AbstractBioactive peptides secreted from amphibians have been studied broadly for their potency as alternative drugs to treat human diseases. This thesis is about a caerin-related peptide derived from red-eyed leaf frog, Agalychnis callidryas, which provided ideas for further antibiotic research. Herein, the objectives included the isolation, identification, and bioactivity assessment of this bioactive peptide named QUB-2984. Agalychnis callidryas skin secretions were collected by stimulating the frogs’ skin. The sequence of QUB-2984 (GMWGTVFKGIKTVAKHLLPHVFSSQQS) was obtained by ‘shotgun’ cloning through constructing a cDNA library with isolated mRNA, and tested by DNA Sanger sequencing. It was synthesised by solid phase peptide synthesis, purified by reversed-phase high-performance liquid chromatography and structurally-confirmed by MALDI-TOF MS. The MIC value against gram-positive bacteria S.aureus was 2μM, gram-negative bacteria E.coli was 2μM, and against the pathogenic yeast C. albicans was 8μM. QUB-2984 showed anticancer potency at the minimum concentration of 10-5M towards human cancer cells. In terms of haemolysis, it caused around 50% haemolytic effect at 64μM. Its haemolytic effect implied the possibility of side-effects towards mammalian cells, but its ability to exert both antibacterial and anticancer biological activity makes this study valuable as a pre-study foundation for designing new antibiotics against cancer or infectious diseases.
Thesis embargoed until 31 December 2026.
|Date of Award||Dec 2021|
|Sponsors||Queen's University & China Scholarship Council|
|Supervisor||Mei Zhou (Supervisor), Lei Wang (Supervisor), Tianbao Chen (Supervisor) & Yuan Ying (Supervisor)|
- Antimicrobial peptides (AMPs)
- molecular cloning
- antimicrobial activity
- haemolytic activity
- MTT antiproliferation assay