Identification, characterization and bioevaluation of a bioactive peptide from the skin secretion of the Chinese forest frog

It was found that the hydrophobic region of the C-terminus affected its haemolytic ability and antibacterial activity at the same time, while increasing the net charge number and hydrophobicity of the N-terminus only increased its antibacterial activity without changing its haemolytic activity. At the same time, the addition of proline and tryptophan into the N-terminus improved the flexibility of the N-terminal and the chelating ability to the bacterial cell membrane.<br><br>Finally, QUB-1623, which was obtained from the structure-activity relationship study, was modified by introducing cyclohexylalanine (Cha) or a branched structure to obtain a peptide with stable antimicrobial activity in different physiological environments.

For the removal of part of the hydrophobic region at the C terminal and the addition of Cha, the reduction of peptide length showed a decrease in membrane breaking ability. The use of a branched structure allowed the active units of the peptide to accumulate, and even though the haemolytic activity increased, the stable antibacterial activity made it possible to enter the next step of in vivo experiments.<br><i><br>Thesis embargoed until 31 December 2026</i>.<br>