Showing papers on "Aldose published in 1995"

Purification and partial characterization of an aldo-keto reductase from Saccharomyces cerevisiae.

Abstract: A cytosolic aldo-keto reductase was purified from Saccharomyces cerevisiae ATCC 26602 to homogeneity by affinity chromatography, chromatofocusing, and hydroxylapatite chromatography. The relative molecular weights of the aldo-keto reductase as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size exclusion chromatography were 36,800 and 35,000, respectively, indicating that the enzyme is monomeric. Amino acid composition and N-terminal sequence analysis revealed that the enzyme is closely related to the aldose reductases of xylose-fermenting yeasts and mammalian tissues. The enzyme was apparently immunologically unrelated to the aldose reductases of other xylose-fermenting yeasts. The aldo-keto reductase is NADPH specific and catalyzes the reduction of a variety of aldehydes. The best substrate for the enzyme is the aromatic aldehyde p-nitrobenzaldehyde (Km = 46 microM; kcat/Km = 52,100 s-1 M-1), whereas among the aldoses, DL-glyceraldehyde was the preferred substrate (Km = 1.44 mM; kcat/Km = 1,790 s-1 M-1). The enzyme failed to catalyze the reduction of menadione and p-benzoquinone, substrates for carbonyl reductase. The enzyme was inhibited only slightly by 2 mM sodium valproate and was activated by pyridoxal 59-phosphate. The optimum pH of the enzyme is 5. These data indicate that the S. cerevisiae aldo-keto reductase is a monomeric NADPH-specific reductase with strong similarities to the aldose reductases.

Five new C-methyl flavonoids, the potent aldose reductase inhibitors from Matteuccia orientalis Trev.

Abstract: Five new compounds, matteuorien, matteuorienin, and matteuorienate A (7), B (8), and C (9) were isolated together with five known compounds from the MeOH extract of the rhizome of Matteuccia orientalis TREV. The structures of these compounds were determined by the use of spectroscopic methods including two dimensional (2D)-NMR experiments and chemical methods, except for the configuration at the C-3t of matteuorienate A (7), B (8), and C (9). Among them, matteuorienate A, B, and C showed very strong aldose reductase inhibitory activity. A structure-activity relationship study showed that a carboxyl group played an important part in aldose reductase inhibitory activity in these three compounds.

Regulation of aldose reductase gene expression in renal cortex and medulla of rats.

Abstract: A role for aldose reductase-mediated production of polyol in the aetiology of diabetic nephropathy has been supported by both animal and clinical studies. In the renal medulla, the rate of polyol production is influenced in part by regulated changes in the level of aldose reductase gene expression. However, little is known about the expression of aldose reductase in the renal cortex. In this study, we evaluated the regulation of aldose reductase gene expression in the renal cortex and medulla in response to galactose feeding. Four groups of rats (n=6) were treated for 9 weeks with control or galactose diet in the presence or absence of sorbinil, an aldose reductase inhibitor. In the renal medulla, galactose treatment produced a significant (p<0.01) decrease in aldose reductase mRNA, to approximately 10% of control levels. Coadministration of sorbinil partially prevented the effect of galactose feeding on medullary aldose reductase mRNA (to 43% of control). Under basal conditions, the concentration of aldose reductase mRNA in the cortex was only 1% that of the renal medulla. Galactose feeding significantly reduced cortical aldose reductase mRNA by 29% relative to control (p<0.01), and this was completely reversed by addition of sorbinil. Sorbinil administration to rats fed a control diet also decreased aldose reductase expression in the renal medulla and cortex. These results demonstrate that galactose feeding results in dynamic, polyol-dependent regulation of aldose reductase gene expression in the renal cortex as well as the medulla. We also describe a method for quantitative analysis of low abundance renal cortical mRNA. [Diabetologia (1995) 38: 46–54]

Ferrocene-containing polymers as electron transfer mediators in carbon paste electrodes modified with PQQ-dependent aldose dehydrogenase

Abstract: This chapter highlights ferrocene-cotnaining polymers as electron transfer mediators in carbon paste electrodes modified with PQQ-dependent aldose dehydrogenase (ALDH). The solubility of the oxidized form of ferrocene can result in a decreased operational stability of the aldose dehydrogenase electrode. In order to decrease the solubility, ferrocene can be bound to flexible siloxane backbone to form a polymeric structure. In the chapter, polymer-bound ferrocene derivatives of this type with five different structures were studied as electron transfer mediators between the coenzyme of ALDH, pyrroloquinoline quinone (PQQ), and the conducting carbon. The ferrocene polymers were mixed into carbon paste that was used for the preparation of carbon paste electrodes. The operational properties of the ferrocene polymer modified electrodes have been studied and the effect of the polymer structure will be discussed. The electrodes modified with all five polymers showed maximum response when working potential was around 300 mV vs. Ag/AgCl. The operational stability of the polymer modified electrodes was better than that of corresponding dimethylferrocene modified electrodes.

Preparation of 2-hydroxymethylated aldose by the stereospecific rearrangement of ketose

Abstract: A simple one-stage reaction system which yields 2-C hydroxymethylated aldopentose has been investigated. Four different 2-C branched aldopentoses (2-C hydroxymethylated D-arabinose, D-ribose (Hamamelose), L-lyxose, and D-xylose) were prepared from the corresponding ketoses (D-psicose, D-fructose, L-sorbose, and D-tagatose, respectively). These branched sugars were synthesized by a similar mechanism to the 2-C epimerization of aldose using a nickel complex. It was confirmed that the isomerization of ketose to the side-branched sugar proceeded in the ternary nickel complex through a sequence of stereospecific rearrangements in the sugar. The yields were dependent upon the structure of the substrate ketose and the nickel-ethylenediamine complex. N,N′-Dialkylated cyclohexanediamines were the most suitable ligands for preparing the 2-C hydroxymethylated branched chain sugar.

Compounds and methods for monosaccharide analysis

Abstract: Compounds and methods are provided for use in monosaccharide analysis. The present invention discloses hydrazino monosaccharide derivatives. Methods for preparing and using hydrazino monosaccharide derivatives for structural analysis of aldose and ketose monosaccharides are also disclosed.

5-substituted alkylidene-2- (N-cyanoimino) thiazolidin-4-one derivatives, their preparation and their use as aldose reductase inhibitors

Abstract: A class of compounds represented by the formula (I) wherein R₁s are the same or different groups and each represents hydrogen atom or alkyl group having 1 to 4 carbon atoms; R₂ is phenyl group, naphthyl group, or either phenyl or naphthyl substituted with at least one hydroxyl, alkyl having 1 to 4 carbon atoms or alkoxy having 1 to 4 carbon atoms; R₃ is hydrogen atom, alkyl group having 1 to 4 carbon atoms or CH₂COOR₄ group, in which R₄ is hydrogen atom or alkyl group having 1 to 12 carbon atoms; n is 0 or 1, the configuration of 5-methylene group includes both E-isomer and Z-isomer, providing excepting the case wherein R₁ is hydrogen atom, R₂ is 3,5-di-t-butyl-4-hydroxyphenyl, R₃ is hydrogen atom and n is 0 or pharmacologically acceptable salts thereof when R₃ or R₄ is hydrogen atom. The invention also concerns preparation methods thereof. The present compounds are useful as prophylactic or therapeutic agents for neuropathy, retinopathy, diabetic cataract, impediment in the kidney as tubulo-nephrosis, all known as complications of chronic diabetes and especially aldose reducing enzyme induced complications.

Efficient Synthesis of Cord Factor Analogs Through Tributylstannylation

Abstract: Cord factor analogs were regioselectively synthesized by reactions of unprotected α, α-D-trehalose with long-chain acyl chlorides through tributylstannylation in good yields.

Method for continuously preparing a ketose solution by isomerising aldose, and apparatus therefor

Abstract: A method and an apparatus for continuously preparing a ketose solution from a starting sugar solution including at least one aldose, wherein at least one vertical continuous multicontact reactor (1) is used, at least one tectosilicate or a clay capable of forming a heterogeneous isomerisation catalyst is continuously circulated through the reactor (1), and at least one microporous selective adsorption solid, selected so that it selectively absorbs the aldoses in the starting solution or the ketoses produced by isomerisation, and is compatible with the isomerisation conditions, is circulated downwards through said reactor (1).

Method for isomerizing aldose structure-having compound into ketose structure-having compound, isomerization and accelerating agent thereof

Abstract: PURPOSE:To isomerize an aldose structure-having compound into a ketose structure-having compound in the presence of an organic germanium compound having a specific partial structure without requiring a special installation and a troublesome operation by eliminating the technical difficulties of the prior art. CONSTITUTION:The isomerization method comprises isomerizing (B) the aldose structure-having compound into (C) the ketose structure-having compound with (A) an organic germanium compound having a partial structure of formula I, preferably in the presence of the component A. The component A and the component B are preferably a compound of formula II or III [R1-R3, R4-R6 are H, lover alkyl, (substituted)phenyl. (protected)amino; X1, X2 are OH, O-lower alkyl, amino, OY1, OY2, (Y1, Y2 are metal, compound having a basic group); n is >=1] and glucose, respectively, and the isomerization is preferably the isomerization of the glucose into fructose.

A Facile Method for the Conversion of Oximes to Ketones and Aldehydes by the Use of Activated MnO2.

Abstract: Activated manganese dioxide (MnO 2 ) was found to be an efficient oxidant in the conversion of oximes to carbonyl compounds. The utility of this method in synthesis was demonstrated by the conversion of galactose to its acyclic aldose derivative 5.