Two analogues of deamino-oxytocin were synthesized in which the original 20-membered cyclic structure of the oxytocin molecule is replaced by a 19-membered ring. In one of these analogues, the disulphide bond is replaced by a single sulphur atom, in the other by a methylene group. Both analogues showed oxytocin-like activity, but far less than that of deamino-oxytocin.
