Colour reactions between sugars and diphenylamine-urea and diphenylamine-p-anisidine on paper chromatograms
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Diphenylamine
Ketose
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The acyclic form of monosaccharides exists in a structural equilibrium, with aldose having the aldehyde group and ketose the ketone group (ketose–aldose equilibrium). A basic catalyst facilitates their transformation, which affects the chemical properties of the monosaccharide. In this study, we investigated the ketose–aldose transformation of 1,3-dihydroxyacetone (1,3-DHA), one of the simplest systems of the ketose–aldose equilibrium. We examined the effects of piperidine as the basic catalyst and used IR electroabsorption spectroscopy to study the responses to an external electric field. We analyzed the changes in IR absorption by considering the changes in the molecular orientation and number of molecules in response to the external electric field. The results of the analysis revealed the permanent dipole moment μP, an angle η between μP and μT (the transition moment of the molecular vibration), and the equilibrium constants. The ketose–aldose transformation of 1,3-DHA can be explained in terms of the equilibrium of three states. In the presence of piperidine, a five-state equilibrium was concluded. On the basis of the experimental data, we propose plausible models of dihydroxyacetone, E-enediols, Z-enediol, or glyceraldehyde for each state. The results of our structural analysis of these tautomers provide a detailed understanding of the ketose–aldose transformation of acyclic saccharides and the effects of the basic catalyst.
Ketose
Glyceraldehyde
Dihydroxyacetone
Monosaccharide
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We previously demonstrated that the organogermanium compound 3-(trihydroxygermyl)propanoic acid (THGP) enhances the enzymatic and alkaline isomerization of an aldose to a ketose through cis-diol complex formation by multiple mechanisms. Its higher affinity for the ketose than the aldose protects the ketose complex from alkaline decomposition. Furthermore, it has been reported that the aldose-ketose alkaline isomerization pathway includes 1,2-enediol. Therefore, we speculated that the complex-forming ability of THGP could also be applied to enediol, a transient intermediate of alkaline isomerization. To test this prediction, we analyzed the initial rates of glucose or lactose isomerization in a region where there was no substantial difference in pH with and without THGP addition. The results showed that THGP enhanced the rate of fructose or lactulose formation per unit time by approximately 2-fold compared to the control. This finding indicated that THGP could form a complex with the transition state of aldose-ketose alkaline isomerization.
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Ketose
Epimer
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Ketose
Epimer
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The isomers of monosaccharide always produce multiple chromatographic peaks as volatile derivatives during gas chromatography, which may result in the overlapping of different sugar peaks. Whereas reduction and oximation of sugar carbonyl groups for GC analysis do eliminate many isomer derivatives, the approaches create new problems. One ketose can yield two peaks by oximation, and different aldoses and ketoses can yield the same alditol upon reduction, leading to the inability to detect some important monosaccharides. This paper reports an optimal method that yields a single peak per sugar by acetylation directly. By using a methyl sulfoxide (Me2SO)/1-methylimidazole (1-MeIm) system, the carbohydrates in acetic anhydride (Ac2O) esterification reactions were solubilized, and the oxidation that normally occurs was inhibited. The results demonstrate that acetylated derivatives of 23 saccharides had unique peaks, which indicates aldose, ketose, and alditol can be determined simultaneously by GC-MS.
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Monosaccharide
Sulfoxide
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Advanced Glycation End Products (AGEs) could be formed with α ‐dicarbonyl compounds as intermediates; however, simultaneous determination of AGES as well as their precursors and intermediates have rarely been mentioned, so as to investigate the reaction. In this work, lysine was reacted with aldoses (galactose, glucose) and ketoses (fructose, sorbose) to investigate the effects of sugar type and heating temperature. Two high‐performance liquid chromatography‐tandem mass spectrometry methods were developed to quantify AGEs and the corresponding α ‐dicarbonyl compounds. The results demonstrated that aldoses were more prone to form intermediates and final products than ketoses from the point of view of absorbance (at 294 and 420 nm). Aldose systems were prone to form glyoxal, whereas ketose systems tended to generate methylglyoxal and 3‐deoxyglucosone. The relative reaction activity of sugars in forming N ε ‐carboxymethyl‐lysine depended upon heating temperature for aldose and ketose systems. The aldose was more liable to generate N ε ‐Carboxyethyl‐lysine (CEL) than ketose, with the CEL generation for each sugar occurred in the order galactose > glucose > sorbose > fructose. The obvious differences between different types of sugars suggest that further research is needed on the degradation of sugars to form intermediates and on the reaction of α ‐dicarbonyl to generate AGEs.
Ketose
Sorbose
Glyoxal
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Diphenylamine
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低温に於て高濃度臭化水素酸の作用により, Heptamethyl-methyl-maltoside及びHeptamethyl-methyl-cellobiosideは夫々d-Glucoseに, Heptamethyl-methyl-lactosideはd-Glucose及びd-Galactoseに分離せり.又Octamethyl-sucroseはd-Glucoseに分離せると共に多量のフーマス質を生成せり.斯くてAldoseのみよりなる重糖類のメチル誘導體は脱メチルと共に成分糖に分離し, Ketoseを一成分糖となせる重糖類のメチル誘導體はKetoseのフーマス質に變化せるためAldoseのみを生成せるを知りたリ.
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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.
Ketose
Stereospecificity
Arabinose
Sorbose
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Ketose
Transketolase
Glycolaldehyde
Cleavage (geology)
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