Showing papers on "Aldose published in 2012"
TL;DR: In this paper, it was shown that Sn-Beta zeolite in the presence of sodium tetraborate catalyses the selective epimerization of aldoses in aqueous media.
Abstract: Carbohydrate epimerization is an essential technology for the widespread production of rare sugars. In contrast to other enzymes, most epimerases are only active on sugars substituted with phosphate or nucleotide groups, thus drastically restricting their use. Here we show that Sn-Beta zeolite in the presence of sodium tetraborate catalyses the selective epimerization of aldoses in aqueous media. Specifically, a 5 wt% aldose (for example, glucose, xylose or arabinose) solution with a 4:1 aldose:sodium tetraborate molar ratio reacted with catalytic amounts of Sn-Beta yields near-equilibrium epimerization product distributions. The reaction proceeds by way of a 1,2 carbon shift wherein the bond between C-2 and C-3 is cleaved and a new bond between C-1 and C-3 is formed, with C-1 moving to the C-2 position with an inverted configuration. This work provides a general method of performing carbohydrate epimerizations that surmounts the main disadvantages of current enzymatic and inorganic processes.
150 citations
01 Oct 2012
TL;DR: This work provides a general method of performing carbohydrate epimerizations that surmounts the main disadvantages of current enzymatic and inorganic processes.
Abstract: Carbohydrate epimerization is an essential technology for the widespread production of rare sugars. In contrast to other enzymes, most epimerases are only active on sugars substituted with phosphate or nucleotide groups, thus drastically restricting their use. Here we show that Sn-Beta zeolite in the presence of sodium tetraborate catalyses the selective epimerization of aldoses in aqueous media. Specifically, a 5 wt% aldose (for example, glucose, xylose or arabinose) solution with a 4:1 aldose:sodium tetraborate molar ratio reacted with catalytic amounts of Sn-Beta yields near-equilibrium epimerization product distributions. The reaction proceeds by way of a 1,2 carbon shift wherein the bond between C-2 and C-3 is cleaved and a new bond between C-1 and C-3 is formed, with C-1 moving to the C-2 position with an inverted configuration. This work provides a general method of performing carbohydrate epimerizations that surmounts the main disadvantages of current enzymatic and inorganic processes.
142 citations
TL;DR: Among derivatives of sugar enantiomers in the current study, the stereoisomer of R- configuration at C-3' retained longer than the corresponding S-configuration isomer, suggesting that the UPLC-MS method can increase sensitivity of detection of the saccharides by more than 10 times compared to previously reported methods.
Abstract: In natural product chemistry, it is often crucial to determine sugar composition as well as the absolute configuration of each monosaccharide in glycosides. An ultra-performance liquid chromatography method using both photodiode array (PDA) and mass spectrometry detectors (UPLC-UV/MS) was developed for qualitative analysis of the absolute configuration of monosaccharide enantiomers. Within a single injection, 16 monosaccharide derivatives including 6 pairs of aldose enantiomers (D/L-glucose, D/L-galactose, D/L-allose, D/L-arabinose, D/L-xylose, and D/L-fucose) and 4 other monosaccharides (L-rhamnose, 2-deoxy-D-glucose, 6-deoxy-D-glucose, and 2-deoxy-D-glalactose) were identified in less than 25 minutes. It was found that the structures of derivatives of sugar enantiomers correlated with retention time. Among derivatives of sugar enantiomers in the current study, the stereoisomer of R-configuration at C-3' retained longer than the corresponding S-configuration isomer. The UPLC-MS method can increase sensitivity of detection of the saccharides by more than 10 times compared to previously reported methods. The one-pot reaction of monosaccharide with L-cysteine methyl ester and phenyl isothiocyanate is easily reproduced, clean, and relatively simple in a screw-capped reaction vial. The developed method was successfully applied for the analysis of different types of glycosides, viz., glycosides of triterpenes, steroids, and flavonoids, that commonly exist in nature. The absolute configurations of composed monosaccharides are clearly characterized from tested samples.
60 citations
TL;DR: A modified HPLC method of pre-column derivatization was developed that is more practical for simultaneous analysis of aldose enantiomers as compared to the literature method, and the absolute configurations of the sugar moieties in clausenosides A and B were determined.
49 citations
TL;DR: In this article, a strategy for simultaneous isomerization and reactive extraction (SIRE) is presented, where the isomersization of aldose sugars and the reactive extraction of ketoses occur concurrently in the same vessel.
27 citations
TL;DR: In this article, an acidic phosphate buffer system was developed to highly selectively catalyze ketoses/aldoses dehydrating into 5-HMF without undesirable rehydration under microwave irradiation.
Abstract: An acidic phosphate buffer system is developed to highly-selectively catalyze ketoses/aldoses dehydrating into 5-HMF without undesirable rehydration under microwave irradiation.
23 citations
TL;DR: A rabbit aldose reductase-like protein that shared an 86% sequence identity to human AKR 1) 1B10 and has been assigned as AKR1B19 in the AKR superfamily was reported in this article.
12 citations
TL;DR: In this article, the redox potentials of neutral and alkaline solutions of glucose, mannose, galactose, and xylose were measured, showing that the lack of primary hydroxy group in going to aldopentopyranose favor destabilization of their cyclic structure, formation of the oxo form, and thermally activated retro-aldol reaction of the latter in alkaline medium.
Abstract: Concentration and temperature dependences of the redox potentials of neutral and alkaline solutions of glucose, mannose, galactose, galacturonic acid, and xylose were measured. Axial orientation of the secondary hydroxy groups in epimeric hexopyranoses, oxidation of C6 to carboxy group, and the lack of primary hydroxy group in going to aldopentopyranose favor increasing (in the order of listing) destabilization of their cyclic structure, formation of the oxo form, and thermally activated retro-aldol reaction of the latter in alkaline medium. This leads to enhancement of their reducing power and chemical reactivity toward 5,5′,7,7′-tetrabromoindigo.
9 citations
Patent•
01 Oct 2012
TL;DR: In this article, a process of dyeing human keratin fibres by applying a composition, comprising, in a cosmetically acceptable medium: * a compound of the iridoid family of formula (I) below, or a plant extract comprising the same: formula(I) in which hydrogen, methyl, hydroxymethyl, aldehyde; -CO 2 R 4 in which R 4 : hydrogen, C 1 -C 2 alkyl; sugar; R 2 : a hydrogen atom, a hydroxyl radical, sugar radical; R 3 : hydrogen and
Abstract: The present invention relates to a process of dyeing human keratin fibres by applying a composition, comprising, in a cosmetically acceptable medium: * a compound of the iridoid family of formula (I) below, or a plant extract comprising the same: formula (I) in which hydrogen, methyl, hydroxymethyl, aldehyde; -CO 2 R 4 in which R 4 : hydrogen, C 1 -C 2 alkyl; sugar; R 2 : a hydrogen atom, a hydroxyl radical, sugar radical; R 3 : hydrogen, hydroxyl, alkyloxy; R: sugar radical (aldose or derivative); integer ranging from 1 to 5; the compound(s) of formula (I) having undergone prior to or simultaneously with the dyeing process, a step consisting in replacing the radical R with a hydrogen atom; ** at least one particular nucleophilic compound or at least one amino or thio polymer, in an amino or thio polymer(s)/compound(s) of formulae (I) and/or (II) weight ratio of at least 0.01. The invention also relates to multi-compartment devices.
5 citations
TL;DR: This is the first tertiary structure of a mutant form of this AKR1B7 orthologue to be reported in order to investigate the structure-function relationship of the nonconserved His269 and its role in coenzyme binding.
Abstract: Rat aldose reductase-like protein (AKR1B14) is an orthologue of mouse vas deferens protein (AKR1B7) and plays roles in the detoxification of reactive aldehydes and synthesis of prostaglandin F2α. Here, the 1.87 A resolution crystal structure of the His269Arg mutant of AKR1B14 complexed with NADPH is described and shows that the negatively charged 2′-phosphate group of the coenzyme forms an ionic interaction with the positively charged guanidinium group of Arg269 that is also observed in the human aldose reductase (AKR1B1) structure. Previous experiments on the site-directed mutagenesis of His269 to Arg, Phe and Met revealed fourfold, sevenfold and 127-fold increases in the K m for NADPH, respectively, which are in agreement with the present molecular-modelling and X-ray crystallographic studies. This is the first tertiary structure of a mutant form of this AKR1B7 orthologue to be reported in order to investigate the structure–function relationship of the nonconserved His269 and its role in coenzyme binding.
Patent•
01 Oct 2012
TL;DR: In this article, the present invention relates to a composition for dyeing human keratin fibres, comprising, in a cosmetically acceptable medium: * a compound of the iridoid family of formula (I) below, or a plant extract comprising the same: in which R 1 : hydrogen, methyl, hydroxymethyl, aldehyde; -CO 2 R 4 in whichR 4: hydrogen, C 1 -C 2 alkyl; sugar; R 2 : a hydrogen atom, a hydroxyl radical, sugar radical; R 3 : hydrogen
Abstract: The present invention relates to a composition for dyeing human keratin fibres, comprising, in a cosmetically acceptable medium: * a compound of the iridoid family of formula (I) below, or a plant extract comprising the same: in which R 1 : hydrogen, methyl, hydroxymethyl, aldehyde; -CO 2 R 4 in which R 4 : hydrogen, C 1 -C 2 alkyl; sugar; R 2 : a hydrogen atom, a hydroxyl radical, sugar radical; R 3 : hydrogen, hydroxyl, alkyloxy; R: sugar radical (aldose or derivative); integer ranging from 1 to 5; the compound(s) of formula (I) having optionally undergone a preliminary step consisting in replacing the radical R with a hydrogen atom, performed using an enzyme; ** at least one aldehyde or imine compound of formulae (i) and (ii), and also oxidized oligo- or polysaccharide comprising at least one aldehyde or imine function: with n equal to 0 or 1; X: O, NR' 1 ; A: COOH, optionally substituted aryl, cationic or non-cationic, saturated or unsaturated 5- or 6-membered heterocycle, comprising one or two heteroatoms, optionally substituted, alkyl, alkenyl; A2 divalent alkylene; the compounds possibly being, in the case of aldehydes, in acetal or hemiacetal form. The invention also relates to a process using such a composition, and also to multi-compartment devices.
TL;DR: Starting from the virtual screening-derived aldose reductase2 inhibitor S12728, a rational receptor-based lead optimization results in the discovery of compounds endowed with low micromolar/submicromolar activities.
Abstract: Starting from the virtual screening-derived aldose reductase2 inhibitor S12728, a rational receptor-based lead optimization results in the discovery of compounds (I) endowed with low micromolar/submicromolar activities.
Patent•
07 Nov 2012
TL;DR: In this paper, a method for preparing ketose sugars, characterised in that: 1) at least one aldose sugar or a solution or a suspension of said sugar in water is solubilised, in one organic solvent; 2/ the organic solution obtained is brought into contact with a catalyst, in order to convert the aldoses into ketose by means of an isomerisation reaction; 3/ then, optionally, the sugar solution obtained was dried; 4/ and finally, the isomerization catalyst is removed by filtration.
Abstract: A method for preparing ketose sugars, characterised in that: 1/ at least one aldose sugar or a solution or a suspension of said sugar in water is solubilised, in at least one organic solvent; 2/ the organic solution obtained is brought into contact with a catalyst, in order to convert the aldose into ketose by means of an isomerisation reaction; 3/ then, optionally, the sugar solution obtained is dried; 4/ and finally, optionally, the isomerisation catalyst is removed by filtration.
TL;DR: In this article, a baseline separation was achieved for 1-phenyl-3-methyl-5-pyrazolone derivatives of six usual aldoses by CZE using acid buffer (pH 2.5).
Abstract: Baseline separation was achieved for 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatives of six usual aldoses by capillary zone electrophoresis (CZE) using acid buffer (pH 2.5). The result showed that the migration times of mannose and rhamnose were much longer than those of the other four aldoses, though the molecular weights of the two monosaccharides were parallel to the others. This phenomenon is due to the intramolecular ring formation in PMP-aldoses, which impairs the conjugate in the pyrazolone ring, and further increases the alkalinity and positive charge of PMP-aldoses in acidic ambience. The aldose having 2,3-trans disposition will be favorable for ring formation and has more positive charge than that of the aldose having 2,3-cis disposition.
Patent•
02 Feb 2012
TL;DR: In this article, the authors determined the total phosphorous quantity in test water safely and in a short time period by breaking down phosphorous compounds and converting to phosphate ions, and then determining the quantity of phosphate ions in the test water.
Abstract: The disclosed method determines the total phosphorous quantity in test water safely and in a short time period by breaking down phosphorous compounds included in test water and converting to phosphate ions, and then determining the quantity of phosphate ions in the test water In the method, first sulfuric acid and alkali metal salts of peroxodisulfuric acid are added to test water, and the mixture is heated for a prescribed time period at a temperature from 65°C to boiling temperature An aqueous solution is added to the test water, said aqueous solution containing at least one hydroxyl group-containing compound selected from the hydroxyl group-containing compound group consisting of hydroxyl carboxylic acids and alditol, a vanadium compound having a vanadium valence of 3-5, a non-reducing oligosaccharide capable of generating a 5 carbon aldose, a 6 carbon aldose or a 6 carbon ketose by means of decomposition, 7-molybdic acid 6-ammonium, and an antimony compound wherein the antimony valence is 3, and after heating the test water to at least 65°C for a prescribed time period, the light absorbance of the test water for an arbitrary wavelength occurring in the range of 600-950nm is measured