Identification and functional study of a bioactive peptide QUB-2558 from the skin secretion of the Wuyi torrent frog, Amolops wuyiensis

Antimicrobial peptides (AMPs), one of the natural products from amphibians, have become the research hotspot as new substitutes for antibiotics. This paper mainly focuses on analysing the structural characteristics and the biological activity of QUB-2558, a Brevinin-1 peptide discovered from the defensive skin secretion of the frog, Amolops wuyiensis.

The peptide sequence was obtained by molecular cloning through constructing a cDNA library. Then it was synthesised using a solid-phase peptide synthesiser, purified using reversed-phase high-performance liquid chromatography (RP-HPLC), and validated using Matrix-Assisted Laser Desorption/Ionisation-Time of Flight analysis (MALDI-TOF). The MIC (minimum inhibitory concentration) of Gram-positive bacterium S. aureus was 2 µM, while the MIC of Gram-negative bacterium E. coli was 4 µM. Moreover, for C. albicans, it also exhibited a dose-dependent inhibitory activity at a minimum concentration of 16 µM. Meanwhile, QUB-2558 could also indicate an anti-proliferation activity toward cancer cell line NCIH838 at the minimum concentration of 100 µM. QUB-2558 was found to possess a wide range of antimicrobial activity but showing high haemolysis at bactericidal concentrations.