Characterisation, bioactivity assessment and rational design of naturally- occurring peptides from frog skin secretion

Among these analogues, brevinin-1pl-del16 displayed an increased bactericidal activity against E. coli , also with a relatively mild haemolysis than the natural peptide. However, its antimicrobial activity was noticed to decreased with the presence of the metal ions. Meanwhile, mechanistic experiments showed that brevinin-1pl and brevinin-1pl-del16, can neutralise LPS and affect the inner and outer membrane permeability of E. coli strains.In chapter five, the peptide ranatensin-R was screened for its antimicrobial and anticancer activities and subjected to haemolytic and cytotoxicity assays.

Meanwhile, 10 analogues were designed based on the parent peptide to increase its antimicrobial potential. After modification, the analogue ranatensin-2277 achieved a MIC of 4 μM for S. aureus, MRSA , and E. coli, whilst the parent peptide shown a much lower bacterial killing ability.<br><br><i>Thesis embargoed until 31 July 2029.</i>