Assessing bioactivity of a peptide from the skin secretion of the central American red-eyed leaf Frog, Agalychnis callidryas

  • Guanxiong Shang

Student thesis: Masters ThesisMaster of Philosophy


Peptides secreted in amphibian skin secretions have a great range of bioactive functions, especially the antimicrobial peptides with positive charge, α-helical structure and strong amphiphilicity. In this study, QUB-2428, a peptide related to the plasticins from the dermaseptin superfamily, was isolated from the skin secretion of the Central American Red-eyed Leaf Frog, Agalychnis callidryas. A cDNA library was constructed by using the isolated mRNA from frog skin secretion and ‘shotgun’ cloning, through use of which the mature peptide sequence was deduced. The purified peptide was obtained by reversed-phase high performance liquid chromatography. In this research, QUB-2428 did not possess broad-spectrum antimicrobial activity against the Gram-positive bacterium, Staphylococcus aureus, the Gram-negative bacterium, Escherichia coli and the yeast, Candida albicans. However, the peptide had activity against PC-3 and H157 human cancer cell lines at a range of concentrations from 1 to 100 μM. Also, it had a weak inhibitory function on U251MG cancer cells at concentrations from 50 to 100 μM. QUB-2428 displayed obvious inhibitory activity against PC-3 cells with an IC50 value of 6.7 μM and activity against H157 cells with an IC50 value of 8.3 μM. With regard to the haemolysis assay, QUB-2428 had no more than 5% haemolysis activity at a 512 μM concentration. With further modifications and experiments, QUB-2428 may be found to have better antimicrobial and anticancer functions in future studies.

Thesis embargoed until 31st October 2024
Date of AwardDec 2019
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorTianbao Chen (Supervisor), Mei Zhou (Supervisor), Lei Wang (Supervisor) & Xinping Xi (Supervisor)

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