Synthesis and some pharmacological properties of [8-L-tryptophan]oxytocin

Condensation of (tert-butyloxycarbonyl)tocinoic acid with L-prolyl-L-tryptophylglycinamide produced the Boc derivative of a nonapeptide (disulfide) which on deprotection afforded [8-L-tryptophan]oxytocin. In assays on the rat uterus in vitro and in vivo the new analogue acts as both an agonist and an antagonist. The duration of both actions is prolonged.