Showing papers on "Aldose published in 2003"

Synthesis of glycosylcurcuminoids.

Abstract: Condensation of glycosylated arylaldehyde with acetylacetone–B2O3 complex gave a corresponding diglycosylcurcuminoid, and a similar reaction using a mixture of arylaldehyde and glycosylarylaldehyde gave an unsymmetrical monoglycosylcurcuminoid, both as boron-complexes. The boron was removed from the complexes by heating in methanol, thus achieving the synthesis of di- and mono-glycosylcurcuminoids.

The Composition of Keto Aldoses in Aqueous Solution as Determined by NMR Spectroscopy

Abstract: Keto aldoses usually form complex mixtures of equilibrating isomers in solution. This is due to the two different positions that may be used for ring closure in dicarbonyl sugars. The composition of various 2-keto aldoses 1–5 and 8, the 3-keto aldose 2-deoxy-D-erythro-hexos-3-ulose (9), and the ketose 1-deoxy-D-ribulose (10) in aqueous solution has been determined by NMR spectroscopy. The investigated keto aldoses form equilibria containing three to fifteen isomers. Among various furanose and pyranose ring structures stemming from 1,4-, 1,5-, 2,5-, and 2,6-cyclization, bicyclic forms were also found in several cases. The 2-keto aldoses mainly exist as hydrated isomers in H2O. Therefore, these forms and their proportions were compared to forms found in two homomorphous aldoses and one homomorphous ketose as model compounds. Besides the NMR data, also the composition of the 2-keto aldoses agreed with the average of forms found in the model compounds, a finding that might eventually be useful for deducing the composition of other keto aldoses.

Method of utilizing physiological activity of rare saccharide and compositions containing rare saccharide

Abstract: A method of utilizing the physiological activity of a rare saccharide, wherein physiological-activity sensitive cells are treated with the rare saccharide to modify the function of the cells. A composition containing, as an active ingredient, a rare saccharide which is introduced into physiological-activity sensitive cells and has an effect of modifying the function of the cells. The cells are human cells. The composition is a functional food, a drug, or a cosmetic. The rare saccharide is a rare saccharide belonging to aldose and/or ketose. The aldose is D-allose, and the cells are selected from the group consisting of cancer-cell proliferation inhibitory activity sensitive cells and active-oxygen production inhibitory activity sensitive cells. The ketose is D-psicose, and the cells are selected from the group consisting of chemokine secretion inhibitory activity sensitive cells, microglia migration inhibitory activity sensitive cells, and hypoglycemic activity sensitive cells.

Palladium(II) complexes of the reducing sugars D-arabinose, D-ribose, rac-mannose, and D-galactose.

Abstract: The cellulose solvent Pd-en, an aqueous solution of [(en)PdII(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 Pd2 complexes, the aldoses are tetra-deprotonated and act as bisdiolato ligands. Two crystalline pentose complexes were isolated: [(en)2Pd2(β-D-Arap1,2,3,4 H−4)]⋅5 H2O (1) and [(en)2Pd2(β-D-Ribp1,2,3,4 H−4)]⋅6.5 H2O (2), along with two hexose complexes. With rac-Man, the major solution species is crystallized as the 9.4-hydrate [(en)2Pd2(β-rac-Manp1,2,3,4 H−4)]⋅9.4 H2O (3). From the respective D-Gal solutions, [(en)2Pd2(β-D-Galf1,3,5,6 H−4)]⋅5 H2O⋅C2H5OH (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.

Chemistry of anhydro sugars

Abstract: Publisher Summary This chapter provides an overview of the chemistry of anhydro sugars. Anhydro sugars, also called “intramolecular anhydrides,” are heteromorphic sugar derivatives that formally arise by the elimination of one or more water molecules from arbitrary hydroxyl groups of the parent aldose or ketose. They usually contain a bicyclic or tricyclic skeleton composed of oxirane, oxetane, oxolane (tetrahydrofuran), and oxane (tetrahydropyran) rings. If the hemiacetal group is involved in the formation of such a ring, the resulting glycose anhydride exhibits properties approaching ordinary glycosides. In general, the reactivity of anhydro sugars is determined mostly by the size of the oxygen rings. Oxirane and oxetane rings show a high reactivity, whereas oxolane and oxane rings are less reactive. However, the position of the anhydro bond, the steric arrangement, and the conformation of the molecule also play a significant role. Nowadays, anhydro sugars constitute very versatile starting materials not only in carbohydrate chemistry but also for the synthesis of noncarbohydrate and nonnatural compounds. In the past two decades, the interest in anhydro sugars has increased because they have been shown to be suitable monomers for preparing stereoregular polysaccharides and their specifically substituted derivatives.

Acids and other products of oxidation of sugars.

Abstract: Publisher Summary This chapter focuses on the low-molecular weight carbohydrates that can be formally considered as the oxidation products of mono- or oligo-saccharides in which an aldehyde group and/or one or more hydroxyl groups have been oxidized to carbonyl and/or carboxyl groups. Some acids are important natural products, for instance, L -ascorbic acid (vitamin C); others, such as the glycuronic acids, are the constituents of abundant polysaccharides. Examples of commercial importance are ascorbic acid, as one of the major water-soluble antioxidants; salts of gluconic acid such as the magnesium salt used in the pharmaceutical industry; and D -ribono-1,4-lactone, a versatile material used in the synthesis of natural products. The oxidation products are divided into two principal categories,—namely, acids (and lactones) and neutral compounds. Three kinds of sugar acids can be formally obtained from the corresponding aldoses: (1) aldonic acids, produced by the oxidation at C–1 of the aldose; (2) uronic acids, formed by the oxidation of the primary alcohol group of the aldose; and (3) aldaric acids, formed by the oxidation of both the aldehyde and the primary alcohol group. Neutral oxidation products such as dialdoses, glycosuloses, and glycodiuloses are also discussed in detail in the chapter.

A flavone from Manilkara indica as a specific inhibitor against aldose reductase in vitro.

Abstract: Isoaffinetin (5,7,3',4',5'-pentahydroxyflavone-6-C-glucoside) was isolated from Manilkara indica as a potent inhibitor of lens aldose reductase by bioassay-directed fractionation. This C-glucosyl flavone showed specific inhibition against aldose reductases (rat lens, porcine lens and recombinant human) with no inhibition against aldehyde reductase and NADH oxidase. Kinetic analysis showed that isoaffinetin exhibited uncompetitive inhibition against both dl-glyceraldehyde and NADPH. A structure-activity relationship study revealed that the increasing number of hydroxy groups in the B-ring contributes to the increase in aldose reductase inhibition by C-glucosyl flavones.

Direct Oxidative Amidation of Aldoses by Iodine in Ammonia Water

Abstract: 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.

Synthesis and characterization of deoxycholyl 2-deoxyglucuronide: A water-soluble affinity labeling reagent

Abstract: 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.

Aldose reductase inhibitor and process for preparation thereof

Abstract: Aldose redcutase inhibitor and pharmaceutically acceptable derivatives thereof of the formula I below derived from cultures of Aspergillus niger CFR 1046 and useful as a rat lens aldose reductase inhibitor

D-psicose for use in the treatment of arteriosclerosis

Abstract: A method of utilizing the physiological activity of a rare saccharide, wherein physiological-activity sensitive cells are treated with the rare saccharide to modify the function of the cells. A composition containing, as an active ingredient, a rare saccharide which is introduced into physiological-activity sensitive cells and has an effect of modifying the function of the cells. The cells are human cells. The composition is a functional food, a drug, or a cosmetic. The rare saccharide is a rare saccharide belonging to aldose and/or ketose. The aldose is D-allose, and the cells are selected from the group consisting of cancer-cell proliferation inhibitory activity sensitive cells and active-oxygen production inhibitory activity sensitive cells. The ketose is D-psicose, and the cells are selected from the group consisting of chemokine secretion inhibitory activity sensitive cells, microglia migration inhibitory activity sensitive cells, and hypoglycemic activity sensitive cells.