Fructose isolation

Bajijiasu. Chen et al. [248] studied the protective effect ofBajijiasu (P-D-fructofuranosyl (2-2) p-D-fructofuranosyl), a dimeric fructose isolated from the Chinese herb radix Morinda officinalis, on Ap-induced neurotoxicity in pheochromocytoma (PC12) cells. Bajijiasu reversed the reduction in cell viability induced by exposure to Ap25 35, reduced Ap25 35-induced toxicity, decreased the accumulation of intracellular ROS and the lipid peroxidation product malondialdehyde, upregulated expression of glutathione reductase and superoxide dismutase, prevented depolarization of the mitochondrial membrane potential ( Em), and blocked... 

Topper and Stetten s work involved (1) the reaction of n-glucose-l-d in ordinary water saturated with calcium hydroxide, and (2) the reaction of D-glucose in deuterium oxide saturated with calcium hydroxide-d2. These isomerizations were carried out at both 25° and 35°. In the experiments with D-glucose-l-d at 35°, the n-mannose isolated (as the phenylhydrazone) contained 44 % of the deuterium in the starting substance, all of which was retained at Cl, whereas the n-fructose isolated (as the phenylosazone) retained 94% of the deuterium. A similar result (100% retention of deuterium) was reported for the n-fructose isolated from the reaction at 25°. These figures for n-fructose were based on the assumption that 50 % of the... 

Action of Heat on D-Fructose. Isolation of Diheterolevulosan and a New Di-D-fruc-tose Dianhydride, M. L. Wolfrom and Mary Grace Blair, J. Amer. Chem. Soc., 70, 2406-2409 (1948). 

Isolation of Di-D-fructose Dianhydrides from Higher Plants. 213... 

In 1926, Pictet and Chavan5 isolated a compound [a-D-Fru/7-1,2 2,T- -d-Frup (4)] from the mixture of products of the low-temperature treatment of fructose with concentrated hydrochloric acid. They called this compound di-hetero-levulosane (diheterolevulosan) and deduced that it was a dimeric dianhydride. The remainder of the product, which they termed hetero-Uvulosane (heterolevu-losan), was ascribed to a monomeric fructose anhydride. 

In 1933, Schlubach and Knoop32 isolated a di-D-fructose dianhydride from Jerusalem artichoke and tentatively identified it as difructose anhydride I [a-D-Fru/-1,2 2,1 - 3-D-Fn / (5)]. Alliuminoside ( -D-fructofuranose- -D-fructofura-nose 2,6 6,2 -dianhydride) was isolated from tubers of Allium sewertzowi by Strepkov33 in 1958. Uchiyama34 has demonstrated the enzymic formation of a-D-Fru/-1,2 2,3 -(3-D-Fru/ [di-D-fructose anhydride III (6)] from inulin by a homogenate of the roots of Lycoris radiata Herbert. 

The treatment of sucrose with anhydrous HF89 results in the formation of a complex mixture of pseudooligo- and poly-saccharides up to dp 14, which were detected by fast-atom-bombardment mass spectrometry (FABMS). Some of the smaller products were isolated and identified by comparison with the known compounds prepared86 88 a-D-Fru/-1,2 2,1 -p-D-Fru/j (1), either free or variously glucosylated, was a major product, and this is in accord with the known stability of the compound. The mechanism of formation of the products in the case of sucrose involves preliminary condensation of two fructose residues. The resultant dianhydride is then glucosylated by glucopyranosyl cation.89 The characterization of this type of compound was an important step because it has permitted an increased understanding of the chemical nature of caramels. 

Di-D-fructose dianhydrides have also been isolated" from commercial chicory, which is used as an additive for coffee or in coffee substitutes. Chicory is obtained by roasting the roots of chicory (Cichorium sp.), a member of the Compositae, which contains inulin (in its roots) as a storage polysaccharide. 

The D-fructose 1,6-bisphosphate aldolase (FruA EC 4.1.2.13) catalyzes in vivo the equilibrium addition of (25) to D-glyceraldehyde 3-phosphate (GA3P, (18)) to give D-fructose 1,6-bisphosphate (26) (Figure 10.14). The equilibrium constant for this reaction of 10 strongly favors synthesis [34]. The enzyme occurs ubiquitously and has been isolated from various prokaryotic and eukaryotic sources, both as class I and class II forms [30]. Typically, class I FruA enzymes are tetrameric, while the class II FruA are dimers. As a rule, the microbial class II aldolases are much more stable in solution (half-lives of several weeks to months) than their mammalian counterparts of class I (few days) [84-86]. 

Secalin. Secalin has been isolated from the stems of unripe rye.46,68 Schlubach and Bandmann69 studied its structure. The great difficulty they encountered in obtaining the polysaccharide and its acetate in homogeneous form made the determination of physical properties uncertain. However, by hydrolysis of the methyl derivative, they obtained, after separation by means of the /3-naphthoates, tetramethyl-, trimethyl-, and dimethyl-D-fructoses in the proportions of 1 2 1. The trimethyl-D-fructose was identified as 1,3,4-trimethyl-D-fructofura-nose by its melting point and specific rotation. 

Irisin — tetrafructose anhydride — difructose anhydride —> D-fructose. The difructose anhydride, although not isolated in pure form, was readily hydrolyzed by acid and thus differed from the difructose anhydrides isolated from inulin. 

Difructose anhydrides I, II, and III have been isolated from the nonreducing residue that remains after removal of D-fructose and d-glucose from acid-hydrolyzed inulin. 

Similar instances, in which analytical data were of prime importance and where no products were isolated, are the oxidations of various di-D-fructose dianhydrides,80 inositols,81 the trisaccharide moiety of the alkaloid solamargine,82 2-O-a-L-fucopyranosyl-L-fucitol derived from fucoidin83 (a polysaccharide sulfate ester), trehalose and neotrehalose,84 maltotetraose,85 D-galactopyranosyl-glyceritol,86 and a 3-pentulose.87... 

It has recently been reported21 that a mixed osazone of 3,4-di-O-methyl-D-glucose can be converted, by treatment with p-nitrobenzaldehyde, into an osone which reacts with phenylhydrazine to give 3,4-di-O-methyl-D-glucose phenylosazone. Von Lebedev29 claimed to have obtained D-glu-cosone 6-phosphate, isolated as an amorphous lead salt, by the action of hydrochloric acid on the phenylosazone prepared from D-fructose 6-phosphate. 

Evans, Nicoll, Strause and Waring46 oxidized D-glucose and D-fructose in aqueous solution with excess cupric acetate at 50° for the purpose of ascertaining whether the general principles underlying the mechanism of carbohydrate oxidation in alkaline solutions are sufficient to explain the course of such oxidations in acid solutions. D-Glucosone was claimed to be one of the first products of oxidation the osone was not isolated, and,... 

Following a report60 that D-fructose, but not D-glucose, is oxidized by selenious acid, Dixon and Harrison61 used this reagent to prepare D-glucosone from D-fructose in aqueous solution isolation and purification were carried out after the manner of Fischer,4 but no yield was given. By this... 

The second mechanism (B) likewise does not agree with the results of recent experiments, as compound XI, from the reaction of D-fructose with ethyl acetoacetate, cannot be formed from either of the enolic forms of D-fructose. The structure of the crystalline compound isolated shows that the substituents at Cl and C2 of D-fructose also take part in the condensa-... 

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