The discovery of a novel peptide from the defensive skin secretion of Hylarana guentheri

  • Lingzhu Chen

Student thesis: Masters ThesisMaster of Philosophy


Amphibian skin secretions are considered as one of the richest storehouses of bioactive compounds. To date, thousands of proteins and peptides with diverse biological activities have been isolated from amphibian skins. Antimicrobial peptides (AMPs) are one of the most essential groups of these molecules. AMPs are relatively small molecules, which have recently been considered as a novel therapeutic strategy and serve as the first barrier of defence for a wide range of organisms against pathogens. They have considerable broad-spectrum antimicrobial activities against microorganisms, including bacteria, fungi and parasites. Some even have inhibitory effects on cancer cells and some may work on the innate immune system.
In this study, a novel bioactive peptide named QUB-1875 was isolated from Guenther's frog, Hylarana guentheri, and several bioactive and cytotoxic assays were performed to evaluate the biological activities of this peptide. Firstly, mRNA from the lyophilised skin secretion was isolated and the nucleotide sequence encoding the precursor of QUB-1875 was identified by a ‘shotgun’ cloning genomic study. Then solid phase peptide synthesis (SPPS) was used to synthesise QUB-1875. Subsequently, the product was identified and purified by mass spectrometry (MALDI-TOF) and reversed-phase high performance liquid chromatography (RP-HPLC). Three microorganisms, S. aureus, E. coli and C. albicans were used to determine antimicrobial activities of QUB-1875. The results showed that it possessed antimicrobial potential against S. aureus and C. albicans with MICs both of 8 µM and MBCs both of 32 µM, while the MIC against E. coli was 64 µM, and the MBC was 128 µM. Cytotoxicity testing of QUB-1875 showed that it had haemolytic effects on horse red blood cells.  

Date of Award2017
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorTianbao Chen (Supervisor), Lei Wang (Supervisor), Lei Li (Supervisor) & Mei Zhou (Supervisor)

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