Identification and functional assessment of a bioactive peptide QUB-2984 from the skin secretion of the red-eyed tree frog, Agalychnis callidryas

  • Ziyan Tang

Student thesis: Masters ThesisMaster of Philosophy


Bioactive 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 AwardDec 2021
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsQueen's University & China Scholarship Council
SupervisorMei Zhou (Supervisor), Lei Wang (Supervisor), Tianbao Chen (Supervisor) & Yuan Ying (Supervisor)


  • Antimicrobial peptides (AMPs)
  • molecular cloning
  • antimicrobial activity
  • haemolytic activity
  • MTT antiproliferation assay

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