Identification and functional study of a bioactive peptide, QUB1333, from the skin secretion of Rana dybowskii

Following the Sanger sequencing, the nucleotide sequences were translated into peptide precursors. Upon the result of BLASTP, a novel peptide was identified and produced by solid phase synthesis and an Fmoc strategy. The reverse-phase high-performance liquid chromatography (RP-HPLC) was employed for purification and the product was determined by matrix-assisted laser desorption/ionization-time of flight mass spectrometry.

The peptide was given a name QUB1333 by its molecular weight. The antimicrobial effects were evaluated by the Minimum Inhibitory Concentration (MIC) assay on E. coli, S. aureus, and C. albicans. The antiproliferation effects were tested using MTT against adenocarcinoma cell line NCI-H838.

The cytotoxicity was evaluated by haemolysis assay with horse erythrocytes. As a result, the peptide only exhibited slight inhibition activity against E. coli, S. aureus, and C. albicans at 512 micromolar. The antiproliferative effect on NCI-H838 cells was detected at 256 and 512 micromolar with 48 hours dosing.

Meanwhile, no significant haemolysis effects were observed up to 512 micromolar. It is important to note that despite the lack of bioactivity observed in these specific assays, QUB1333 might still possess a distinct biotarget within other tissues, cells, or host organisms.<br><br><i>Thesis is embargoed until 31 December 2028.</i>