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oai:figshare.com:article/32640126 2026-10-01T16:33:59Z portal_1172 item_type_8 month_year_10_2026

Characterisation and analysis of QUB-1400: a peptide from the skin secretion of the Chinese frog, (Rana pleuraden) Ziyi Wang (1956610) PUREID: 613054188 Antimicrobial peptides (AMPs) Rana Pleuraden QUB-1400 peptide antibacterial activity peptide synthesis and purification Antimicrobial peptides (AMPs) have emerged as promising alternatives to conventional antibiotics due to their broad-spectrum antimicrobial activity and low likelihood of inducing resistance. This thesis focuses on a newly discovered AMP, QUB-1400, belonging to the pleurain family, which was isolated from the skin secretion of the Chinese southwestern frog, Rana pleuraden. Initially, the cDNA encoding the biosynthetic precursor of QUB-1400 was successfully cloned using 'shotgun' cloning techniques. From this sequence, the structure of the mature peptide was deduced as FLGGLLSGIFKHL-NH2. Following this, the peptide was identified in the frog's skin secretion and synthesised for further investigation. QUB-1400 is a probable member of the pleurain-B AMP family. It underwent a series of bioactivity assays, including antimicrobial assays, a haemolysis assay, and an anti-proliferation assay. These assays aimed to assess the peptide's efficacy in combating microorganisms, its potential toxicity to mammalian cells, and its ability to inhibit cell proliferation.QUB-1400 demonstrated potent antimicrobial activity against various pathogens. Specifically, it displayed a low minimum inhibitory concentration (MIC) and mini-mum bactericidal concentration (MBC) against Staphylococcus aureus (MIC = 4 μM; MBC = 4 μM) and Escherichia coli (MIC = 4 μM; MBC = 8 μM), as well as Can-dida albicans (MIC = 16 μM; MBC = 32 μM). Additionally, it exhibited an-ti-proliferative properties against the NCI-H838 lung cancer cell line, with an IC50 value of 21.29 μM. However, despite its promising bioactivity, the QUB-1400 pep-tide showed a relatively high half-maximal haemolysis concentration (HC50) of 50.12 μM. This could potentially limit its clinical utility and warrants further opti-misation to enhance its safety profile.<br><br><i>Thesis embargoed until 31 December 2029.</i> 2026-10-01T16:33:59Z Text Thesis 10.17034/32640126.v1 https://figshare.com/articles/thesis/Characterisation_and_analysis_of_QUB-1400_a_peptide_from_the_skin_secretion_of_the_Chinese_frog_Rana_pleuraden_/32640126 All Rights Reserved Open Access after 2029-12-31