of 25 μM. The peptide possessed a moderate haemolysis effect, and the HC50 value was 283.8 μM.

Thesis is embargoed until 31 December 2028.

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