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 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.     

Synthesis of 9-β-d-Glucopyranosyl-Adenine-6′-Phosphate

Synthesis of 9-β-d-glucopyranosyl-adenine-6′-phosphate is described. The method developed here involves the process of condensation of base (chloromercuri-6-benzamidopurine) (I) with phosphorylated sugar (2,3,4-tri-O-acetyl-6-diphenylphosphoryl-α-d-glucopyranosyl bromide) (II). This reaction gives crystalline 6-benzamido-9-(2′,3′,4′-tri-O-acetyl-6′-diphenylphosphoryl-β-d-glucopyranosyl)-purine (III) in high yield, which is converted to the desired nucleotide by alkaline hydrolysis.     

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.     

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%.     

2-O-(3-O-Carbamoyl-D-mannosyl)-6-deoxy-L-gulose The Constitutional Sugar of the Antibiotic YA-56

From the methanolysis product of the antibiotic YA–56 X (Zorbamycin) and Y belonging to phleomycin-bleomycin group, two monosaccharides and one disaccharide were isolated as their fully acetylated derivatives. The structures of these compounds were determined to be methyl 2,3,4-tri-O-acetyl-6-deoxy-β-L-gulopyranoside, methyl 2,4,6-tri-O-acetyl-3-O-carbamoyl-α-D-mannopyranoside and methyl 2-O-(2,4,6-tri-O-acetyl-3-O-carbamoyl-α-D-mannopyranosyl)-3,4-O-0-acetyl-6-deoxy-β-L-“gulopyranoside,

Based on these results, it was concluded that 2-O-(3-O-carbamoyl-α-D-mannosyl)-6-deoxy-L-gulose is present as a sugar moiety of the antibiotic YA–56.     

A Simple Transductional Method for Construction of Adenylate- cyclase or cAMP Receptor Protein-deficient Mutants of Escherichia coli K-12

The substrate specificity of α-d-xylosidase from Bacillus sp. No. 693–1 was further investigated. The enzyme hydrolyzed α-1,2-, α-1,3-, and α-1,4-xylobioses. It also acted on some heterooligosaccharides such as O-α-d-xylopyranosyl-(1→6)-d-glucopyranose, O-α-d-xylopyranosyl-(1→6)-O-β-d-glucopyranosyl-(1→4)-d-glucopyranose, O-α- d-xylopyranosyl-(1→6)-O-d-glucopyranosyl-(1→4)-O-[α-d-xylopyranosyl-(1→6)]-d-glucopyranose, and O-α-d-xylopyranosyl-(1→3)-l-arabinopyranose. The enzyme was unable to hydrolyze tamarinde polysaccharides although it could hydrolyze low molecular weight substrates with similar linkages.     

The Mutational Effect of Ile58 at Subsite C in Hen Egg-White Lysozyme on Substrate Binding,Enzymatic Activity,and Protein Stability

Partial acid hydrolysis of Saccharomyces cerevisiae mannan gave 2-O-α-d-Manp-d-Man (1), 3-O-α-d-Manp-d-Man (2), 6-O-α-d-Manp-d-Man (3), O-α-d Manp-(1→2)O-α-d-Manp-(1→2)-d-Man (4), O-α-d-Manp-(1→2)-O-α-d-Manp-(1→6)-d-Man (5), O-α-d Manp-(1→6)-6-O-α-d-Manp-(1→6)-d-Man (6), O-α-d Manp-(1→2)-O-α-d-Manp-(1→2)-6-O-α-d-Manp-(1→6)-d-Man (7), O-α-d-Manp-(1→2)-O-α-d-Manp-(1→6)-O-α-d-Manp-(1→6)-d-Man (8), and O-α-d-Manp-(1→6)-O-[α-d-Manp-(1→2)]-O-α-d-Manp-(1→6)-d-Man (9).     

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.     

Nucleosides and Related Substances

A new procedure which involves 1-trichloroacetyl sugars as the starting material has been developed for the synthesis of purine nucleosides. 7-β-d-Glucopyranosyl-, 7-β-d-xylopyranosyl-, 7-β-d-ribopyranosyl-theophylline, 9-(tetra-O-acetyl-β-d-glucopyranosyl)-2,6,8-trichloropurine and 9-β-d-glucopyranosyl adenine were prepared in good yields by the reaction in fusion of purine bases with 1-trichloroacetyl sugars, using zinc chloride, p-toluenesulfonic acid, or ethyl polyphosphate as catalyst. 9-d-Ribofuranosyl adenine was also prepared by the same procedures, although the anomeric configuration of the compound is not yet definite. The effect of catalysts on the yields of purine nucleosides is discussed.     

The Structure of Latosillan,a New Differentiation Inducer of Mouse Myeloid Leukemia Cells (M 1)

The structure of latosillan was elucidated by a degradative study and NMR spectral analysis. This revealed that latosillan is a heteroglycan composed of repeating units of the pentasaccharide, →2)-β-d-Man-(1→2)-{β-d-G1CNAC-(1→4)}.-α-l-Rha-(1→4)-α-l-Rha-(1→4)-α-l-Rha-(1→, shown in Fig. 1.     

Structure of Oligosaccharides Obtained by Controlled Degradation of Mung Bean Xyloglucan with Acid and Aspergillus oryzae Enzyme Preparation

A xyloglucan (MBXG) from the cell walls of etiolated mung bean hypocotyls was characterized by analyzing the fragment oligosaccharides from controlled degradation products of the polymer with acid and enzyme.

Cellobiose, cellotriose and cellotetraose were isolated from the partial acid hydrolyzate of MBXG. Isoprimeverose (6-O-α-d-xylopyranosyl-d-glucopyranose) and a pentasaccharide, α-l-fucosyl-(1 → 2)-β-d-galactosyl-(1 → 2)-α-d-xylosyl-(1 → 6)-β-d-glucosyl-(1 → 4)-d-glucose, were isolated from the hydrolyzate of MBXG with an Asp. oryzae enzyme preparation.     

Isolation and Characterization of Oligosaccharides from the Hydrolyzate of Larch Wood Glucomannan with Endo-β-d-Mannanase

The glucomannan isolated from larch holocellulose was hydrolyzed by a purified endo-d-β-mannanase. The products were fractionated by gel filtration on a Polyacrylamide gel in water and partition chromatography on ion exchange resins in 80% ethanol. The following oligosaccharides were isolated and identified: (a) 4-O-β-d-Manp-d-Man, (b) 4-O-β-d-Glcp-d-Man, (c) 4-O-β-d-Glcp-d-Glc, (d) O-β-d-Manp-(1 →4)-O-β-d-Manp-(1 →4)-d-Man, (e) O-β-dGlcp-(l →4)-O-β-d-Manp-(l →4)-d-Man, (f) O-β-d-Manp-(l →4)-Oβ-d-Glcp-(l →4)-d-Man, (g) O-β-d-Manp-(l →4)-O-[α-d-Galp-(l →6)]-d-Man, (h) O-β-d-Manp-(l →4)-O-β-d-Manp-(l →4)-O-β-d-Manp-(l →4)-d-Man, and (i) O-β-d-Glcp-(1 →4)-O-β-d-Manp-(1 →4)-O-β-d-Manp-(1 →4)-d-Man.     

Formation of Three New Trisaccharide-azoxyglycosides by Transglucosylation by Cycad β-Glucosidase

transglucosylation by a β-d-glucosidase from cycad seeds. These azoxyglycosides, named neocycasin H, I, and J, were identified as O-β-d-glucopyranosyl-(1→4)-O-β-d-glucopyranosyl-(l→3)-O-β-d-glucopyranoside of methylazoxymethanol (MAM), O-β-d-glucopyranosyl-(1→3)-[O-β-d-glucopyranosyl-(1→6)]-O-β-d-glucopyranoside of MAM, and O-β-d-glucopyranosyl-(1→3)-[O-β-d-xylopyranosyl-(1→6)]-O-β-d-glucopyranoside of MAM, respectively. On the basis of their structures, the mechanism of the formation of these neocycasins is also discussed.     

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.     

A Bitter Principle of Asparagus: Isolation and Structure of Furostanol Saponin in Asparagus Storage Root

During an examination of components contributing to the bitter taste of asparagus bottom cut (Asparagus officinalis L.), two new furostanol saponins were isolated from roots extractives. Their chemical structures were established as 5β-furostane-3β,22,26 triol-3-O-β-d-glucopyranosyl (1→2)-β-d-glucopyranoside 26-O-β-d-glucopyranoside and 5β-furostane-3β,22,26 triol-3-O-β-d-glucopyranosyl (1→2) [β-d-xylopyranoxyl (1→4)]-β-d-glucopyranoside 26-O-β-d-glucopyranoside respectively.     

Enzyme-Substrate Complex of p-Hydroxybenzoate Hydroxylase; One of the Activated Intermediates of the Overall Reaction

The transglucosidation reaction of brewer’s yeast α-glucosidase was examined under the co-existence of l-sorbose and phenyl-α-glucoside. As the transglucosidation products, three kinds of new disaccharide were chromatographically isolated. It was presumed that these disaccharides consisting of d-glucose and l-sorbose were 1-O-α-d-glucopyranosyl-l-sorbose ([α]_D+89.0), 3-O-α-d-glucopyranosyl-l-sorbose ([α]_D+69.1) and 4-O-α-d-glucopyranosyl-l-sorbose ([α]_D+81.0). The principal product formed in the enzyme reaction was 1-O-α-d-glucopyranosyl-l-sorbose.     

Studies on the Chemical Structure of Konjac Mannan

The electrophoretically homogeneous glucomannan isolated from konjac flour was composed of d-glucose and d-mannose residues in the approximate ratio of 1: 1.6. Controlled acid hydrolysis gave 4-O-β-d-mannopyranosyl-d-mannose, 4-O-β-d-mannopyranosyl-d-glucose_T 4-O-β-d-glucopyranosyl-d-glucose(cellobiose), 4-O-β-d-glucopyranosyl-d-mannose(epicellobiose), O-β-d-mannopyranosyl-(1→4)-O-β-d-mannopyranosyl-(1→4)-d-mannose, O-β-d-glucopyranosyl- (1→4)-O-β-d-mannopyranosyl-(1→4)-d-mannose, O-β-d-mannopyranosyl-(1→4)-O-β-d-glucopy- ranosyl-(1→4)-d-mannose and O-β-d-glucopyranosyl-(1→4)-O-β-d-glucopyranosyl-(1→4)-d-mannose.     

A New Synthesis of (—)-exo-Brevicomin

Rubusoside derivatives by transgalactosylation of various β-galactosidases were isolated and their structures were analyzed. Escherichia coli β-galactosidase produced mainly 13-O-β-d-glucosyl-19-O-[β-d-galactosyl-(1→6)-β-d-glucosyl]-steviol (RGal-2). Bacillus circulans β-galactosidase produced mainly 13-O-β-d-glucosyl-19-O-[β-d-galactosyl-(1→4)-β-d-glucosyl]-steviol (RGal-1a) in the early stage of the reaction and then produced 13-O-[β-d-galactosyl-(1→4)-β-d-glucosyl]-19-O-β-d-glucosyl-steviol (RGal-1b). With decreasing the amount of these products (RGal-1a and RGal-1b), RGal-2 was produced.     

Structure and Bitterness in Flavanone Glycosides

Naringenin-7-β-kojibioside, -7-β-sophoroside, -7-[α-d-galactosyl(l→2)β-d-glucoside], -7-[β-d-glucosyl(l→2)β-d-galactoside], and also hesperetin-7-β-kojibioside and -7-β-sophoroside were prepared by the coupling of naringenin or hesperetin with the α-acetobromo derivatives of the appropriate disaccharides, followed by saponification.

Their relative bitterness values were discussed in comparison with naringin and neo-hesperidin.