The studies on the active peptide on smooth muscle in the skin of Rana rugosa, Thr6-bradykinin and its analogous peptide, ranakinin-R.

Abstract

Thr⁶-bradykinin and three kinds of its analogous peptides have been isolated from the methanol extract of the fresh skin of Rana rugosa. The longest bradykinin analogue, Thr⁶-bradykinyl-Ile-Ala-Pro-Glu-Ile-Val, was named ranakinin-R. Serotonin was also identified in the extract. The new peptide which contracts the rat uterus, guinea pig gall bladder and is hypertensive, was isolated and suggested to be the ranatensin or bombesin analogue by these pharmacological properties and by partial sequence analysis of the peptide.