- A novel acid polysaccharide from Boletus edulis: extraction, characteristics and antitumor activities in vitro
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A novel cold-water-soluble polysaccharide (BEP), with a molecular weight of 6.0 × 106?Da, was isolated from Boletus edulis. BEP consists of galactose, glucose, xylose, mannose, glucuronic, and galacturonic acid in a ratio of 0.34:0.28:0.28:2.57:1.00:0.44. The IR results showed that BEP was an acid polysaccharide, containing α-type and β-type glucoside bonds. MTT assay showed BEP could inhibit cell proliferation significantly. Morphological observation demonstrated that BEP-treated MDA-MB-231 and Ca761 cells exhibited typical apoptotic morphological features. Flow cytometry analysis revealed that BEP caused mitochondrial membrane potential collapse. Annexin V-FITC/PI staining indicated that BEP induced apoptosis of MDA-MB-231 and Ca761 cells through cell block in S phase and G0/G1 phase, respectively. Western blot results showed that BEP could increase the Bax/Bcl-2 ratios, promote the release of cytochrome C, and activate the expression of caspase-3 and caspase-9 in MDA-MB-231 and Ca761 cells. In conclusion, our results demonstrated that BEP could inhibit the proliferation of breast cancer cells and induce apoptosis through mitochondrial pathways.
- Meng, Ting,Yu, Sha-sha,Ji, Hai-yu,Xu, Xiao-meng,Liu, An-jun
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- Steroidal glycosides from the underground parts of Hosta ventricosa and their anti-inflammatory activities in mice
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Two new pregnane glycosides, 2α, 3β-dihydroxy-5α-pregn-16-en-20-one-3-O-{α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-β-D-galactopyranoside} (1) and 2α, 3β-dihydroxy-5α-pregn-16-en-20-one-3-O-{β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside}(2), have been isolated along with two known spirostanol saponins from the underground parts of Hosta ventricosa. Their structures were elucidated on the basis of chemical and spectral evidence. The anti-inflammatory activities of these steroidal glycosides were evaluated using a xylene-induced ear edema model. Our results indicated that the compounds exhibited promising anti-inflammatory activities.
- Chu, Hong-Biao,Li, Nan-Nan,Zhang, Zong-Ping,Hu, Xiao-Yue,Yu, Cai-Yun,Hua, Lei
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p. 1766 - 1774
(2019/07/16)
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- Electrochemical Activation of Galactose Oxidase: Mechanistic Studies and Synthetic Applications
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The enzyme galactose oxidase (GOase) is a copper radical oxidase that catalyzes the aerobic oxidation of primary alcohols to the aldehydes and has been utilized to that end in large-scale pharmaceutical processes. To maintain its catalytic activity and ensure high substrate conversion, GOase needs to be continuously (re)activated by 1e- oxidation of the constantly formed out-of-cycle species (GOasesemi) to the catalytically active state (GOaseox). In this work, we report an electrochemical activation method for GOase that replaces the previously used expensive horseradish peroxidase activator in a GOase-catalyzed oxidation reaction. First, the formation of GOaseox of a specifically engineered variant via nonenzymatic oxidation of GOasesemi was studied by UV-vis spectroscopy. Second, electrochemical oxidation of GOase by mediators was studied using cyclic voltammetry. The electron-transfer rates between GOase and various mediators at different pH values were determined, showing a dependence on both the redox potential of the mediator and the pH. This observation suggests that the oxidation of GOase by mediators at pH 7-9 likely occurs via a concerted proton-coupled electron-transfer (PCET) mechanism under anaerobic conditions. Finally, this electrochemical GOase activation method was successfully applied to the development of a bioelectrocatalytic GOase-mediated aerobic oxidation of benzyl alcohol derivatives, cinnamyl alcohol, and aliphatic polyols, including the desymmetrizing oxidation of 2-ethynylglycerol, a key step in the biocatalytic cascade used to prepare the promising HIV therapeutic islatravir.
- Fryszkowska, Anna,Klapars, Artis,Marshall, Nicholas,Ruccolo, Serge,Strotman, Neil A.,Zhang, Shaoguang
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p. 7270 - 7280
(2021/06/30)
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- Antiproliferative activity of new pentacyclic triterpene and a saponin from: Gladiolus segetum Ker-Gawl corms supported by molecular docking study
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A new triterpenoidal saponin identified as 3-O-[β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 4)-β-d-xylopyranosyl]-2β,3β,16α-trihydroxyolean-12-en-23,28-dioic acid-28-O-α-l-rhamnopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 2)-α-l-arabinopyranoside 1 together with a new oleanane triterpene identified as 2β,3β,13α,22α-tetrahydroxy olean-23,28-dioic acid 2 and 6 known compounds (3-8) have been isolated from Gladiolus segetum Ker-Gawl corms. The structural elucidation of the isolated compounds was confirmed using different chemical and spectroscopic methods, including 1D and 2D NMR experiments as well as HR-ESI-MS. Moreover, the in vitro cytotoxic activity of the fractions and that of the isolated compounds 1-8 were investigated against five human cancer cell lines (PC-3, A-549, HePG-2, MCF-7 and HCT-116) using doxorubicin as a reference drug. The results showed that the saponin fraction exhibited potent in vitro cytotoxic activity against the five human cancer cell lines, whereas the maximum activity was exhibited against the PC-3 and A-549 cell lines with the IC50 values of 1.13 and 1.98 μg mL-1, respectively. In addition, compound 1 exhibited potent activity against A-549 and PC-3 with the IC50 values of 2.41 μg mL-1 and 3.45 μg mL-1, respectively. Interestingly, compound 2 showed the maximum activity against PC-3 with an IC50 of 2.01 μg mL-1. These biological results were in harmony with that of the molecular modeling study, which showed that the cytotoxic activity of compound 2 might occur through the inhibition of the HER-2 enzyme.
- Abd El-Kader, Adel M.,Abdelmohsen, Usama Ramadan,Hajjar, Dina,Hayallah, Alaa M.,Mahmoud, Basma Khalaf,Mohamed, Mamdouh F. A.
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p. 22730 - 22741
(2020/07/03)
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- Kinetics and mechanism of quinolinium dichromate mediated oxidation of sugar alcohols in Bronsted acid media
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Bronsted acid catalyzed oxidation of certain sugar alcohols (polyols) has been studied by quinolinium dichromate (QDC) using aqueous sulfuric, perchloric, and hydrochloric acids at different temperatures. At constant acidity, reaction kinetics revealed the second-order kinetics with a first order in [Alcohol] and [QDC]. Zucker-Hammett, Bunnett, and Bunnett-Olsen criteria were used to analyze acid-dependent rate accelerations. Bunnett-Olsen plots of (log k + Hν) versus (Hν + log [H+]), and (log k) versus (Hν + log [H+]) afforded slope values (? and ?*, respectively)?>?0.47, suggesting that a water molecule acts as a prton transfer agent in the slow step of the mechanism in the oxidation of alcohols by QDC in the presence of aqueous sulfuric, perchloric, and hydrochloric acids.
- Kodali, Satish Babu,Jakku, Narendar Reddy,Kamatala, Chinna Rajanna,Yerraguntla, Rajeshwar Rao
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p. 167 - 177
(2019/12/27)
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- Chemical synthesis method of L-xylose
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The invention discloses a novel chemical synthesis method of L-xylose. According to the novel chemical synthesis method, 2, 2-dimethoxypropane protects hydroxyl of L-(-)2,3-dihydroxypropionaldehyde, and then a product is coupled with (1-bromovinyl)trimethylsilane so as to establish a basic framework of a target product; after production of 99% of ee is guaranteed by a sharpless epoxidation or Jacobsen-Katsuki expoxidation method, a three-membered ring is opened by protecting groups to guarantee that the configuration thereof is unchanged; then, the hydroxyl group produced by selectively removing one protecting group is oxidized into an aldehyde group; finally, the remaining protecting groups are removed to obtain the target product L-xylose, and the total yield is 46-48%. By the novel chemical synthesis method, the condition is mild, raw materials are cheap and easy to obtain, and a synthesis thought and the synthesis method are provided for chemical synthesis of a series of aldoses.
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Paragraph 0068-0070
(2018/11/22)
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- Exploring the biocatalytic scope of alditol oxidase from Streptomyces coelicolor
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The substrate scope of the flavoprotein alditol oxidase (AldO) from Streptomyces coelicolor A3(2), recombinantly produced in Escherichia coli, was explored. While it has been established that AldO efficiently oxidizes alditols to D-aldoses, this study revealed that the enzyme is also active with a broad range of aliphatic and aromatic alcohols. Alcohols containing hydroxy groups at the C-1 and C-2 positions like 1,2,4-butanetriol (Km=170 mM, k cat -4.4s-1), 1,2-pentanediol (Km=52 mM, k cat=0.85 s-1) and 1,2-hexanediol (Km=97 mM, kcat=2.0s-1) were readily accepted by AldO. Furthermore, the enzyme was highly enantioselective for the oxidation of 1,2-diols [e.g., for l-phenyl-1,2-ethanediol the (R)-enantiomer was preferred with an Is-value of 74]. For several diols the oxidation products were determined by GC-MS and NMR. Interestingly, for all tested 1,2-diols the products were found to be the a-hydroxy acids instead of the expected α-hydroxy aldehydes. Incubation of (R)-1-phenyl-1,2-ethanediol with 18O-labelled water (H 218O) revealed that a second enzymatic oxidation step occurs via the hydrate product intermediate. The relaxed substrate specificity, excellent enantioselectivity, and independence of coenzymes make AldO an attractive enzyme for the preparation of optically pure 1,2-diols and α-hydroxy acids.
- Van Hellemond, Erik W.,Vermote, Linda,Koolen, Wilma,Sonke, Theo,Zandvoort, Ellen,Heuts, Dominic P. H. M.,Janssen, Dick B.,Fraaije, Marco W.
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experimental part
p. 1523 - 1530
(2011/03/22)
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- L-Ribose: An easily prepared rare sugar
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A method to synthesize L-ribose was described by molybdate-catalyzed epimerization of the readily available L-arabinose. The synthesis is one-step and except for a catalytic amount of molybdic acid do not require any expensive reagents, while the solvents used are water and a small amount of methanol. The process can be carried out in 2-3 days. Although the yield of L-ribose is only 20%, being in equilibrium with arabinose, most of the unreacted arabinose is recoverable and can be used again.
- Angyal, Stephen J.
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- PROCESSES FOR THE PRODUCTION OF XYLITOL
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Methods of producing xylitol comprising the oxidative decarboxylation of a reactant substrate are provided herein. The oxidative decarboxylation is performed in one of two ways. In the first, the oxidative decarboxylation is performed by an electrochemical process, preferably an anodic odixative decarboxylation of a reactant substrate. In the second, the oxidative decarboxylation of the reactant substrate is carried out by a series of oxidation-reduction chemical reactions.
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Page/Page column 26
(2008/06/13)
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- Phenylpropanoid glucosides from leaves of Coussarea hydrangeifolia (Rubiaceae)
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Phenylpropanoid glycosides, 1′-O-benzyl-α-l-rhamnopyranosyl- (1″ → 6′)-β-d-glucopyranoside (1) and α-l- xylopyranosyl-(4″ → 2′)-(3-O-β-d-glucopyranosyl)-1′- O-E-caffeoyl-β-d-glucopyranoside (2), together with the known derivatives, 1,6-di-O-caffeoyl-β-d-glucopyranoside (3), 1-O-(E)-caffeoyl-β-d- glucopyranoside (4) and 1-O-(E)-feruloyl-β-d-glucopyranoside (5), were isolated from leaves of Coussarea hydrangeifolia. Their structures were determined by IR, HRESIMS, and 1D and 2D NMR experiments, and their antioxidant activities, evaluated by assaying the free radical scavenging capacity using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical as substrate. The antioxidant activities of 3 and 4 (IC50 values of 15.0 and 19.2 μM, respectively) were comparable to that of the standard positive control caffeic acid, whilst 2 and 5 were only weakly active and 1 was inactive.
- Hamerski, Lidilhone,Bomm, Mauro Dionei,Silva, Dulce Helena Siqueira,Young, Maria Claudia Marx,Furlan, Maysa,Eberlin, Marcos Nogueira,Castro-Gamboa, Ian,Cavalheiro, Alberto Jose,Da Silva Bolzani, Vanderlan
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p. 1927 - 1932
(2007/10/03)
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- Process for the production of xylitol
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The present invention relates to the production of xylitol. In particular, processes utilising L-xylose as an intermediate for xylitol production are described. The present invention also relates to process for the preparation or L-xylose, as an intermediate, by-product or end-product to be used per se.
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- The synthesis of L-gulose and L-xylose from D-gluconolactone
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L-Gulose, an essential component for the antibiotic and antitumor activities of bleomycin A2, was synthesized in 47% yield from D-glucono-1,5-lactone. The effective cleavage of acetonides by SnCl2 in the presence of tert-butyldimethylsilyl ethers was of importance in the course of synthesis. Elaboration of D-glucono-1,5-lactone that includes a step of oxidative degradation by Dess-Martin periodinane also afforded a respectable yield of L-xylose.
- Yang, Wen-Bin,Patil, Sachindra S,Tsai, Cheng-Hsin,Lin, Chun-Hung,Fang, Jim-Min
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p. 253 - 259
(2007/10/03)
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- Synthesis of racemic ribose from D-glucose
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Racemic ribose is a valuable starting material for investigations of the origins of biomolecular homochirality. It can be synthesized in seven steps starting from D-glucose.
- Miculka, Christian
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p. 948 - 950
(2007/10/03)
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- Chemo-Enzymatic Synthesis of Carbohydrates: The Preparation of L-Xylose and 2-Deoxy-L-xylo-hexose
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A synthetic approach to L-xylose (6) and 2-deoxy-L-xylo-hexose (8) has been developed.The strategy utilizes achiral starting materials and employs two enzymatic reactions to introduce the desired chiral centers.Rabbit muscle aldolase (RAMA)-catalyzed condensation of (3-phenylthio)propanal (1) with dihydroxyacetone phosphate (DHAP) affords the C-6 skeleton 2 with D-threo configuration between C-3 and C-4.Diastereoselective reduction of 2 with sorbitol dehydrogenase (SDH) introduces the final stereocenter of the tetrahydroxy derivative 3.After oxidation of sulfide 3 to the corresponding diastereotopic sulfoxides 4, L-xylose (6) is obtained by thermal elimination of phenylsulfenic acid followed by ozonolysis. 2-Deoxy-L-xylo-hexose (8) is yielded from 4 by a Pummerer rearrangement and subsequent reductive deprotection (DIBAL-H) of the rearrangement product 7. Key Words: L-Xylose / 2-Deoxy-L-xylo-hexose / Enzymatic syntheses / Carbohydrates
- Schmid, Walther,Heidlas, Juergen,Mathias, John P.,Whitesides, George M.
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- Substrate Specificity and Carbohydrate Synthesis Using Transketolase
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This paper describes the use of the enzyme transketolase as a catalyst in organic synthesis.The properties of transketolase from both yeast and spinach were investigated.The yeast enzyme was found to be more convenient for routine use.Examination of the substrate specificity of yeast tansketolase demonstrated that the enzyme accepts a wide variety of 2-hydroxy aldehydes as substrates.A practical protocol for tansketolase-catalyzed condensation of hydroxypyruvic acid with these aldehydes has been developed and used for the synthesis of four carbohydrates: L-idose, L-gulose, 2-deoxy-L-xylohexose, and L-xylose.
- Kobori, Yoshihiro,Myles, David C.,Whitesides, George M.
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p. 5899 - 5907
(2007/10/02)
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- Intermediates for preparing optically active carboxylic acids
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A process is described for preparing optically active alpha-arylalkanoic acids consisting of rearranging an optically active ketal of formula STR1 in which the substituents have the meaning given in the description of the invention.
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- SYNTHESIS OF MONOSACCHARIDES WITH THE AID OF A NEW SYNTHETIC EQUIVALENT FOR THE GLYCOLALDEHYDE ANION
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The synthesis and characterization of previously unknown B-aryl- and B-alkyl-1,3,2-dioxaboroles is reported.These compounds can act as synthetic equivalents for the glycolaldehyde anion, because they undergo an aldol-type reaction with aldehydes yielding mono, and large amounts of multiple, addition products.By immobilizing the 1,3,2-dioxaboroles on a polymeric support, which accomplishes the site separation of the enediolate intermediates, further addition beyond the primary stage could be inhibited.As a first example of a synthetic application, the synthesis of the otherwise arduously accesible l-ribose was undertaken. 2,3-O-Cyclohexyliden-L-glyceraldehyde reacted with polymer-bound 1,3,2-dioxaborole to give a mixture of pentoses in good yield, from which 54percent of enantiomerically pure L-ribose could be isolated.This work provides a general methodology for the lengthening of sugar chains by two C-atoms, thus furnishing a novel route for the synthesis of rare sugars.
- Wulff, Gunther,Hansen, Achim
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p. 123 - 140
(2007/10/02)
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- Kinetics, Catalysis, and Mechanism of the Secondary Reaction in the Final Phase of the Formose Reaction
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In the final phase of the formose reaction sugars are formed by the reaction of glycolaldehyde, glyceraldehyde and dihydroxyacetone.The application of high-pressure liquid chromatography allows for the first time to investigate intermediate and final products quantitatively.The results of kinetical investigations allow to suggest a reaction mechanism for the secondary reaction in the final phase of the formose reaction.This mechanism is compared with that of the starting phase and other known mechanisms.From the results metal ion-catalyzed aldol reactions have to be assumed.
- Harsch, Guenther,Bauer, Hermann,Voelter, Wolfgang
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p. 623 - 635
(2007/10/02)
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- THE FORMOIN REACTION
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The formoin reaction, i.e., the autocondensation of formaldehyde in an aprotic solvent catalysed by the conjugate base of a thiazolium ion, has been studied in detail.Glucose, galactose, dihyroxyacetone dimer, xylose, and arabinose have been identified as products.The influence of catalysts, temperature, basicity, and reaction time is documented.N,N-Dimethylformamide is a more convenient solvent than ether, benzene, or diglyme.Ethyldi-isopropylamine affords better yields of carbohydrate material than triethylamine.At =60 deg, aldol condensations are reduced to a minimum.After 1-2 h of reaction (depending on the conditions), the yields begin to decrease and become zero after ca. 24 h.
- Castells, Josep,Lopez-Calahorra, Francisco,Geijo, Fernando
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p. 197 - 208
(2007/10/02)
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