Abstract: Analogues of 8-D-homoarginine vasopressin were prepared with the general formula ##STR1## where X is L-O-methyltyrosine, L-p-ethylphenylalanine, D-p-ethylphenylalanine, L-p-methylphenylalanine or D-methylphenylalanine and R is cysteine or .beta.-mercaptopropionic acid. These vasopressin analogues exhibited an increased affinity to uterus receptors for oxytocin, where they acted as ocytocin antagonists. Moreover, the analogues of deamino vasopressin have a significantly reduced antidiuretic activity in comparison with [8-D-arginine]vasopressin.

Abstract: Stepwise synthesis in solution and cyclization by means of active esters or another method suitable for peptide bond formation were used to prepare analogues of deamino-vasopressin with the disulphide bridge altered to the thioether group. In sequence position 8 of the peptide chain the analogs differed by the nature of basic amino acid. Typical vasopressin-like activities, mainly antidiuretic, were very high in these analogs; of particular importance will be their haemodynamic activity.