Identification and functional study of a novel antimicrobial peptide, QUB-1976, from the skin secretion of the frog, Phyllomedusa bicolor

Abstract

Antibiotic resistance has led to a significant shortage of effective antibiotics. The aim of this study is to identify a novel peptide drug that has the potential to kill microorganisms and to evaluate its therapeutic value. From the skin secretion of Phyllomedusa bicolor, a precursor cDNA encoding QUB-1976 was obtained through molecular cloning. Sequence alignment confirmed its classification within the phylloseptin family. I-TASSER predicted it to be an alpha-helical peptide. The mature peptide sequence, FLSLIPKIVSGVAALAKHL-NH2, was synthesised via Fmoc solidphasepeptide synthesis. Subsequent reverse-phase high-performance liquid chromatography purification and MALDI-TOF mass spectrometry confirmed successful synthesis. Antimicrobial activities against Staphylococcus aureus NCTC 10788, Escherichia coli NCTC 10418 and Candida albicans ATCC 10231, were evaluated, the Minimum Inhibitory Concentration (MIC) / Minimum Bactericidal Concentration (MBC) of QUB-1976 against S. aureus was 0.25/0.25 μM, against E. coli was 4/8 μM, and against C. albicans, was 16/16 μM. QUB-1976 shows the strongest antibacterial effect against S. aureus, with decreasing effectiveness against E. coli and C. albicans. QUB-1976 also inhibits non-small cell lung cancer cells with an IC50 of 10.48 μM, indicating potential anticancer activity, and its haemolytic activity with an HC50 of 24.42 μM, suggesting blood toxicity at this concentration.

Thesis is embargoed until 31st December 2029.

Date of Award	Dec 2024
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Lei Wang (Supervisor), Tianbao Chen (Supervisor) & Mei Zhou (Supervisor)