The inhibitory activity of 2-acetamido-2-deoxy-D-gluconolactones and their isopropylidene derivatives on 2-acetamido-2-deoxy-beta-D-glucosidase

2-Acetamido-2-deoxy-D-glucono-1,4-lactone (1) and 2-acetamido-2-deoxy-D-gluconic acid (3) have been examined for inhibitory activity against 2-acetamido-2-deoxy-β-D-glucosidase from bull epididymis. Crystalline 1 and 3 were compared with the known, crystalline 2-acetamido-2-deoxy-D-glucono-1,5-lactone (2), and a correlation of the activities of these compounds with various factors is presented. The inhibition constant of the 1,5-lactone 2 is lower (0.45μM) than that (4.43μM) of the 1,4-lactone 1. The effect of time is the opposite; whereas the activity of solutions of 2 decreases with time, solutions of 1 show an increase in inhibitory power, but both reach an equilibrium after 5 h. The free acid 3 exhibits no inhibitory activity. 2-Acetamido-2-deoxy-5,6-O-isopropylidene-D-glucono- 1,4-lactone (4) and 2-acetamido-2-deoxy-4,6-O-isopropylidene-D-glucono-1,5-lactone (5), which are appropriately protected to prevent conversion into the other lactone isomer, were also tested; 4 has 1/1000th the activity of 5.     

Structure of 2-acetamido-3-amino-2,3-dideoxy-d-glucofuranurono-6,3-lactam

An X-ray crystallographic analysis of the title compound, an N-acetyl derivative of the 2,3-diamino-2,3-dideoxy-d-glucofuranurono-6,3-lactam found in the hydrolyzate of Pseudomonas aeruginosa P14 lipopolysaccharide, was performed. The crystals are monoclinic, space group P2₁, a = 11.704(2), b = 5.333(1), c = 7.399(2) Å, β = 91.63(2)°, and Z = 2. The structure was solved by direct methods and refined by the block-diagonal least-squares method to a final R value of 0.046 for 796 independent reflections. The dihedral angle between the mean plane through the furanose ring and that through the γ-lactam ring is 106.2(2)°, the furanose ring is ¹T₂, and the C-3, C-4, C-6, and N-3 atoms of the γ-lactam ring are nearly coplanar. The conformation in aqueous solution is discussed, based on the ¹H-n.m.r. data.     

The metabolism of acetamidothiazoles in the rat. 2-Acetamido-, 2-acetamido-4-methyl- and 2-acetamido-4-phenyl-thiazole

The metabolism of some anti-inflammatory acetamidothiazoles was studied in the rat. The main metabolites were the corresponding acetylthiohydantoic acids, produced by fission of the thiazole ring. Minor metabolites arising from oxidation of the methyl or phenyl substituents were also identified. The structures of metabolites were established spectroscopically (u.v., i.r., n.m.r. and mass spectroscopy) and by identification with authentic specimens. The excretion of the original compounds and of metabolites, labelled with (14)C is also reported.     

1,4-Rearrangement of 7-(2-acetamido-2,3-dideoxyhex-2-enopyranosyl)theophylline derivatives

Treatment of 7-2(-acetamido-2,3-dideoxyhex-2-enopyranosyl)theophylline derivatives with boron trifluoride etherate in boiling methanol led to the isolation of 7-(methyl 2-acetamido-2,3,4-trideoxyhex-2-enopyranosid-4-yl)theophylline derivatives. Some mechanistic features of this 1,4-rearrangement followed by solvolysis are discussed, and a rationalization of the formation of the C-4′ derivatives in the fusion reaction of 2-acetamido-3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy-d-arabino-hex-l-enitol with theophylline is offered.     

Synthesis of p-nitrophenyl 2-acetamido-2-deoxy-O-beta-D-galactopyranosyl-beta-D-glucopyranosides.

Reaction of p-nitrophenyl 2-acetamido-2-deoxy-4,6-O-(p-methoxybenzylidene)-beta-D-glucopyranoside (2) with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide (3) under the usual conditions, followed by removal of the p-methoxybenzylidene group and O-deacylation, produced crystalline p-nitrophenyl 2-acetamido-2-deoxy-3-O-beta-D-galactopyranosyl-beta-D-glucopyranoside (6). Starting from p-nitrophenyl 2-acetamido 3,4-di-O-acetyl-2-deoxy-beta-D-glucopyranoside, the synthesis of p-nitrophenyl 2-acetamido-2-deoxy-6-O-beta-D-galactopyranosyl-beta-D-glucopyranoside was also accomplished.     

Formation of UDP-2-acetamido-2-deoxy-L-galactose and UDP-2-acetamido-2-deoxy-L-galacturonic acid by Pseudomonas aeruginosa.

The O-specific polysaccharide from the lipopolysaccharide of Pseudomonas aeruginosa NCTC 8505 (IATS serotype O:3) consists of a tetrasaccharide repeating unit comprising L-rhamnose, N-acetyl-D-glucosamine (GlcNAc), bacillosamine, and N-acetyl-L-galactosaminuronic acid (L-GalNAcA) (Y. Tahara and S. G. Wilkinson, Eur. J. Biochem. 134:299-304, 1983). Incubation of GlcN or UDP-GlcNAc with cell extracts or EDTA-treated cells of P. aeruginosa NCTC 8505 yielded a mixture of UDP-ManNAc, UDP-GalNAc, UDP-GlcNAcA, UDP-ManNAcA, UDP-L-GalNAc, and UDP-L-GalNAcA. The last two compounds, here identified for the first time, may be intermediates in the synthesis of the L-GalNAcA moiety of the O-specific portion of the lipopolysaccharide of P. aeruginosa.     

Identification of 3-acetamidino-2-acetamido-2,3-dideoxy-L-guluronic acid in lipopolysaccharide from Pseudomonas aeruginosa immunotype 7

O-Specific polysaccharide chain of Pseudomonas aeruginosa immunotype 7 lipopolysaccharide is composed of 3-acetamidino-2-acetamido-2,3-dideoxy-L-guluronic acid (GulNAcAmA), 2,3-diacetamido-2,3-dideoxy-D-mannuronic acid (ManN2Ac2A), and N-acetyl-D-fucosamine (FucNAc). On solvolysis with anhydrous hydrogen fluoride, the polysaccharide afforded a trisaccharide containing all its components. Borohydride reduction of the trisaccharide in boric acid solution resulted in conversion of reducing fucosamine into fucosaminitol, whereas in water the reduction was accompanied by reductive deamination of acetamidino function into ethylamino group. On hydrolysis with aqueous triethylamine, acetamidino group gave acetamido group. Analysis of the trisaccharides thus obtained by 1H NMR spectroscopy (including nuclear Overhauser effect), 13C NMR spectroscopy, and fast-atom bombardment mass spectrometry allowed the determination of the structure of the unusual uronic acid derivative and the following structure of the polysaccharide repeating unit: -4)-alpha-L-GulNAcAmA-(1-4)-beta-D-ManN2Ac2A-(1-3)-alpha-D-+ ++FucNAc-(1-.     

The inhibitory effect of cysteine on the mutagenic activities of several carcinogens.

The Salmonella/microsome mutagenesis assay was used to determine the effect of cysteine (alpha-amino-beta-mercaptopropionic acid) on the mutagenic actions of several carcinogens: N-methyl-N'-nitro-N-nitrosoguanidine. N-acetoxy-2-acetylaminofluorene, N-hydroxy-2-acetylaminofluorene, 4-nitroquinoline-1-oxide, methyl methanesulfonate, 5-nitro-2-furaldehyde semicarbazone, 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide, aflatoxin B1 and the nitrosation products of methylurea and methylguanidine. Cysteine, at non-toxic concentrations, significantly decreased the frequency of reversion to histidine prototrophy when it was added to treatment mixtures. The extent of the inhibition of mutagenic action by cysteine depended on the carcinogen studied as well as the doses of cysteine and carcinogen employed. Cysteine (2.5--10 mM) completely inhibited the mutagenic actions of N-methyl-N'-nitro-N-nitrosoguanidine and methylguanidine nitrosation products while only partially preventing the mutagenic effects of the other carcinogens assayed. Inhibition of 5-nitro-2-furaldehyde semicarbazone-induced mutagenesis occurred only with higher cysteine concentrations (20--200 mM).     

Synthesis of 4-deoxy analogues of 2-acetamido-2-deoxy-D-glucose and 2-acetamido-2-deoxy-D-xylose and their effects on glycoconjugate biosynthesis

4-Deoxy analogues of 2-acetamido-2-deoxy-D-glucose and 2-acetamido-2-deoxy-D-xylose were synthesized and evaluated as inhibitors of glycoconjugate biosynthesis. Methyl 2-acetamido-2,4-dideoxy-beta-D-xylo-hexopyranoside (11) showed a reduction in [3H]GlcN and [14C]Leu incorporation into hepatocyte cellular glycoconjugates by 89 and 88%, of the control cells, respectively, at 20 mM, whereas the free sugars, 2-acetamido-2,4-dideoxy-alpha,beta-D-xylo-hexopyranoses (15), showed a reduction of [3H]GlcN and [14C]Leu incorporation by 75 and 64%, respectively, at 20 mM. The acetylated analogues of 11 and 15, namely methyl 2-acetamido-3,6-di-O-acetyl-2,4-dideoxy-beta-D-xylo-hexopyranoside and 2-acetamido-1,3,6-tri-O-acetyl-2,4-dideoxy-alpha,beta-D-xylo-hexopyra noses, showed a greater inhibition of [3H]GlcN and [14C]Leu incorporation at 1 mM compared with their non-acetylated counterparts, but were toxic to hepatocytes at concentrations of 10 and 20 mM. Corresponding derivatives of 2-acetamido-2,4-dideoxy-L-threo-pentopyranose showed no biological effect up to 20 mM, suggesting that the C-6 substituent is important for the biological activity.     

Synthesis and anticonvulsant activities of N-benzyl (2R)-2-acetamido-3-oxysubstituted propionamide derivatives

Lacosamide has been submitted for regulatory approval in the United States and Europe for the treatment of epilepsy. Previous synthetic methods did not permit the elaboration of the structure-activity relationship (SAR) for the 3-oxy site in lacosamide. We report an expedient five-step stereospecific synthesis for N-benzyl (2R)-2-acetamido-3-oxysubstituted propionamide analogs beginning with D-serine methyl ester. The procedure incorporated alkyl (e.g. methyl, primary, secondary, and tertiary) and aryl groups at this position. The SAR for the 3-oxy site showed maximal activity in animal seizure models for small 3-alkoxy substituents.     

Determination of position of substitution on 2-acetamido-2-deoxy-D-galactosyl residues in glycolipids.

The substitution site on 2-acetamido-2-deoxy-D-galactosyl residues in oligosaccharide chains of glycolipids was determined by permethylation of the glycolipid with methyl iodide in the presence of dimethylsulfinyl carbanion, methanolysis of the permethylated product under mild conditions, acetylation with acetic anhydride-pyridine, and identification of the resulting substituted methyl glycosides of 2-deoxy-2(N-methylacetamido)-D-galactose by g.l.c. The method was applied to glycolipids of known structure, including normal brain ganglioside, Tay-Sachs ganglioside, and Forssman glycolipid.     

Synthesis of N-[2-O-(2-acetamido-2,3-dideoxy-5-thio-d-glucopyranose-3-yl)-d-lactoyl]-l-alanyl-d-isoglutamine

N-[2-O-(2-Acetamido-2,3-dideoxy-5-thio-d-glucopyranose-3-yl)-d-lactoyl]-l-alanyl-d-isoglutamine, in which the ring-oxygen atom of the sugar moiety in N-acetylmuramoyl-l-alanyl-d-isoglutamine (MDP) has been replaced by sulfur, was synthesized from 2-acetamido-2-deoxy-5-thio-α-d-glucopyranose (1). O-Deacetylation of the acetylated acetal, derived from the methyl α-glycoside of 1 by 4,6-O-isopropylidenation and subsequent acetylation, gave methyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-5-thio-α-d-glucopyranoside (4). Condensation of 4 with l-2-chloropropanoic acid, and subsequent esterification, afforded the corresponding ester, which was converted, viaO-deisopropylidenation, acetylation, and acetolysis, into 2-acetamido-1,4,6-tri-O-acetyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-5-thio-α-d-glucopyranose (12). Coupling of the acid, formed from 12 by hydrolysis, with the methyl ester of l-alanyl-d-isoglutamine, and de-esterification, yielded the title compound.