Characterization of aminoalkylphosphonyl cerebrosides in muscle tissue of Turbo cornutus

From muscle tissues of the marine snail (Turbo cornutus) aminoalkylphosphonyl cerebrosides, which had been shown to be present in visceral parts, were isolated.Their structure was determined by degradative methods and by characterization of components by gas chromatography-mass spectrometry.The aminoalkylphosphonyl cerebroside fraction consisted of a major portion of 1-O-[6′-O-(N-methylaminoethylphosphonyl)galactosyl] ceramide and a minor portion of a novel lipid, 1-O-[6′-O-(aminoethylphosphonyl)galactosyl] ceramide.The fatty acids of the fraction were mainly palmitic (53.3%) and 2-hydroxy palmitic acid (14.6%). The long chain bases were mainly dihydroxy C_{22 : 2} (36.6%), C_{18 : 1} (14.6%) and C_{18 : 2} (11.3%), and trihydroxy bases were also found as minor components.     

Synthèse du méthyl-2-acétamido-2-désoxy-β-D-glucofuranoside et de dérivés

Methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside was prepared in excellent yield from methyl 2-benzamido-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside by alkaline hydrolysis, followed by selective N-acetylation. Treatment with 60% acetic acid at room temperature gave syrupy methyl 2-acetamido-2-deoxy-β-D-glucofuranoside, characterized by a crystalline tri-O-p-nitrobenzoyl derivative. The same treatment, at 100° gave methyl 2-acetamido-2-deoxy-β-D-glucopyranoside. In an alternative procedure, the selective N-acetylation was performed after acetic acid hydrolysis of methyl 2-amino-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside. Several derivatives of methyl 2-acetamido-2-deoxy-β-D-glucofuranoside were prepared and compared with the corresponding pyranosides. The furanoside structure was clearly demonstrated by mass spectrometry and periodate oxidation.     

Identification by gas-liquid chromatography-mass spectrometry of 4-O-acetyl-9-O-lactyl-N-acetylneuraminic acid,a new sialic acid from horse submandibular gland

The novel sialic acid 4-O-acetyl-9-O-lactyl-N-acetylneuraminic acid has been identified as a constituent of horse submandibular gland glycoproteins in addition to the already know equine sialic acids, N-acetylneuraminic acid, 4-O-acetyl-N-acetylneuraminic acid, 9-O-acetyl-N-acetylneuraminic acid, 4,9-di-O-acetyl-N-acetylneuraminic acid, N-glycolylneuraminic acid, 4-O-acetyl-N-glycolylneuraminic acidand 9-O-acetyl-N-glycolylneuraminic acid. The structure has been established by combined gas-liquid chromatography-mass spectrometry.     

The linkage of 4-O-methyl-L-galactose in the sulphated polysaccharide of Aeodes ulvoidea

Methyl 2-acetamido-5,6-di-O-benzyl-2-deoxy-β-d-glucofuranoside (11) was obtained in six steps from the known methyl 3-O-allyl-2-benzamido-2-deoxy-5,6-O-isopropylidene-β-d-glucofuranoside. Mild acid hydrolysis, followed by benzylation gave the 5,6-dibenzyl ether. The benzamido group was exchanged for an acetamido group by strong alkaline hydrolysis, followed by N-acetylation, and the allyl group was isomerized into a 1-propenyl group that was hydrolyzed with mercuric chloride. Treatment of 11 with l-α-chloropropionic acid and with diazomethabe gave methyl 2-acetamido-5,6-di-O-benzyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-β-d-glucofuranoside which formed on mercaptolysis the internal ester 16, further converted into 2-acetamido-4-O-acetyl-5,6-di-O-benzyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-d-glucose diethyl dithioacetal (18) by alkaline treatment followed by esterification with diazomethane and acetylation. Attempts to remove the O-acetyl group of the corresponding dimethyl acetal 20 with sodium methoxide in mild conditions were not successful.     

Synthesis of 2-O-benzyl- and 2,3- and 2,6-di-O-benzyl-D-galactose

The following ethers, of potential value for the synthesis of α-D-galactopyranosides, were prepared: 2-O-benzyl-D-galactose, 2,6-di-O-benzyl-D-galactose, and 2,3-di-O-benzyl-D-galactose. Isopropylidenation of methyl α-D-galactopyranoside in the presence of phosphorus pentaoxide gave its 3,4-, and 4,6-O-isopropylidene derivatives. Treatment of the 3,4-acetal with trityl chloride in pyridine produced the 6-trityl ether, which was benzylated with benzyl chloride and sodium hydride in N,N-dimethylformamide to yield the 2-benzyl ether. Acid hydrolysis of this product gave 2-O-benzyl-D-galactose. Benzylation of methyl 3,4-O-isopropylidene-α-D-galactopyranoside, followed by hydrolysis, gave 2,6-di-O-benzyl-D-galactose. Similarly, 2,3-di-O-benzyl-D-galactose was obtained by acid hydrolysis of methyl 2,3-di-O-benzyl-4,6-O-isopropylidene-α-D-galactopyranoside and of methyl 2,3-di-O-benzyl-4,6-O-benzylidene-β-D-galactopyranoside.     

Pseudo-halogen sugar derivatives: Synthesis and hofmann-rearrangement reactions; 6-O-[2-(N,N-dichlorocarbamoyl)-ethyl]-1,2:3,4-di-O-isopropylidene-α-d-galactopyranose

6-O-[2-(N,N-Dichlorocarbamoyl)ethyl]-1,2:3,4-di- O-isopropylidene-α-d-galactopyranose, a highly reactive pseudo-halogen, was conveniently prepared in 97% yield by addition of sodium hypochlorite to an aqueous acidic (pH <2) solution of 6-O-(2-carbamoylethyl)-1,2:3,4-di-O-isopropylidene-α-d-galactopyranose. Mild, reductive dechlorination or alkaline hydrolysis readily converted the nonpolar N,N-di-chloroamide sugar derivative into the corresponding water-soluble N-monochloroamide form. Hofmann rearrangement of the N-chloroamide group provides a synthetic route to novel binary sugar-derivatives having carbamoyl, ureylene, and allophanoyl linkages. Structural proof for the pseudo-halogens and their Hofmann-rearrangement products was obtained from i.r., ¹H-n.m.r., mass-spectral, and chemical data.     

Glycosyl esters of amino acids. V. Synthesis and properties of 1-O-acylaminoacyl-alpha- and -beta-D-glucopyranoses and 1-O-(1-beta-aspartyl)-beta-D-glucopyranose

Catalytic hydrogenation of the tetrabenzyl ethers of 1-O-acetamidoacyl- and 1-O-tert-butyloxycarbonylaminoacyl-α- and -β-D-glucopyranoses (1–6) afforded the corresponding 1-O-acylaminoacyl-D-glucopyranoses 8–13 which were fully characterised by physical methods and by conversion into the peracetylated derivatives 14–19. The α anomers of 1-O-tert-butyloxycarbonylaminoacyl-D-glucopyranoses underwent 1→2 acyl migration, and, in order to characterize the rearrangement product of 1-O-(tert-butyloxycarbonyl-L-alanyl)-α-D-glucopyranose (12α), 1,3,4,6-tetra-O-acetyl-2-O-(tert-butyloxycarbonyl-L-alanyl)-α- and -β-D-glucopyranoses (22 and 23) were synthesized by definitive methods. Initial studies of the simultaneous deprotection of the amino and hydroxyl functions were performed with D-glucose-amino acid 6-esters; catalytic hydrogenation of methyl 2,3,4-tri-O-benzyl-6-O-(N-benzyloxycarbonylglycyl)-β-D-glucopyranose (24) gave methyl 6-O-glycyl-β-D-glucopyranose (25) as the stable hydrochloride. Hydrogenolysis of the β anomer of 2,3,4,6-tetra-O-benzyl-1-O-[1-benzyl N-(benzyloxycarbonyl)-L-aspart-4-oyl]-D-glucopyranose (7) afforded 1-O-(L-β-aspartyl)-β-D-glucopyranose (27). The rates of hydrolysis of the unprotected D-glucose-amino acid 1-ester 27 in water and in 0.1M hydrochloric acid were compared with those of the D-glucose-amino acid 6-ester 25.     

Identification of N, O-diacetyl-, N-acetyl- and N-glycolylneuraminyl-(2 → 3)-lactose in rat urine

The structure of three neuraminyl-oligosaccharides isolated from rat urine-have been studied by chromatographic and mass spectrometric analyses of different hydrolysis and methylation products. The structures of the oligosaccharides were identifies as O-α-N-acetyl(O-acetyl)neuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose, O-α-N-acetylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose and O-α-N-glycolylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose.     

Biotransformation of o- and p-aminobenzoic acids and N-acetyl p-aminobenzoic acid by cell suspension cultures of Solanum mammosum

Some new biotransformation products, p-aminobenzoic acid 7-O-β-d-glucopyranosyl ester, N-acetyl p-aminobenzoic acid 7-O-β-d-glucopyranosyl ester, o-aminobenzoic acid 7-O-β-d-(β-1,6-O-d-glucopyranosyl)glucopyranosyl ester and o-aminobenzoic acid 7-O-β-d-glucopyranosyl ester were isolated from cell suspension cultures of Solanum mammosum following administration of p-aminobenzoic acid, N-acetyl p-aminobenzoic acid or o-aminobenzoic acid respectively. N-acetyl p-aminobenzoic acid and N-formyl p-aminobenzoic acid were also identified as cell suspension metabolites of p-aminobenzoic acid.     

Synthèse de l'acide 5-acétamido-3,5-didésoxy-4-O-méthyl- d-glycéro-d-galacto-2-nonulosonique (acide 4-O-méthyl-N-acétylneuraminique). Partie II

3-Acetamido-3-deoxy-4,5:6,7-di-O-isopropylidene-d-glycero-d-galacto-heptose diethyl dithioacetal was transformed into 3-acetamido-3-deoxy-4,5:6,7-di-O-isopro-pylidene-2-O-methyl-aldehydro-d-glycero-d-galacto-heptose after O-methylation followed by desulfuration. A Wittig reaction with an excess of [ethoxy(ethoxycarbonyl)-methylene]triphenylphosphorane in the presence of benzoic acid gave a mixture of ethyl 5-acetamido-3.5-dideoxy-2-O-ethyl-6,7:8,9-di-O-isopropylidene-4-O-methyl-d-glycero-d-galacto-non-2-enonate (23 %) and the d-glycero-d-talo (22 %) isomer. An ethoxymercuration-demercuration reaction, followed by acid hydrolysis, converted the former into ethyl 4-O-methyl-N-acetylneuraminate and the latter into the C-4 stereoisomer. 4-O-Methyl-N-acetylneuraminic acid was then obtained in crystalline form, and its structure ascertained by mass spectrometry and ¹H- and ¹³C-nuclear magnetic resonance.     

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.     

Monoacylation of 2-O-α-d-glucopyranosyl-l-ascorbic acid by protease in N,N-dimethylformamide with low water content

2-O-α-d-Glucopyranosyl-l-ascorbic acid (AA-2G) laurate was synthesized from AA-2G and vinyl laurate with a protease from Bacillus subtilis in N,N-dimethylformamide (DMF) with low water content. Addition of water to DMF dramatically enhanced monoacyl AA-2G synthesis. Maximum synthetic activity was observed when 3% (v/v) water was added to the reaction medium. Under the optimal reaction conditions, 5-O-dodecanoyl-2-O-α-d-glucopyranosyl-l-ascorbic acid, 2-O-(6′-O-dodecanoyl-α-d-glucopyranosyl)-l-ascorbic acid, and 6-O-dodecanoyl-2-O-α-d-glucopyranosyl-l-ascorbic acid were synthesized in yields of 5.5%, 3.2%, and 20.4%, respectively.     

Comparative analysis of diacylglyceryl-trimethylhomoserine in Ochromonas danica and in Chlamydomonas reinhardtii 137+

The fatty acid compositions of the ether lipid 1(3),2-diacylglyceryl-(3)-O-4′-(N,N,N-trimethyl)homoserine (DGTS) from Ochromonas danica a     

The reaction of ammonia with acylated disaccharides : XI. The wohl reaction with octa-O-acytylmelibiononitrile

Octa-O-acetylmelibiononitrile (1) was prepared from melibiose oxime. The reaction of aqueous ammonia with 1 gave 1,1-bis(acetamido)-1-deoxy-5-O-α-D-galactopyranosyl-D-arabinitol (2), N-acetyl-5-O-α-D-galactopyranosyl-α-D-arabinofuranosylamine (3), and the anomeric pair of 5-O-α-D-galactopyranosyl-D-arabinofuranoses (4 and 5). The hepta-O-acetyl derivative of 2 was prepared, and the acyclic structure of the nitrogen-containing moiety was established by oxidation with periodate. The α anomeric configuration of 3 was demonstrated by periodate oxidation and subsequent reduction with sodium borohydride and hydrolysis.     

Phosphono-sphingomyelins. I: Synthesis of ceramide (trimethyl) aminoethyl phosphonate

The synthesis of the phosphono-analogue of sphingomyelin is described. The N-acyl-D-erythro-sphingosyl-1-(N,N,N-trimethyl-2-aminoethyl) phosphonate was obtained by phosphonylation of N-acyl-3-O-benzoyl-D-erythro-sphingosine with (2-bromoethyl)phosphonic acid chloride and triethylamine, subsequent quaternisation with anhydrous trimethylamine and benzene at 55–60°C for four days, and finally, consecutive removal of the protective group by mild alkaline hydrolysis. Comparison of the CD spectra of both, natural sphingomyelin and its phosphono-analogue, confirmed that their structures and configurations were identical.     

The nature of sialic acids in human lymphocytes

Analysis of the sialic acids obtained by mild acid hydrolysis of B lymphocytes reveals the presence of N-acetylneuraminic acid and 9-O-acetyl-N-acetylneuraminic acid. For T lymphocytes only N-acetylneuraminic acid has been demonstrated to occur. The applied methods include quantitative colorimetry, thin-layer chromatography and combined gas-liquid chromatography-mass spectrometry.     

The structure of bael (Aegle marmelos) gum

Purified, bael-gum polysaccharide containsd-galactose (71%),l-arabinose (12.5%),l-rhamnose (6.5%), andd-galacturonic acid (7%). Hydrolysis of one mole of the fully methylated polysaccharide gave: (a) from the neutral part, 2,3,4-tri-O-methyl-l-rhamnose (2 moles), 2,3,5-tri-O-methyl-l-arabinose (4 moles), 2,3,4,6-tetra-O-methyl-d-galactose (8 moles), 3,4-di-O-methyl-l-rhamnose (2 moles), 2,5-di-O-methyl-l-arabinose (1 mole), 2,4,6-tri-O-methyl-d-galactose (10 moles), 2,3-di-O-methyl-l-arabinose (1 mole), 2,4-di-O-methyl-d-galactose (14 moles), and 2-O-methyl-d-galactose (2 moles); and (b) from the acidic part, 2,3,4-tri-O-methyl-d-galacturonic acid (1 mole), 2,4,6-tri-O-methyl-3-O-(2,3,4-tri-O-methyl-d-galactopyranosyluronic acid)-d-galactose (2.6 moles), and 2,4,6-tri-O-methyl-3-O-[2,4,6-tri-O-methyl-3-O-(2,3,4-tri-O-methyl-d-galactopyranosyluronic acid)-d-galactopyranosyl]-d-galactose (1 mole). Mild hydrolysis of the whole gum yielded oligosaccharides from which 3-O-β-d-galactopyranosyl-l-arabinose, 5-O-β-d-galactopyranosyl-l-arabinose, 3-O-β-d-galactopyranosyl-d-galactose, and 6-O-β-d-galactopyranosyl-d-galactose could be isolated and characterized. The results of methylation, periodate oxidation, Smith degradation, Barry degradation, and graded hydrolysis studies were employed for the elucidation of the structure of the whole gum.     

Covalent structure of the extracellular polysaccharide from Xanthomonas campestris: evidence from partial hydrolysis studies.

Partial, acid hydrolysis of the extracellular polysaccharide from Xanthomonas campestris gave products that were identified as cellobiose, 2-O-(β-d-glucopyranosyluronic acid)-d-mannose, O(β-d-glucopyranosyluronic acid)-(1→2)-O-α-d-mannopyranosyl-(1→3)-d-glucose, O-(β-d-glucopyranosyluronic acid)-(1→2)-O-α-d-mannopyranosyl-(1→3)-[O-β-d-glucopyranosyl-(1→4)]-d-glucose, and O-(β-d-glucopyranosyluronic acid)-(1→2)-O-α-d-mannopyranosyl-(1→3)-[O-β-d-glucopyranosyl-(1→4)-O-β-d-glucopyranosyl-(1→4)-d-glucose. This and other evidence supports the following polysaccharide structure (1) which has been proposed independently by Jansson, Kenne, and Lindberg:

     

Influence of the location of substituents in substituted celluloses on solution hydrolysis of the d-glucosidic linkages

Sensitivity of the d-glucosidic linkages in cellulose to hydrolysis in homogeneous acidic media was found to be directly related to the location of a substituent in the d-glucoyranosyl unit. The 2-diethylaminoethyl (DEAE) substituent caused sensitivity toward hydrolysis to decrease in the order d-glucose > 3-O >6-O- 2-O-DEAE-d-glucopyranosyl-unit in hydrolyses beginning in 72% sulfuric acid and in 100% trifluoroacetic acid (TFA). Differences in the substituent effects were larger in TFA than in sulfuric acid. The effects reported for acid-catalyzed hydrolyses in homogeneous media are discussed relative to enzymic hydrolysis of a water-soluble, O-substituted cellulose.     

A substrate for the fluorogenic assay of exo-beta-N-acetylmuramidase: synthesis and purification of 4-methylumbelliferyl N-acetylmuramide.

A fluorogenic substrate for exo-β-N-acetylmuramidase from Bacillus subtilis B was synthesized. 4-Methyl-2-oxo-1,2-benzopyran-7-yl 2-acetamido-4,6-O-benzylidene-2-deoxy-β-d-glucopyranoside was prepared from 4-methyl-2-oxo-1,2-benzopyran-7-yl 2-acetamido-2-deoxy-β-d-glucopyranoside, condensed with dl-2-chloropropionic acid, the benzylidene residue removed by acetolysis and the 4-methyl-2-oxo-1,2-benzopyran-7-yl 2-amino-3-O-(d-1-carboxyethyl)-2-deoxy-β-d-glucopyranoside purified by chromatography on silica gel and Sephadex G-10 and by high-voltage paper electrophoresis. The identity of the product was confirmed by pmr studies, acid hydrolysis followed by chromatography of the products, and enzymic digestion.