Identification and activity assessment of a bioactive peptide QUB-1368 from the skin secretion of the American bullfrog (Rana catesbeiana)

Abstract

Polypeptides in amphibian skin secretions have various bioactive functions, especially the positively-charged, alpha-helical and amphipathic polypeptides. In this study, a novel antimicrobial peptide isolated from the skin secretions of Rana catesbeiana was named QUB-1368. After establishing the cDNA library, the biosynthetic precursor was obtained through molecular cloning, and then the mature peptide QUB-1368 was deduced from the precursor. QUB-1368 was then obtained in quantity by solid-phase peptide synthesis for biological activity experiments. The purified synthetic peptide QUB-1368 was identified by reversed-phase high-performance liquid chromatography (HPLC) and Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry (MALDI-TOF). In this study, QUB-1368 showed a broad-spectrum antibacterial activity to Gram-negative bacteria (64 µM against E. coli ATCC CRM 8739), Gram-positive bacteria (32 µM against S. aureus ATCC CRM 6538) and yeast (64 µM against C. albicans ATCC CRM 10231). In addition, in the concentration range of 102-10-3 µM, QUB-1368 has no inhibitory effect on the human lung cancer cell line (H838). In the haemolysis assay, QUB-1368 showed haemolytic activity at a concentration of 256 µM, when QUB-1368 showed antibacterial activity, the concentration did not reach to produce hemolysis. In summary, QUB-1368 may have good clinical research value.

Thesis embargoed until 31 December 2026.

Date of Award	Dec 2021
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Mei Zhou (Supervisor), Lei Wang (Supervisor), Tianbao Chen (Supervisor) & Xinping Xi (Supervisor)