Nonreducing Saccharides Research Articles

Intracellular Protective Functions and Therapeutical Potential of Trehalose.

Trehalose is a naturally occurring, non-reducing saccharide widely distributed in nature. Over the years, research on trehalose has revealed that this initially thought simple storage molecule is a multifunctional and multitasking compound protecting cells against various stress factors. This review presents data on the role of trehalose in maintaining cellular homeostasis under stress conditions and in the virulence of bacteria and fungi. Numerous studies have demonstrated that trehalose acts in the cell as an osmoprotectant, chemical chaperone, free radical scavenger, carbon source, virulence factor, and metabolic regulator. The increasingly researched medical and therapeutic applications of trehalose are also discussed.

Ethylamine as new derivatization reagent differentiating reducing from non-reducing saccharides

Typical derivatization reagents for saccharides in high-performance thin-layer chromatography, like 2-naphthol sulfuric acid, aniline diphenylamine orthophosphoric acid, or p-aminobenzoic acid, generally detect both reducing and non-reducing saccharides. A new reagent was found with ethylamine, specifically reacting with reducing saccharides on normal-phase silica gel plates, resulting in strongly fluorescent zones after heating the plate at 150 °C for 15 min. In contrast, non-reducing saccharides generally did not reveal fluorescent signals tested with 26 different saccharides. Optimal chromatographic separation was achieved with a mixture of 2-propyl acetate, methanol, and water with 1 mg/mL natural product reagent A when the plate was twofold developed. The high sensitivity of the ethylamine derivatization was shown with mean limits of detection and quantification of 10 and 30 ng per zone, respectively, calculated by different methods for selected mono- and disaccharides. The developed method has exemplarily been used for the digestion control of starch by α-amylase, the determination of lactose in lactose-free milk, and for the quantitative and qualitative study of honey. The analysis of honey gave an excellent example of the advantageous consecutive derivatization with ethylamine and aniline diphenylamine orthophosphoric acid reagent as reagent sequence to detect the coelution of reducing and non-reducing saccharides.

Phyto-Courier, a Silicon Particle-Based Nano-biostimulant: Evidence from Cannabis sativa Exposed to Salinity.

Global warming and sea level rise are serious threats to agriculture. The negative effects caused by severe salinity include discoloration and reduced surface of the leaves, as well as wilting due to an impaired uptake of water from the soil by roots. Nanotechnology is emerging as a valuable ally in agriculture: several studies have indeed already proven the role of silicon nanoparticles in ameliorating the conditions of plants subjected to (a) biotic stressors. Here, we introduce the concept of phyto-courier: hydrolyzable nanoparticles of porous silicon, stabilized with the nonreducing saccharide trehalose and containing different combinations of lipids and/or amino acids, were used as vehicle for the delivery of the bioactive compound quercetin to the leaves of salt-stressed hemp (Cannabis sativa L., Santhica 27). Hemp was used as a representative model of an economically important crop with multiple uses. Quercetin is an antioxidant known to scavenge reactive oxygen species in cells. Four different silicon-based formulations were administered via spraying in order to investigate their ability to improve the plant's stress response, thereby acting as nano-biostimulants. We show that two formulations proved to be effective at decreasing stress symptoms by modulating the amount of soluble sugars and the expression of genes that are markers of stress-response in hemp. The study proves the suitability of the phyto-courier technology for agricultural applications aimed at crop protection.

Elegant Chemistry to Directly Anchor Intact Saccharides on Solid Surfaces Used for the Fabrication of Bioactivity-Conserved Saccharide Microarrays

An easy chemical strategy was proposed and used to establish a method for direct anchoring of intact saccharides on solid surfaces with well conserved bioaffinity. The anchoring was achieved by temperature-modulated stepwise reactions with cyanuric chloride as a key linker, and was successfully applied to the fabrication of saccharide chips. To demonstrate, 15 intact reducing and nonreducing saccharides with various molecular sizes were dotted on a cyanuric-chloride-modified chip (1.0 × 1.0 cm(2)) and made to react with lectins. As expected, the anchored saccharides were capable of recognizing their target lectins, and more exciting were the perfect conservation of the specific recognizing ability of the anchored monosaccharides such as mannose, glucose, and even fructose (interacting only weakly with concanavalin A). This conservation was ascribed to the maintenance of the original structure (especially the anomeric configuration) of saccharides after immobilization and to the allowance of the anchored saccharides to rotate with and/or on the scaffold of cyanuric chloride, which makes them easily adapt to the recognition-preferred spatial position. The expected linkage of saccharides on cyanuric chloride and the maintenance of their anomeric configuration were characterized by mass spectrometry and nuclear magnetic resonance, respectively. The new method can be highlighted not only by its conservation of saccharide bioaffinity and universal applicability but also by its merits of easy manipulation or facile control of the reactions and cost-effectiveness due to the use of extremely cheap cyanuric chloride.

Synthesis, Characterization, and Lectin Recognition of Hyperbranched Polysaccharide Obtained from 1,6-Anhydro-d-hexofuranose

1,6-Anhydro-D-hexofuranoses, such as 1,6-anhydro-β-D-glucofuranose (1), 1,6-anhydro-β-D-mannofuranose (2), and 1,6-anhydro-α-D-galactofuranose (3), were polymerized using a thermally induced cationic catalyst in dry propylene carbonate to afford hyperbranched polysaccharides (poly1-3) with degrees of branching from 0.40 to 0.46. The weight-average molecular weights of poly1-3 measured by multiangle laser light scattering varied in the range from (1.02 to 5.84) × 10(4) g·mol(-1), which were significantly higher than those measured by size exclusion chromatography. The intrinsic viscosities ([η]) of poly1-3 were very low in the range from 4.9 to 7.4 mL·g(-1). The exponent (α) in the Mark-Houkwink-Sakurada equation ([η] = KM(α)) of the polymers was 0.20 to 0.33, which is <0.5. The steady shear flow of poly1-3 in an aqueous solution exhibited a Newtonian behavior with steady shear viscosities independent of the shear rate. These viscosity characteristics were attributed to the spherical structures of hyperbranched polysaccharides in an aqueous solution. Poly1-3 contained a high portion of terminal units of 31-43 mol % nonreducing D-hexopyranosyl and D-hexofuranosyl units, in which the D-hexofuranosyl units were 20-44 mol %. Moreover, poly1 and poly2 showed a strong interaction to Concanavalin A due to the cluster effect or multivalent effect of numerous nonreducing saccharide units on their surfaces with binding constants in the range from 1.7 × 10(4) to 2.7 × 10(5) M(-1).

Structural analysis and differentiation of reducing and nonreducing neutral model starch oligosaccharides by negative-ion electrospray ionization ion-trap mass spectrometry

Negative-ion electrospray tandem mass spectrometry with an ion-trap provided a sensitive tool for sequence determination of oligosaccharides derived from starch. Fragmentations of [M−H] − as well [M+Cl] − ions allow an unambiguous differentiation between α-(1 → 4) and α-(1 → 6) linkage based on the presence of diagnostic [M−H−90] − and [M−H−78] − ions. For nonreducing saccharides with terminal sucrose groups, the fragmentation starts with elimination of the fructose unit, followed by cross-ring cleavages of the remaining rings. The specific fragmentation features of reducing and nonreducing saccharides can be used for their differentiation.

Highly efficient analysis of underivatized carbohydrates using monolithic-silica-based capillary hydrophilic interaction (HILIC) HPLC

A polyacrylamide (PAAm)-modified monolithic silica capillary column of increased phase ratio, 200T-PAAm, for hydrophilic interaction liquid chromatography (HILIC) was prepared. The column showed high separation efficiency, with a theoretical plate height H = 7-20 microm at a linear velocity, u = 1-7 mm/s. From a kinetic plot analysis, it was expected that the monolithic column could provide three times faster separation than particle-packed HILIC columns under a pressure limit at 20 MPa. HILIC coupled with electrospray ionization (ESI)-mass spectrometry (HILIC-ESI-MS) using the 200T-PAAm column was employed for the analysis of underivatized carbohydrates to achieve fast and efficient separations of mixtures containing mono-, di-, and trisaccharides within 5 min. Under single MS full scan mode, 200 pg of oligosaccharides was detected by the system. The limit of detection (LOD) of the LC-ESI-MS/MS system was determined using selected reaction monitoring (SRM) to be as low as 3.2 ng/mL (attomol level) for nonreducing saccharides. The system was successfully applied to the detection of disaccharides in extracts of plant, such as corn, soybean, and Arabidopsis thaliana.

First Direct Glycosylation of Unprotected Nonreducing Mono‐ and Disaccharides

AbstractThe first single‐step random‐glycosylation methodology for fully unprotected glycosyl acceptors is reported by random glycosylation leading to all possible regioisomers. For such systems conventional glycosylation methods such as Koenigs–Knorr glycosylation, Schmidt's trichloroacetimidate glycosylation and reactions employing glycosyl fluoride donors fail entirely. Starting from unprotected nonreducing saccharides, the glycosylation of β‐glucosylated and β‐galactosylated monosaccharides (Glc, Gal), symmetric disaccharides (e.g. α,α‐trehaloses) as well as unsymmetric disaccharides (e.g. sucrose) were studied. The influence of base type and concentration were examined. Several libraries of di‐ and trisaccharides were generated. All regioisomers were formed in approximately equal proportions, and their partial separation was achieved by flash column chromatography. Even though it appears that overall yields are lower when comparing to classical protecting‐group chemistry, this synthetic effort may be superior especially for access to higher saccharides. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)

Suppressive Effect of Trehalose on Acrylamide Formation from Asparagine and Reducing Saccharides

The influence of saccharides on the formation of acrylamide (AcA) was investigated. The reducing saccharides reacted with asaparagine to form AcA, but the non-reducing saccharides, except sucrose, gave no AcA. AcA formation from a mixture containing glucose and asaparagaine was suppressed by the non-reducing saccharides, especially trehalose (76% suppression) and neotrehalose (75% suppression). Glucose is heat-degraded into pyruvaldehyde and 5-hydroxymethyl-2-furfural in the water system. The degradation products react with asparagines to generate AcA. Trehalose appears to inhibit not only the formation of these intermediates and asparagines for AcA, but also the AcA formation from these intermediates.

Carbon Partitioning and Assimilation as Affected by Nitrogen Deficiency in Cassava

Plants of cassava (Manihot esculenta Crantz) were raised in a sand root medium watered with nutrient solutions, under greenhouse conditions. As the N-supply increased, shoot dry mass was enhanced to a greater extent than root dry mass, thus leading to an increased shoot to root ratio. In leaves, contents of total soluble saccharides, non-reducing saccharides, and inorganic phosphate increased linearly with increasing N-supply. An opposite response was found for reducing saccharides and starch. In general, content of non-reducing saccharides was considerably greater than starch content. Activity of sucrose synthase was not detected, regardless of the N-treatments; by contrast, activity of neutral and acid invertases increased with increasing N-availability. Roots accumulated more total soluble saccharides, but less reducing saccharides and starch, as the N-supply increased. Photosynthetic rates decreased with increasing N-deficiency. Such a decrease was circumstantially associated to reducing saccharide, but not starch, accumulation. Results suggest a limited capacity for carbon export from source leaves under N-limitation.

Derivatization of small oligosaccharides prior to analysis by matrix-assisted laser desorption/ionization using glycidyltrimethylammonium chloride and Girard's reagent T.

In matrix-assisted laser desorption/ionization (MALDI) analyses of small oligosaccharides a very large increase in sensitivity (by a factor of 1000) may be obtained by introducing a quaternary ammonium center ('quaternization'). Such a quaternary ammonium center may be introduced into the saccharide by reaction with commercially available glycidyltrimethylammonium chloride (GTMA), or by using Girard's reagent T (Naven and Harvey, Rapid Commun. Mass Spectrom. 1996; 10: 829). GTMA reacts with alcohol functionalities, whereas Girard's reagent T is specific for aldehyde and keto groups. Thus reducing saccharides can be derivatized by both GTMA and Girard's reagent T. For example, glucose or cellobiose having a stock concentration of 3 x 10(-5) M (5 microg/mL) produces no sugar-derived signals in conventional MALDI, but their quaternized derivatives, also at 3 x 10(-5) M, yield intense signals, with the matrix-derived signals only being weak. Similar results were obtained for glucosamine. Non-reducing saccharides as well as sugar alcohols can be derivatized using GTMA; thus, although sucrose, raffinose and sorbitol do not react with Girard's reagent T, they all produce intense signals after derivatization with GTMA. An example of the application of these derivatization reactions is provided by the analysis of oligosaccharides in beer.

Biochemical constraints for survival under Martian conditions

A wide variety of terrestrial organisms, the so-called “anhydrobiotes,” has learned to survive in a state of extreme dehydration in dry environments. Strategies for survival include the accumulation of certain polyols and nonreducing saccharides, which help to prevent damage to membranes and proteins, but at low water partial pressure DNA is also progressively damaged by various lesions, including strand breaks and cross-linking to proteins. These lesions, if they are not too numerous, can be repaired before the first replication step after rehydration, but long-term exposure to dry conditions finally diminishes the chances of survival as these lesions accumulate. If an organism has no chance to repair the accumulated DNA damage during intermittent periods of active life, survival will not exceed a few decades. The restriction of survival by dryness-induced DNA lesions is corroborated by new data on conidia of Aspergillus and the free plasmid pBR 322. Our results will be discussed with respect to the chance of finding dormant life or biochemical fossils on the surface of Mars.

Lectin-histochemical analysis of glycans in ovine and bovine near-term placental binucleate cells.

Chorionic binucleate cells (BNC) occur in several ruminants including cow, deer, goat and sheep. They migrate through the chorionic tight junction to fuse with uterine epithelial cells and discharge their granules into maternal connective tissue. We have compared the BNC of near-term, resin-embedded, ovine and bovine placentae using 15 biotinylated lectins and an avidinperoxidase revealing system. There was pronounced conservation of saccharides between the two species. Several sub-types of N-glycan were present, with highly branched structures being abundant, as shown by Galanthus nivalis, Pisum sativum and Phaseolus vulgaris (leuko) agglutinins. Among the non-reducing terminal saccharides conserved were GalNAc alpha 1,3(Fuc alpha 1,2)-Gal beta 1,4GlcNAc beta 1-, GalNAc alpha 1,6Gal beta 1-, Gal beta 1-, Gal beta 1,4GlcNAc- and Gal beta 1,3GalNAc alpha 1- shown by Dolichos biflorus, Wisteria floribunda, Erythrina cristagalli, and Maclura pomifera agglutinins, respectively. Arachis hypogaea and Glycine max agglutinins tended to bind to bovine BNC at different stages of maturity, while fucosyl residues detectable by Tetragonolobus purpureus and Ulex europaeus-1 agglutinins were not observed in either species. The only major difference related to sialyl residues, with alpha 2,3-linked sialic acid being present in bovine (Maackia amurensis, Limax flavus) and alpha 2,6 sialic acid being present in ovine (Sambucus nigra agglutinin) cells. This conservation of glycan may be related to glycosylation of peptide hormones in the granules, and may thus be important in the targeting of these hormones to their receptors.

Effect of iso-osmotic levels of salts and PEG-6000 on saccharides, free proline and nitrogen content during early seedling growth of pea (Pisum sativum L.)

Effects of iso-osmotic levels of salts (NaCl, CaCl2, Na2So2) and PEG-6000 on saccharides, free proline and nitrogen contents were studied in cotyledons of pea. Saccharide (total, reducing andnon-reducing) and nitrogen contents decreased with increasing the salt and water stress as compared to control at all the stages of seedling growth. PEG-induced stress had more deleterious effect on total saccharide content and non-reducing saccharide (NRS) content, while salt stress was more harmful to reducing saccharide (RS) and nitrogen content. Free proline content of cotyledons increased with increasing the salt and especially PEG-induced stress at all the stages of seedling growth.

Mechanisms for hydroperoxide degradation of disaccharides and related compounds

The reactions of disaccharides with alkaline hydrogen peroxide were studied under diverse conditions. Treatment of cellobiose, lactose, and maltose with aqueous sodium peroxide afforded, in each instance, the corresponding aldobionic acid, the next lower aldobionic acid 2- O- d-glucopyranosyl- d-erythronic acid, and formic acid. On the other hand, melibiose and gentiobiose afforded the corresponding aldobionic acid, the next lower aldobionic acid, and a 2- O- d-glycopyranosylglycolic acid. The yields of products varied widely with the experimental conditions, especially with the proportions of alkali peroxide and hydrogen peroxide. The reactions with alkali peroxide were slow, but rapid in the presence of hydrogen peroxide with the gradual addition of alkali. The results indicate that degradation of carbohydrates by alkaline hydrogen peroxide takes place by five reaction paths. These are designated the alpha-hydroxy hydroperoxide cleavage-mechanism, the Baeyer-Villiger mechanism, the ester mechanism, the dihydroxy-epoxide mechanism, and a newly proposed peroxy-radical mechanism. The last-named mechanism is more rapid than the others. With an excess of hydrogen peroxide and slow addition of alkali, it results in rapid, stepwise conversion of both reducing and nonreducing saccharides into formic acid. The process begins with formation of a hydroperoxide adduct of the carbohydrate. Reaction of the adduct with hydrogen peroxide affords a peroxy radical and a hydroxyl radical. The peroxy radical decomposes, affording formic acid, the next lower aldose and hydroxyl radical. Hydroxyl radical produced in a chain reaction oxidizes alditols and aldonic acids by reactions analogous to those of the Fenton reagent.

Photo-Induced Formation of Peroxide in Saccharides and Related Compounds

Photo-induced formations of peroxide in saccharides, poly(vinyl alcohol) (PVA), and cellulose were examined in aqueous media, and the reaction mechanisms were discussed. Three factors, light shorter than 300 nm, saccharide, and oxygen, were essential to the formation of peroxide. Greater amounts of peroxide were formed with reducing saccharides, D-glucose, D-fructose, and cellobiose than with nonreducing saccharides, sucrose and methyl-α-D-glucopyranoside. Based on the determinations of reducing power and carbonyl group, spectrophotometric measurements, and the detection of lactone in photo-irradiated aqueous solutions of D-glucose, reaction mechanisms involving the formation of hydrogen peroxide and the change of D-glucose into lactone or ketone structure were discussed. The formation of peroxide was also observed in PVA and cellulose samples. The peroxide was postulated to be hydrogen peroxide. It is concluded that the structure —HC(OH)— of saccharide and related compounds contributes generally to the formation of hydrogen peroxide induced by a photolysis reaction.

Photopolymerization of methyl methacrylate in the presence of saccharide

AbstractPhotopolymerization of methyl methacrylate (MMA) in aqueous solution of saccharide was investigated. Glucose, cellobiose, maltose, and fructose accelerated the photopolymerization in the hard glass system, but α‐methyl‐d‐glucoside was inactive. On the other hand, on remarkable effect of saccharide except fructose was observed in the quartz glass system. A conversion in the hard glass system increased with irradiation time and with concentration of saccharide, which showed the effect in the order of ketose &gt; aldose &gt; nonreducing saccharide. Scission of glucosidic bonds and decomposition of reducing groups of saccharide molecule took place in the quartz glass system, but there was no reduction in the reducing power of saccharide in the hard glass system. By studying the ESR of the photoirradiated system containing saccharide, MMA, and water, no radical of saccharide was found in hard glass systems, but an increase in growing radical of MMA was clearly observed in systems with the coexistence of ketose and aldose, while α‐methyl‐d‐glucoside was inactive. It is believed, therefore, that both ketose and aldose contribute effectively to initiate the photopolymerization without any change in their own structures. On the other hand, reducing groups of saccharide play a very important role in the sensitizing action of the initiation.

A method for detection of non-reducing saccharides

A method for detection of non-reducing saccharides

Prof. E. C. Grey

EGERTON CHARLES GREY, who died on Aug. 10 at the early age of forty-one years, had long been engaged in researches on the biochemistry of fermentation by bacteria. Working with large inoculations of the organism and synthetic media, he made a careful study of the time relations of the chemical changes and found that well-defined phases of fermentation existed, characterised by different products. Thus, B. coli, under these conditions, produces from glucose, in the period immediately following inoculation, alcohol, formic acid, and succinic acid, whereas in the next subsequent period these products are partially decomposed, some of the sugar is synthesised to a non-reducing saccharide and lactic acid is formed; finally, a prolonged period of mixed fermentation occurs.