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Advanced Glycation End Products (AGEs) could be formed with α-dicarbonyl compounds as intermediates; however, simultaneous determination of AGES as well as their precursors and intermediates have rarely been mentioned, so as to investigate the reaction. In this work, lysine was reacted with aldoses (galactose, glucose) and ketoses (fructose, sorbose) to investigate the effects of sugar type and heating temperature. Two high-performance liquid chromatography-tandem mass spectrometry methods were developed to quantify AGEs and the corresponding α-dicarbonyl compounds. The results demonstrated that aldoses were more prone to form intermediates and final products than ketoses from the point of view of absorbance (at 294 and 420 nm). Aldose systems were prone to form glyoxal, whereas ketose systems tended to generate methylglyoxal and 3-deoxyglucosone. The relative reaction activity of sugars in forming Nε-carboxymethyl-lysine depended upon heating temperature for aldose and ketose systems. The aldose was more liable to generate Nε-Carboxyethyl-lysine (CEL) than ketose, with the CEL generation for each sugar occurred in the order galactose > glucose > sorbose > fructose. The obvious differences between different types of sugars suggest that further research is needed on the degradation of sugars to form intermediates and on the reaction of α-dicarbonyl to generate AGEs.

Unprotected aldoses in water undergo an isomerization reaction via a radical pathway when irradiated with light in the presence of water-soluble benzophenone. Whereas its anomeric carbon (C1) is oxidized to a carboxy group, the hydroxy group on the C2 carbon is replaced by hydrogen. The generated 2-deoxy lactones are readily reduced to the corresponding 2-deoxy aldoses, which are often contained in bioactive compounds.

Water enriched with oxygen-18 (H2 18 O) is a potential tracer for evaluating the sources of glucose and glycogen synthesis since it is incorporated into specific sites of glucose-6-phosphate via specific enzyme-mediated exchange/addition mechanisms. Unlike 2 H, 18 O does not experience significant isotope effects for any of these processes. Therefore, H2 18 O might provide more precise estimates of endogenous carbohydrate synthesis compared with deuterated water provided that positional 18 O enrichments of glucose can be measured. As a proof of concept, H2 18 O was incorporated into a well characterized hemolysate model of sugar phosphate metabolism and 13 C NMR was applied to quantify positional 18 O enrichment of glucose-6-phosphate oxygens. Human erythrocyte hemolysate preparations were incubated overnight at 37 °C with a buffer containing sugar phosphate precursors and 20% (n = 5) and 80% (n = 1) H2 18 O. Enrichment of glucose-6-phosphate was analyzed by 13 C NMR analysis of 18 O-shifted versus unshifted signals following derivatization to monoacetone glucose (MAG). 13 C NMR MAG spectra from hemolysate revealed resolved 18 O-shifted signals in Positions 1-5. Mean 18 O enrichments were 16.4 ± 1.6% (Position 1), 13.3 ± 1.3% (Position 2), 4.1 ± 1.1% (Position 3), 12.6 ± 0.8% (Position 4), 10.7 ± 1.4% (Position 5), and no detectable enrichment of Position 6. No 18 O-shifted glucose-6-phosphate signals were detected in preparations containing sugar phosphate precursors only. H2 18 O is incorporated into Positions 1-5 of glucose-6-phosphate in accordance with spontaneous aldose hydration and specific enzymatic reaction mechanisms. This provides a basis for its deployment as a tracer for glucose and glycogen biosynthesis.

d-Mannose is not only the epimer of d-glucose at the C-2 position, but also the aldose isomer of d-fructose. Because of its physiological properties and health benefits, d-mannose has attracted public interest. It has been confirmed that d-mannose has broad applications in food, cosmetics, and pharmaceutical industries. According to the Izumoring strategy, d-glucose isomerase (d-GI) and d-lyxose isomerase (d-LI) play important roles in the conversions of d-fructose from d-glucose and of d-mannose from d-fructose respectively. In this study, a one-step enzyme process of d-mannose production from d-glucose has been constructed by co-expression of the d-GI from Acidothermus cellulolyticus and d-LI from Thermosediminibacter oceani in Escherichia coli BL21(DE3) cells.; Results: The co-expression system exhibits maximum activity at pH 6.5 and 65 °C with Co2+ supplement. It is relatively thermostable at less than 65 °C. When the reaction reaches equilibrium, the ratio of d-glucose, d-fructose, and d-mannose is approximately 34 : 49.6 : 16.4. By using this co-expression system, about 60.0 g L-1 d-mannose is obtained from 400 g L-1 d-glucose in 8 h.; Conclusion: This co-expression of d-GI and d-LI system provides a novel and efficient approach for d-mannose production. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

We report a novel mechanism for the interconversion of 2-hydroxypropanal with its more-stable ketone isomer hydroxyacetone. Reaction proceeds via concerted transfer of two H atoms, requires a barrier of only ∼40 kcal mol−1, bypasses the enediol intermediate, and is general for α-hydroxy carbonyls. A similar isomerization mechanism is shown to persist for β, γ, and δ-hydroxy carbonyls; these compounds are skeletal forms of the monosaccharides and this work, therefore, discloses the gas-phase mechanism for aldose-ketose isomerization. As an example, the isomerization of glyceraldehyde to dihydroxyacetone is shown to proceed via this mechanism with a barrier of 31 kcal mol−1. Rate coefficients and thermochemical properties are reported for the isomerization of 2-hydroxypropanal and hydroxyacetone for use in detailed kinetic models. Additionally, RRKM theory k(E) values for this reaction suggest that it may transpire in the troposphere following solar excitation.

The competitive hydrogenation of glycolaldehyde and glucose over 1% Ru/C catalyst was studied in a batch reactor at 373–403 K and 6 MPa hydrogen pressure, with or without the presence of ammonium metatungstate (AMT). It was found that the presence of AMT retarded significantly the hydrogenation of both aldoses, and this suppressing effect was more pronounced on the glucose hydrogenation. The hydrogenation of glycolaldehyde occurred always preferentially to the glucose hydrogenation, with or without the presence of AMT. The kinetic data in the absence of AMT were well modeled based on Langmuir–Hinshelwood–Hougen–Watson kinetics assuming the surface reaction being rate-determining and noncompetitive adsorption of dissociatively chemisorbed hydrogen and aldose. However, in the presence of AMT, the complexing between AMT and aldose and the strong adsorption of AMT on Ru surface must be considered in the development of new kinetic model. The as-modified model described the data satisfactorily. © 2014 American Institute of Chemical Engineers AIChE J, 61: 224–238, 2015

5-Hydroxymethylfurfural (HMF) is considered an important building block for future bio-based chemicals. Here, we present an experimental study using different ketoses (fructose, sorbose, tagatose) and aldoses (glucose, mannose, galactose) under aqueous acidic conditions (65gL(-1) substrate, 100-160 degrees C, 33-300mM H2SO4) to gain insights into reaction pathways for hexose dehydration to HMF. Both reaction rates and HMF selectivities were significantly higher for ketoses than for aldoses, which is in line with literature. Screening and kinetic experiments showed that the reactivity of the different ketoses is a function of the hydroxyl group orientation at the C3 and C4 positions. These results, in combination with DFT calculations, point to a dehydration mechanism involving cyclic intermediates. For aldoses, no influence of the hydroxyl group orientation was observed, indicating a different rate-determining step. The combination of the knowledge from the literature and the findings in this work indicates that aldoses require an isomerization to ketose prior to dehydration to obtain high HMF yields.

Disaccharides that contain 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) and d-glycero-d-talo-oct-2-ulosonic acid (Ko) substituted at the 8-position by 4-amino-4-deoxy-β-l-arabinopyranosyl (Ara4N) residues have been prepared. Coupling an N-phenyltrifluoroacetimidate-4-azido-4-deoxy-l-arabinosylglycosyl donor to acetyl-protected allyl glycosides of Kdo and Ko afforded anomeric mixtures of disaccharide products in 74 and 90 % yield, respectively, which were separated by chromatography. Further extension of an intermediate Ara4N-(1→8)-Kdo disaccharide acceptor, which capitalized on a regioselective glycosylation with a Kdo bromide donor under Helferich conditions, afforded the branched trisaccharide α-Kdo-(2→4)[β-l-Ara4N-(1→8)]-α-Kdo derivative. Deprotection of the protected di- and trisaccharide allyl glycosides was accomplished by TiCl4-promoted benzyl ether cleavage followed by the removal of ester groups and reduction of the azido group with thiol or Staudinger reagents, respectively. The reaction of the anomeric allyl group with 1,3-propanedithiol under radical conditions afforded the thioether-bridged spacer glycosides, which were efficiently coupled to maleimide-activated bovine serum albumin. The neoglycoconjugates serve as immunoreagents with specificity for inner core epitopes of Burkholderia and Proteus lipopolysaccharides.

Four conformationally constrained fused oxa-aza spiro sugars have been synthesized from perbenzylated D-glucono-lactone involving C-glycosylation of ketoses by using Me 3 -SiCN, ring-closing metathesis, and diastereoselective dihydroxylation as key steps. Two of the four spiro sugars were found to be highly selective but moderate inhibitors of α-mannosidase.

A new 2-oxazolines containing S-galactosyl substituents linked to alkyl chains of different lengths; (S-glycooxazoline) were prepared relatively in high yields. By using a 1:1 adduct of 2-methyl-2-oxazoline and methyl triflate, as the initiator, the monomer was polymerized via ring-opening polymerization (ROP) to give products with relatively narrow molecular weight distributions. Homo- and copolymerization were performed, and the kinetics of these new S-glycooxazolines in the ROP are investigated. After a quantitative deprotection, poly(2-oxazoline)s having pendant carbohydrate were obtained. The interaction of the poly(S-glycooxazoline) with RCA120 lectin was investigated, the binding constant between glycopolymer and lectin was increased by 102 times compared with that of the monosaccharide (D-galactose). The in vivo expression of green fluorescent protein using the synthesized poly(S-glycooxazoline)s as polymeric inducers in Escherichia coli host were performed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

The application of carbohydrate-derived amino alcohols in the asymmetric arylation of aldehydes by using arylboronic acids as the source of transferable aryl groups is described. The best ligand is derived from the readily available sugar D-xylose and it mediates the addition of a range of arylboronic acids to various aromatic aldehydes in excellent yields and high enantiomeric excesses.

We investigated the hydrothermal conversion of the carbohydrates including glucose, cellulose, and starch to lactic acid using NaOH and Ca(OH)2 as alkaline catalysts. Both catalysts significantly promoted the lactic acid formation. The highest yield of lactic acid from glucose was 27% with 2.5 M NaOH and 20% with 0.32 M Ca(OH)2 at 300°C for 60 s. The lactic acid yields from cellulose and starch were comparable with the yield from glucose with 0.32 M Ca(OH)2 at 300°C, but the reaction time in the case of cellulose was 90 s. The mechanism of lactic acid formation from glucose was discussed by identifying the intermediate products. Lactic acid may be formed via the formation of aldoses of two to four carbons including aldose of three carbons, which are all formed by reverse aldol condensation and double bond rule of hexose. This implies that carbon–carbon cleavage occurs at not only C3C4 but also at C2C3. © 2010 American Institute of Chemical Engineers AIChE J, 2010

Two bioactive flavonol glucosides, hyperoside and quercitrin, were successfully isolated in one step from the phytochemically unknown medicinal plant Osteomeles schwerinae by high-speed counter-current chromatography using a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (0.5:5.5:1.5:4.5 v/v). From 160 mg of crude extract, 2.1 mg of hyperoside (98.6% purity, 83.3% recovery) and 4.5 mg of quercitrin (99.2% purity, 81.7% recovery) were separated and then their chemical structures were identified by (1)H and (13)C NMR analysis. In addition, the isolates were subjected to an in vitro bioassay to evaluate their inhibitory activity on rat lens aldose reductase. Both quercitrin and hyperoside showed excellent inhibitory activities toward rat lens aldose reductase with the IC(50) values of 0.16 and 4.33 microM, respectively, as compared with positive control, 3,3-tetramethyleneglutaric acid (28.7 microM). So far, chemical constituents and biological activities of O. schwerinae have never been reported. This is the first report on the chemical constituents and biological activity of this plant using semi-preparative high-speed counter-current chromatography separation technique.

Molecular recognition of Glu, Glc 2 -Glc 6 and Mal 3 by a tetrakis(bile acid)―porphyrin conjugate has been studied by using ESI-FTICR mass spectrometry. The bile acid conjugate was observed to form 1:1 noncovalent complexes with saccharides. The conjugate was found to have size-selectivity towards saccharides with three or more glucose residues. The Glc 3 and Glc 4 also formed kinetically the most stable complexes. The electron capture dissociation (ECD) experiments revealed that in complexation of an oligosaccharide three glucose residues interact with the bile acid conjugate, whereas additional glucose residues are susceptible to fragmentation. The ECD results also showed the significance of the porphyrin centre for complexation of an intact oligosaccharide. It is obvious that the complexation of an intact sugar requires at least one bile acid side arm and the porphyrin centre.

The nonproteinogenic amino acids (3S,4S)-L- and (3S,4S)-D-β-hydroxyenduracididine (βhEnd), each containing a cyclic guanidine group and three contiguous stereocenters, have been synthesized for the first time, starting from commercially available diacetone D-glucose. The key inversion reactions for the introduction of the two nitrogen groups at C-2 and C-4 afford products that are diastereomerically pure and easy to purify, thereby allowing the gram-scale preparation of βhEnd derivatives that are suitably protected for peptide coupling reactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

From readily available di-O-isopropylidene-D-glucose, a D-ribofuranoid glycoaminoxy acid and its tBu ester have been efficiently prepared as a new family of sugar building blocks by introducing the phthalimido aminoxy group by a Mitsunobu reaction. We found that the tBu ester can be selectively deprotected with 13.7 % TFA in CH2Cl2 at 0 °C in the presence of the 1,2-O-isopropylidene acetal. This selective deprotection has made possible the synthesis of homo-oligomers of glycoaminoxy acids (up to six sugar units) as a novel type of oligosaccharide mimetics. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Mannose (α-Man)-containing neoglycoconjugates possessing aliphatic-, aromatic-, and carbohydrate-centered architectures and differing in structural characteristics such as valency, topology, and nature of the linker have been synthesized using click chemistry that shows its value as an efficient and versatile methodology for accessing tailor-made multivalent neoglycoconjugates. The binding behaviour of these glycomimics toward Concanavalin A (Con A) has been evaluated to determine the influence of the structural parameters. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A new anhydroribotrisaccharide monomer, A2B3LR (1), was synthesized and ROP was carried out to elucidate the polymerizability and to obtain oligosaccharide-branched polysaccharides with defined structures. The new trisaccharide monomer was found to be polymerized readily with BF(3) . OEt(2) as a catalyst at -40 degrees C to give a lactose-branched polymer. Copolymerization with ADBR gave the corresponding copolymers in good yields. After removal of protective benzyl groups, D-lactose-branched ribofuranans with free hydroxyl groups were obtained in good yields. The structure of polymers was analyzed by (1)H, 13C, and two-dimensional NMR measurements, suggesting that D-lactose-branched ribofuranans had (1 --> 5)-alpha stereoregularity.

A new anhydro disaccharide monomer, 1,6-anhydro-2,3-di-o-benzyl-4-o-(2′,3′,4′,6′-tetra-o-benzyl-β-D-galactopyranosyl)-β-D-glucopyranose (benzylated 1,6-anhydro lactose (LSHBE)), was synthesized from D-lactose to investigate the polymerizability and biological activities of the resulting branched polysaccharides. The ring-opening polymerization of LSHBE was carried out with phosphorus pentafluoride as a catalyst under high vacuum to give a stereoregular benzylated (1 → 6)-α-D-lactopyranan. The molecular weights of poly(LSHBE)s increased with an increase in the amount of CH2Cl2 solvent, and polymerization temperatures were affected in both molecular weights and yields of the polymers. The copolymerization of LSHBE with benzylated 1,6-anhydro-β-D-glucopyranose (LGTBE) gave the corresponding copolysacchrides having different proportions of lactose and glucose units in good yields. After debenzylation to recover hydroxyl groups and then sulfation, sulfated homopoly(lactose)s and copoly(lactose and glucose)s were obtained. Sulfated homopoly(lactose)s had moderate anti-HIV (EC50 = 5.9 and 1.3 μg/mL) and blood anticoagulant activities (AA = 18 and 13 unit/mg), respectively. Sulfated copoly(lactose and glucose) having 15 mol % lactose units gave high anti-HIV and blood anticoagulant activities of 0.3 μg/mL and 54 unit/mg, respectively. These biological results suggest that the distance between branched units on the main chain plays an important role in the anti-HIV and blood anticoagulant activities. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 913–924, 2009

This paper reports the chemoenzymatic synthesis of an amylose-grafted cellulose. A maltoheptaose was chemically introduced to the amine-functionalized cellulose by reductive amination to produce the maltoheptaose-grafted cellulose. Then, the phosphorylase-catalyzed enzymatic polymerization of glucose 1-phosphate from the graft-chain ends on the cellulose derivative was performed, giving the amylose-grafted cellulose. The obtained material is shown to form gels and films. The dry and wet cycles of the materials were repeated.

2C-Methyl-d-erythritol-4-phosphate synthase, encoded by the ispC gene (also designated dxr), catalyzes the first committed step in the nonmevalonate isoprenoid biosynthetic pathway. The reaction involves the isomerization of 1-deoxy-d-xylulose 5-phosphate, giving a branched-chain aldose derivative that is subsequently reduced to 2C-methyl-d-erythritol 4-phosphate. The isomerization step has been proposed to proceed as an intramolecular rearrangement or a retroaldol–aldol sequence. We report the preparation of 13C-labeled substrate isotopologs that were designed to optimize the detection of an exchange of putative cleavage products that might occur in the hypothetical retroaldol–aldol reaction sequence. In reaction mixtures containing large amounts of 2C-methyl-d-erythritol-4-phosphate synthase from Escherichia coli, Mycobacterium tuberculosis or Arabidopsis thaliana, and a mixture of [1-13C1]-2C-methyl-d-erythritol 4-phosphate and [3-13C1]2C-methyl-d-erythritol 4-phosphate, the reversible reaction could be followed over thousands of reaction cycles. No fragment exchange could be detected by NMR spectroscopy, and the frequency of exchange, if any, is less than 5 p.p.m. per catalytic cycle. Hydroxyacetone, the putative second fragment expected from the retroaldol cleavage, was not incorporated into the enzyme product. In contrast to other reports, IspC did not catalyze the isomerisation of 1-deoxy-d-xylulose 5-phosphate to give 1-deoxy-l-ribulose 5-phosphate under any conditions tested. However, we could show that the isomerization reaction proceeds at room temperature without a requirement for enzyme catalysis. Although a retroaldol–aldol mechanism cannot be ruled out conclusively, the data show that a retroldol–aldol reaction sequence would have to proceed with very stringent fragment containment that would apply to the enzymes from three genetically distant organisms.

The polymerization of [S]-lactide was accomplished using an initiating system comprising an alkyl zinc complex and a series of well defined carbohydrate co-initiators derived from D-glucose, D-xylose, and 2-deoxy-D-ribose. The monosaccharide co-initiators were aldonate esters and pyranoses, they were all prepared in high yield and had only a single alcohol co-initiating group; the remaining carbohydrate hydroxyl functionalities were protected as acetyl, benzyl ether and isopropylidene acetal groups. The polymerizations were all well controlled, illustrated by the linear increase in poly(S-lactide) M n with percentage conversion of lactide, the increase in poly(S-lactide) M n with [lactide] 0 -[lactide] t /[co-initiator] and the narrow polydispersity indices of the polylactides. Thus, the novel initiating systems were used to produce poly(S-lactides) end functionalized with a variety of different aldonate ester and pyranose groups and with degrees of polymerization from 10 to 250. The polyesters were fully characterized, including by NMR spectroscopy, size exclusion chromatography (SEC), matrix-assisted laser deposorption/ionization (MALDI) mass spectrometry and by static water contact angle measurements.

The glucose and fructose contents of samples of sugar-cane molasses from Queensland (Australia) have been determined by oxidizing aldose groups with iodine and sodium hydroxide and estimating the residual fructose by using Luff's modified method of reductiometric analysis. Glucose is determined by subtracting the value for fructose from the total reducing sugar content, also estimated by using Luff's modified method. The Luff modified method of analysis is preferred because of the equal reducing power for glucose and fructose. The glucose/fructose ratio of the molasses samples was found to vary over a wide range from 0–84/1 to 1/3.5, according to the district in which the cane had been grown.

An amphiphilic poly(N-propargylamide) with galactose and lauryloyl groups was synthesized by copolymerization of the corresponding N-propargylamide monomers using a Rh catalyst. The obtained copolymer formed a one-handed helical conformation and molecular aggregates in water. The observations by fluorescence microscopy in a cell culture experiment in the presence of dye-labeled copolymer indicated that the copolymer was incorporated into the cells.

The complexation of saccharides with poly(anilineboronic acid) as a function of pH has been studied with simultaneous measurements of open-circuit potential and mass change. This study provides an insight into this reaction as well as the relationship between complexation and open-circuit potential and the optimum pH for complexation of D-fructose and d-glucose. The optimum pH values for poly)anilineboronic acid)-D-fructose and -D-glucose complexation are near the pK a values of the complex reported in homogeneous solution. At physiological pH (7.4), the apparent binding constant of D-fructose and D-glucose with poly(anilineboronic acid) is 19.2 and 0.2 M -1 , respectively. In contrast, at pH 9.0, the apparent binding constant of D-glucose with poly(anilineboronic acid) is 12 M -1 , double than that of D-fructose. The decrease in complexation in the polymer films at pH values above the pK a of the complexes is in contrast to the behavior in homogeneous solutions. This trend is observed for both D-fructose and D-glucose using open-circuit potential, mass change and polarization modulated infrared reflection absorption spectroscopic measurements. Also, the complexation is limited in the polymer film, i.e., ≤23% boron is involved. These results suggest that steric and/or electrostatic interactions may play an important role in complexation within polymer films.

A method has been established by which to determine aldoses and ketoses in plant material simultaneously. Monosaccharides were extracted by sonication with 80% ethanol and sugar oximes formed by treatment of the resultant extract with hydroxylamine and pyridine at 90C. After reaction, one aliquot of the product was derivatised with acetic anhydride at 90C, whilst a second aliquot was silylated with HMDS and TMCS at 80C. Both reaction mixtures were analysed by GC-MS in the SIM mode. Quantivation was linear within the range 1–4 mg/mL and the detection limit for monosaccharides was 5–25 ng/mL. The absolute recoveries were between 73.0 and 90.2% and the RSDs were 3.1–10.0%. This method was applied to analyse the free monosaccharides in Lyceum barbarum L.; eight monosaccharides were present in amounts between 0.26 and 368.65 mg/mg. Copyright © 2006 John Wiley & Sons, Ltd.

We compared two 18F-glycosylation methods, the BF3-mediated 18F-glycosylation versus the newly developed AgOTf-activated 18F-glycosylation procedure. The AgOTf-activated 18F-glycosylation makes use of 3,4,6-tri-O-acetyl-2-deoxy-2-[18F]fluoro-glucopyranosyl bromide and revealed an improved radiochemical yield of 67±6% in the case of a protected serinyl precursor as compared to 27±4% obtained by the BF3-method. This suggests the suitability of Koenigs–Knorr conditions for 18F-glycosylation of protected bioactive peptides. Copyright © 2006 John Wiley & Sons, Ltd.

The vapor-based synthesis and characterization of a reactive polymer, poly[(4-formyl-p-xylylene)-co-(p-xylylene)] (1), have been reported. The reactive polymer coating enables the immobilization of oligosaccharides via the chemoselective aldehyde-hydrazide coupling reaction.

Two [3,22]-ionenes with pendent chiral groups, glucopyranosyl-[3,22]-ionene and β-cyclodextrin-[3,22]-ionene, were synthesized by the reaction between the tosyl derivatives of the carbohydrate (methyl alpha-glucopyranoside or betacyclodextrin) and the tertiary [3,22]-polyamine obtained by selective demethylation of [3,22]-ionene. The derivatives were characterized by 1 H NMR spectroscopy, presenting degrees of substitution of 30 and 45% for the glucosyl and cyclodextrin derivatives, respectively. It was shown by using pyrene as the fluorescent probe, that both polymers form hydrophobic domains, characteristic of micelle-mimetic polysoaps in aqueous solution.

Monosaccharide functionalized polysiloxanes bearing either terminal or pendant mannose moieties have been obtained starting from the allyloxyethyl glycoside and appropriate H-containing siloxane compounds, via hydrosilylation reactions. The starting modified monosaccharide was reacted as trimethylsilyl protected derivative and a convenient method for deprotection of the hydroxyl groups was found in order to avoid the degradation of the polysiloxane chains. The reaction products were characterized by IR and NMR spectroscopy. The water solubility of these functionalized polysiloxanes was investigated and critical micelle concentration values were found to be in the range 10 -4 -10 -5 M. Some of the water soluble compounds were used as non ionic surfactants for the elaboration of poly(e-caprolactone) nanoparticles by nanoprecipitation, and particle sizes of less than 200 nm were observed.

Mannose-functionalized and ethoxyethanol-functionalized poly(amido)amine dendrimers bound multiple vanadate-substituted polyoxotungstate Wells–Dawson-type polyoxometalates (POMs). Dendrimers incorporating 10–30 POMs were characterized with NMR, transmission electron microscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry techniques. The number of metal clusters per dendrimer molecule varied according to the dendrimer generation and the nature of the surface functional groups. Efforts aimed at using the poly(polyoxometalate) dendrimers as oxidation catalysts are also described. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3059–3066, 2005

Single-walled carbon nanotubes (SWNTs)mechanically dispersed in HEPES buffer were incubated with a dispersion of A-B-A block telomers, composed of 2-methacryloyloxyethyl-D)glucopyranoside telomers (A block) and a styrene telomer (B block), which had been prepared by the macroinitiator technique. After the incubation, the polymer-wrapped SWNT could be stably dispersed in the buffer without any precipitation for several months. The glucose residue above the SWNT was definitely recognized by lectin (Concanavalin A) as proven by the increase in turbidity. Using a similar procedure, a block telomer composed of N-isopropylacrylamide telomers (A block) and a styrene telomer (B block) could easily be deposited onto the SWNT. A temperature-responsive aggregation and the subsequent precipitation of the modified SWNT could clearly be observed. The usage of the block-telomer examined here would be promising for the preparation of stable dispersions of SWNTs with various functions.

2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) was reacted with 4-ethylphenyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside using tert-butyl hydroperoxide and cobalt(II)acetate tetrahydrate in acetonitrile. The reaction provided 4-[1'-(2,2,6,6-tetramethyl-1-piperidinyloxy)-ethyl]phenyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside, glycoconjugated initiator. Star-shaped polystyrene architectures in which glucose was covalently bonded in the core and chain-end were successfully prepared from the glycoconjugated initiator, styrene, and 1,4-divinylbenzene as starting materials.

In the 1990's, carbohydrate modified silicones were developed as a novel class of hydrophilic modified silicones which are now ready for marketing and industrially available, mainly as ingredients of cosmetic formulations. This report focuses on the synthesis of α,ω-carbohydrate modified linear poly(dimethylsiloxane)s by hydrosilylation reactions. Thus, a series of carbohydrate derivatives was synthesised and reacted with a hydrodimethylsily-terminated poly(dimethylsiloxane) applying Speier's catalyst. The resulting oils were characterised by MALDI TOF MS and NMR spectroscopy. Deprotection gave a series of novel amphiphilic modified silicones, which were more viscous than their protected analogues, due to hydrogen bonding.

Porphyrin derivatives having a galactose or a bis(isopropylidene)galactose structural unit, linked by ester or ether bonds, were characterized by electrospray tandem mass spectrometry (ES-MS/MS). The electrospray mass spectra of these glycoporphyrins show the corresponding [M + H](+) ions. For the glycoporphyrins with pyridyl substituents and those having a tetrafluorophenyl spacer, the doubly charged ions [M + 2H](2+) were also observed in ES-MS with high relative abundance. The fragmentation of both [M + H](+) and [M + 2H](2+) ions exhibited common fragmentation pathways for porphyrins with the same sugar residue, independently of the porphyrin structural unit and type of linkage. ES-MS/MS of the [M + H](+) ions of the galactose-substituted porphyrins gave the fragment ions [M + H - C(2)H(4)O(2)](+), [M + H - C(3)H(6)O(3)](+), [M + H - C(4)H(8)O(4)](+) and [M + H - galactose residue](+). The fragmentation of the [M + 2H](2+) ions of the porphyrins with galactose shows the common doubly charged fragment ions [porphyrin + H](2+), [M + 2H - C(2)H(4)O(2)](2+), [M + 2H - C(4)H(8)O(4)](2+), [M + 2H - galactose residue](2+) and the singly charged fragment ions [M + H - C(3)H(6)O(3)](+) and [M + H - galactose residue](+). The fragmentation of the [M + H](+) ions of glycoporphyrins with a protected galactosyl residue leads mainly to the ions [M + H - CO(CH(3))(2)](+), [M + H - 2CO(CH(3))(2)](+), [M + H - 2CO(CH(3))(2) - CO](+), [M + H - C(10)H(16)O(4)](+) and [M + H - protected galactose](+). The doubly charged ions [M + 2H](2+) fragment to give the doubly charged ions [porphyrin + H](2+) and the singly charged ions [M + H - protected galactose residue](+) and [M + H - CO(CH(3))(2)](+). For the porphyrins where the sugar structural unit is linked by an ester bond, [M + 2H](2+), ES-MS/MS showed a major and typical fragmentation corresponding to combined loss of a sugar structural unit and further loss of water, leading to the ion [M + 2H - sugar residue - H(2)O](2+), independently of the structure of the sugar structural unit. These results show that ES-MS/MS can be a powerful tool for the characterization of the sugar structural unit of glycoporphyrins, without the need for chemical hydrolysis.

UDPgalactose 4-epimerase (epimerase) catalyzes the reversible conversion between UDPgalactose and UDPglucose and is an important enzyme of the galactose metabolic pathway. The Saccharomyces cerevisiae epimerase encoded by the GAL10 gene is about twice the size of either the bacterial or human protein. Sequence analysis indicates that the yeast epimerase has an N-terminal domain (residues 1-377) that shows significant similarity with Escherichia coli and human UDPgalactose 4-epimerase, and a C-terminal domain (residues 378-699), which shows extensive identity to either the bacterial or human aldose 1-epimerase (mutarotase). The S. cerevisiae epimerase was purified to95% homogeneity by sequential chromatography on DEAE-Sephacel and Resource-Q columns. Purified epimerase preparations showed mutarotase activity and could convert either alpha-d-glucose or alpha-d-galactose to their beta-anomers. Induction of cells with galactose led to simultaneous enhancement of both epimerase and mutarotase activities. Size exclusion chromatography experiments confirmed that the mutarotase activity is an intrinsic property of the yeast epimerase and not due to a copurifying endogenous mutarotase. When the purified protein was treated with 5'-UMP and l-arabinose, epimerase activity was completely lost but the mutarotase activity remained unaffected. These results demonstrate that the S. cerevisiae UDPgalactose 4-epimerase is a bifunctional enzyme with aldose 1-epimerase activity. The active sites for these two enzymatic activities are located in different regions of the epimerase holoenzyme.

Here we report the chemoenzymatic synthesis and recognition function of glycoconjugate polymers carrying nonreducing disaccharides [α-D-glucopyranosyl-(1-1)-α-D-glucopyranoside (trehalose) and α-D-galactopyranosyl-(1-1)-α-D-glucopyranoside (Gal-type trehalose)]. The lipase-catalyzed esterification of the disaccharides with divinyl sebacate is completely selective at the primary Glc 6-OH position of trehalose and at the Gal 6-OH position of Gal-type trehalose. The resultant vinyl esters can be polymerized to yield glycoconjugate polymers with poly(vinyl alcohol) backbones. The interactions of the glycoconjugate polymers with lectins (concanavalin A and Bandeiraera simplicifolia) are amplified because of the glycocluster effect. The polymer carrying pendant α-D-galactopyranosyl-(1-1)-α-D-glucopyranoside shows inhibition activity against Shiga toxin-1 based on a stereochemical structure similar to that of globosyl Gb2 disaccharide. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4598–4606, 2004

A polymeric aminoglycoside was prepared by a facile chemoenzymatic reaction. Boc-protected aminoglycoside, amikacin, was chemoselectively esterified with divinyl sebacate at a hydroxyl group in the C6″ position by protease from Bacillus subtilis. The resulting 3,6′,3″,4‴-tetra-N-Boc-6″-O-vinyl sebacate was copolymerized with maltitol 6-vinyl sebacate to yield a polymeric amikacin. The polymeric amikacin showed a modest inhibitory effect on in vitro protein synthesis, and a little antibiotic activity in minimum inhibitory concentration (MIC) assay in the presence of protease. The synthesis of Boc-protected amikacin ester by an enzyme-catalyzed (protease) esterification.

Acyl glucuronides, which are biosynthesized by the action of glucuronosyltransferases to material for detoxification, are water-soluble and chemically active; they produce irreversible protein adducts via both the transacylation mechanism and the imine mechanism. The acyl group at the C-1 position migrates from the anomeric carbon to the C-2 position of the glucuronic acid moiety, producing the aldehyde group at the C-1 position, where the protein easily condenses through a Schiff's base, in the open-chain aldose form. The elimination of the hydroxyl group at the C-2 position therefore may prevent a protein-bound adduct via the imine mechanism. In this paper, we describe the synthesis and characterization of an acyl 2-deoxyglucuronide of deoxycholic acid as a model compound to investigate its possible utility as a water-soluble affinity labeling reagent for lipophilic carboxylic acids. The solubility of deoxycholyl 2-deoxyglucuronide in an aqueous solution was sufficient under physiological conditions, and the desired material reacted with model peptides to produce covalently bound adducts only via the transacylation mechanism.

The cellulose solvent Pd-en, an aqueous solution of [(en)Pd(II)(OH)(2)] (en=ethylenediamine), reacts with the monosaccharides D-arabinose (D-Ara), D-ribose (D-Rib), rac-mannose (rac-Man), and D-galactose (D-Gal) under formation of dimetalated aldose complexes, if the molar ratio of Pd and sugar is 2:1 or larger. In the Pd(2) complexes, the aldoses are tetra-deprotonated and act as bisdiolato ligands. Two crystalline pentose complexes were isolated: [(en)(2)Pd(2)(beta-D-Arap1,2,3,4 H(-4))].5 H(2)O (1) and [(en)(2)Pd(2)(beta-D-Ribp1,2,3,4 H(-4))].6.5 H(2)O (2), along with two hexose complexes. With rac-Man, the major solution species is crystallized as the 9.4-hydrate [(en)(2)Pd(2)(beta-rac-Manp1,2,3,4 H(-4))].9.4 H(2)O (3). From the respective D-Gal solutions, [(en)(2)Pd(2)(beta-D-Galf1,3,5,6 H(-4))].5 H(2)O.C(2)H(5)OH (4), with the sugar tetraanion in its furanose form, is crystallized though it is not the major species, rather the second most abundant in purely aqueous solutions. The Galf species is enriched in the mother liquors to the extent of 25 % of total sugar content. Substitution of the en ligand by two molecules of ammonia, methylamine, or isopropylamine, respectively, results in the formation of different solution species. With the bulkiest ligand, isopropylamine, monometalation of the aldoses in the 1,2-position is exclusively observed.

Aldose 1-epimerase or mutarotase (EC 5.1.3.3) is a key enzyme of carbohydrate metabolism catalysing the interconversion of the α- and β-anomers of hexose sugars such as glucose and galactose. We identified an open reading frame in the human genome (BC014916) which has high sequence similarity to previously identified bacterial aldose 1-epimerases. This sequence was cloned into a bacterial expression vector, and expressed and purified from this source. Enzyme assays show that the protein has aldose 1-epimerase activity and exhibits a preference for galactose over glucose. Site-directed mutagenesis confirmed the involvement of three residues involved in catalysis and substrate binding.

6-Deoxy sugars having only secondary alcohols, namely, D-fucose-L-fucose, and L-rhamnose, were regioselectively esterified with divinyl adipate by enzymes. The compounds 2-O-vinyl adipolyl D-fucose and 2-O-vinyl adipolyl L-fucose were effectively produced in dimethylformamide by protease from Bacillis subtilis and Streptomyces griseus. Furthermore, 4-O-vinyl adipolyl L-rhanmose was effectively produced in pyridine by lipase from Pseudomonas sp. Each polymerizable sugar ester was polymerized by 1,1'-azoisobutyronitrile to give polymers having a number average molecular weight of 5000-14000.

Aldopentoses, aldohexoses and the benzylated derivatives reacted with iodine in ammonia water at room temperature to give their corresponding saccharide amides in high yields. The reactions proceeded with oxidation of the aldose hemiacetals by iodine to generate the saccharide lactone intermediates, which underwent ammonolysis in situ to give the saccharide amides.

The reaction of the reducing aldopentose lyxose towards the metal centres in the copper-based cellulose solvents Schweizer’s reagent (cupric hydroxide in aqueous ammonia) and Cu-en (cupric hydroxide in aqueous ethylenediamine) was investigated. Crystals of the trinuclear complexes [(NH3)4Cu II(β-D-Lyxp1,2,3H−3)2(H2O)2]·4H2 O( 1) and [(en)2Cu II(β-DLyxp1,2,3H−3)2(H2O)2]·4H2 O( 2 )( Lyxp = lyxopyranose) were grown upon preventing Fehling-type aldose oxidation. One of the three cupric centres is coordinated by two chelating diolato ligands only, hence both ammonia and ethylenediam

Novel well-defined chain-end- and in-chain-functionalized polystyrenes with six, eight, twelve, and sixteen benzyl chloride moieties and with four and eight D-glucose residues have been successfully synthesized by developing the methodology based on living anionic polymerization of using new functionalized agents derived from functionalized 1,1-diphenylethylene (DPE) derivatives. They are 1,10-dichloro-4,4-7,7-tetra(3-methoxymethylphenyl)decane, its iodide derivative, the dianion prepared from 1,1-bis(3-methoxymethylphenyl)ethylene and potassium naphthalenide, and 1,1-bis[3',5'-bis(1,2:5,6-di-O-isopropylidene-α-D-glucofuranose-3-oxymethyl)phenyl]ethylene. The developed methodology involves diverse modes of reactions of polystyryllithium with new functionalized agents and either the subsequent transformation reaction with BCl 3 into benzyl chloride moieties or acid-hydrolysis to regenerate D-glucose residues. The resulting chain-multi-functionalized polystyrenes were precisely controlled with respect to chain length and quantitatively functionalized within experimental errors.