AbstractAnurans, including frogs and toads, account for approximately 90 % of extant amphibian species. Most peptides secreted from the anuran skin have bioactive functions to prevent the invasion of microorganisms in their habitats.
In this study, a bioactive peptide belonging to the phylloseptin family, named QUB-2022, was identified from the skin secretion of the tiger-striped leaf frog, Phyllomedusa tomopterna. After the construction of the cDNA library, the biosynthetic precursor was obtained through the molecular cloning. Thereafter, the mature peptide (QUB-2022) was deduced and analyzed from the precursor. Through the solid-phase peptide synthesis (SPPS), a sufficient quantity of QUB-2022 were obtained. Following the reverse phase high performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS), the purified peptide, QUB-2022, was subjected to a series of bioassays. It was found that QUB-2022 showed a broad-spectrum antimicrobial activity against E. coli (MIC = 64 µM; MBC = 64 µM), S. aureus (MIC = 4 µM; MBC = 64 µM), and C. albicans (MIC = 16 µM; MBC = 32 µM). Besides, it also exhibited anticancer activity against the human non-small cell lung cancer cell line, NCI-H23, at the concentration of 10-4 M. Also, this peptide was found to possess a high degree of haemolysis (63%) while showing activity against E.coli, whereas negligible haemolytic effects toward normal cells of this peptide were observed at the MIC values for S. aureus and C. albicans. However, the half maximal haemolysis concentration (HC50) of QUB-2022 was 49.89 µM, which might limit the clinical use of that bioactive peptide and require optimization.
|Date of Award||Dec 2019|
|Supervisor||Tianbao Chen (Supervisor), Mei Zhou (Supervisor), Lei Wang (Supervisor) & Yuxin Wu (Supervisor)|