Synthesis of α-L-Mannopyranosyl-containing Disaccharides and Phenols as Substrates for the α-L-Mannosidase Activity of Commercial Naringinase

In order to clarify the substrate specificity of the α-L-mannosidase activity of naringinase (Sigma), the following disaccharides and phenol glycosides were freshly prepared: methyl 2-O-(α-L-mannopyranosyl)­β-D-glucoside (1), methyl 3-O-(α-L-mannopyranosyl)-α-D-glucoside (2), methyl 4-O-(α-L-mannopyranosyl)-α-D-glucoside (3), methyl 5-O-(α-L-mannopyranosyl)-β-D-glucoside (4), methyl 6-O-(α-L-mannopyranosyl)-α-D­glucoside (5), 6-O-(α-L-mannpyranosyl)-D-galactose (6), p-nitrophenyl α-L-mannoside (7), and 4-methyl umbelliferone α-L-mannoside (8).These compounds, except for 3 and 5, were hydrolyzed with naringinase.     

Oligonucleotides Containing Disaccharide Nucleosides: Synthesis,Physicochemical, and Substrate Properties

Abstract

The efficient synthesis of oligonucleotides containing 2′-O-β-D-ribofuranosyl (and β-D-ribopyranosyl)nucleosides, 2′-O-α-D-arabinofuranosyl (and α-L-arabinofuranosyl)nucleosides, 2′-O-β-D-erythrofuranosylnucleosides, and 2′-O-(5′-amino-5-deoxy-β-D-ribofuranosyl)nucleosides have been developed.     

Efficient Production and Purification of Extracellular 1,2-α-L-Fucosidase of Bacillus sp. K40T

When Bacillus sp. K40T was cultured in the presence of L-fucose, 1,2-α-L-fucosidase was found to be produced specifically in the culture fluid. The enzyme was purified to homogeneity from a culture containing only L-fucose by chromatography on hydroxylapatite and chromatofocusing. The molecular weight of the enzyme was estimated to be 200,000 by gel filtration on Sephadex G-200. The enzyme was optimal at pH 5.5–7.0 and was stable at pH 6.0–9.0. The enzyme hydrolyzed the α(1 → 2)-L-fucosidic linkages in various oligosaccharides and glycoproteins such as lacto-N-fucopentaose (LNF)-I 〈O-α-L-fucose-(1 → 2)-O-β-D-galactose-(1 → 3)-N-acetyl-O-β-D-glucosamine-(1 → 3)-O-β-D-galactose-(1 → 4)-D-glucose〉, porcine gastric mucin, and porcine submaxillary mucin. The enzyme also acted on human erythrocytes, which was confirmed by the hemagglutination test using Ulex anti-H lectin. The enzyme did not hydrolyze α(1 → 3)-, α-(1 → 4)- and α-(1 → 6)-L-fucosidic linkages in LNF-III 〈O-β-D-galactose-(1 → 4)[O-α-L-fucose-(1 → 3)-]-N-acetyl-O-β-D-glucosamine-(1 → 3)-O-β-D-galactose-(1 → 4)-D-glucose〉, LNF-II 〈O-β-D-galactose-(1 → 3)[O-α-L-fucose-(1 → 4)-]-N-acetyl-O-β-D-galactose-(1 → 3)-O-β-D-galactose-(1 → 4)-D-glucose〉 or 6-O-α-L-fucopyranosyl-N-acetylglucosamine.     

Studies on the d-Xylose Series

This paper deals with the partial correction of our previous paper and with some new results in regard to ammonolysis of the epoxide ring of 2,3-anhydroribofuranoside derivatives.

Treatment of methyl 2,3-anhydro-5-deoxy-α-d-ribofuranoside, prepared from d-xylose, with ammonia gave methyl 2-amino-2,5-dideoxy-α-d-arabinoside and no methyl 3-amino-3,5-dideoxy-α-d-xyloside which we reported to obtain previously.

The exclusive attack of the nucleophilic reagent at C-2 is inconsistent with a result of C. D. Anderson et al. in regard to ammonolysis of methyl 2,3-anhydro-α-d-ribofuranoside.

In contrast to α-anomer, methyl 2,3-anhydro-5-deoxy-β-d-ribofuranoside gave mainly methyl 3-amino-3,5-dideoxy-β-d-xyloside. The difference of ammonolysis products between α- and β-anomer will be due to existence of steric hindrance.     

Synthesis of Some New α- and β-(l→2) Linked Disaccharides Containing L-Quinovose (6-Deoxy L-Glucose)

Hepta-O-acetyl-2-0-β-l-quinovopyranosyl-α-d-glucose (VI) and hepta-O-acetyl-2-O-α-l-quinovopyranosyl-β-d-gIucose (VIII) were prepared by the coupling of 2,3,4-tri-O-acetyl-α-l-quinovopyranosyl bromide (IV) with l,3,4,6-tetra-O-acetyl-α-D-glucose (V) in the presence of mercuric cyanide and mercuric bromide in absolute acetonitrile.

Similarly, hepta-O-acetyW-O-α-l-quinovopyranosyl-α-d-galactose (X) and hepta-O-acetyl-2-O-β-L-quinovopyranosyl-α-d-galactose (XI) were prepared by the reaction of IV with 1,3,4,6-tetra-O-acetyl-α-d-galactose (IX).

Removal of the protecting groups of VI, VIII, X and XI afforded the corresponding disaccharides. On treatment with hydrogen bromide, VI, VIII, X and XI gave the corresponding acetobromo derivatives.     

Syntheses of Some Derivatives of Glycosyl Pantothenic Acids,Analogues of Growth Factor for MLF Bacteria

A growth factor (TJF) for a malo-lactic fermentation bacterium (Leuconostoc sp.) has been found to be 4′-O-(β-D-glucopyranosyl)-D-pantothenic acid with structural and synthetical studies. Now other 4′-O-glycosides (β-D-ribofuranosyl, α-D-glucopyranosyl, β-D-galacto-pyranosyl, β-maltosyl and β-cellobiosyl) and 2′,4′-O-di-β-D-glucopyranoside of DL-pantothenic acid, and 4′-O-β-D-glucopyranoside of DL-pantethine were synthesized to examine their biological activities. The improved syntheses of TJF were also examined.     

Conversion of Cellobiose into Lactose

Benzyl 2, 3, 6-tri-O-acetyl-4-O-(2,3-di-O-acetyl-4,6-di-O-methylsulfonyl-β-d-glucopyranosyl)-β-d-glucopyranoside (VI) was prepared from α-cellobiose octaacetate. Displacement of the sulfonyl esters of VI with acyloxy-groups in N, N-dimethyl formamide in the presence of sodium benzoate gave 4-O-β-d-galactopyranosyl-d-glucopyranose derivative (lactose derivative). Elimination of blocking groups of the derivative yielded lactose hydrate (IX), though the overall yield of lactose from cellobiose octaacetate was less than 2%.     

Screening of the regioselectivity of acetyl xylan esterase from Bacillus pumilus as a catalyst for the deacetylation of glycoside acetates

Regioselective deacetylations of nine glycosides catalyzed by acetyl xylan esterase from Bacillus pumilus have been studied. The glycosides were methyl and benzyl glycosides of the tetraacetates of α-D-glucopyranose, α-D-galactopyranose and α-D-mannopyranose, and the methyl glycosides of tetra-O-acetyl-β-D-glucopyranose, tetra-O-acetyl-β-D-galactopyranose and tetra-O-acetyl-α-D-glucopyranose. The kinetics of successive deacetylations was monitored by GLC and 21 sugar acetates have been identified.     

First Synthesis And Antimicrobial Activity Of N- and S-α-L-Arabinopyranosyl-1,2,4-Triazoles

Arabinosylation of some 4-amino- and 4-arylideneamino-5-(pyridin-3-yl)-2,4-dihydro-[1,2,4]-triazole-3-thiones with 2,3,4-tri-O-acetyl-β-L-arabinopyranosyl bromide led to an efficient synthetic approach to the corresponding N-and S-α-L-arabinopyranosides. Structure assignment of these two regiosiomers was based on chemical and spectroscopic evidences. Antimicrobial activities of two selected regioisomeric N-and S-α-L-arabinopyranosides were compared. The N-α-L-arabinopyranoside showed higher inhibitory effect than its regioisomeric S-α-L-arabinopyranoside against Aspergillus fumigatus, Penicillium italicum, Staphylococcus aureus, and Pseudomonas aeruginosa.     

Syntheses of a Neobiosamine C Derivative and Its Analogs

Methyl 2,5-di-O-p-nitrobenzoyl-β-d-ribofuranoside was prepared via methyl 2,3-O-ethoxyethylidene-β-d-ribofuranoside from d-ribose. It was condensed with 3,4,6-tri-O-acetyl-2-deoxy-2-(2′,4′-dinitroanilino)-α-d-glucopyranosyl bromide and 3,4-di-O-acetyl-2,6-dideoxy-2-(2′,4′-dinitroanilino)-6-phthalimido-α-d-glucopyranosyl bromide by a modified Königs-Knorr reaction to give neobiosamine analogs. The condensation reaction gave α-glucosides as the minor product, and the corresponding β-glucoside as the major product.     

Synthetic Studies on Carbohydrate Antibiotics

New synthetic methods for the preparation of 6-deoxy-1,2-O-isopropylidene-α-d-xylo-hexofuranos-5-ulse (VIa) were described.

Methyl 2,3,4-tri-O-benzoyl-6-deoxy-α-d-arabino-hex-5-enopyranoside (IIIa) was synthesized starting from methyl α-d-altroside (IIa). This enose derivative (IIIa) was hydrolyzed to methyl 6-deoxy-α-d-arabino-hex-5-enopyranoside (IIIb), and then converted with acid into 6-deoxy-d-arabino-hexofuranos-5-ulose (I), the sugar component of antibiotic hygromycin A.     

The Structure of an Antibiotic Kanamycin

The antibiotic kanamycin was degraded with methanolic hydrogen chloride and was determined to be composed of three compounds: deoxystreptamine, 6-amino-6-deoxy-d-glucopyranose and 3-amino-3-deoxy-d-glucopyranose. From the chemical and physical data on the antibiotic and its fragments, kanamycin was shown to be O-α-6-amino-6-deoxy-d-glucopyranosyl-(1→4 or 6)-O-[α-3-amino-3-deoxy-d-glucopyranosyl-(1→6 or 4)]-1,3-diamino-1, 2, 3-trideoxy-myo-inositol.     

Studies on Protopectinase-C Mode of Action: Analysis of the Chemical Structure of the Specific Substrate in Sugar Beet Protopectin and Characterization of the Enzyme Activity

Chemical structures of pectic substances degraded by protopectinase-C (PPase-C) were characterized to identify the releasing mechanism of pectin from sugar beet protopectin by the action of that enzyme. The substrate of PPase-C was a polysaccharide isolated from sugar beet pulp by extraction with NaOH and sequential digestions with rhamnogalacturonase (PPase-T), β-1,4-D-galactanase, and α-L-arabinofuranosidase. The structure of this polysaccharide was analyzed by gas-liquid chromatography (GLC), NMR analysis, and gas chromatography-mass spectrometry (GC-MS), and it was identified as α-1,5-L-arabinan. According to our results, arabinan chains seemed to be connected to rhamnogalacturonan through a chain of β-l,4-D-galactan. PPase-C hydrolyzed both linear α-1,5-L-arabinan and ramified L-arabinan in a random manner, producing L-arabinose. From these results, PPase-C could be classified as arabinan endo-1,5-α-L-arabinase [EC 3.2.1.99]. Moreover, PPase-C seemed to split the L-arabinan of the polysaccharides connecting the rhamnogalacturonan to the other constituents of the plant cell wall in sugar beet pulp, releasing water-soluble pectin.     

Anti-Diabetic Effects of a Kaempferol Glycoside-Rich Fraction from Unripe Soybean (Edamame,Glycine max L. Merrill. ‘Jindai’) Leaves on KK-Ay Mice

The anti-diabetic effects of a kaempferol glycoside-rich fraction (KG) prepared from leaves of unripe Jindai soybean (Edamame) and kaempferol, an aglycone of kaempferol glycoside, were determined in genetically type 2 diabetic KK-A^y mice. The hemoglobin A_1c level was decreased and tended to be decreased by respectively feeding KG and kaempferol (K). The area under the curve (AUC) in the oral glucose tolerance test (OGTT) tended to be decreased by feeding K and KG. The liver triglyceride level and fatty acid synthase activity were both decreased in the mice fed with KG and K when compared to those parameters in the control mice. These results suggest that KG and K would be useful to improve the diabetes condition. The major flavonoids in KG were identified as kaempferol 3-O-β-D-glucopyranosyl(1→2)-O-[α-L-rhamnopyranosyl(1→6)]-β-D-galactopyranoside, kaempferol 3-O-β-D-glucopyranosyl(1→2)-O-[α-L-rhamnopyranosyl(1→6)]-β-D-glucopyranoside, kaempferol 3-O-β-D-(2-O-β-D-glucopyranosyl) galactopyranoside and kaempferol 3-O-β-D-(2,6-di-O-α-L-rhamnopyranosyl) galactopyronoside, suggesting that these compounds or some of them may be concerned with mitigation of diabetes.     

Isolation of Oligosaccharides Corresponding to the Branching-point of Konjac Mannan

Ultracentrifugically homogeneous glucomannan acetate derived from konjac mannan was subjected to acetolysis. Besides β-1,4-linked oligosaccharides composed of D-mannose and/or D-glucose, three oligosaccharides corresponding to the branching point of the polysaccharide were isolated and identified as (1) 3-O-β-D-mannopyranosyl-D-mannose, (2) O-β-D-mannopyranosyl-(1→4)-O-β-D-mannopyranosyl-(1→3)-D-mannose, and (3) O-β-D- mannopyranosyl-(1→3)-O-β-D-mannopyranosyl-(1→4)-D-glucose. The average chain length (CL) was, moreover, determined to be about 46 by methylation analysis. The structural pattern of the glucomannan, including the branching point, is discussed.     

Acceptor Specificity of Cyclodextrin Glycosyltransferase from Bacillus stearothermophilus and Synthesis of α-D-Glucosyl O-β-D-galactosyl-(1→4)-β-D-glucoside

Bacillus stearothermophilus CGTase had a wider acceptor specificity than Bacillus macerans CGTase did and produced large amounts of transfer products of various acceptors such as D-galactose, D-mannose, D-fructose, D- and L-arabinose, d- and L-fucose, L-rhamnose, D-glucosamine, and lactose, which were inefficient acceptors for B. macerans CGTase. The main component of the smallest transfer products of lactose was assumed to be α-D-glucosyl O-β-D-galactosyl-(l→4)-β-D-glucoside.     

Structure of Carbohydrate Moiety of Asterosaponin A

Partial acid hydrolysis of asterosaponin A, a steroidal saponin, afforded two new disaccharides in addition to O-(6-deoxy-α-d-glucopyranosyl)-(l→4)-6-deoxy-d-glucose which has been characterized in the preceding paper. The formers were demonstrated as O-(6-deoxy-α-d-galactopyranosyl)-(1→4)-6-deoxy-d-glucose and O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-6-deoxy-d-galactose, respectively.

Accordingly, the structure of carbohydrate moiety being composed of two moles each of 6-deoxy-d-galactose and 6-deoxy-d-glucose, was established as O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-O-(6-deoxy-α-d-glucopyranosyl)-(l→4)-6-deoxy-d-glucose, which is attached to the steroidal aglycone through an O-acetal glycosidic linkage.     

Synthesis of Certain Disaccharides Containing a α-or β- Rhamnopyranosidic Group and the Substrate Specificity of α-l-Rhamnosidase from Aspergillus niger

To investigate the substrate specificity of α-l-rhamnosidase from Aspergillus niger, the following seven substrates were synthesized: methyl 3-O-α-l-rhamnopyranosyl-α-d-mannopyranoside (1), methyl 3-O-α-l-rhamnopyranosyl-α-l-xylopyranoside (2), methyl 3-0-α-l-rhamnopyranosyl-α-l-rhamnopyranoside (3), methyl 4-0-α-l-rhamnopyranosyl-α-d-galactopyranoside (4), methyl 4-O-α-l-rhamnopyranosyl-α-d-mannopyranoside (5), methyl 4-0-α-l-rhamnopyra-nosyl-α-d-xylopyranoside (6), and 6-0-β-l-rhamnopyranosyl-d-mannopyranose (7). Compounds 1~6 were well-hydrolyzed by the crude enzyme, but 7 was unaffected.     

Synthesis and Properties of 6-Deoxy-6-mercapto-d-glucosamine

6-Deoxy-6-mcrcapto-α-d-glucosamine hydrochloride was synthesized from N-anisylidene-1,3,4-tri-O-acetyl-6-O-tosyl-β-d-glucosamine, and some of its properties were compared with those of α-d-glucosamine hydrochloride.     

Glycosidic Aroma Precursors of 2–Phenylethyl and Benzyl Alcohols from Jasminum sambac Flowers

Benzyl 6-O-β-D-xylopyranosyl-β-D-glucopyranoside (β-primeveroside) (1), 2-phenylethyl β-primeveroside (2), and 2-phenylethyl 6-O-α-L-rhamnopyranosyl-β-D-glucopyranoside (β-rutinoside) (3) were isolated as aroma precursors of benzyl alcohol and 2-phenylethanol from flower buds of Jasminum sambac Ait. The isolation was guided by an enzymatic hydrolysis and GC and GC-MS analyses.