2026-10-13T13:02:39Z https://api.figshare.com/v2/oai

oai:figshare.com:article/32633370 2026-10-01T17:03:51Z portal_1172 item_type_8 month_year_10_2026

Identification and bioactivity assessment of a host-defence peptide, QUB-2654, from the skin secretion of the frog, Agalychnis callidryas Ruiling Chen (24165612) PUREID: 366309743 Antimicrobial peptides Agalychnis callidryas antibacterial anti-lung cancer haemolytic activity Amphibian skin secretions contain a wide array of antimicrobial peptides with biological activities, providing an effective first-line of defence against microbial invasion. This thesis aims to characterise an antimicrobial peptide from the skin secretion of the Central American red-eyed tree frog, Agalychnis callidryas and to study its biological properties. Firstly, the cDNA sequence encoding an antimicrobial peptide (QUB-2654) precursor, was identified from the frog skin secretions extracted mRNAs through rapid-amplification of cDNA ends (RACE) PCR, molecular cloning and Sanger sequencing strategies. Next, the peptide was synthesised using a solid-phase peptide synthesiser, purified by reversed-phase high-performance liquid chromatography and corroborated by MALDI-TOF mass spectrometry. The purified peptide was tested for its antimicrobial activity, anti-lung cancer cell activity and haemolytic effect, by a series of bioassays. This study showed that QUB-2654 had significant bacteriostatic and bactericidal activities against a Gram-positive bacterium, Staphylococcus aureus (ATCC-CRM 6538) (MIC=3.125 µM, MBC=6.25 µM) and a Gram-negative bacterium, Escherichia coli (ATCC-CRM 8739) (MIC/MBC=6.25 µM), but the MIC value against Candida albicans (ATCC-CRM 10231) was not detected even at the highest peptide concentration. In addition, QUB-2654 statistically demonstrated anti-proliferative and killing effects against NCI-H838 human lung cancer cells at and above a concentration of 10 µM. The peptide concentration required to achieve half-maximal inhibition (IC50) of the NCI-H838 cells was 11.32 µM. This peptide was not haemolytic (<5% haemolysis) at the MBC values for S.aureus and E.coli, and at the IC50 value for NCI-H838 cells. These results suggest that peptide QUB-2654 has the potential to be developed as an antibacterial and anticancer drug.<br><br><i>Thesis is embargoed until 31 December 2027.</i> 2026-10-01T17:03:51Z Text Thesis 10.17034/32633370.v1 https://figshare.com/articles/thesis/Identification_and_bioactivity_assessment_of_a_host-defence_peptide_QUB-2654_from_the_skin_secretion_of_the_frog_Agalychnis_callidryas/32633370 All Rights Reserved Open Access after 2027-12-31