Biological Chemistry and Molecular Recognition

We have isolated and characterised some 200 active peptides from the skin glands of 25 species of Australian amphibians.1 Mo t of these are host defence compounds, including vasoconstrictors, antimicrobials and anticancer agents.2 For example, the hinged peptide caerin 1.9 (1) is both a potent antibiotic and anticancer agent. We have recently discovered that amphibians also produce peptides which inhibit the formation of NO from nitric oxide synthase (NOS). We believe amphibians use these peptides to regulate their own body functions, and as defence agents against predators both large and small. There are three groups of these peptides, the caerins [e.g. caerin 1.9, (1)], the frenatins [e.g. frenatin 3 (2)] and the citropins [e.g. citropin 1.1 (3)].