The discovery of a novel bioactive peptide, QUB-2575, from the defensive skin secretion of Pelophylax kl. esculentus

  • Meixiang Liu

Student thesis: Masters ThesisMaster of Philosophy


Frog skin plays an important role in daily survival and antimicrobial peptides (AMPs) from frog skin secretions form the first line of defence against microbial infection. Due to their special antimicrobial mode of action, it is harder for bacteria to generate resistance to them. As a result, AMPs are regarded as potential candidates for treating bacterial infections.

In this thesis, a novel bioactive peptide, QUB-2575, was discovered by constructing a cDNA library for the purpose of “shotgun” cloning from Pelophylax kl. esculentus (P. kl. esculentus) skin secretions. According to the deduced primary structure of QUB-2575, it was defined as a brevinin-1 family peptide. QUB-2575 showed antimicrobial and anticancer activity but also had haemolytic activity. The minimal inhibitory concentrations (MICs) of QUB-2575 against three tested microorganisms, S. aureus, E. coli, and C. albicans, were 2 μM, 8 μM, and 4 μM, respectively. The half inhibitory concentrations (IC50) of QUB-2575 against the four tested human cancer cell lines, MB435S, U251MG, H157 and PC-3, were 3.04 μM, 3.65 μM, 3.53 μM and 4.26 μM, respectively. The haemolytic activity of QUB-2575 was determined using horse red blood cells. QUB-2575 was haemolytic with an HC50 of 23.48 μM. QUB-2575 exhibited 0.72%, 7.97% and 16.38% haemolysis at the MIC (2 μM) against S. aureus, the MIC (4 μM) against C. albicans and the MIC (8 μM), against E. coli, respectively.
Date of AwardDec 2017
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorTianbao Chen (Supervisor), Mei Zhou (Supervisor), Lei Wang (Supervisor) & Lei Li (Supervisor)

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