Discovery of an antibacterial peptide QUB-2503 derived from Odorrana schmackeri skin secretion and testing of its antibacterial activity and cytotoxicity

Abstract

Due to the widespread use of antibiotics, bacterial resistance has become a huge challenge in human society. Therefore, it is important to find alternative treatment methods. In this process, the excellent antibacterial effects and low side effects of natural antimicrobial peptides (AMPs), have attracted the attention of researchers. At the same time, natural AMPs are widely present in nature. Therefore, extracting and studying natural AMPs is of great significance for the development of human society. In this thesis, gentle electrical stimulation was used to extract skin secretions from Odorlana schmackeri from which a new bioactive peptide was cloned, sequenced and named, QUB-2503. Through sequence comparison, it was confirmed that QUB-2503 belongs to the Brevinin-1 family. The peptide was successfully synthesised using solid-phase peptide synthesis, then purified, identified and isolated using RP-HPLC and MALDI-TOF MS. Finally, the antibacterial activity and cytotoxicity of the purified peptide were tested. QUB-2503 has a stable biological structure, is easy to synthesize and purify, and has good water solubility. In addition, QUB-2503 has good antibacterial activity against Gram positive Staphylococcus aureus, with a MIC of 32 μM. Meanwhile, QUB-2503 has low cytotoxicity towards red blood cells (HC50＞256 μM) and normal lung cells (IC50 of MRC-5＞100 μM), indicating good safety.QUB-2503 is thus a bioactive peptide with potential medical value.

Thesis is embargoed until 31 December 2030.

Date of Award	Dec 2025
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Lei Wang (Supervisor), Chengbang Ma (Supervisor) & Tianbao Chen (Supervisor)