Amino acid derivatives and their therapeutical applications

A compound of the formula

• H.sub.2 N--CH(R.sub.1)--CH(R.sub.2)--S--S--CH(R.sub.3)--CH(R.sub.4)--A--B--Z
• in which R.sub.1 is saturated or unsaturated, linear or branched hydrocarbon chain containing from 1 to 6 carbon atoms, unsubstituted or substituted with =OR in which R is hydrogen, a linear or branched C1 to C4 hydrocarbon chain or phenyl or benzyl;
• =SR, R having the same definition as above, or an oxidized thioether group S(O)R, R having the same definition as above,
• methylcycloalkyl of 5 to 6 carbon atoms, benzyl or phenyl optionally substituted:
• with 1 to 5 halogen,
• or OR' or SR', R' being an alkyl group having 1 to 4 carbon atoms, =SR' being optionally oxidized on the sulfur atom,
• or with an amino group optionally mono- or disubstituted with an aliphatic of 1 to 6 carbon atoms, optionally oxidized on the amine, R.sub.2 is hydrogen or methyl, R.sub.3 is hydrogen or a linear or branched alkyl chain, R.sub.4 is saturated or unsaturated, linear or branched hydrocarbon chain containing from 1 to 6 carbon atoms, unsubstituted or substituted with a hydroxyl group, =OR in which R has the same meaning as above, =SH, =SR thioether group oxidized to sulfoxide,
• or a methylcycloalkyl group having 5 to 6 carbon atoms, a benzyl or phenyl group, optionally substituted with 1 to 5 halogen, with a hydroxyl or a thiol, =OR' or =SR', R' being alkyl of 1 to 4 carbon atoms, the thioether being optionally oxidized on the sulfur atom, with an amino group optionally mono- or disubstituted with an aliphatic of 1 to 6 carbon atoms, optionally oxidized on the amine function,
• Z is --CH(R.sub.5)--CH(R.sub.6).sub.n --COO(R.sub.7) in which R.sub.5 and R.sub.6 are individually selected from the group consisting of hydrogen,
• alkyl group having 1 to 6 carbon atoms, unsubstituted or substituted with hydroxyl or =OR, =SH or =SR groups,
• or a phenyl (Phe) or benzyl unsubstituted or substituted with 1 to 5 halogen atoms;
• =OR' or =SR', R' having the definition specified above,
• R.sub.5 and R.sub.6 can also each represent saturated or unsaturated hydrocarbon chains containing from 1 to 6 carbon atoms in which 1 to 2 carbon atoms may be substituted by an oxygen, sulfur or nitrogen atom, capable of leading to the formation of one or more saturated or aromatic 5- to 6-membered hydrocarbon rings,
• n is 0 or 1,
• R.sub.7 is selected from the group consisting of hydrogen, saturated or unsaturated, linear or branched alkyl group having 1 to 6 carbon atoms and benzyl, A--B represents an amide CONH or retro-amide NHCO in the forms of racemic mixtures or in the form of enantiomers, of diastereoisomers or of stereoisomers, as well as mixtures thereof and their non-toxic, pharmaceutically acceptable salts.