The discovery and functional study of an antimicrobial peptide QUB-1955 from the skin secretion of the northern orange-legged leaf frog, phyllomedusa hypochondrialis

  • Yanghui Shao

Student thesis: Masters ThesisMaster of Philosophy


Due to the increasing resistance of bacteria to conventional antibiotics, new antimicrobial drugs need to be discovered urgently. Natural active substances extracted from skin secretions of anurans have attracted much interest in recent years. Among them, anti-bacterial peptides with broad-spectrum antibacterial activity have become promising drug candidates for the development of new antibiotics.

In this research, a bioactive peptide which belongs to the phylloseptin family, named QUB- 1955, was isolated from Phyllomedusa hypochondrialis skin secretions. Initially, the mature peptide was identified from the cloned biosynthetic precursor encoding cDNA. Sufficient QUB-1955 was produced by solid-phase peptide synthesis and then, reverse phase high performance liquid chromatography (RP-HPLC) and matrix-assisted, laser desorption, ionisation, time-of-flight mass spectrometry (MALDI-TOF MS) were used to purify and confirm the structure of QUB-1955 for subsequent biological activity experiments (antimicrobial assays, anti-cancer cell assays and haemolysis assay).

In the order of potency, QUB-1955 had relatively potent antibacterial activity against Gram- positive bacteria (S. aureus), while it was weak against Gram-negative bacteria (E. coli), and had no activity against yeast (C. albicans). When incubated with cancer cell lines, QUB-1955 had no obvious anti-cancer cell activity against colorectal cancer cells and brain cancer cells at the concentrations tested. It did not induce haemolysis at the MIC for S. aureus. These data provide evidence that QUB-1955 could be further evaluated and manipulated as a possible lead compound for a new anti-bacterial drug against Gram-positive bacteria.
Date of AwardDec 2020
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorMei Zhou (Supervisor) & Lei Wang (Supervisor)

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