Collect. Czech. Chem. Commun. 1994, 59, 718-720

Weak Oxytocin Antagonists from Minor Modification of the Cyclic Portion of Agonists

N. Assimomytisa, E. Manessi-Zoupab, P. Cordopatisa and D. Theodoropoulosb

a Department of Pharmacy, University of Patras, Patras 26010, Greece
b Department of Chemistry, University of Patras, Patras 26010, Greece


[(OMe)Ser5]-oxytocin (I), [(OMe)Thr5]-oxytocin (II) and [Aib3]-oxytocin (III) were synthesized by solid phase techniques. The three analogs were found to be relatively weak antagonists with pA2 values 5.7 (for I), 5.8 (for II) and 5.8 (for III), respectively, in the rat uterotonic in vitro assay. They were all inactive in the pressor and galactogonic assays.