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: Analogs of neurohypophysial hormones with inhibition properties are described. The hormones are of the formula ##STR1## wherein in all chiral amino acids are of the L-series and the aromatic amino acid in the position 2, indicated with an asterisk, is of the D-series, and where R.sup.1 and R.sup.2 are hydrogen or a methyl group, R.sup.3 is hydrogen, an amino group, or a triglycylamine grouping, R.sup.4 is hydrogen, a methyl, ethyl or ethoxy group, R.sup.5 is S--CH.sub.2 or S--S group, X.sup.1 is a residue of isoleucine or phenylalanine, X.sup.2 is a residue of leucine or lysine, and X.sup.3 is a glycinamide residue or a hydroxyl group.These compounds exhibit inhibition effects towards the uterotonic and pressor activity of natural hormones. The common structural feature of all these analogues is the presence of an aromatic hydrophobic D-amino acid in the position 2.