Synthesis of (N-acetyl-1-O-acylmuramoyl)-L-alanyl-D-isoglutamines, and their immunoadjuvant activities

Immunostimulatory activity of 1-O-acylated muramyl dipeptides, with or without a 6-O-phosphoryl group, in aqueous form

Immunostimulatory effects of 1-O-acylated derivatives of N-acetyl-muramyl-L-alanyl-D-isoglutamine (MDP) methyl ester, with or without the 6-O-phosphoryl group, on augmentation of IgG antibody response against influenza hemagglutinin (HA) vaccine, in vivo macrophage activation and enhancement of non-specific host resistance against Pseudomonas aeruginosa infection were investigated. The activities were tested intraperitoneally (i.p.) in mice administered test samples solubilized or suspended in saline. The introduction of longer chain acyl groups into MDP methyl esters significantly induced enhancement of the IgG antibody response. Among them, the adjuvant activity of 1-O-linked 2-tetradecylhexadecanoyl (B30)-MDP methyl ester was comparable to that of 6-O-B30-MDP used as a positive control. Phosphorylation at the C6 position of the acylated MDP analogs did not induce a significant increment in the activity. With respect to phagocytic, cellular acid phosphatase and cytostasis-inducing activities, i.p. administration of acylated MDP analogs caused significant increment and activation of peritoneal macrophages. The cytostasis-inducing activity of 1-O-octadecanoyl- or 1-O-B30-MDP methyl ester with or without a phosphoryl group was more intensive than that of 6-O-B30-MDP. Acylated MDP analogs enhanced non-specific resistance against P. aeruginosa infection when the analogs were administered i.p. on the day before the infection. The enhancement was closely related to the accumulation of polymorphonuclear cells in the peritoneal cavity. The manifestation of these immunostimulatory activities by 1-O-acylated MDP analogs depended closely on the increasing carbon chain length of fatty acid substituents when administered in aqueous form.

Synthesis and biological activity of some lipophilic derivatives of 1-thio-muramoyl-L-alanyl-D-isoglutamine

2-N-Octadecanoyl derivatives of 1-S-acetyl-, 1-S-octadecanoyl-, and of 6-O-octadecanoyl-1-S-octadecanoyl-1-thiomuramoyl-L-ala nyl-D-isoglutamine were synthesized from benzyl 3,4,6-tri-O-acetyl-2-deoxy-2-(octadecanoylamino)-beta-D-glucopy ran oside. Their immunoadjuvant activities were examined in guinea-pigs.

Synthesis and biological activities of N-acetyl-1-thiomuramoyl-L-alanyl-D-isoglutamine and some of its lipophilic derivatives

N-Acetyl-1-thiomuramoyl-L-alanyl-D-isoglutamine and some lipophilic analogs were synthesized from benzyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-3-O-[D-1-(methoxycarbonyl)ethyl ]- alpha-D-glucopyranoside (1). O-Debenzoylation of 2, derived from 1 by oxidation, gave 2-acetamido-2-deoxy-4,6-O-isopropylidene-3-O-[D-1-(methoxycarbonyl)ethyl ]-D-glucopyranose (3). Condensation of the alkoxy-tris(dimethylamino)phosphonium chloride (4), formed from 3 by the action of carbon tetrachloride and tris(dimethylamino)phosphine, with potassium thioacetate afforded 2-acetamido-1-S-acetyl-2-deoxy-4,6-O-isopropylidene-3-O-[ D-1-(methoxycarbonyl)ethyl]-1-thio-beta-D-glucopyranose (8). Coupling of the acid 9, obtained from 8 by hydrolysis and subsequent S-acetylation, with the methyl ester of L-alanyl-D-isoglutamine gave N-[2-O-(2-acetamido-1-S-acetyl-2,3-dideoxy-4,6-O- isopropylidene-1-thio-beta-D-glucopyranose-3-yl)-D-lactoyl]-L-alan yl-D- isoglutamine methyl ester (10), which was converted, via O-deisopropylidenation, S-deacetylation, and de-esterification, into the N-acetyl-1-thiomuramoyl dipeptide. Condensation of 11 (derived from 10 by S-deacetylation) and of 12 (obtained from 10 by S-deacetylation and de-esterification) with various acyl chlorides yielded the corresponding 1-S-acyl-N-acetylmuramoyl-L-alanyl-D-isoglutamine derivatives, which were converted into the desired, lipophilic 1-thiomuramoyl dipeptides by cleavage of the isopropylidene group. Condensation of 11 with the alkyl bromides yielded the 1-S-alkyl derivatives, which were also converted, via O-deisopropylidenation and de-esterification, into the corresponding 1-S-alkylmuramoyl dipeptides. The biological activities were examined in guinea-pigs and mice.