Aldonic Acids Research Articles

Gas chromatography–mass spectrometry resolution of sugar acid enantiomers on a permethylated β-cyclodextrin stationary phase

Analysis of compounds in meteorites revealed a need to simultaneously characterize multiple enantiomers of sugar acids (aldonic acids) present in trace amounts. Analyses by gas chromatography–mass spectrometry demonstrated that all but two of the three-carbon through six-carbon straight-chained sugar acid enantiomer pairs could be resolved using a single derivatization procedure and one set of GC parameters. Compounds were analyzed as their ethyl ester/O-triflouroacetyl, isopropyl ester/O-triflouroacetyl and isopropyl ester/O-pentafluoropropionyl derivatives on a capillary column containing permethylated β-cyclodextrin (Chirasil-Dex CB) as the stationary phase. Characteristic mass fragments are related to the ester groups while several ions are also common to derivatized monosaccharides.

Short and highly stereoselective total synthesis of d- ribo-configured ureido sugars

An highly stereoselective, flexible and very short synthetic approach to d- ribo-configured ureido monosaccharides of the aldose, aldonic acid and alditol series has been performed starting from the 5-(alditol-1- C-yl)-hydantoin intermediates, obtained via aldol-type addition reaction of hydantoin based building blocks to enantiomerically pure aldehydes. A study to assess the stereoselectivity of this reaction has been undertaken and a very high increase of diastereoselectivity was observed depending on the hydantoin protecting group. The imidazolidinone ring elaboration of 5-(alditol-1- C-yl)-hydantoin intermediates to give ureido sugar derivatives was studied.

TMAH-preparative thermochemolysis for the characterization of organic matter in densimetric fractions of a Mediterranean forest soil

Physical protection is one of the most important ways for stabilization of organic carbon in soils, and in order to properly manage soils as a sink for carbon, it is necessary to know how much organic carbon a given soil could protect and to have information on the molecular composition of this protected organic matter in soil. To this end, we studied individual horizons taken from a soil profile under Quercus rotundifolia stands over calcareous parent material. Horizons were subjected to a sequential extraction using solutions of sodium polytungstate (NaPT) of increasing density (1.6, 1.8 and 2.0) to differentiate five fractions: a free light, extractable without sonication, three occluded (extractable by sonication) and a dense (retained in the dense residue, after sonication). The obtained fractions were analyzed by preparative thermochemolysis followed by gas chromatography–mass spectrometry (GC/MS) in order to get some insight on the molecular composition. The total ion chromatograms obtained for the pyrolysates of both of the densimetric fractions show various series of fatty acids (as their methyl esters), n-alkanols (as their methyl ethers), methylated α,ω-diacids, methylated ω-hydroxyacids, various lignous subunits and permethylated deoxy aldonic acids derived from carbohydrates. The comparison of the distributions of the thermochemolysis products shows that organic carbon in the dense fractions of the deepest horizons were more influenced by a microbial reworking than the others dense fractions from the upper horizons. It is also the case for the occluded fraction 1 of the H horizon even the vegetal part of the organic carbon in that occluded fraction appears to have a non-woody origin. On the other hand, the dense fraction of the H horizon is strongly marked by vegetal origin.

Formation of carboxylic acids during degradation of monosaccharides

The formation of low molecular carboxylic and hydroxycarboxylic acids as well as sugar and deoxysugar acids from monosaccharides (D-glucose, D-fructose, D-arabinose, DL-glyceraldehyde, and 1,3-dihydroxyacetone) was studied in three different model systems: aqueous and alkaline solutions of potassium peroxodisulfate (K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>), and sodium hydroxide solution. In total, 3 low molecular carboxylic acids (formic, acetic and propionic), 24 hydroxycarboxylic acids, and 12 corresponding lactones were identified and quantified by GC/MS. Formic, acetic, and propionic acids were isolated by extraction with diethyl ether and directly analysed by GC/MS; hydroxycarboxylic acids and their lactones were monitored as their trimethylsilylated derivatives using the same method. Formic, acetic, L-lactic, glycollic, DL-2,4-dihydroxybutanoic acids and aldonic acids derived from the parent sugars were the most abundant compounds in all model systems. Within the models investigated, the yield of carboxylic acids and hydroxycarboxylic acids (together with their lactones) ranged between 9.3–22.2% (n/n) and between 3.6–116.9% (n/n), respectively. The amount of acids was significantly lower in aqueous solutions of K<sub>2</sub>S<sub>2</sub>O<sub>8</sub> than in the alkaline solutions. The data obtained indicate that lower carboxylic acids are formed by both subsequent reactions (oxidation and/or intramolecular Cannizzaro reaction) of the sugar fragmentation products and direct decomposition of some intermediates such as uloses or hydroperoxides derived from the parent sugars. The acids possessing the original sugar skeleton are formed as a result of sugar oxidation or benzilic acid type rearrangement of deoxyuloses. Lower acids may also be formed by a recombination of free radicals.

A new chemical process for catalytic conversion of d-glucose into lactic acid and gluconic acid

Abstract In this work, the catalytic conversion of monosaccharides, such as d -glucose, d -fructose, d -mannose, d -galactose, and d -xylose, into lactic acid and aldonic acid in an alkaline media using supported noble metal catalysts under flowing air was investigated. Thus far, the conventional chemical conversions of d -glucose into lactic acid, such as alkaline degradations and hot water reactions, involved large amounts of by-products including unidentified compounds. To improve the atom economy for the d -glucose conversion, we examined a one-pot reaction of d -glucose into lactic acid and gluconic acid with the alkaline degradation and the air oxidation using supported metal catalysts. It succeeded in yielding about 45 C-% of lactic acid and about 45 C-% of gluconic acid from d -glucose using Pt/C catalysts with a 1.0 mol L −1 of sodium hydroxide aqueous solution at 353 K under flowing air.

Nonvolatile Oxidation Products of Glucose in Maillard Model Systems: Formation of Saccharinic and Aldonic Acids and Their Corresponding Lactones

By using pyrolysis-gas chromatography-mass spectrometry-based methodologies, nonvolatile oxidation products of isotopically labeled glucose/glycine model systems were studied through a postpyrolytic in situ derivatization technique by using trimethylsilyldiethylamine. Analysis of the data indicated that the known reactive sugar intermediates such as glucosone and its deoxy derivatives can undergo in Maillard model systems three types of transformations: oxidation of the aldehydic groups into carboxylic acids, oxidative cleavage of alpha-dicarbonyl moieties into aldonic acids, and benzylic acid rearrangement of 1-deoxy-glucosone into saccharinic acids. The aldonic and saccharinic acids were identified through silylation of their lactone derivatives, and their origin was verified through (13)C-labeling studies. The following lactones were identified in glucose and glucose/glycine model systems: trans-dihydro-3,4-bis[(trimethylsilyl)oxy]-2(3 H)-furanone, cis-dihydro-3,4-bis[(trimethylsilyl)oxy]-2(3H)-furanone, 2-C-methyl-2,3,5-tris-O-(trimethylsilyl)-D-ribonic acid gamma-lactone, 3-deoxy-2,5,6-tris-O-(trimethylsilyl)-D-ribo-hexonic acid gamma-lactone, 2-deoxy-3,5-bis-O-(trimethylsilyl)-pentonic acid gamma-lactone, and 2,3,5-tris-O-(trimethylsilyl)-D-arabinonic acid gamma-lactone. The observed reduction in color and aroma in Maillard reactions performed under oxidative conditions may be attributed to the oxidation of reactive dicarbonyls into the corresponding carboxylic acids or their corresponding lactones.

<i>Paraconiothyrium</i> sp. KD-3由来の乳糖酸化酵素によるラクトビオン酸カルシウムの生産

Paraconiothyrium sp. KD-3の培養上清から乳糖酸化酵素を精製し，その性質を調べた．本酵素の分子量は54 kDaで分子内にFADを有していた．また酸素や2,6-ジクロロフェノールインドフェノールを電子受容体に用い，乳糖以外に，セロオリゴ糖，マルトオリゴ糖，D-グルコース，D-ガラクトース，D-キシロース，L-アラビノースなどを酸化し，各々のアルドン酸と過酸化水素を生成した．本酵素は安定性が市販のヘキソースオキシダーゼ剤に比べ高く，物質変換に適していた．通気，撹拌，pH調整しながら2L容リアクター中で反応液500 mLを反応させたところ，10-20%(w/v)の乳糖は完全にラクトビオン酸に変換された．この際，10%炭酸カルシウムスラリー添加によるpH制御が有効で，25% NaOHによる中和では酵素が徐々に失活した．カタラーゼの添加は，過酸化水素の分解による酵素安定化と溶存酸素濃度の上昇に効果的であった．陽イオン交換樹脂を担体に用い，シクロヘキシルカルボジイミド処理した固定化酵素を調製した．この固定化酵素はバッチ反応において18.5%(w/v)の乳糖を完全に変換することができた．D-ガラクトース，D-キシロース，L-アラビノースから，本酵素により対応するアルドン酸を得た．これらは，いずれも高いカルシウム安定性と，カルシウムイオンに対して比較的低い結合力を示した．

Thermodynamic characterization of substrate and inhibitor binding to Trypanosoma brucei 6‐phosphogluconate dehydrogenase

6-Phosphogluconate dehydrogenase is a potential target for new drugs against African trypanosomiasis. Phosphorylated aldonic acids are strong inhibitors of 6-phosphogluconate dehydrogenase, and 4-phospho-d-erythronate (4PE) and 4-phospho-d-erythronohydroxamate are two of the strongest inhibitors of the Trypanosoma brucei enzyme. Binding of the substrate 6-phospho-d-gluconate (6PG), the inhibitors 5-phospho-d-ribonate (5PR) and 4PE, and the coenzymes NADP, NADPH and NADP analogue 3-amino-pyridine adenine dinucleotide phosphate to 6-phospho-d-gluconate dehydrogenase from T. brucei was studied using isothermal titration calorimetry. Binding of the substrate (K(d) = 5 microm) and its analogues (K(d) =1.3 microm and K(d) = 2.8 microm for 5PR and 4PE, respectively) is entropy driven, whereas binding of the coenzymes is enthalpy driven. Oxidized coenzyme and its analogue, but not reduced coenzyme, display a half-site reactivity in the ternary complex with the substrate or inhibitors. Binding of 6PG and 5PR poorly affects the dissociation constant of the coenzymes, whereas binding of 4PE decreases the dissociation constant of the coenzymes by two orders of magnitude. In a similar manner, the K(d) value of 4PE decreases by two orders of magnitude in the presence of the coenzymes. The results suggest that 5PR acts as a substrate analogue, whereas 4PE mimics the transition state of dehydrogenation. The stronger affinity of 4PE is interpreted on the basis of the mechanism of the enzyme, suggesting that the inhibitor forces the catalytic lysine 185 into the protonated state.

Electricity production from twelve monosaccharides using microbial fuel cells

Direct generation of electricity from monosaccharides of lignocellulosic biomass was examined using air cathode microbial fuel cells (MFCs). Electricity was generated from all carbon sources tested, including six hexoses ( d-glucose, d-galactose, d(−)-levulose (fructose), l-fucose, l-rhamnose, and d-mannose), three pentoses ( d-xylose, d(−)-arabinose, and d(−)-ribose), two uronic acids ( d-galacturonic acid and d-glucuronic acid) and one aldonic acid ( d-gluconic acid). The mixed bacterial culture, which was enriched using acetate as a carbon source, adapted well to all carbon sources tested, although the adaptation times varied from 1 to 70 h. The maximum power density obtained from these carbon sources ranged from 1240 ± 10 to 2770 ± 30 mW m −2 at current density range of 0.76–1.18 mA cm −2. d-Mannose resulted in the lowest maximum power density, whereas d-glucuronic acid generated the highest one. Coulombic efficiency ranged from 21 to 37%. For all carbon sources tested, the relationship between the maximum voltage output and the substrate concentration appeared to follow saturation kinetics at 120 Ω external resistance. The estimated maximum voltage output ranged between 0.26 and 0.44 V and half-saturation kinetic constants ranged from 111 to 725 mg L −1. Chemical oxygen demand (COD) removal was over 80% for all carbon sources tested. Results from this study indicated that lignocellulosic biomass-derived monosaccharides might be a suitable resource for electricity generation using MFC technology.

Application of Squaric Acid Esters in Aminodeoxy Sugar Chemistry

Abstract The reaction of dimethyl squarate with aminodeoxy sugars, aminodeoxy alditols, amino aldonic acids, and glycosyl amines under neutral conditions furnished the squaric amide esters, which were converted in more alkaline media (pH ≈8) into the asymmetric squaric diamides. The unprotected squaric acid amide esters are suitable for constructing a specific anchor (spacer, linker) function that favorably influences the water-solubility of the resulting drugs and glycoconjugates.

Homochiral carbon branched piperidines from carbon branched sugar lactones: 4- C-methyl-deoxyfuconojirimycin (DFJ) and its enantiomer—removal of glycosidase inhibition

The value of readily available 2- C-methyl aldonic acids in short syntheses of carbon branched piperidines containing quaternary centers is demonstrated. The effect of the introduction of a 4- C-methyl group into piperidine imino sugar inhibitors of l-fucosidases and d-galactosidases is reported.

The Hofer–Moest decarboxylation of d-glucuronic acid and d-glucuronosides

Research was undertaken to effect the oxidative decarboxylation of glycuronosides. Experiments with free d-glucuronic acid and aldonic acids were also executed. Both anodic decarboxylation and variants of the Ruff degradation reaction were investigated. Anodic decarboxylation was found to be the only successful method for the decarboxylation of glucuronosides. It was, therefore, proposed that glycuronosides can only undergo a one-electron oxidation to form an acyloxy radical, which decomposes to form carbon dioxide and a C-5 radical, that is, a Hofer–Moest decarboxylation. The radical is subsequently oxidized to a cation by means of a second one-electron oxidation. The cation undergoes nucleophilic attack from the solvent (water), whose product (a hemiacetal) undergoes a spontaneous hydrolysis to yield a dialdose ( xylo-pentodialdose from d-glucuronosides).

Enzymatic synthesis of aldonic acids

Several aldonic acids ( d-mannonic, d-galactonic, d-xylonic, 2-deoxy- d-arabinohexonic (2-deoxy- d-gluconic)) were prepared on a scale of several grams by a simple oxidation catalyzed by glucose oxidase in pure water.

A new environmental friendly method for the preparation of sugar acids via catalytic oxidation on gold catalysts

A novel and efficient way of producing of aldonic acids is reported. The selective catalytic oxidation of monosaccharides (arabinose, ribose, xylose, lyxose, mannose, rhamnose, glucose, galactose, N-acetyl-glucosamine) and disaccharides (lactose, maltose, cellobiose, melibiose) on Au, Pd and Pt catalysts was investigated. By using the gold catalyst, a total selectivity with respect to aldonic acids and a high catalytic activity for all investigated sugars was found. The reaction conditions for the production of maltobionic and lactobionic acids via oxidation on gold catalysts were optimised. A high long-term stability of two different gold catalysts for the oxidation of maltose and lactose, respectively, was found.

New biotransformations of some reducing sugars to the corresponding (di)dehydro(glycosyl) aldoses or aldonic acids using fungal pyranose dehydrogenase

The fungal enzyme pyranose dehydrogenase (PDH) (EC 1.1.99.29) purified to apparent homogeneity from culture media of Agaricus meleagris catalyzed the substrate-dependent C-1, C-2, C-3, C-1,3′ or C-2,3(′) (di)oxidation of a number of mono- and disaccharides with 1,4-benzoquinone as an electron acceptor. d-Ribose, d-allose, d-gulose and d-talose were oxidized to the corresponding aldonic acids. l-Arabinose was converted exclusively to 2-dehydro- l-arabinose ( l- erythro-pentos-2-ulose) whereas d-xylose underwent competing C-2 and C-3 oxidation followed by dioxidation to 2,3-didehydro- d-arabinose ( d- glycero-pentos-2,3-diulose). The major final oxidation products of maltose and cellobiose were the novel compounds 2,3′-didehydromaltose and 2,3′-didehydrocellobiose (α- and β- d- ribo-hexos-3-ulopyranosyl-(1 → 4)- d- arabino-hexos-2-ulose), formed via 2- and 3′-monooxidation intermediates. Minor concomitant (di)oxidation at C-1,(3′) to the corresponding bionic acids also took place. Maltotriose was preferentially oxidized at C-3″ of the terminal glucopyranosyl unit and at C-1 of the reducing moiety. The structures of these sugar oxidation products were established by in situ 1D and 2D NMR spectroscopy and ESI–MS. Based on HPLC analysis, conversions of (glycosyl)aldoses in non-buffered systems were nearly quantitative within 3–24 h, depending on the substrate. As the enzyme allows an easy access to highly reactive di- or tricarbonyl sugars, it might become a useful catalyst in carbohydrate chemistry.

Catalytic Promiscuity in Dihydroxy-Acid Dehydratase from the Thermoacidophilic Archaeon Sulfolobus solfataricus

Dihydroxy-acid dehydratase (DHAD) is one of the key enzymes involved in the biosynthetic pathway of the branched chain amino acids. Although the enzyme has been purified and characterized in various mesophiles, including bacteria and eukarya, the biochemical properties of DHAD from hyperthermophilic archaea have not yet been reported. In this study we cloned, expressed in Escherichia coli, and purified a DHAD homologue from the thermoacidophilic archaeon Sulfolobus solfataricus, which grows optimally at 80 degrees C and pH 3. The recombinant S. solfataricus DHAD (rSso_DHAD) showed the highest activity on 2,3-dihydroxyisovalerate among 17 aldonic acids tested. Interestingly, this enzyme also displayed high activity toward d-gluconate and some other pentonic and hexonic sugar acids. The k(cat)/K(m) values were 140.3 mM(-1) s(-1) for 2,3-dihydroxyisovalerate and 20.0 mM(-1) s(-1) for d-gluconate, respectively. A possible evolutionary explanation for substrate promiscuity was provided through amino acid sequence alignments of DHADs and 6-phosphogluconate dehydratases from archaea, bacteria and eukarya.

Production of Aldonic Acids from Monosaccharides by Washed Cells of Burkholderia cepacia and their Calcium Binding Capability

Microbial oxidation of monosaccharides and calcium binding capability of the resulting aldonic acids were investigated. When washed cells of a strain of Burkholderia cepacia were shaken with 15% (w/v) D-galactose, D-mannose, D-xylose and L-arabinose in the presence of CaCO3, corresponding aldonates were produced with yields of 99.4, 93.6, 94.5 and 93.0%, respectively, after 2 d for D-galactose and 8 d for the others. Free aldonic acids of high purity were obtained from the reaction supernatants by the treatment with activated carbon followed by cation exchange resin. The aldonic acids showed lower sequestering capacities compared with EDTA and citrate, suggesting weak binding with a calcium ion. Such weak calcium binding and high aqueous solubility of the aldonates suggested their possible application not to builders of detergents, but to functional saccharides that promote intestinal absorption of minerals.

The Development of Cement and Concrete Additive

The present work attempted to utilize xylose by converting it to an aldonic acid. In the present study, xylose was converted to xyloni acid by using commercial glucose oxidase enzyme, palladium catalysis, and microbial bioconversion. The enzyme conversion was successfully done using a commercial glucose oxidase. The microbial conversion with Gluconobactor oxydans proceeded even with the presence of a large amount of lignosulfonate. Thus obtained xylonic acid products were evaluated as a cement dispersing agent in cement and concrete tests. It was found that xylonic acid is approximately twice as effective as lignosulfonate. Xylonic acid can be effectively utilized in concrete water reducer application.

Amadori ketoses with calcium hydroxide and the Kiliani reaction on 1-deoxy ketoses: two approaches to the synthesis of saccharinic acids

Saccharinic acids (2- C-methyl aldonic acids) may be formed by treatment of Amadori ketoses with calcium hydroxide or by the Kiliani reaction of 1-deoxy ketoses with cyanide. Thus (i) N, N-dibenzyl or N, N-dimethyl-1-amino-1-deoxy- d-fructose with aqueous calcium hydroxide afforded 2- C-methyl- d-ribono-1,4-lactone under green conditions and (ii) reaction of methyl magnesium bromide with 2,3- O-isopropylidene- d-erythronolactone gave 1-deoxy-3,4- O-isopropylidene- d-ribulose, which on subsequent treatment with aqueous sodium cyanide and hydrolysis, formed 2- C-methyl- d-arabinono-1,4-lactone. Such branched sugar lactones are likely to be of value as chirons containing branched carbon chains.

Catalytic properties of Pd–Tl/SiO 2 systems in the reaction of liquid phase oxidation of aldoses

The influence of thallium addition on the catalytic properties of palladium catalysts supported on SiO 2 in the reaction of aldoses (glucose and lactose) oxidation to aldonic acid was studied. It was found that thallium does not have any activity by itself, but acts as “promoter” for the catalytic activity and selectivity of monometallic Pd/SiO 2 catalysts. The XRD studies proved the presence of intermetallic compounds, which probably increases activity and selectivity of bimetallic catalysts in those reactions. The same interaction was found using ToF-SIMS. The TPO studies show that palladium oxidation occurs at much higher temperatures than in the case of thallium. A reaction involving bimetallic catalysts in oxidizing atmosphere at 333 K should not lead to surface oxidation of palladium and thus their deactivation.