A novel dermaseptin peptide from the defensive skin secretion of Phyllomedusa camba

  • Haohao Zhu

Student thesis: Masters ThesisMaster of Philosophy

Abstract

Hundreds of dermaseptin peptides have been isolated from the skins or the skin secre-tions of Phyllomedusa species and other related frogs and they all possess strong an-timicrobial activity with little or no haemolytic activity, which made it possible for the dermaseptin peptides to be considered for clinical development. Phyllomedusa frog skins and their secretions have been researched in the quest for novel peptides like the dermaseptins, for many years.
In this study, a novel dermaseptin, named DRS-CA-1, was successfully obtained from the skin secretion of Phyllomedusa camba through molecular cloning method. Then, this peptide was chemically synthesised by solid-phase peptide synthesis and after the cleavage reaction, the structural determination was performed through the use of MALDI-TOF mass spectrometry and purity was determined by RP-HPLC. In order to perform functional research, including antimicrobial assays and haemolysis assay, it was necessary to purify the crude peptide product to obtain the authentic peptide.
After the functional research was performed, it was found that the novel dermaseptin peptide had strong antimicrobial activity against both Gram-positive and Gram-negative bacteria and a pathogenic yeast (MICs=4μM) and MBC values of 16, 32, 32μM, respectively. Besides, low haemolytic activity (HC50=114.7μM) were observed at effective concentrations, which ensures its safety in clinical use. In the future, after structure modification, the analogues of the peptide may have potential to be devel-oped into novel antibiotic against the infections by drug-resistance bacteria.
Date of Award2017
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorTianbao Chen (Supervisor), Lei Wang (Supervisor), Chengbang Ma (Supervisor), Xinping Xi (Supervisor) & Chris Shaw (Supervisor)

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