A variety of N-acetylmuramyl-peptides (or -amino acids) were prepared by condensation of benzyl N-acetyl-4, 6-O-brnzylidene-alpha-muramide with various peptide (or amino acid) benzyl esters by the dicyclohexylcarbodiimide--N-hydroxysuccinimide or ethylchlorocarbonate--N-methylmorpholine method and removal of the protecting groups by hyderogenolysis. N-Acetylmuramyl-L-alanyl-D-isoglutamine was identified as the minimum structural entity essential for the immunoadjuvant activities characteristic of bacterial cell walls. Consequently N-acetylmuramyl-L-alanine was not adjuvant active. The tetrapeptide portion of adjuvant-active N-acetylmuramyl-L-alanyl-D-isoglutaminyl-L-lysyl-D-alanine proved to be inert, at least in induction of delayed-type hypersensitivity. The possible adjuvant activities of various analogues or diastereomers of the above N-acetylmuramyl-dipeptide and related compounds were studied. N-Acetylmuramyl-L-alanyl-D-glutamic acid exhibited weak, but definite adjuvancy, but none of the others, including N-acetylmuramyl-L-alanyl-L-isoglutamine, N-acetylmuramyl-L-alanyl-D-glutamine and N-acetylmuramyl-L-alanyl-D-isoasparagine, had any adjuvant activity. This clearly indicated the importance of the configuration of the glutamic acid residue or its amides, i.e. the presence of the D-isoglutamine residue in the N-acetylmuramyl-dipeptide, for manifestation of adjuvant activities in stimulation of both antibody-mediated and cell-mediated immune responses. Neither N-acetylmuramyl-D-isoglutamine nor N-acetylmuramyl-D-alanine had any adjuvancy.

Adjuvants, Immunologic↗

PubMed1975

Immunoadjuvant activities of peptidoglycan subunits from the cell walls of Staphyloccus aureus and Lactobacillus plantarum.

Attempts were made to isolate and identify the unit chemical structure essential for manifestation of the immunoadjuvant activities characteristic of bacterial cell walls. The N-acetylmuramyl-peptide subunit monomers, Nalpha-(N-acetylmuramyl-L-alanyl-D-isoglutaminyl)-Nepsilon-(glycylglycyl)-L-lysyl-D-alanine from the cell walls of Staphylococcus aureus (FDA 209P) and N-acetylmuramyl-L-alanyl-D-isoglutaminyl-meso-diaminopimelic acid and/or N-acetylmuramyl-L-alanyl-D-isoglutaminyl-meso-diaminopimelyl-D-alanine from those of Lactobacillus plantarum (ATCC 8014), were shown to be unit chemical entities with definite adjuvant activity both in stimulation of antibody production and in induction of delayed-type hypersensitivity to ovalbumin when administered to guinea-pigs as water-in-oil emulsions.

Adjuvants, Immunologic↗

PubMed1975