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oai:figshare.com:article/32638206 2026-10-01T16:46:53Z portal_1172 item_type_8 month_year_10_2026

Identification and characterisation of a bioactive peptide, namely QUB-2624, from the skin secretion of the Australian green tree frog, Litoria caerulea Yuxing Chen (381885) PUREID: 526184925 Antimicrobial peptides (AMPs) minimum inhibitory concentration cytotoxicity haemolysis therapeutic agent Antimicrobial peptides (AMPs) derived from natural sources have gained significant attention as potential alternatives to conventional antibiotics. This study focused on the identification, characterisation, and functional evaluation of QUB-2624, a bioactive peptide isolated from the skin secretion of the Australian green tree frog, Litoria caerulea. Molecular cloning techniques were employed to obtain the peptide sequence, which was then synthesised for functional studies following HPLC purification. The results revealed that QUB-2624 displayed differential inhibitory effects on tested microorganisms. The minimum inhibitory concentration (MIC) values of QUB-2624 against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were both determined as 16 µM. Interestingly, QUB-2624 exhibited stronger inhibitory activity against E. coli compared to S. aureus at a concentration of 8 µM. Moreover, it demonstrated higher bactericidal activity against E. coli than S. aureus, with minimum bactericidal concentration (MBC) values of 16 µM and 32 µM, respectively. However, QUB-2624 exhibited limited activity against the yeast Candida albicans, with MIC and MBC values of 32 µM and 64 µM, respectively. The anticancer potential of QUB-2624 was evaluated using the MTT assay on human lung cancer cells (NCI-H838). The peptide demonstrated significant antiproliferative activity against NCI-H838 cells at the highest concentration tested (128 µM), with an IC50 value of 98.43 µM. Furthermore, the haemolytic activity of QUB-2624 was assessed on horse red blood cells, revealing a significant haemolytic effect starting at a concentration of 64 µM. In conclusion, QUB-2624 from Litoria caerulea skin secretions exhibits considerable potential as a novel antimicrobial agent against S. aureus and E. coli. However, further studies are needed to minimize its haemolytic activity, ensuring its safety for potential therapeutic applications. <br><br><i>Thesis is embargoed until 31 December 2028.</i> 2026-10-01T16:46:53Z Text Thesis 10.17034/32638206.v1 https://figshare.com/articles/thesis/Identification_and_characterisation_of_a_bioactive_peptide_namely_QUB-2624_from_the_skin_secretion_of_the_Australian_green_tree_frog_Litoria_caerulea/32638206 All Rights Reserved Open Access after 2028-12-31