Identification and activity assessment of a bioactive peptide QUB-1368 from the skin secretion of the American bullfrog (Rana catesbeiana)

In this study, a novel antimicrobial peptide isolated from the skin secretions of Rana catesbeiana was named QUB-1368. After establishing the cDNA library, the biosynthetic precursor was obtained through molecular cloning, and then the mature peptide QUB-1368 was deduced from the precursor.

QUB-1368 was then obtained in quantity by solid-phase peptide synthesis for biological activity experiments. The purified synthetic peptide QUB-1368 was identified by reversed-phase high-performance liquid chromatography (HPLC) and Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry (MALDI-TOF). In this study, QUB-1368 showed a broad-spectrum antibacterial activity to Gram-negative bacteria (64 µM against E. coli ATCC CRM 8739), Gram-positive bacteria (32 µM against S. aureus ATCC CRM 6538) and yeast (64 µM against C. albicans ATCC CRM 10231).