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Title: Novel peptides from the defensive skin secretion of Asian and American frogs
Author: Ge, Beier
ISNI:       0000 0004 6425 3306
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2017
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Anurans have lived on earth for more than 300 million years. During this long period of time, they learned how to adapt to the environment and defend against microorganisms. Amphibian skin secretions generally contain complex peptidomes. These skin peptides constitute the first line of defence of amphibians against bacteria and fungi. Until now, more than 600 antimicrobial peptides (AMPs) from amphibians have been authenticated. AMPs selectively retard bacterial growth and kill bacteria. Compared with conventional antibiotics, AMPs have a number of clinical application advantages. Chapter 3 describes the study of two AMPs from Phyllomedusa sauvageiand Phyllomedusa hypochondrialis, named QUB2897 and QUB2869.These two peptides were synthesised by a solid phase peptide synthesis method and were purified by HPLC. A Q-TOF mass spectrometer was used to determine the peptides purity. Staphylococcus aureus (S.aureus), Escherichia coli (E.coli) and Candida albicans (C.albicans) were used to test the antimicrobial activities of QUB2897 and QUB2869 and horse blood was used to test their haemolytic activities. Both peptides were found to possess antimicrobial and haemolytic activities and they also had anti-cancer cell proliferation activity. Chapter 4 describes three novel peptides identified as QUB2897 and QUB2869 metabolism products from rat urinary bladder and ileum smooth muscle. The novel peptides, named QUB 2208 and QUB2179, were found as products of QUB2897 and QUB2869 metabolism of rat bladder smooth muscle, respectively. The novel peptide, named QUB501,was identified as a metabolite of both QUB2897 and QUB2869 by rat ileum smooth muscle. Using solid phase peptide synthesis (SPPS), these three novel peptides were successfully synthesised. QUB2208 and QUB2179 displayed more potent antimicrobial activities than their parent peptides, QUB2897 and QUB2869, respectively. The bioactivity of QUB501, however, was lower than that of the parent peptides. Chapter 5 describes the isolation and identification of two novel peptides, named QUB2582 and QUB1889, from the defensive skin secretion of the toad, Bombina maxima. The two peptides were synthesised by solid phase peptide synthesis and were purified by HPLC. The Q-TOF mass spectrometer was used to determine the peptides purity. Both peptides were found to possess anti-cancer cell proliferation activities.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available