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b has been isolated and identified as bradykinyl-isoleucyl-tyrosine 0-sulphate (Anastasi, Erspamer, Bertaccini & Cei, unpublished).The proposed structure has been confirmed by synthesis (Bernardi, Bosisio, De Castiglione & Goffredo, 1966).For the new naturally occurring bradykinin-like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.This paper describes some of the pharmacological actions of natural and synthetic phyllokinin in comparison with synthetic bradykinyl-isoleucyl-tyrosine and with synthetic bradykinin. METHODSAmphibian material.The Phyllomedusa rohdei material used in this study was as follows:(1) One hundred and seventy adult specimens captured near Rio de Janeiro in March 1964.The dried skins weighed together 28.8 g, and the average weight of a skin was 0.17 g.Pool 1964.(2) Five hundred and eighty adult specimens captured at the same place in January 1965.The dried skins weighed together 83.4 g, and the average weight of a skin was 0.144 g.Pool 1965 A. (3) Five hundred and ten adult specimens captured at the same place in February and March 1965.The dried skins weighed together 59.6 g, and the average weight of a skin was 0.115 g.Pool 1965 B. (4) Two thousand two hundred and ninety-five adult specimens captured at the same place in January-March 1966.The dried skins weighed together 283 g, and the average weight of a skin was 0.124 g.Pool 1966.