Pharmacological data on phyllokinin (bradykinyl-isoleucyl-tyrosine o-sulphate) and bradykinyl-isoleucyl-tyrosine.

Phyllomedusa rohdei, a small Brazilian amphibian, contains in its skin, in addition to a number of inactive polypeptides, at least three peptides active on plain muscle. The first one (polypeptide a) is characterized by a stimulant action on the rat uterus and the rat colon combined with a moderate hypotensive action in the dog; the second (polypeptide b) by a typical bradykinin-like activity; the third (polypeptide c) by a physalaemin-like activity (cf. Bertaccini, Cei & Erspamer, 1965a, 1965b). The three polypeptides may be separated from each other by chromatography on alkaline alumina column followed by elution with descending concentrations of ethanol. Polypeptide a emerges from the column in the 95% ethanol eluates, polypeptide b in the 70% ethanol eluates, and polypeptide c in the 60% and 50% ethanol eluates. Polypeptide a is possibly a tryptophan-containing pentapeptide, the synthesis of which is in progress; polypeptide c has not yet been obtained in a pure state; polypeptide b has been isolated and identified as bradykinyl-isoleucyl-tyrosine 0-sulphate (Anastasi, Erspamer, Bertaccini & Cei, unpublished). The proposed structure has been confirmed by synthesis (Bernardi, Bosisio, De Castiglione & Goffredo, 1966). For the new naturally occurring bradykinin-like endecapeptide the name of phyllokinin has been suggested.