Identification and bioactivity evaluation of peptide QUB-1909 from the skin secretion of Sylvirana nigrovittata

Abstract

Bacterial resistance to antibiotics has become an issue of concern to many researchers. Antimicrobial peptides not only inhibit microorganisms such as bacteria, fungi and parasites, but also inhibit and kill viruses and tumour cells, and are less likely to develop drug resistance. Therefore, research on antimicrobial peptides continues to intensify. Here, a novel antimicrobial peptide was identified in the skin secretions of the frog (Sylvirana nigrovittata), which was predicted to belong to the temporin family. A cDNA library was first constructed and itsa cloned cDNA isolated from this, was sequenced to obtain a mature peptide sequence. The peptide was then chemically-synthesised, followed by identification as well as purification steps and then mass spectrometry analysis. Finally, the purified peptide was tested for antibacterial, anticancer and haemolytic activity. The peptide sequence was determined to be FFPLLFGALSSLLPKLFa, and was named QUB-1909. The peptide showed significant inhibition of Gram-positive and Gram-negative bacteria (Staphylococcus aureus and Escherichia coli, respectively) at 4 µM and 32 µM. In an anti-cancer cell assay, the peptide showed an inhibitory effect against cancer cells (NCI-H838 lung cancer cells) at a concentration of 100 μM. In the haemolysis assay, the peptide showed significant haemolytic effects at 4 μM.The above experimental results indicated that QUB-1909 has potential for subsequent clinical application because of its antibacterial and anticancer activity. However, it possesses an excessive haemolytic effect, so subsequent modifications are needed to reduce this cytotoxicity.

Thesis embargoed until 31 December 2027

Date of Award	Dec 2022
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Lei Wang (Supervisor), Tianbao Chen (Supervisor) & Yangyang Jiang (Supervisor)