A bioactive peptide from the skin secretion of the Red-eyed Leaf Frog, Agalychnis callidryas

  • Yan Zhang

Student thesis: Masters ThesisMaster of Philosophy


Natural products, as rich and varied resources for the discovery of novel drugs, have been essential for human healthcare systems throughout history. A variety of bioactive components with unique structures and functions isolated from the skin secretion of amphibians, especially peptides, have enormous potential for medical purposes.

Here, a peptide from the phylloseptin family was identified from the Red-eyed Leaf Frog, Agalychnis callidryas, by molecular cloning. This peptide was named as QUB-1541 based on its molecule weight. Then the mature peptide was successfully synthesised by Tribute® 2-channel peptide synthesiser. Reversed-phase high- performance liquid chromatography (RP-HPLC) was used for purification and matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) MS was used to confirm its molecular mass. QUB-1541 has better inhibitory activity against gram-positive bacteria than gram-negative bacteria. The MIC for S. aureus is 8 μM while for E. coli is 512 μM. Also, QUB-1541 inhibits the growth of yeast, C. albicans and the MIC is 128 μM. The results of MBC show that QUB-1541 has no bactericidal effect on E. coli and C. albicans at the highest concentration. However, QUB-1541 kills S. aureus at a lower level of 16 μM, while the haemolysis is weak. QUB-1541 was only effective against cancer cells, PC-3, U251MG and H157 at the highest concentration of 10-4 M. Thus, QUB-1541 has the value of subsequent research.

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) & Chengbang Ma (Supervisor)

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