Showing papers on "Aldose published in 2007"

Facile Discrimination of Aldose Enantiomers by Reversed-Phase HPLC

Abstract: One-pot reactions of aldoses with L-cysteine methyl ester and o-tolyl isothiocyanate yielded methyl 2-(polyhydroxyalkyl)-3-(o-tolylthiocarbamoyl)-thiazolidine-4(R)-carboxylates. Direct HPLC analysis of the reaction mixture and UV detection at 250 nm discriminated D- and L-enantiomers of aldoses. The reaction was applied to the determination of absolute configuration the sugar residues of an aroma precursor.

Strain and Near Attack Conformers in Enzymic Thiamin Catalysis: X-ray Crystallographic Snapshots of Bacterial Transketolase in Covalent Complex with Donor Ketoses Xylulose 5-phosphate and Fructose 6-phosphate, and in Noncovalent Complex with Acceptor Aldose Ribose 5-phosphate.

Abstract: Transketolase is a prominent thiamin diphosphate-dependent enzyme in sugar metabolism that catalyzes the reversible transfer of a 2-carbon dihydroxyethyl fragment between a donor ketose and an acceptor aldose. The X-ray structures of transketolase from E. coli in a covalent complex with donor ketoses d-xylulose 5-phosphate (X5P) and d-fructose 6-phosphate (F6P) at 1.47 A and 1.65 A resolution reveal significant strain in the tetrahedral cofactor−sugar adducts with a 25−30° out-of-plane distortion of the C2−Cα bond connecting the substrates' carbonyl with the C2 of the cofactor's thiazolium part. Both intermediates adopt very similar extended conformations in the active site with a perpendicular orientation of the scissile C2−C3 sugar bond relative to the thiazolium ring. The sugar-derived hydroxyl groups of the intermediates form conserved hydrogen bonds with one Asp side chain, with a cluster of His residues and with the N4‘ of the aminopyrimidine ring of the cofactor. The phosphate moiety is held in pla...

Production of lactic acid from glucose by alkaline hydrothermal reaction

Abstract: In this paper, alkaline hydrothermal conversion of glucose, a model compound of carbohydrate biomass, into lactic acid was discussed. Results showed that both NaOH and Ca(OH)2, can promote the formation of lactic acid in a hydrothermal reaction of glucose. In the case of the addition of NaOH, lactic acid was obtained with a yield of 27% based on a starting carbon mass of glucose at 300 °C for 60 s with a NaOH concentration of 2.5 M. In the case of the addition of Ca(OH)2, the highest yield of lactic acid is 20%, which occurred at 300 °C for 60 s with a Ca(OH)2 concentration of 0.32 M. The formation mechanisms of lactic acid from glucose were also discussed according to intermediate products identified, to examine if lactic acid is also formed via the aldose having one and two carbon atoms besides via the aldose having three carbon atoms. Result showed that lactic acid may be generated via formaldehyde, glycolaldehyde besides via the aldose having three carbon atoms in hydrothermal reaction which all formed by the reverse aldol condensation of hexoses.

Selectivity determinants of the aldose and aldehyde reductase inhibitor-binding sites.

Abstract: Aldose reductase and aldehyde reductase belong to the aldo-keto reductase superfamily of enzymes whose members are responsible for a wide variety of biological functions. Aldose reductase has been identified as the first enzyme involved in the polyol pathway of glucose metabolism which converts glucose into sorbitol. Glucose over-utilization through the polyol pathway has been linked to tissue-based pathologies associated with diabetes complications, which make the development of a potent aldose reductase inhibitor an obvious and attractive strategy to prevent or delay the onset and progression of the complications. Structural studies of aldose reductase and the homologous aldehyde reductase in complex with inhibitor were carried out to explain the difference in the potency of enzyme inhibition. The aim of this review is to provide a comprehensive summary of previous studies to aid the development of aldose reductase inhibitors that may have less toxicity problems than the currently available ones.

Biorenewable Resources in the Biginelli Reaction: Cerium(III)-Catalyzed Synthesis of Novel Iminosugar-Annulated Perhydropyrimidines

Abstract: An unprecedented version of the Biginelli reaction using an unprotected aldose as a biorenewable aldehyde component and 2-phenyl-1,3-oxazol-5-one as a novel active methylene building block with urea/thiourea is reported. The reaction is cerium(III)--catalyzed, expeditious, and effected under solvent-free microwave irradiation conditions to yield diastereoselectively, iminosugar-annulated polyfuntionalized perhydropyrimidines via ring transformation of an isolable intermediate followed by cyclodehydration.

Structure-Activity Relationships of Components from the Roots of Pueraria thunbergiana Having Aldose Reductase Inhibitory and Antioxidative Activity

Abstract: but their inhibitory activities on aldose reductasehave not yet been reported. Aldose reductase (AR), the keyenzyme of the polyol pathway, has been demonstrated toplay an important role in the etiology of diabetic com-plications; therefore, AR inhibitors would be expected to beeffective in preventing cataract formation in diabetesmellitus.

Structural-based inhibitors of the glutathione binding site in aldose reductase, methods of screening therefor and methods of use

Abstract: Provided herein is a crystallized ternary structure of aldose reductase (AR) bound to NADPH and γ-glutamyl-S-(1,2-dicarboxyethyl)cysteinylglycine (DCEG). Also provided are specific inhibitors of glutathione-aldehyde binding to aldose reductase which are designed via at least computer modeling of the ternary AR:NADPH:DCEG structure and methods of designing and of screening the inhibitors for inhibition of glutathione-aldehyde binding to aldose reductase. In addition methods of treating a pathophysiological state or symptoms thereof resulting from aldose reductase-mediated signaling in a cytotoxic pathway using a small interfering RNA (siRNA) or the designed inhibitors.

Microwave assisted stereospecific synthesis of d-erythro-l-gluco-nonulose

Abstract: A convenient, highly efficient synthesis of d -erythro- l -gluco-nonulose from a new 2-C-(hydroxymethyl) branched-chain aldose is presented. The nucleophilic addition of the appropriately protected aldose to formaldehyde afforded 2-C-(hydroxymethyl)- d -erythro- l -manno-octose. The branched sugar bearing a CH2OH group at C-2 provides access to a nine-carbon sugar in a single step through a stereospecific isomerization. The isomerization exploited the catalytic effect of molybdate ions and microwave irradiation. The structure of the product was analyzed by NMR spectra and quantum-chemical DFT calculations. DFT-computed proton–proton coupling constants were found to be comparable with the experimentally obtained coupling constants and agreed with the pyranose form of this branched-chain aldose.

Tanshinone derivative and its application in preparing aldose reduction enzyme inhibitor pharmaceutical

Abstract: The invention discloses a tanshinone derivant and application to make aldose reductase inhibitor drug, which possesses chemical formula as formula I-IV, wherein R in the formula II and IV represents -COOH, -NO2, -CN; NR2 in the formula V and VI represents molecular formula (A).

Glycoside derivative, non-reducing disaccharide and method for producing the same

Abstract: PROBLEM TO BE SOLVED: To provide a method for producing a glycoside in high efficiency by reacting an aldose derivative having freed anomer hydroxy group with an alcohol in the presence of an activation agent and a method for efficiently producing a non-reducing disaccharide by reacting aldose derivatives having the same structure and containing freed anomer hydroxy group with each other in the presence of an activation agent. SOLUTION: A glycoside is produced in high efficiency under a mild condition by reacting an aldose derivative having a freed anomer hydroxy group with an alcohol under microwave radiation using only several mol% to several tens mol% of an activation agent such as bismuth(III) triflate. A non-reducing disaccharide can be produced in high efficiency from aldose derivatives having the same structure and containing freed anomer hydroxy group. COPYRIGHT: (C)2008,JPO&INPIT

Preparation and uses of locked-ring sugar C-glycoside derivatives

Abstract: “Locked-ring” C-glycoside derivatives may be prepared wherein the ring of the sugar molecule remains intact without the need for any protecting groups. These C-glycoside derivatives may be produced by first reacting an aldose reducing sugar, which may be a hexose or a pentose, with a β-diketone to form a C-glycoside ketone. The C-glycoside ketone is then reacted with a ketone reactive compound, such as a hydrazine or hydroxylamine, optionally linked to a detectable label, to form a C-glycoside derivative wherein the ketone reactive compound is conjugated to the C-glycoside at the site of the ketone. The aldose reducing sugar used in the first reaction may a simple pentose or hexose monosaccharide, or it may be optionally substituted.

Use of l-rhamnose isomerase having new catalytic function

Abstract: PROBLEM TO BE SOLVED: To provide a method for isomerizing D-psicose to D-allose by reacting with an L-rhamnose isomerase. SOLUTION: D-allose is produced by isomerizing D-psicose to D-allose by treating D-psicose with a protein composed of an amino acid sequence having a specific sequence, specified by the chemical properties (i), originated from Pseudomonas stutzeri (IPOD FERM BP-08593) and having L-rhamnose isomerase activity. (i) Action: catalyzing the isomerizing reaction between an aldose and a ketose selected from the group consisting of D-allose and D-psicose, and D-altrose and D-psicose as shown by thick black lines. COPYRIGHT: (C)2008,JPO&INPIT

Metallic-ions independent isomerase and methods for isomerization by using it

Abstract: Metallic ion independent isomerase and a method for isomerization of sugars by using the same enzyme are provided to prevent loss of isomerization activity in the enzyme when metallic ion is released by EDTA(ethylenediamine tetraacetic acid) treatment, and induce non-specific conversion of aldose-ketose. The metallic ion independent isomerase has the amino acid sequences of SEQ ID NO:7 and SEQ ID NO:8 and is encoded by genes having the nucleotide sequences of SEQ ID NO:5 and SEQ ID NO:6. The metallic ion dependent isomerase is produced by transforming a host cell such as Escherichia coli with an expression vector containing the genes of metallic ion independent isomerase, and culturing the transformed host cell. The ketose selected from tagatose, ribulose, fructose, xylulose and psicose is produced from aldose by using the metallic ion independent isomerase. The aldose selected from D-glucose, D-galactose, D-xylose, D-mannose, D-allose, D-fucose, D-ribose, L-arabinose, D-arabinose and L-ribose is produced from ketose by using the metallic ion independent isomerase.

Thermostable l-ribose isomerase and method for producing same and use of same

Abstract: Object: To provide a thermostable L-ribose isomerase. Means for Resolution: The thermostable L-ribose isomerase with MW. 32,000 (by SDS-PAGE), optimal temperature of 45° C., optimal pH of pH 9.0 (glycine-NaOH buffer), and stable physicochemical properties such as temperature stability up to 45° C. during thermal treatment at pH 9.0 for 10 minutes, and with an action to isomerize L-ribose to generate L-ribulose or of inversely to isomerize L-ribulose to generate L-ribose. A conversion method between an aldose and a ketose comprising allowing the thermostable L-ribose isomerase as an enzyme derived from (1) Raoultella ornithinolytica strain MB426 (NITE BP-277) to interact with an aldose selected from L-ribose, D-lyxose, D-tallose, D-mannose, L-allose and L-gulose to isomerize the aldose to generate a ketose selected from the individually corresponding L-ribulose, D-xylulose, D-tagatose, D-fructose, L-psicose and L-sorbose or to interact with a ketose selected from L-ribulose, D-xylulose, D-tagatose, D-fructose, L-psicose and L-sorbose to isomerize the ketose to generate an aldose selected from the individually corresponding L-ribose, D-lyxose, D-tallose, D-mannose, L-allose and L-gulose.

Process for producing aldose derivative

Abstract: [PROBLEMS] To provide a simple process by which 5-deoxy-L-arabinose can be efficiently produced. [MEANS FOR SOLVING PROBLEMS] The process includes a step in which a compound represented by the formula (5) is hydrolyzed to obtain an aldose derivative represented by the formula (6). (In the formula (5), n is an integer of 1-3 and R1 represents alkyl.) (In the formula (6), n is an integer of 1-3.)

Thermostable l-ribose isomerase, process for producing the same and use thereof

Abstract: [PROBLEMS] To provide a thermostable L-ribose isomerase. [MEANS FOR SOLVING PROBLEMS] There is provided a thermostable L-ribose isomerase having physical and chemical properties such that molecular weight: 32,000 (SDS-PAGE), optimum temperature: 45°C, optimum pH: 9.0 (glycine-NaOH buffer) and temperature stability: being stable up to 45°C in heat treatment at pH 9.0 for 10 min, which thermostable L-ribose isomerase has the activity of isomerizing L-ribose into L-ribulose and reversely isomerizing L-ribulose into L-ribose. The thermostable L-ribose isomerase is an enzyme derived from Raoultella ornithinolytica MB426(NITE BP-277) (1). There is provided a method of conversion between aldose and ketose, characterized in that an aldose selected from among L-ribose, D-lyxose, D-talose, D-mannose, L-allose and L-gulose is acted on by the above thermostable enzyme to isomerize the aldose, thereby producing the corresponding ketose selected from among L-ribulose, D-xylulose, D-tagatose, D-fructose, L-psicose and L-sorbose, respectively, or alternatively a ketose selected from among L-ribulose, D-xylulose, D-tagatose, D-fructose, L-psicose and L-sorbose is acted on by the above L-ribose isomerase to isomerize the ketose, thereby producing the corresponding aldose selected from among L-ribose, D-lyxose, D-talose, D-mannose, L-allose and L-gulose, respectively.

Method for producing benzylated fructofuranose derivative and benzylated aldose derivative by acid hydrolysis of perbenzylated sucrose oligosaccharide

Abstract: PROBLEM TO BE SOLVED: To provide a method for efficiently producing 3-O-(2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl)-1,4,6-tri-O-benzyl-D-fructofuranose, 6-O-(2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl)-2,3,4-tri-O-benzyl-D-glucopyranose, and a benzylated D-fructofuranose derivative and a benzylated aldose derivative containing di- or multi-saccharide oligosaccharide by the selective acid hydrolysis of a fructofuranosyl bond of a perbenzylated sucrose oligosaccharide. SOLUTION: A fructofuranosyl bond of a perbenzylated sucrose oligosaccharide is selectively hydrolyzed by using 75% aqueous solution of sulfuric acid in dioxane. COPYRIGHT: (C)2008,JPO&INPIT

Biorenewable Resources in the Biginelli Reaction: Cerium(III)‐Catalyzed Synthesis of Novel Iminosugar‐Annulated Perhydropyrimidines.

Abstract: An unprecedented version of the Biginelli reaction using an unprotected aldose as a biorenewable aldehyde component and 2-phenyl-1,3-oxazol-5-one as a novel active methylene building block with urea/thiourea is reported. The reaction is cerium(III)--catalyzed, expeditious, and effected under solvent-free microwave irradiation conditions to yield diastereoselectively, iminosugar-annulated polyfuntionalized perhydropyrimidines via ring transformation of an isolable intermediate followed by cyclodehydration.