N-(aminoacyl)-amino compound, represented by the following formulaWherein R1 denotes hydrogen, low alkyl or carbonyl, and N1 denotes an NH group andR2 denotes hydrogen or low alkylphenyl or aralkyl or imidazoalkyl or indolylalkyl,R1 and R2 together may complete a pyrrolidine or piperidine or thiazolidine ring andR3 denotes hydrogen or methyl or low alkyl and R4 denotes hydrogen or alkyl or the group remaining on exclusion of R4 from the formula andZ is a straight chain or branched alkylene, which may contain up to 3 carbon atoms. and R5 is nitrogen or sulphur or oxygen or salts thereof and ester compounds, characterised in that A is an ester or amino acid or alternatively sodium or a potassium salt of arginate and/or of ornithate and/or of aspharaginate.
