Identification and functional analyses of a novel dermaseptin peptide from the skin secretion of the frog, Phyllomedusa duellmani

  • Xiyan Ding

Student thesis: Masters ThesisMaster of Philosophy


Natural products are good resources for applications as diverse as scientific research and gastronomy. Amphibians, including frogs and toads, are rich sources of bioactive molecules acting against microbial pathogens. These bioactive components, especially the antimicrobial peptides, which possess antimicrobial and antifungal functions, have been studied in-depth. Dermaseptin peptides, derived from frogs of the Phyllomedusa genus, have been found to have broad-spectrum antimicrobial activities and relatively low haemolytic activities.

Here, one novel dermaseptin, named DS-Du, was discovered from the skin secretion of the purple and orange leaf frog, Phyllomedusa duellmani through molecular cloning method. Reversed-phase high-performance liquid chromatography (RP-HPLC) and matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry analyses were employed to isolate and structurally-characterise respective encoded peptides from skin secretions. This peptide exhibited growth inhibitory activity against E. coli, as a standard Gram-negative bacterium, S. aureus, as a standard Gram-positive bacterium and C. albicans, as a standard pathogenic yeast, all as planktonic cultures. The MIC/MBC values were 8/8 μM, 4/32 μM and 4/4 μM, respectively. At the same time, it showed low haemolytic activity. No obvious anticancer activity was observed during the cell viability assay. The results not only highlights the importance of peptide in the hose defense system, but also suggest the discovered peptide might be promising candidate of novel antibiotic.
Date of AwardJul 2017
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorTianbao Chen (Supervisor), Lei Wang (Supervisor), Chengbang Ma (Supervisor) & Xinping Xi (Supervisor)

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