Identification and activity assessment of a bioactive peptide, QUB-1938, from the skin secretion of the Broad-folded frog (Hylarana latouchii)

Abstract

In this study, the main topic was to extract a novel bioactive peptide from the skin secretion of the frog, Hylarana latouchii. The detailed steps of which are as follows:1) Molecular cloning begins with the extraction of mRNA from skin secretions of target frog and the construction of its cDNA library. The full-length cDNA-encoded precursors were obtained through ‘shotgun’ cloning, and then amino acid sequences of peptide was predicted from the precursors. 2) After obtaining the sequence of the mature peptide, the solid-phase peptide synthesis (SPPS) was performed to synthesis the target peptide. The synthesized crude peptide product was purified by Reverse phase high performance liquid chromatography (HPLC), and the purified collected product was further verified by matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS). 3) A series of bioassays including antibacterial experiments, anticancer experiments, haemolysis experiments and trypsin inhibitor experiments, were carried out to evaluate bioactivity of the target peptide. Consequently, QUB-1938 was found to possess trypsin inhibitory activity with a Ki value of 0.3577 μM and showed no significant cytotoxicity to horse red blood cells when the concentration was lower than 256 μM. Meanwhile, QUB-1938 exhibited no antibacterial activity against C. albicans, and slight activity against E. coli and S. aureus below the concentration of 512 μM. In addition, QUB-1938 was also tested by MTT assay at the concentration of 200 μM, and this indicated it had no antiproliferative activity against U251MG and HCT-116 cancer cells.

Date of Award	Dec 2020
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Mei Zhou (Supervisor), Lei Wang (Supervisor), Xinping Xi (Supervisor) & Tianbao Chen (Supervisor)