Adjuvant activity of 6-O-mycoloyl derivatives of N-acetylmuramyl-L-seryl-D-isoglutamine and related compounds in mice and guinea pigs.

Adjuvant and antitumor activities of synthetic-6-O-mycoloyl-N-acetylmuramyl-L-seryl-D-isoglutamine and 6-O-mycoloyl-N-acetylmuramyl-glycyl-D-isoglutamine were examined in comparison with those of 6-O-mycoloyl-N-acetylmuramyl-L-alanyl-D-isoglutamine. Synthetic 6-O-mycoloyl-N-acetylmuramyl-L-seryl-D-isoglutamine was active as an adjuvant for the induction of delayed-type hypersensitivity to m-[4-(4'-arsono-phenylazo)-phenyl]-N-acetyl-L-tyrosine in guinea pigs and for cell-mediated cytotoxicity in allogeneic mice. 6-O-mycoloyl-N-acetylmuramyl-glycyl-D-isoglutamine was inactive as an adjuvant for the induction of delayed-type hypersensitivity in guinea pigs; however, it was active for cell-mediated cytotoxicity in allogeneic mice. 6-O-mycoloyl-N-acetylmuramyl-L-seryl-D-isoglutamine and 6-O-mycoloyl-N-acetylmuramyl-glycyl-D-isoglutamine were not pyrogenic in rabbits. The antitumor activity of these 6-O-mycoloyl-N-acetylmuramyldipeptides was examined preliminarily by using transplantable syngeneic mouse tumors.