Uperolein and other active peptides in the skin of the Australian leptodactylid frogs Uperoleia and Taudactylus.

Methanol extracts of the skin of the Australian leptodactylid frogs Uperoleia rugosa, Uperoleia marmorata and Taudactylus acutirostris contain several highly active polypeptides belonging to different peptide families. The most abundant peptide was uperolein, a tachykinin closely related to physalaemin and possessing the same spectrum of biological activity. Uperolein was present in the three species examined. Other tachykinins were represented by Rugosa-uperolein II and Marmorata-uperolein II, the structures of which still await full elucidation. Another peptide family represented in both Uperleia and Taudactylus was that of bombesin-like peptides. They were abundant in Uperoleia rugosa and scarce in Uperoleia marmorata and in Taudactylus. These bombesins are possibly similar to the bombesins, among which is litorin, present in the skin of other Australian leptodactylid frogs. Finally, Taudactylus contained a bradykinin-like peptide and both the Uperoleia species an hitherto unclassified peptide. These new findings have further enriched the already considerable list of active peptides and biogenic amines occurring in the amphibian skin.