Identification and functional assessment of a bioactive peptide from the skin secretion of the frog, Amolops wuyiensis

Abstract

The widespread use of conventional antibiotics is accelerating the spread of antibiotic-resistant bacterial pathogens, appealing to an urgent need to discover and develop alternative antimicrobial agents. Antimicrobial peptides from amphibian skin secretions are promising candidates as alternatives to antibiotics. In this study, the isolated mRNAs from the skin secretion of the frog, Amolops wuyiensis (A. wuyiensis), were subject to ‘shotgun’ cloning and Sanger sequencing methods to identify an antimicrobial peptide, namely QUB-2514, from its biosynthetic precursor-encoding cDNA. The antimicrobial peptide was then chemically synthesised and purified by solid-phase synthesiser and high-performance liquid chromatography, respectively. Finally, the purified peptide was tested for biological activities, including antibacterial, anti-lung cancer and haemolytic activities. QUB-2514 was found to have the most potent inhibitory and bactericidal effects on Enterococcus coli (E. coli ATCC 8739) (MIC=4 µM, MBC= 8 µM) than Staphylococcus aureus (S. aureus ATCC 6538) (MIC=8 µM, MBC= 16 µM) and Candida albicans (C. albicans ATCC 10231) (MIC=64 µM, MBC= 128 µM). Additionally, after 24 h of exposure to QUB-2514, the proliferation activity of NCI-H838 lung cancer cells was decreased by about 98% at a concentration of 10 µM, and no viable NCI-H838 cells survived at 20 µM. However, this peptide started to show a significant haemolytic effect (approximately 18 % haemolysis, ***p<0.001) on horse red blood cells from a concentration of 8 µM. The results suggest that QUB-2514 has potential for antibacterial and anticancer applications, but further structural modifications are needed to reduce its haemolytic activity.

Thesis embargoed until 31st December 2027 

Date of Award	Dec 2022
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Mei Zhou (Supervisor), Tianbao Chen (Supervisor) & Xiaoling Chen (Supervisor)