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Chemoselective reactions can contribute to streamlining synthesis of pharmaceuticals, agrochemicals, and other functional molecules by avoiding use of protecting groups. In this review, copper catalysts were demonstrated useful for developing two types of chemoselective reactions: C-C bond-forming reactions at an anomeric carbon of unprotected aldoses and difunctionalization reaction of C-C multiple bonds. The "soft" nucleophilic copper species exhibit orthogonal reactivity toward "hard" polar functional groups and preferentially react with "soft" functional groups. The catalysis also controls stereoselectivity and/or regioselectivity to provide value-added products from readily available feedstock compounds.

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.

New sugar hydrazones incorporating furan and/or 1,3,4-thiadiazole ring systems were synthesized by reaction of the corresponding hydrazide with different aldose sugars. Heterocyclization of the formed hydrazones afforded the derived acyclic nucleoside analogues possessing the 1,3,4-oxadiazoline as modified nucleobase via acetylation followed by the heterocyclization process. The anticancer activity of the synthesized compounds was studied against human liver carcinoma cell (HepG-2) and at human normal retina pigmented epithelium cells (RPE-1). High activities were revealed by compounds 3, 12 and 14 with IC50 values near to that of the reference drug doxorubicin.

Poly-trans-[(2-carboxyethyl)germasesquioxane], Ge-132, is a water-soluble organogermanium compound reported to have physiological effects such as immunostimulatory and antiviral effects. The hydrolysate of Ge-132, 3-(trihydroxygermyl)propanoic acid (THGP), can interact with diols; therefore, it likely can interact with diol-containing sugars in sugar chains, glycoproteins, and glycolipids, which have important physiological functions. In this study, we quantitatively assessed the ability of THGP to interact with saccharides using nuclear magnetic resonance (NMR) spectroscopy and THGP derivatives. THGP was complexed by binding its trihydroxy group with saccharides in aqueous solutions via the cis-diol group rather than the trans-diol group. The spectra of THGP and monosaccharides indicated that THGP has a higher affinity for ketose than aldose. Moreover, the complexation ability between THGP and saccharides was influenced by the number of cis-diol groups on the saccharide structure. Thus, interactions of THGP with important biological sugars might be involved in the physiological functions of Ge-132.

A variety of scientific and technical fields rely on the analysis of monosaccharides (sugars). However, the multiple isomer forms of individual monosaccharides have long hampered their analyses in complex samples: significant chromatographic co-elution often leads to the loss of information on individual compounds. In addition, the chromatographic enantiomer resolution of monosaccharides has of course received less attention than molecular resolution. This would be expected in the case of rare monosaccharides, but enantiomer resolution of erythrose and threose have also received relatively little attention in the literature. Methods that are capable of the simultaneous molecular and enantiomer resolution/identification of suites of monosaccharides in single complicated mixtures are desirable. Here we report the results of attempts to resolve mixtures of the enantiomers of all three‑carbon (3C) to six‑carbon (6C) aldehyde (aldose) monosaccharides as acetal-trifluoroacetyl (acetal-TFA) derivatives by gas chromatography–mass spectrometry (GC–MS); glyceraldehyde (3C) is included as its TFA-only derivative. After a relatively simple derivatization procedure, the analyzed acetals are in the ethyl-, 2-propyl- and 2-butyl-TFA forms. Using chiral (cyclodextrin) and non-chiral (DB-17) GC columns we show that these enantiomer pairs can be baseline resolved - depending on the derivative/GC column combination - and that any single acetal/TFA combination can resolve the majority of enantiomers in a single run. Importantly, ribose and lyxose form only one significant (in abundance) stereoisomer with all derivative combinations while other monosaccharides form a maximum of only two significant stereoisomers: this greatly reduces obfuscation due to crowding on a given chromatogram. We conclude that GC–MS of acetal-TFA derivatives is the best (overall) analytical technique, to date, for the analysis of aldose-monosaccharide enantiomer ratios and reduces chromatogram clutter by favorably restricting the proliferation of monosaccharide isomers.

(R)-2-amino-2-ethoxycarbonylsuccinimide (ASI-2) is a key intermediate used in the pharmaceutical industry and is valuable for the industrial synthesis of ranirestat, which is a potent aldose reductase inhibitor. ASI-2 was synthesized in a process combining chemical synthesis and bioconversion. Bioconversion in this study is a key reaction, since optically active carboxylic acid derivative ((R)-1-ethyl hydrogen 3-benzyloxycarbonylamino-3-ethoxycarbonylsuccinate, Z-MME-AE) is synthesized from a prochiral ester, diethyl 2-benzyloxycarbonylamino-2-ethoxycarbonylsuccinate, Z-MDE-AE, at a theoretical yield of 100%. Upon screening for microorganisms that asymmetrically hydrolyze Z-MDE-AE, Bacillus thuringiensis NBRC13866 was found. A novel esterase EstBT that produces Z-MME-AE was purified from Bacillus thuringiensis NBRC13866 and was stably produced in Escherichia coli JM109 cells. Using EstBT rather than porcine liver esterase (PLE), ASI-2 was synthesized with a 17% higher total yield by a novel method, suggesting that the esterase EstBT is a PLE substitute enzyme and therefore, may be of interest for future industrial applications.

Many species use Fe+2 and H2O2 to oxidize a wide variety of compounds to simpler molecules. Both pathogen killing by leukocytes (neutrophils and lymphocytes) and degradation of cellulose by brown rot fungi rely on excretion of Fe+2 ions and H2O2, the Fenton reagent. To elucidate the mechanism of Fenton oxidation of carbohydrates, β1,3 glucan (laminaran), a major fungal wall polysaccharide, was oxidized using a molar ratio of monomer/Fe+2/H2O2 of 10:1:1 (primarily). We labeled the reaction products and profiled them as fluorescent-labeled molecules in polyacrylamide gels and as hydrophobic-tagged molecules using reverse phase liquid chromatography/mass spectrometry (HPLC/MS). Sub-stoichiometric concentrations of Fe+2 and H2O2 fragmented laminaran into smaller molecules containing carbonyl and carboxylic acid groups visible on fluorescent-labeled carbohydrate polyacrylamide gel electrophoresis. HPLC/MS analysis of glucan fragments showed masses consistent with six classes of molecules: aldoses, dialdoses, uronic acids, hexosuloses, aldonic acids, and hexulosonic acids. The results were consistent with published mechanisms where hydrogen radical (H•) abstraction from a C–H or O–H bond begins a cascade of reactions leading to 1) C–C bond cleavage to produce aldose/dialdose pairs; 2) oxo-group (O = ) addition to produce uronic and aldonic acids; 3) hydroxyl group (HO-) addition to produce gluconolactone and hexosuloses; and 4) hexulosonic acids. Most products resulted from regioselective H• abstractions characteristic of oxidations by ferryl-oxo ion [(Fe O)+2] or perferryl-oxo ion [(Fe O)+3] in close contact with specific positions in the glycan. Therefore, oxidations initiated by regioselectively-bound Fe ions were the predominant initiators of polysaccharide degradations.

Pentoses represent monosaccharides with five carbon atoms. They are organized into two main groups, aldopentoses and ketopentoses. There are eight aldopentoses and four ketopentoses and each ketopentose corresponds to two aldopentoses. Only D-xylose, D-ribose, and L-arabinose are natural sugars, but others belong to rare sugars that occur in very small quantities in nature. Recently, rare pentoses attract much attention because of their great potentials for commercial applications, especially as precursors of many important medical drugs. Pentoses Izumoring strategy provides a complete enzymatic approach to link all pentoses using four types of enzymes, including ketose 3-epimerases, aldose-ketose isomerases, polyol dehydrogenases, and aldose reductases. At least 10 types of epimerases and isomerases have been used for biotransformation of all aldopentoses and ketopentoses, and these enzymes are reviewed in detail in this article.

Palladium-catalyzed cross-couplings of O-peracylated and O-permethylated 2,6-anhydro-aldose tosylhydrazones with aryl halides were studied under thermic conditions in the presence of LiOtBu and phosphine ligands. The reactions gave the corresponding aryl substituted exo-glycals as mixtures of diastereomers in 11–75% yields. The transformations represent a new access to these types of glycomimetic compounds. The double bond of some aryl substituted exo-glycals was saturated to give good yields of benzylic C-glycosyl derivatives.

We describe here the characterization of a novel enzyme called aldose-aldose oxidoreductase (Cc AAOR; EC 1.1.99) from Caulobacter crescentus. The Cc AAOR exists in solution as a dimer, belongs to the Gfo/Idh/MocA family and shows homology with the glucose-fructose oxidoreductase from Zymomonas mobilis. However, unlike other known members of this protein family, Cc AAOR is specific for aldose sugars and can be in the same catalytic cycle both oxidise and reduce a panel of monosaccharides at the C1 position, producing in each case the corresponding aldonolactone and alditol, respectively. Cc AAOR contains a tightly-bound nicotinamide cofactor, which is regenerated in this oxidation-reduction cycle. The highest oxidation activity was detected on D-glucose but significant activity was also observed on D-xylose, L-arabinose and D-galactose, revealing that both hexose and pentose sugars are accepted as substrates by Cc AAOR. The configuration at the C2 and C3 positions of the saccharides was shown to be especially important for the substrate binding. Interestingly, besides monosaccharides, Cc AAOR can also oxidise a range of 1,4-linked oligosaccharides having aldose unit at the reducing end, such as lactose, malto- and cello-oligosaccharides as well as xylotetraose. (1)H NMR used to monitor the oxidation and reduction reaction simultaneously, demonstrated that although D-glucose has the highest affinity and is also oxidised most efficiently by Cc AAOR, the reduction of D-glucose is clearly not as efficient. For the overall reaction catalysed by Cc AAOR, the L-arabinose, D-xylose and D-galactose were the most potent substrates.

In this work, it was found that some monosaccharides normally used to stabilize enzymes at high temperatures, however, actually caused a deactivation of chloroperoxidase (CPO). The red native CPO was converted to a stable pale species that lost enzymatic activity. This deactivation was irreversible and was sensitive to temperature. It was different from the general peroxide-mediated deactivation of CPO. Data from measurement of chlorination activity as well as UV-vis, fluorescent, and CD spectral analysis indicated that monosaccharide-induced deactivation can be attributed to precipitation of protein in the presence of monosaccharide and the interaction of the aldehyde group of sugar with amino groups, especially the terminal amino group, on proteins to form Schiff bases which then rearrange to the stable amino ketone. It is further noted that the deactivation efficiency depends on the stereostructure of monosaccharides. D-glucose was the most efficient inactivating agents due to its aptitude for both of the interactions mentioned in the above paragraphs. The deactivation was specific to aldose. No deprivation of the heme iron was involved in this deactivation.

The methanolic extract from the flower buds of Prunus mume, cultivated in Zhejiang province, China, showed an inhibitory effect on aldose reductase. From the methanolic extract, five new acylated sucroses, mumeoses F-J, were isolated together with 29 known compounds. The chemical structures of the new compounds were elucidated on the basis of chemical and physicochemical evidence. The inhibitory effects of the isolated compounds on aldose reductase were also investigated. Acylated quinic acid analogs, which are one of the major compounds of the flower buds of P. mume, were shown to substantially inhibit aldose reductase. In particular, mumeic acid-A was found to exhibit a potent inhibitory effect [IC50=0.4 µm].

Glucitol, also known as sorbitol, is a major photosynthetic product in plants from the Rosaceae family. This sugar alcohol is synthesized from glucose-6-phosphate by the combined activities of aldose-6-phosphate reductase (Ald6PRase) and glucitol-6-phosphatase. In this work we show the purification and characterization of recombinant Ald6PRase from peach leaves. The recombinant enzyme was inhibited by glucose-1-phosphate, fructose-6-phosphate, fructose-1,6-bisphosphate and orthophosphate. Oxidizing agents irreversibly inhibited the enzyme and produced protein precipitation. Enzyme thiolation with oxidized glutathione protected the enzyme from insolubilization caused by diamide, while incubation with NADP+ (one of the substrates) completely prevented enzyme precipitation. Our results suggest that Ald6PRase is finely regulated to control carbon partitioning in peach leaves. Fil: Hartman, Matias Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Figueroa, Carlos Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Arias, Diego Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Iglesias, Alberto Alvaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina

6-Tuliposide A {6-O-(4-hydroxy-α-methylenebutyryl)-D-glucopyranose} was isolated from thunberg spiraea (Spiraea thunbergii) leaves. Acid-hydrolysis of this compound generated tulipalin A (α-methylene-γ-butyrolactone). This compound is thus considered as a precursor of insecticidal tulipalin A.

As a model experiment for the stereoselective synthesis of optically active cis-α,β-dibenzyl-α-hydroxy-γ-butyrolactone, (2R, 3S)-2-benzyl-2-hydroxy-3-(3,4-methylenedioxybenzyl)-γ-butyrolactone (3) was stereoselectively synthesized from L-(+)-arabinose.

Two unidentified sugars were isolated from rose petals using HPLC. The isolated compounds were identified as methyl β-glucopyranoside and xylose using (1)H-NMR, (13)C-NMR, and GC-MS. Methyl β-glucopyranoside and xylose were distributed in three cultivars tested relatively in large amounts. These results indicate that methyl β-glucopyranoside and xylose occur universally as soluble sugar constituents in roses.

A practical total synthesis of (2S,3S,4R)-l-O-(α-d-galactopyranosyl)-N-hexacosanoyl-2-amino-l,3,4-octadecanetriol (KRN7000), an antitumorial and immunostimulatory glycosphingolipid derived from agelasphins, was achieved in 14 steps starting from d-lyxose in a 16% overall yield.

Rare sugars have recently drawn attention because of their potential applications and huge market demands in the food and pharmaceutical industries. All L-hexoses are considered rare sugars, as they rarely occur in nature and are thus very expensive. L-Hexoses are important components of biologically relevant compounds as well as being used as precursors for certain pharmaceutical drugs and thus play an important role in the pharmaceutical industry. Many general strategies have been established for the synthesis of L-hexoses; however, the only one used in the biotechnology industry is the Izumoring strategy. In hexose Izumoring, four entrances link the D- to L-enantiomers, ketose 3-epimerases catalyze the C-3 epimerization of L-ketohexoses, and aldose isomerases catalyze the specific bioconversion of L-ketohexoses and the corresponding L-aldohexoses. In this article, recent studies on the enzymatic production of various L-hexoses are reviewed based on the Izumoring strategy.

The scope of a one-pot tandem approach for the synthesis of C-1 alkyl iminoalditol derivatives with a Staudinger/aza-Wittig/Grignard cascade has been evaluated. The reaction conditions have been optimized for two azidodeoxy aldose substrates and a range of Grignard reagents. The nature of both, substrate as well as nucleophile, was found to control the stereoselectivity of the alkyl addition to the cyclic iminium intermediate at position C-1. This approach enabled the synthesis of a collection of C-alkyl iminoalditols, which were biologically evaluated as inhibitors against a set of standard glycoside hydrolases. All compounds were found to exhibit highly selective inhibition of β-glucosidase activity.

Glycosides, clausenosides A and B, and carbazole alkaloids, clausenaline A, claulamine A, and claulamine B, together with 50 known compounds, were isolated from the stems of Clausena lansium. Their structures were determined by means of spectroscopic methods, including that of CD and 1D/2D NMR analysis. Claulamine A has a 1-oxygenated carbazole skeleton with a rare 2,3-lactone ring, and claulamine B represents an hitherto unknown acetal carbazole alkaloid. Thirty-one of the isolated known compounds were evaluated in various assays for anti-inflammatory activity. Among them, imperatorin, isoheraclenin, and osthol exhibited selective and potent inhibition of formyl-l-methionyl-l-leucyl-l-phenylalanine/cytochalasin B (fMLP/CB)-induced superoxide anion generation, and lansiumarin C also decreased nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production in lipopolysaccharide (LPS)-induced macrophages. In addition, 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. The absolute configurations of the sugar moieties in clausenosides A and B were determined with this modified method.

The O-glycosidation of hydroxysuccinimides and hydroxyphthalimides with a variety of aldose derived propargyl 1,2-orthoesters under the gold(III)-catalyzed glycosidation conditions is reported. A wide range of hydroxysuccinimidyl and hydroxyphthalimidyl glycosides were synthesized from corresponding glycosyl orthoesters including glucosyl, mannosyl, galactosyl, ribofuranosyl, arabinofuranosyl, lyxofuranosyl and xylofuranosyl using gold catalysis repertoire. The protocol is identified to be compatible for the synthesis of aminooxy glycosides of higher oligosaccharides as well.

Phenylboronic acid esters are formed by the three common 2-deoxy aldoses: 2-deoxy-d-erythro-pentose ('2-deoxy-d-ribose'), 2-deoxy-d-lyxo-hexose ('2-deoxy-d-galactose'), and 2-deoxy-d-arabino-hexose ('2-deoxy-d-glucose'). The major species that was formed from equimolar quantities of boronic acid and the aldose, was the 3,4-monoester of the pentopyranose in a skew-boat conformation, and the 4,6-monoester in the case of the two hexopyranoses. A double molar quantity of boronic acid led, for both 2-deoxy-hexoses, to the diester of the open-chain aldehydo isomer as the major product: the 3,5:4,6-diester for the lyxo-configured deoxy-hexose, and the 3,4:5,6-diester of the arabino-configured isomer. Minor products of all reactions were identified by a combined NMR/DFT methodology.

In order to investigate SAR regarding proximal phenyl ring in novel C-aryl glucoside SGLT2 inhibitors containing a thiazole motif, a series of chemical modifications on proximal phenyl ring was conducted. During a series of lead optimization efforts, ortho-allyloxyphenyl 10p or ortho-hydroxyphenyl 11a showed subnanomolar inhibitory activity against hSGLT2.

3,12-Dihydroxy-cis-3,4-methylenedodecanoic acid 3-O-β-d-glucopyranoside, trivially named litchioside C (1), the first cyclopropyl-containing fatty acid glycoside, was isolated along with three previously uncharacterized galactosylacylglycerols from the seeds of Litchi chinensis. Its structure was established on the basis of spectroscopic analysis including HRESIMS and 2D NMR spectra. Its antioxidant and antibacterial activities were evaluated and its biogenetic pathway was discussed.

This research communication is toward the investigation of the antibacterial, antifungal and antioxidant activities of the synthesized compounds 1-(4′-O-β- d -glucopyranosyloxy-2′-hydroxyphenyl)-3-aryl-propane-1,3-diones (5a)–(5h). These compounds have been obtained by the interaction of α-acetobromoglucose with 1-(2′,4′-dihydroxyphenyl)-3-aryl-propane-1,3-diones (3a)–(3h) under anhydrous condition and at lower temperature. The structures of these newly synthesized O-β- d -glucopyranosides were established on the basis of chemical, elemental, and spectral analyses. Further, the compounds (5b), (5c), (5d) and (5g) showed potent antibacterial and antifungal activity. A good correlation was obtained between the theoretical predictions of bioavailability using Lipinski’s rule-of-five and experimental verification.

Fluorescently labeled derivatives of a xyloglucan (XG) nonasaccharide Glc(4)Xyl(3)Gal(2) (XLLG) were used as glycosyl acceptors in assays of xyloglucan endotransglycosylase (XET) from germinated nasturtium (Tropaeolum majus) seeds. We have investigated how the type of the oligosaccharide label influences the kinetic parameters of the reaction. The fluorescent probes used to label XLLG were anthranilic acid (AA), 8-aminonaphtalene-1,3,6-trisulfonic acid (ANTS), fluorescein isothiocyanate (FITC), and sulforhodamine (SR), respectively. The obtained data were compared with those of the reactions where aldose and/or alditol forms of tritium-labeled xyloglucan-derived nonasaccharide served as the respective acceptors. Modification at C-1 of the reducing-end glucose in XLLG by substitution with the fluorophore markedly affected the kinetic parameters of the reaction. The Michaelis constants K(m) for individual acceptors increased in the order [1-(3)H]XLLGXLLG-SR[1-(3)H]XLLGolXLLG-FITCXLLG-ANTSXLLG-AA, while the turnover numbers characterized by k(cat) decreased in the order XLLG-FITCXLLG-SRXLLG-ANTS[1-(3)H]XLLGol[1-(3)H]XLLGXLLG-AA. Catalytic efficiency (expressed as k(cat)/K(m)) with XLLG labeled with SR or FITC was 15 and 28 times, respectively, higher than with the tritium-labeled natural substrate [1-(3)H]XLLG. Comparison of the kinetic parameters found with acceptors labeled with different types of labels enables to select the most effective substrates for the high-throughput assays of XET.

Condensation between unprotected aldoses and dibenzoylmethane catalyzed by NaHCO3 in the cosolvents EtOH and H2O (4:1) under microwave irradiation gave aryl ketone β-C-glycosides 6b–i in higher yields (from 50% with C-riboside 6g up to 99% with C-glucoside 6b) and better anomeric selectivities (β-configuration >95%) in a shorter reaction time (90 min), compared with previous conventional methodologies. This method provides an attractive alternative to the existing means for the preparation of high value ketone β-C-glycosides.

Synthesis of a series of novel (6-deoxy-glycopyranosid-6-yl) sulfone derivatives has been achieved using a general synthetic strategy. Yields were excellent in every case. The synthetic compounds were evaluated for their biological potential against Ca 2+ -ATPase, an important enzyme involves in tranporting Ca 2+ across the cell membranes.

The activity of ribose-5-phosphate isomerases (RpiB) from Clostridium difficile for D-ribose isomerization was optimal at pH 7.5 and 40 degrees C, while that from Thermotoga maritima for L-talose isomerization was optimal at pH 8.0 and 70 degrees C. C. difficile RpiB exhibited activity only with aldose substrates possessing hydroxyl groups oriented in the right-handed configuration (Fischer projections) at the C2 and C3 positions, such as D-ribose, D-allose, L-talose, L-lyxose, D-gulose, and L-mannose. In contrast, T. maritima RpiB displayed activity only with aldose substrates possessing hydroxyl groups configured the same direction at the C2, C3, and C4 positions, such as the D- and L-forms of ribose, talose, and allose.

A recombinant L-fucose isomerase from Caldicellulosiruptor saccharolyticus was purified as a single 68 kDa band with an activity of 76 U mg(-1). The molecular mass of the native enzyme was 204 kDa as a trimer. The maximum activity for L-fucose isomerization was at pH 7 and 75 degrees C in the presence of 1 mM Mn(2+). Its half-life at 70 degrees C was 6.1 h. For aldose substrates, the enzyme displayed activity in decreasing order for L-fucose, with a k (cat) of 11,910 min(-1) and a K (m) of 140 mM, D-arabinose, D-altrose, and L-galactose. These aldoses were converted to the ketoses L-fuculose, D-ribulose, D-psicose, and L-tagatose, respectively, with 24, 24, 85, 55% conversion yields after 3 h.

The first synthesis of adicardin, a compound with anti-chronic renal failure activity isolated from Hydrangea macrophylla, has been described. The structures of the target compound and intermediates have been validated by MS, NMR, and identical with the natural product.

Two new phenolic glycosides were isolated from the seeds of Cucurbita moschata. Their structures were elucidated as (2-hydroxy)phenylcarbinyl 5-O-benzoyl-beta-D-apiofuranosyl(1-->2)-beta-D-glucopyranoside (1) and 4-beta-D-(glucopyranosyl hydroxymethyl)phenyl 5-O-benzoyl-beta-D-apiofuranosyl(1-->2)-beta-D-glucopyranoside (2) on the basis of spectroscopic analysis and chemical evidence.

Two new dihydrochalcone glycosides named 6''-O-acetyltrilobatin (1) and 3''-O-acetylphloridzin (2) as well as four known compounds were isolated from the leaves of Lithocarpus litseifolius (Hance) Chun (family Fagaceae). Their structures were elucidated on the basis of spectroscopic analyses. The phenomena of C-H --> C-D exchange were observed in NMR spectra of the isolated phenolic components when measured in deuterated methanol.

We purified recombinant glucose-6-phosphate isomerase from Pyrococcus furiosus using heat treatment and Hi-Trap anion-exchange chromatography with a final specific activity of 0.39 U mg(-1). The activity of the glucose-6-phosphate isomerase for L: -talose isomerization was optimal at pH 7.0, 95 degrees C, and 1.5 mM Co(2+). The half-lives of the enzyme at 65 degrees C, 75 degrees C, 85 degrees C, and 95 degrees C were 170, 41, 19, and 7.9 h, respectively. Glucose-6-phosphate isomerase catalyzed the interconversion between two different aldoses and ketose for all pentoses and hexoses via two isomerization reactions. This enzyme has a unique activity order as follows: aldose substrates with hydroxyl groups oriented in the same direction at C2, C3, and C4C2 and C4C2 and C3C3 and C4. L: -Talose and D: -ribulose exhibited the most preferred substrates among the aldoses and ketoses, respectively. L: -Talose was converted to L: -tagatose and L: -galactose by glucose-6-phosphate isomerase with 80% and 5% conversion yields after about 420 min, respectively, whereas D: -ribulose was converted to D: -ribose and D: -arabinose with 53% and 8% conversion yields after about 240 min, respectively.

Sesquiterpene glucoside was isolated from the aqueous extract of the aerial parts of Dryopteris fragrans (L.) schot. Three new sesquiterpene glucoside xianglinmaojuesides A–C ( 1 – 3 ), 3β,11-dihydroxy-drim-8 (12)-en-11-O-β- d -glucopyranoside ( 1 ), 3β,11-dihydroxy-drim-8(12)-en-3-O-β- d -glucopyranoside ( 2 ), and 11,14-dihydroxy-drim-8(12)-en-11-O-β- d -glucopyranoside ( 3 ) were finally obtained by reversed-phase HPLC and their structures were elucidated by HRESIMS and 1D, 2D NMR analyses.

Thermus thermophilus HB8 is a hyperthermophilic bacterium, thriving at environmental temperature near 80 degrees C. The genomic analysis of this bacterium predicted 18 genes for proteins belonging to the short-chain dehydrogenase/reductases (SDR) superfamily, but their functions remain unknown. A SDR encoded in a gene (TTHA0369) was chosen for functional and structural characterization. Enzymatic assays revealed that the recombinant tetrameric protein has a catalytic activity as NAD(+)-dependent aldose 1-dehydroganse, which accepts various aldoses such as d-fucose, d-galactose, d-glucose, l-arabinose, cellobiose and lactose. The enzyme also oxidized non-sugar alicyclic alcohols, and was competitively inhibited by hexestrol, 1,10-phenanthroline, 2,3-benzofuran and indole. The enzyme was stable at pH 2-13 and up to 85 degrees C. We have determined the crystal structure of the enzyme-NAD(+) binary complex at 1.65A resolution. The structure provided evidence for the strict coenzyme specificity and broad substrate specificity of the enzyme. Additionally, it has unusual features, aromatic-aromatic interactions among Phe141 and Phe249 in the subunit interface and hydrogen networks around the C-terminal Asp-Gly-Gly sequence at positions 242-244. Stability analysis of the mutant D242N, F141A and F249A enzymes indicated that the two unique structural features contribute to the hyperthermostability of the enzyme. This study demonstrates that aldose 1-dehydrogenase is a member of the SDR superfamily, and provides a novel structural basis of thermostability.

Mono- and diacylated derivatives of galactopyranosyl amines were obtained from d -galactose, via aminated intermediates prepared by reaction of 6-deoxy-6-iodo-1,2:3,4-di- O -isopropylidene-α- d -galactopyranose with 1,3-propanediamine, 1,2-ethanediamine or ethanolamine. Monoacylated derivatives displayed antitubercular activity.

Two new monoterpene glycosides named bidensmenthosides A, B and a new (+)-jasmololone glucoside, were isolated from the air-dried whole plant of Bidens parviflora Willd. Their structures were determined as (1S, 3S, 4R)-3-hydroxy-p-menth-6-one 3-O-beta-D-glucopyranoside (1), (3R, 4R)-3-hydroxy-p-menth-1 (2)-en-6-one 3-O-beta-D-glucopyranoside (2) and (4R)-hydroxy-3-methyl-2-(2 Z-pentenyl)-cyclopent-2-enone 4-O-beta-D-glucopyranoside (3) based on spectroscopic analysis and physiochemical properties, respectively. The bidensmenthosides A, B and aglycone of 3 were found to reduce 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radicals.

Four new water-soluble constituents, oblongaroside A (1), oblongar ester A (2), oblongaroside B (3), and oblongaroside C (4), were isolated along with four known compounds: 4-O-beta-D-glucopyranosyl-3-hydroxybenzalcohol (5), 7-methoxyl-4-O-beta-D-glucopyranosyl-3-hydroxybenzalcohol (6), 4-O-beta-D-glucopyranosyl-3-hydroxybenzoic acid (7), and 3,4-dihydroxybenzoic acid (8) from the leaves of Ilex oblonga. Identification of their structures was achieved by 1D and 2D NMR experiments, including (1)H-(1)H COSY, NOESY, HMQC, and HMBC methods and FAB mass spectral data.

The new compound (R)-4-phenyl-2-O-[beta-d-xylopyranosyl(1 --> 6)-beta-D-glucopyranosyl]butane (1) and its epimer (2), together with (R)-4-phenyl-2-O-beta-D-glucopyranosyl butane (24) and (S)-4-phenyl-2-O-beta-D-glucopyranosyl butane (25) were firstly synthesized from 4-phenylbutan-2-one and glucose. The absolute configuration of C-2 for 1 was confirmed as R. Their anti-tumour activities were evaluated.

D-fructose strongly stimulates peroxidation of natural lipid-protein supramolecular complexes in vitro regardless of the oxidation initiation method. Fructose (ketose) intensifies free radical peroxidation to a much greater extent than glucose (aldose), which is important for the etiology and pathogenesis of diabetes mellitus.

Monosaccharides are polyhydroxyl compounds containing several chiral carbons, giving rise to tens of isomeric forms. Only minority of them are natural carbohydrates existing in nature abundantly, and most of them are rarely in nature, called rare sugars. These rare sugars attract increasing attention because of their low-calorie property and promising beneficial effects. Izumoring strategy has been established for linking all monosaccharides by three types of enzymes including ketose 3-epimerases, polyol dehydrogenases, and aldose isomerases. Recently, more attention has been paid on the Izumoring of hexoses, especially the D-zone hexoses. So far, at least ten isomerases have been used for the isomerization reactions between D-aldohexoses and D-ketohexoses. In this article, the interconnections and potential physiological effects of D-ketohexoses and D-aldohexoses are summarized, the D-zone hexose Izumoring is shown by giving the exact biocatalysts, and importantly, the isomerases for D-hexose biotransformation are reviewed in detail.

High-performance liquid chromatography (HPLC) with diode array detection interfaced to electrospray ionization (ESI) mass spectrometry (MS) is applied to identify the two epimers of a novel and minor constituent, podophyllotoxin-4-O-(D)-6-acetylglucopyraniside from high-altitude Podophyllum hexandrum for the first time. This is done by matching the structural information from the tandem MS data with the reported lignan markers. The results show that LC-MS-MS is the method of choice for fast detection and detailed chemical analysis of mixtures in the crude extracts of Podophyllum. The method can be employed in the absence of reference standards for the markers and is particularly useful in view of the scarcity of these rare chemical standards.

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.

Two new triterpenoid saponins, biondianosides F and G, together with 13 known compounds, were isolated from the ethanolic extract of the roots of Biondiachinensis Schltr. (Asclepiadaceae). Their structures were characterized as 3-O-beta-D-glucopyranosyl-2alpha,3beta-dihydroxyurs-12-en-28-oic acid-beta-D-glucopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->6)]-beta-D-glucopyranosyl ester (biondianoside F) and 3-O-beta-D-glucopyranosyl-2alpha,3beta,23-trihydroxyolean-12-en-28-oic acid-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl ester (biondianoside G) by spectral and chemical evidence.

Two new ellagic acid glycosides, named stachyanthuside A (1) and B (6), have been isolated along with four known ellagic compounds (2-5) from the leaves of Diplopanax stachyanthus. The structures of the new compounds were established as 3'-O-methylellagic acid 4-O-beta--glucopyranoside (1) and 3,3',4'-tri-O-methylellagic acid 4-O-beta--(2'-acetyl)-glucopyranoside (6) on the basis of detailed spectroscopic analysis and comparison with related model compounds.

An optimized capillary electrophoresis (CZE) method to analyze complex mixtures of aldoses was developed. The approach allows simultaneous quantitative analysis of all four isomeric aldopentoses, eight aldohexoses, as well as xylo- and cellooligosaccharides up to the tetraoses. UV tagging with 4-aminobenzoic acid ethyl ester (ABEE) in combination with reductive amination was used as pre-column derivatization. With optimum baseline separation and short run times, the method is very robust, and especially suited to follow reaction and isomerization kinetics of monosaccharides.

Wild type (SR1) tobacco line and transgenic lines ALR1/5 and ALR1/9, overexpressing aldose/aldehyde reductase were cold treated at 0 °C. Both transgenic lines showed significantly higher Fv/Fm values than the control (SR1) during the first 3 days of treatment. There was an equally low Fv/Fm ratio in each line after the fifth day. Both the chlorophyll content and the malondialdehyde levels reflected the more restricted oxidative damage to transgenic tobacco plants. These transgenic lines were less susceptible to cadmium-induced stress effects as well, as could be seen from the less pronounced decrease in photosynthetic pigment contents. These results suggest that alfalfa aldose/aldehyde reductase overexpression may generally induce higher stress tolerance.

Unprotected aldose sugars react smoothly with 1,3-diones or β-ketoesters in the presence of CeCl 3 ·7H 2 O in aqueous solution to produce polyhydroxylalkyl- and C -glycosylfuran derivatives in excellent yield. Operationally simple, mild neutral reaction conditions in aqueous solution is the key feature of this methodology.

1- O -Benzylpentitols (with d - arabino , d - lyxo , d , l - xylo and d , l - ribo configurations) and aldose dibenzyldithioacetals (with l - arabino , d - lyxo , d - xylo , d - ribo , d - galacto , d - gluco and d - manno configurations) were directly and efficiently transformed into their cyclic bis-thionocarbonate derivatives (61–73%) by reaction with diimidazolyl thione (Im 2 CS) in 1,4-dioxane. These bis-electrophilic adducts react regioselectively with Na 2 S·9H 2 O to lead to 1,4-, 2,5- or 3,6-thioanhydroalditol derivatives in good yields (47–65%). Thioanhydro configurations d , l - arabino , l - ribo and l - xylo from pentitols, and d - lyxo , l - ribo , d - xylo , d - allo , d - gulo and d - altro from aldoses were obtained.