Hypotensive peptides and their use

A method of treating angiotensin-induced hypertension in a mammal, by administering to said mammal an effective amount of a renin inhibitor, wherein said renin inhibitor is selected from the group consisting of compounds of formula (I):

• ##STR41## wherein:
• R.sup.1 represents a C.sub.1 -C.sub.4 alkyl group having:
• (a) an amino or protected amino substituent on its .alpha.-carbon atom and
• (b) a phenyl or naphthyl group, a 5- or 6-membered heterocyclic group having one or more of hetero atoms selected from nitrogen, oxygen and sulfur atoms, a 3-indolinyl group or a 1,2,3,4-tetrahydro-.beta.-carbolin-3-yl group, said R.sup.1 CO-- having one or more substituents selected from an amino group and a protected amino group;
• or
• R.sup.1 represents a 1,2,3,4-tetrahydro-.beta.-carbolin-3-yl group or a 1,2,3,4-tetrahydro-.beta.-carbolin-1-yl group;
• But represents a butyl group selected from the isobutyl and sec-butyl groups;
• X represents
• the formyl group or,
• a group of formula --CH(R.sup.2)--Y
• wherein R.sup.2 is a hydrogen atom, an alkyl group of 1 to 8 carbon atoms or a substituted alkyl group of 1 to 8 carbon atoms and having at least one substituent selected from a hydroxy, mercapto, amino, carbamoyl, formyl, phenyl, naphthyl or 5- or 6-membered heterocyclic group having one or more of hetero atoms of N, O and S, and Y is hydroxy, mercapto or formyl;
• and
• the carbon atoms marked with (S) are of the S-configuration;
• provided that R.sup.1 does not represent the benzyloxycarbonyl-L-phenylalanyl group or the benzyloxycarbonyl-L-prolyl-L-phenylalanyl group when X represents the formyl group;
• and pharmaceutically acceptable salts and esters thereof.