Identification and functional study of a bioactive peptide QUB-2413 from the skin secretion of the Red-Eyed Tree Frog, Agalychnis callidryas

Abstract

Antimicrobial peptides secreted from amphibian skin secretions have many important bioactivities and act as the first line to defense against invading microorganisms. In this thesis, QUB-2413, a peptide belonging to the plasticins family of the dermaseptins superfamily, was derived from the skin secretion of the Central American Red-eyed Leaf Frog, Agalychnis callidryas. The peptide sequence was obtained by molecular cloning through constructing a cDNA library with isolated mRNA from frog skin secretion. The peptide was synthesised by solid phase peptide synthesiser, purified using reversed-phase high performance liquid chromatography and confirmed by MALDI-TOF. In broth microdilution assays, QUB-2413 showed no significant antimicrobial activities against the Gram-negative bacterium, Escherichia coli (E. coli ATCC CRM8739), and the yeast, Candida albicans (C. albicans ATCC CRM10231) at concentration of 512 µM, while it had inhibitory effects on the Gram-positive bacterium, Staphylococcus aureus (S. aureus ATCC CRM6538). In terms of MTT anticancer cell proliferation assays, QUB-2413 was proved to have no remarkable anticancer activities against U251-MG cells and HCT-116 cells in a range of concentration from 10 -6 M to 10 -4 M. With regard to haemolysis assay, QUB-2413 had no more than 10% haemolysis activity at 512 µM. Although the biological activities of QUB-2413 are not ideal, it is still expected to become a safe anti-positive bacteria drugs in the future after its antimicrobial activities get optimised through structural modification.

Date of Award	Dec 2020
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Lei Wang (Supervisor)