Abstract: Tripeptides having hypotensive activity, defined by the following general formula:A--B--C--OZ (I)wherein:A represents a residue of L-pyroglutamic acid, L-proline of L-proline bearing a substituent on its amino group ##STR1## wherein R.sub.1 is an acyl with a number of carbon atoms in straight chain not higher than 9, a benzyloxycarbonyl group or an alkyloxycarbonyl group;B is an .alpha.-aminoacide residue derived from one of the natural aminoacids;C is a residue of L-tryptophan (Trp), of L-phenylalanine (Phe) or of L-tyrosine (Tyr);Z is a hydrogen atom or an alkyl group with a number of carbon atoms in straight chain not higher than 9.

Abstract: Retro-inverted peptides, analogues of Bradykinin Potentiator Pentapeptide (BPP.sub.5a), definable by the general formula (I) ##STR1## useful as antihypertensives and diagnostics.

Abstract: Peptido-mimetic compounds of hypotensive action definable by the general formula: ##STR1## in which: X represents the pyroglutamic acid residue or a ##STR2## residue where R.sub.2 represents a hydrogen atom, an alkyloxycarbonyl, an arylalkyloxycarbonyl or an acyl group with from 1 to 7 carbon atoms in the linear chain,R.sub.1 represents the aromatic residue of L-phenylalanine, L-tyrosine or L-tryptophan, andZ represents a hydroxyl, hydroxyalkyl, amino or alkylamino group, and their salts and alkyl amides or esters.

Abstract: New partially retro-inverso peptides of the following general formula ##STR1## wherein R.sup.1 and R.sup.2 are the same or different and represent, each independently, the side chain of the aminoacid residues present in the naturally occuring peptides, X is --S--Ph or --O--CH.sub.2 --Ph and Z is a hydroxy, alkoxy or amino group, are described as well as a suitable method for their preparation. The new compounds are useful as antihypertensive agents.

Abstract: This invention relates to new retro-inverso peptides and peptide derivatives in the form of analogues of the bradykinin potentiating peptide (BPP.sub.