Identification and evaluation of the bioactive peptide QUB-2925 from the defensive skin secretion of Phyllomedusa tomopterna

In broth microdilution assays, QUB-2925 showed significant antimicrobial activities against the Gram-negative bacterium, Escherichia coli (E. coli ATCC CRM8739) at 1 µM, the Gram-positive bacterium, Staphylococcus aureus (S. aureus ATCC CRM6538) at 2 µM and the yeast, Candida albicans (C. albicans ATCC CRM10231) at 8 µM. In the MTT anticancer cell proliferation assay, QUB-2925 significantly inhibited the proliferation of NCI-H838 cells at a concentration of 10-5 M, with an inhibition of 80.1%.

Also, it showed haemolytic activity with 8.5% haemolysis at 64 μM. In conclusion, QUB-2925 showed obvious antibacterial activity against E. coli, S. aureus and C. albicans at a non-haemolytic concentration and had strong antiproliferation activity against NCI-H838 cells. It may be optimised by modification and is expected to be a promising polypeptide drug.<br><br><i>Thesis embargoed until 31 December 2026</i>.