Host-defence peptides from frog skin secretions
: Identification and bioactivity evaluation and optimisation

  • Xinjie Pei

Student thesis: Doctoral ThesisDoctor of Philosophy


With the rapid development of antibiotic resistance, new types of antimicrobial drugs are urgently needed. A novel AMP, Brevinin-1H, was isolated from skin secretion of Amolops hainanensis (A. hainanensis) with broad spectrum antimicrobial activity, anti-proliferative activity, and strong haemolytic activity. Two analogues were designed based on the secondary structure. Results revealed that the helical structure is critical for antimicrobial activity and haemolytic activity of peptides. The kink structure is important in antimicrobial activity against Gram-negative bacteria. A novel AMP, brevinin-1W peptide, was identified from skin secretion of Amolops wuyiensis (A. wuyiensis) with antimicrobial activity against Gram-positive bacteria, anti-proliferative activity, and strong haemolytic activity. A series of peptides were designed based on brevinin-1W peptide. Results indicated that proline and glycine could both influence the bioactivity of peptide while the proline exhibited stronger impact than the glycine residue and where the kink structure interrupted helical structure, was critical to balance the antimicrobial activity and haemolytic activity. To test the interactions between positive charges and hydrophobicity with bioactivity of peptide, five analogues were designed based on peptide PSN-PC. The hydrophobicity played a more important role in haemolytic activity compared with positive charges. Therefore, the balance between hydrophobicity and positive charges is essential for peptides to balance the cytotoxicity and antimicrobial activity.

Thesis embargoed until 31 December 2026.
Date of AwardDec 2021
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorLei Wang (Supervisor), Tianbao Chen (Supervisor), Mei Zhou (Supervisor) & Xiaoling Chen (Supervisor)


  • Antibiotic resistance
  • peptides
  • antimicrobial activity
  • haemolytic activity
  • anti-proliferative activity

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