Discovery and bioactivity assessment of a novel peptide from the skin secretion of the Senegal running frog Kassina senegalens

Abstract

Frog skin is characterised with an abundance of biologically active antimicrobial peptides (AMPs) with a broad-spectrum effect against a variety of microorganisms. The contribution of their complex and diverse structures, physicochemical properties and mechanisms of biological activity, have been discovered and widely reported. In this study, a novel peptide named QUB-1923 was identified from the skin secretion of the Senegal running frog, Kassina senegalensis. The sequence of the mature peptide (FYHLSALIHGIKQRLK) was deduced from the cloned cDNA encoding a prepropeptide. Subsequently, this peptide was chemically synthesised by solid-phase synthesis. Following on from the purification by RP-HPLC and MALDI-TOF MS, the antimicrobial, anti-cancer cell proliferative and haemolytic activities of the purified peptide QUB-1923 were investigated. Results from antimicrobial assays have shown that this peptide has a broad-spectrum antimicrobial effect on S. aureus, E. coli and C. albicans. Notably, this peptide displayed the highest antimicrobial activity against E. coli (MIC=4 μM, and MBC=8 μM). On the other hand, this peptide only caused approximately 20% growth inhibition on lung cancer cell line H838 at a concentration of 100 μM. Additionally, this peptide demonstrated less than 10% haemolysis at a concentration of 256µM. These results suggest that this novel peptide is worthy of attention as a new antibacterial lead due to its potent inhibitory and bactericidal effects against Gram-ve bacteria, along with a low level of haemolysis.

Thesis embargoed until 31 December 2026.

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