New caerin antibacterial peptides from the skin glands of the Australian tree frog Litoria xanthomera



The secretion of the skin glands of the ‘orange-thighed frog’ Litoria xanthomera contains seven peptides. One of these is the known hypotensive peptide caerulein. Two new peptides, caerin 1.6 [GLFSVLGAVAKHVLPHVVPVIAEKL(NH2)], and caerin 1.7 [GLFKVLGSVAKHLLPHVAPVIAEKL(NH2)] show antibacterial properties. Two other peptides lack the first two amino acid residues of caerins 1.6 and 1.7 and show no antibacterial activity. The identification of the peptides in Litoria xanthomera confirms that this species is related to Litoria caerula, Litoria gilleni and Litoria splendida but not as closely as those three species are related to each other. © 1997 European Peptide Society and John Wiley & Sons, Ltd.