Hylin a1, the first cytolytic peptide isolated from the arboreal South American frog Hypsiboas albopunctatus ('spotted treefrog')

RP-HPLC fractionation of the electrically stimulated skin secretion of the arboreal South American frog Hypsiboas albopunctatus (“spotted treefrog”) led to the isolation of a cytolytic C-terminally amidated peptide. This novel peptide, named hylin a1 (Hy-a1), consists of 18 amino acid residues (IFGAILPLALGALKNLIK-NH 2 ). The α-helical structure of the synthetic hylin a1 peptide was confirmed by CD spectroscopy in the presence of 60% (v/v) TFE. The synthetic peptide displayed broad-spectrum antimicrobial activity against Gram-negative and Gram-positive bacteria including Escherichia coli , Staphylococcus aureus , Enterococcus faecalis , Bacillus subtilis and Pseudomonas aeruginosa and also against fungi ( Candida albicans , C. krusei , C. parapsilosis and Cryptococcus neoformans ) . Hylin a1 was also able to disrupt human erytrocytes (HC 50 = 18 μM). Similarity analysis using PSI-BLAST revealed 50–44% of identity to maximins Hv, H16, H15 and H10 from Bombina maxima and also to hylins b1 and b2 (Hy-b1 and Hy-b2) from Hypsiboas lundii (synonym: Hyla biobeba ).