Muramyl peptide derivatives and pharmaceutical compositions

A compound which is an immunological adjuvant and effective against Klebsiella, which compound has the formula:

• ##STR18## in which the substituents R, R.sub.1, R.sub.2, R.sub.4, R.sub.6, X, Y and Z has the following definition:
• R is hydrogen or an alkyl group having 1 to 4 carbon atoms,
• R.sub.1 is hydrogen hydroxyl or phenylamino,
• R.sub.2 is hydrogen or methyl,
• R.sub.4 is hydrogen or acyl group having 1 to 4 carbon atoms,
• R.sub.6 is hydrogen, saturated or unsaturated acyl having from 1 to about 4 carbon atoms, mycolyl group having 80 to 90 carbon atoms or corynomycoyl,
• X is L-alanyl, L-seryl, L-valyl, or glycyl,
• Y is -OH, an alkoxy radical having from 1 to 10 carbon atoms, or -NH.sub.2, the hydrogens of the amino group being optionally substituted by alkyl residues having 1 to 10 carbon atoms, or an aminoacyl residue,
• A is an aminoacyl residue selected from the group consisting of L-alanyl, L-arginyl, L-asparagyl, L-aspartyl, L-cystenyl, L-glutaminyl, L-glutamyl, glycyl, L-histidyl, L-hydroxyprolyl, L-isoleucyl, L-leucyl, L-lysyl, L-methionyl, L-orinthyl, L-phenylalanyl, L-prolyl, L-seryl, L-threonyl, L-tryptophanyl, L-tyrosyl and L-valyl or an aminoalcohol residue (-NH-CH-CH.sub.2 -O-) corresponding to these aminoacyls (-NH-CH-CO-), wherein when the A groups are present in the same compound they may be identical or different, n is zero or 1,
• Z is selected from the group consisting of -OR', -NHR', -OCH.sub.2 -CH.sub.2 O-COR' or -OCH.sub.2 -CHOH-CH.sub.2 O-R.degree., wherein
• R.degree. is a mycolic acid group having from 80 to 90 carbon atoms, or corynomycoyl and R' is a linear or branched alkyl group having 4 to 20 carbon atoms.