Derivatives of L-proline, their preparation and their biological uses

A L-proline derivative of the formula I:

• ##STR15## or a pharmacologically acceptable salt thereof, wherein R.sub.1 is a group corresponding to Formula II:
• ##STR16## in which R is selected in group consisting of a carbonyl radical CO--, an acyl radical Y--CO-- or an oxy-acyl radical O--Y--CO--, Y being an alkyl or alkenyl group containing from 1 to 4 carbon atoms and,
• Z represents in the ortho and/or ortho' and/or meta and or meta' and/or para positions hydrogen or a substituent chosen from among halogen atoms, CF.sub.3 group, alkyl or alkoxy radicals containing from 1 to 4 carbon atoms, and in the case of 2 neighbouring substituents, an alkylenedioxy group, in which the alkyl group contains from 1 to 3 carbon atoms,
• R.sub.2 is a NH2 or OH radical or functional derivative
• A.sub.1 and A.sub.2, identical or different, are naturally occurring amino acid residues, and
• B.sub.1 and B.sub.2, identical or different, represent a hydrogen atom or a methyl group,
• with the provisos that on the one hand A.sub.1 be different from a phenylalanyl residue when B.sub.1 and B.sub.2 represent H, R.sub.2 represents OH, R.sub.1 is benzoyl and A.sub.2 is an alanyl residue, and, on the other hand, that A.sub.2 be different from a proline residue, when B.sub.1 and B.sub.2 represent H, R.sub.2 represents --OH or --NH.sub.2, or the functional derivatives thereof and R is --CO-- or --Y--CO, with Y being an alkyl group.