Identification and functional study of a novel antimicrobial peptide, QUB-2014, from the skin secretion of the frog, Phyllomedusa tomopterna

Abstract

Amphibian skin secretion contains various bioactive compounds. Among these, antimicrobial peptides (AMPs) are vitally important as they protect amphibians from the attack of microorganisms. Some studies showed that AMPs are considered the new potential antibiotic candidates for humans and these molecules are also beneficial for solving antibiotic resistance. In this thesis, the aims are to identify a novel peptide from the skin secretion of Phyllomedusa tomopterna and to study its activities. Molecular cloning was utilised to acquire a full-length cDNA sequence from lyophilised skin secretion, and then the cDNA sequence was translated through ExPasy translating tool to obtain the peptide sequence of QUB-2014. After that, the peptide was synthesised through solid-phase peptide synthesis, and the crude peptide was purified via reverse-phase HPLC (RP-HPLC). MALDI-TOF mass spectrometry was used further to confirm the target peptide from the RP-HPLC fractions. Significantly, antimicrobial assays showed that this novel peptide QUB-2014 had a broad-spectrum antimicrobial activity against E.coli (ATCC CRM 8739), S.aureus (ATCC CRM 6538) and C.albicans (ATCC CRM 10231) with minimum inhibitory concentrations of 16 μM, 4 μM and 32 μM, respectively. This peptide also showed anticancer cell proliferative activity on lung adenocarcinoma cells at a concentration of 10-4 M. On the other hand, the haemolytic activity of this novel peptide was relatively weak, which was approximately below 10% of haemolytic rate from the concentration of 1 μM to 32 μM. Taken together, peptide QUB-2014 displayed a therapeutic potential to become an antimicrobial agent, and it may offer a possibility in cancer research due to its anticancer activity.

Thesis embargoed until 31 December 2026.

Date of Award	Dec 2021
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Lei Wang (Supervisor), Mei Zhou (Supervisor), Tianbao Chen (Supervisor) & Xiaoling Chen (Supervisor)