Molecular cloning and functional evaluation of an antimicrobial peptide, QUB 1985, from the skin secretions of Phyllomedusa bicolor

In this thesis, the skin secretions of the South American, Giant Leaf Frog, Phyllomedusa bicolor, were used to identify QUB-1985, peptide that is a member of the plasticin family of the phylloseptins superfamily. Molecular cloning was used to create a cDNA library using extracted mRNA from frog skin secretions to obtain the peptide sequence.

By using a solid phase peptide synthesiser, reversed-phase high performance liquid chromatography was used to purify the peptide, and MALDI-TOF MS was used to confirm its identity. Biological assays were used to test QUB-1985, and the results indicated strong antimicrobial activity against S. aureus, E. coli, and C. albicans, with MIC values of 8, 16, and 32 μM, respectively. Against the human lung cancer cell line, H838, it exhibited strong anticancer activity, particularly at concentrations of 6.25 to 12.5 μM. Additionally, at 32 μM, it demonstrated 15% haemolysis, indicating haemolytic activity.