Identification and evaluation of a novel bioactive peptide QUB-2665 from the frog skin secretion of Phyllomedusa bicolor

Abstract

In recent years, due to the increasing antibiotic resistance among microorganisms, the development of alternative drugs to antibiotics has become urgent. Peptide-based therapeutics have gained popularity as a promising direction in drug development, owing to their low resistance profile and other advantages. The skin secretions of frogs are well-known for their medicinal value, and peptides derived from these secretions have been found to possess various functions, including antibacterial activity. In this thesis, a novel antibacterial peptide from the skin secretions of Phyllomedusa bicolor, named QUB-2665, was discovered and studied. Through molecular cloning, the QUB-2665 biosynthetic precursor sequence was obtained. Solid-phase peptide synthesis was used to synthesise the peptide. After that, the main structure of this new peptide was identified and purified using RP-HPLC and MALDI-TOF-MS. Utilising several microbes, minimum inhibitory concentration (MIC) assays were performed and the haemolytic activity assay was conducted using horse red blood cells to test QUB-2665. The results showed that QUB-2665 exhibited antimicrobial ability against E. coli with an MIC value of 16 mg/L and an MBC value of 16 mg/L, but showed no antibacterial activity towards S. aureus or yeast C. albicans. QUB-2665 demonstrated strong haemolytic activity when the concentration was no less than 64 μM. Moreover, QUB had little effect on cancer cells. Based on these findings, it is evident that QUB-2665 has the potential to become an antibacterial drug.

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) & Chengbang Ma (Supervisor)