Characterisation, bioactivity evaluation and rational modification of bioactive peptides from frog skin secretion and scorpion venom

This thesis examines a range of bioactive peptides from the East Asia frog- Pelophylax nigromaculatus, the Chinese bamboo leaf frog - Odorrana versabilis, and the scorpion Androctonus bicolor. In chapter 3 a novel Bowman-Birk type protease inhibitor (ranacyclin-NF) was identified in the skin secretion of Pelophylax nigromaculatus. Besides studying its potential applications, two analogues were designed to study structure-activity relationship of peptide. In Chapter 4, a previously-reported short peptide, Kunitzin-OV, was used as a template to design a set of variants to explore the structure-antimicrobial activity relationship and provide a potent alternative for novel antibiotic agents. In Chapter 5, a deduced venom peptide (AbCCT-1) from the scorpion, Androctonus bicolor, reported in previous literature, was studied. This peptide was used as a template and hybridised with a reported short antimicrobial motif to acquire analogues with antibacterial and anticancer activities. Functional screening and exploration of structure-activity relationship in this work would help in a great understanding of naturally-occurring disulphide-bridged peptides. These bioactive peptides are likely to become potent candidates for novel generation of therapeutic agents in the treatment of several clinic challenges, such as cancer, inflammation, and drug-resistant infections.