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.     

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.     

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.     

Regioselectivity in Sulfation of Galactosides by Sulfuric Acid and Dicyclobexylcarbodi-imide

Methyl α- and β-D-galactopyranosides and 4-O-β-D-galactopyranosyl-3,6-anhydro-L-galactose dimethylacetal were sulfated with sulfuric acid and dicyclohexylcarbodi-imide as a condensation reagent. The sulfated sugars were isolated by ion-exchange chromatography, characterized, and assigned by methylation analyses. On the basis of the yield of each sulfated product that was isolated, sulfation on O-6 appeared to be predominant.     

A Growth Factor for Malo-lactic Fermentation Bacteria

A growth factor (TJF) for a malo-lactic fermentation bacterium has been isolated from tomato juice, and found to be a β-glucoside. The NMR spectra of TJF and its acetate revealed that the glucosyl residue linked to the hydroxyl group at C-2′ or C-4′ of d- or l-pantothenic acid moiety. Then, 2′-O-(β-d-glucopyranosyl)-dl-pantothenic acid (I), 4′-O-(β-d-glucopyranosyl)-dl-pantothenic acid (II) and 4′-O-(β-d-glucopyranosyl)-d(R)-pantothenic acid (II-a) were synthesized, and Il-a and 4′-O-(β-d-glucopyranosyl)-l-pantothenic acid (II-b) were obtained by the optical resolution of the acetate of II. Among the above compounds, II-a was identical with natural TJF regarding to the biological activity, NMR and ORD spectra, and thin-layer chromatography.     

Novel Glycerolipids and Glycolipids from the Surface Lipids of Nicotiana benthamiana

The surface lipids of Nicotiana benthamiana contained novel glycerolipids and several varieties of glycolipids. As glycerolipids, the triacylglycerol, 1,3-diacylglycerol, and 1,2-diacylglycerol types of glycerolipids were isolated and identified. Each lipid contained acetyl, 16–methylheptadecanoyl, and 18–methylnonadecanoyl moieties. The acetylated position of each lipid was determined by 2D-NMR, using the HMBC technique. The structures were 1,3-di-O-acetyl-2-O-acylglycerol, 1-O-acetyl-3-O-acylglycerol, and 1-O-acetyl-2-O-acylglycerol. As glycolipids, one glucose ester and four types of sucrose esters were isolated and identified. These glycolipids contained acetic acid and such branched short-chain fatty acids as 5-methylhexanoic, 4-methylhexanoic, 6-methylheptanoic, and 5-methylheptanoic acids. The structure of the glucose ester was 3,4-di-O-acyl-α-D-glucopyranose. The structures of the sucrose esters were 6-O-acetyl-4-O-acyl-α-D-glucopyranosyl-(3-O-acyl)-β-D-fructofuranoside, 4-O-acyl-α-D-glucopyranosyl-(3-O-acyl)-β-D-fructofuranoside, 3,4-di-O-acyl-α-D-glucopyranosyl-β-D-fructofuranoside, and 6-O-acetyl-α-D-glucopyranosyl-β-D-fructofuranoside.     

Formation of β-Fructosyl Compounds of Pyridoxine in Growing Culture of Aspergillus niger

Two pyridoxine compounds were found to be formed in a culture filtrate of Aspergillus niger and A. sydowi, when grown in a medium containing sucrose and pyridoxine. Each of the two compounds I and II was obtained as a white powdered preparation by preparative paper chromatography, gel filtration on Toyopearl HW-40S and Sephadex G-10 columns, DEAE-cellulose column chromatography, and lyophilization. Compounds I and II were identified as 5?-O-(β-D-fructofuranosyl)-pyridoxine and 5?-O-(β-D-fructofuranosyl-(2→1)-β-D-fructofuranosyl]-pyridoxine, on the basis of the various experimental results, viz., elementary analyses, UV, ¹H-, and ¹³C-NMR spectra, products by hydrolysis with acid and yeast β-D-fructofuranosidase, migration on paper electrophoresis, and Gibbs reaction in the presence and absence of boric acid. Levansucrase from Microbacterium laevaniformans and yeast β-D-fructofuranosidase did not catalyze the β-D-fructofuranosyl transfer from sucrose to pyridoxine to give rise to β-D-fructofuranosyl-pyridoxine.     

Methylation of Heparien,Heparitinsulfate, and Hexa,Tetra and Trisaccharides from Hyaluronic Acid

The methylations of heparin, heparitinsulfate, and three oligosaccharides (hexa, tetra and trisaccharides) from hyaluronic acid were carried out. Theoretical amounts of methoxyl group were obtained from the oligosaccharides and the desulfated product of carboxyl-reduced heparitinsulfate, but not from heparin and heparitinsulfate. The acid hydrolysis of the methylated trisaccharide confirms that the structure is β-d-glucopyranosyl uronic acid-(1→3) -2-acetamido-2-deoxy-β-d-glucopyranosyl- (1→4) -d-glucopyranosyl uronic acid.     

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.     

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.     

Glycosidase-catalyzed Deoxy Oligosaccharide Synthesis. Practical Synthesis of Monodeoxy Analogs of Ethyl β-Thioisomaltoside Using Aspergillus niger α-Glucosidase

Enzymatic transglycosylation using four possible monodeoxy analogs of p-nitrophenyl α-D-glucopyranoside (Glcα-O-pNP), modified at the C-2, C-3, C-4, and C-6 positions (2D-, 3D-, 4D-, and 6D-Glcα-O-pNP, respectively), as glycosyl donors and six equivalents of ethyl β-D-thioglucopyranoside (Glcβ-S-Et) as a glycosyl acceptor, to yield the monodeoxy derivatives of glucooligosaccharides were done. The reaction was catalyzed using purified Aspergillus niger α-glucosidase in a mixture of 50 mM sodium acetate buffer (pH 4.0)/CH₃CN (1: 1 v/v) at 37°C. High activity of the enzyme was observed in the reaction between 2D-Glcα-O-pNP and Glcβ-S-Et to afford the monodeoxy analogs of ethyl β-thiomaltoside and ethyl β-thioisomaltoside that contain a 2-deoxy α-D-glucopyranose moiety at their glycon portions, namely ethyl 2-deoxy-α-D-arabino-hexopyranosyl-(1,4)-β-D-thioglucopyranoside and ethyl 2-deoxy-α-D-arabino-hexopyranosyl-(1,6)-β-D-thioglucopyranoside, in 6.72% and 46.6% isolated yields (based on 2D-Glcα-O-pNP), respectively. Moreover, from 3D-Glcα-O-pNP and Glcβ-S-Et, the enzyme also catalyzed the synthesis of the 3-deoxy analog of ethyl β-thioisomaltoside that was modified at the glycon α-D-glucopyranose moiety, namely ethyl 3-deoxy-α-D-ribo-hexopyranosyl-(1,6)-β-D-thioglucopyranoside, in 23.0% isolated yield (based on 3D-Glcα-O-pNP). Products were not obtained from the enzymatic reactions between 4D- or 6D-Glcα-O-pNP and Glcβ-S-Et.     

Effects of Metal Ions on Cattle Liver Phosphoenolpyruvate Carboxykinase Activity in Vitro

A plant glycosphingolipid, O-(β-d-mannopyranosyl)-(l → 4)-O-(β-d-glucopyranosyl)-(l → l)-(2S,3S,4R)-4-hydroxy-N-tetracosanoylsphinganine 1, and the stereoisomer, O-(α-d-mannopyranosyl)-(1 → 4)-O-(β-d-glucopyranosyl)-(l → l)-(2S,3S,4R)-4-hydroxy-N-tetracosanoylsphinganine 6, were synthesized in a stereo- and regio-controlled way.     

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.     

Lipase-catalyzed Synthesis of Arbutin Cinnamate in an Organic Solvent and Application of Transesterification to Stabilize Plant Pigments

Arbutin cinnamate was synthesized from arbutin (4-hydroxy-phenyl β-D-glucopyranoside) and vinyl cinnamate by regioselective transesterification with a bacterial lipase in acetonitrile. The product was identified by NMR and FAB-MS analyses. These spectra showed that one ester bond was formed between the primary alcohol moiety of the D-glucose of arbutin and the carboxyl residue of cinnamic acid. Furthermore, plant pigments such as isoquercitrin (quercetin 3-O-β-D-glucopyranoside) and callistephin (pelargonidin 3-O-β-D-glucopyranoside) were also converted to their corresponding cinnamate esters in the same manner.     

Antitumor Activities and Immunochemical Properties of the Cell-wall Polysaccharides from Aureobasidium pullulans

Delipidated cell walls from Aureobasidium pullulans were fractionated systematically.

The cell surface heteropolysaccharide contains D-mannose, D-galactose, D-glucose, and D-glucuronic acid (ratio, 8.5:3.9:1.0:1.0). It consists of a backbone of (1→6)-α-linked D-mannose residues, some of which are substituted at O-3 with single or β-(1→6)-linked D-galactofuranosyl side chains, some terminated with a D-glucuronic acid residue, and also with single residues of D-glucopyranose, D-galactopyranose, and D-mannopyranose.

This glucurono-gluco-galactomannan interacted with antiserum against Elsinoe leucospila, which also reacted with its galactomannan, indicating that both polysaccharides contain a common epitope, i.e., at least terminal β-galactofuranosyl groups and also possibly internal β-(1→6)-linked galactofuranose residues.

It was further separated by DEAE-Sephacel column chromatography to gluco-galactomannan and glucurono-gluco-galactomannan.

The alkali-extracted β-D-glucan was purified by DEAE-cellulose chromatography to afford two antitumor-active (1→3)-β-D-glucans. One of the glucans (M_r, 1–2 × 10⁵) was a O-6-branched (1→3)-β-D-glucan with a single β-D-glucosyl residue, d.b., 1/7, and the other (M_r, 3.5–4.5 × 10⁵) had similar branched structure, but having d.b., 1/5. Side chains of both glucans contain small proportions of β-(1→6)-and β-(1→4)-D-glucosidic linkages.     

Characterization of an Extracellular Polysaccharide Elaborated by TX-1, a New Strain of Beijerinckia indica

An extracellular polysaccharide elaborated by a new species of Beijerinckia indica, named TX-1, was composed of D-glucose, L-fucose, D-glycero-D-manno-heptose, and D-glucuronic acid in a molar ratio of 5.0:1.0:2.0:0.9, in addition to 16.2% of the acetyl group. Among the polysaccharides of the Beijerinckia species, the present polysaccharide might be the first acidic type having an L-fucose residue. A methylation analysis, Smith degradation study and fragmentation analysis show that this polysaccharide consisted of non-reducing terminal D-glucose, O-4 substituted D-glucose, O-2 substituted D-glycero-D-manno-heptose, O-4 substituted D-glucuronic acid, O-3 and O-4 substituted D-glucose, and O-3 substituted L-fucose residues. A D-glucuronic acid residue was linked to the O-3 position of the L-fucose residue by an α-glycosidic linkage. Most of the D-glucose residues in the backbone chain were substituted at the O-3 position, with the side chain having non-reducing terminal D-glucose residues. It is suggested by the reaction with Con A that the anomeric configuration of the terminal D-glucose residues was β.     

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.     

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.     

Synthesis and Properties of Isomeric Di- and Mono-Glucopyranosyl Hypoxanthines

Four isomeric glucosyl hypoxanthines, bis-1,9-(β-d-glucopyranosyl) hypoxanthine (I), bis-1,7-(β-d-glucopyranosyl) hypoxanthine (II), 7-β-d-glucopyranosyl hypoxanthine (III) and 9-β-d-glucopyranosyl hypoxanthine (IV) were synthesized simultaneously by using the so- called Davoll-Lowy’s method. Their synthetic procedures and structural evidences are presented.     

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.