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oai:figshare.com:article/32641902 2026-10-01T16:19:52Z portal_1172 item_type_8 month_year_10_2026

Identification and functional study of a bioactive peptide, QUB-2323, from the skin secretion of the orange-legged monkey tree frog, <i>Phyllomedusa azurea</i> Yue Tang (235893) PUREID: 658700942 AMPs dermaseptin antimicrobial activity anti-proliferative activity toxicity The widespread use of antibiotics has contributed significantly to the emergence of bacterial resistance. Antimicrobial peptides (AMPs) have emerged as promising antibacterial drug candidates due to their broad-spectrum of activity and low potential for resistance development. In this study, the precursor cDNA encoding an AMP, named QUB-2323, was isolated from the skin secretion of the orange-legged monkey tree frog, Phyllomedusa azurea, using shotgun cloning. Sequence analysis identified QUB-2323 as a member of the Dermaseptin family of AMPs, with the mature peptide sequence of GLWSTIKNVGKEAAIAAGKAALGAL-amide. <br><br>A series of experiments was conducted to evaluate the biological activity of QUB-2323. The peptide displayed broad-spectrum antimicrobial activity, with minimum inhibitory concentrations (MICs) of 1 µM against Staphylococcus aureus (NCTC 10788) and Candida albicans (NCYC 1467), and 0.5 µM against Escherichia coli (NCTC 10418). QUB-2323 also exhibited anti-proliferative activity, with an IC50 value of 6.44 µM against the lung cancer cell line, NCI-H838. However, the peptide showed notable cytotoxicity: a haemolytic concentration (HC₅₀) of approximately 128 µM against horse erythrocytes and an IC₅₀ of 2.377 µM against normal human lung fibroblasts (MRC-5). Comparison of these values revealed therapeutic indices of 128–256 for antibacterial activity but a low selectivity index of 0.37 for anti-proliferative activity, indicating higher toxicity toward normal fibroblasts than cancer cells. Collectively, these findings suggest that QUB-2323 holds promise as a lead candidate for developing novel antibacterial and anticancer therapies, although its therapeutic applications may be limited by cytotoxicity.<br><br><i>Thesis is embargoed until 31 December 2030.</i> 2026-10-01T16:19:52Z Text Thesis 10.17034/32641902.v1 https://figshare.com/articles/thesis/Identification_and_functional_study_of_a_bioactive_peptide_QUB-2323_from_the_skin_secretion_of_the_orange-legged_monkey_tree_frog_i_Phyllomedusa_azurea_i_/32641902 All Rights Reserved Open Access after 2030-12-31