- Anti-inflammatory active components of the roots of Datura metel
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One new phenolic glycoside, methyl 3,4-dihydroxyphenylacetate-4-O-[2-O-β-D-apisoyl-6-O-(2-hydroxybenzoyl)]-β-D-glucopyranoside (1), together with 10 known compounds (2–11), were isolated from the roots of Datura metel. The structures of these compounds we
- Qin, Ze,Zhang, Jin,Chen, Liang,Liu, Shu-Xiang,Zhao, Hai-Feng,Mao, Hui-Min,Zhang, Hong-Yang,Li, De-Fang
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p. 392 - 398
(2020/03/30)
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- Orthogonal Active-Site Labels for Mixed-Linkage endo-β-Glucanases
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Small molecule irreversible inhibitors are valuable tools for determining catalytically important active-site residues and revealing key details of the specificity, structure, and function of glycoside hydrolases (GHs). β-glucans that contain backbone β(1,3) linkages are widespread in nature, e.g., mixed-linkage β(1,3)/β(1,4)-glucans in the cell walls of higher plants and β(1,3)glucans in yeasts and algae. Commensurate with this ubiquity, a large diversity of mixed-linkage endoglucanases (MLGases, EC 3.2.1.73) and endo-β(1,3)-glucanases (laminarinases, EC 3.2.1.39 and EC 3.2.1.6) have evolved to specifically hydrolyze these polysaccharides, respectively, in environmental niches including the human gut. To facilitate biochemical and structural analysis of these GHs, with a focus on MLGases, we present here the facile chemo-enzymatic synthesis of a library of active-site-directed enzyme inhibitors based on mixed-linkage oligosaccharide scaffolds and N-bromoacetylglycosylamine or 2-fluoro-2-deoxyglycoside warheads. The effectiveness and irreversibility of these inhibitors were tested with exemplar MLGases and an endo-β(1,3)-glucanase. Notably, determination of inhibitor-bound crystal structures of a human-gut microbial MLGase from Glycoside Hydrolase Family 16 revealed.
- Jain, Namrata,Tamura, Kazune,Déjean, Guillaume,Van Petegem, Filip,Brumer, Harry
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p. 1968 - 1984
(2021/05/26)
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- Method for preparing lactic acid through catalytically converting carbohydrate
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The invention relates to a method for preparing lactic acid through catalytically converting carbohydrate, and in particular, relates to a process for preparing lactic acid by catalytically convertingcarbohydrate under hydrothermal conditions. The method disclosed by the invention is characterized by specifically comprising the following steps: 1) adding carbohydrate and a catalyst into a closedhigh-pressure reaction kettle, and then adding pure water for mixing; 2) introducing nitrogen into the high-pressure reaction kettle to discharge air, introducing nitrogen of 2 MPa, stirring and heating to 160-300 DEG C, and carrying out reaction for 10-120 minutes; 3) putting the high-pressure reaction kettle in an ice-water bath, and cooling to room temperature; and 4) filtering the solution through a microporous filtering membrane to obtain the target product. The method can realize high conversion rate of carbohydrate and high yield of lactic acid, and has the advantages of less catalyst consumption, good circularity, small corrosion to reaction equipment and the like.
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Paragraph 0029-0040
(2020/11/01)
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- Formation of Chiral Structures in Photoinitiated Formose Reaction
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The possibility to synthesize biologically important sugars and other chiral compounds without any initiators in the UV-initiated reaction of formaldehyde in aqueous solution has been shown for the first time. An optically active condensed phase due to an
- Stovbun,Skoblin,Zanin,Tverdislov,Taran,Parmon
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p. 108 - 116
(2018/04/05)
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- Shape-selective Valorization of Biomass-derived Glycolaldehyde using Tin-containing Zeolites
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A highly selective self-condensation of glycolaldehyde to different C4 molecules has been achieved using Lewis acidic stannosilicate catalysts in water at moderate temperatures (40–100 °C). The medium-sized zeolite pores (10-membered ring framework) in Sn-MFI facilitate the formation of tetrose sugars while hindering consecutive aldol reactions leading to hexose sugars. High yields of tetrose sugars (74 %) with minor amounts of vinyl glycolic acid (VGA), an α-hydroxyacid, are obtained using Sn-MFI with selectivities towards C4 products reaching 97 %. Tin catalysts having large pores or no pore structure (Sn-Beta, Sn-MCM-41, Sn-SBA-15, tin chloride) led to lower selectivities for C4 sugars due to formation of hexose sugars. In the case of Sn-Beta, VGA is the main product (30 %), illustrating differences in selectivity of the Sn sites in the different frameworks. Under optimized conditions, GA can undergo further conversion, leading to yields of up to 44 % of VGA using Sn-MFI in water. The use of Sn-MFI offers multiple possibilities for valorization of biomass-derived GA in water under mild conditions selectively producing C4 molecules.
- Tolborg, S?ren,Meier, Sebastian,Saravanamurugan, Shunmugavel,Fristrup, Peter,Taarning, Esben,Sádaba, Irantzu
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p. 3054 - 3061
(2016/11/17)
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- Acid-Assisted Ball Milling of Cellulose as an Efficient Pretreatment Process for the Production of Butyl Glycosides
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Ball milling of cellulose in the presence of a catalytic amount of H2SO4 was found to be a promising pre-treatment process to produce butyl glycosides in high yields. Conversely to the case of water, n-butanol has only a slight effect on the recrystallization of ball-milled cellulose. As a result, thorough depolymerization of cellulose prior the glycosylation step is no longer required, which is a pivotal aspect with respect to energy consumption. This process was successfully transposed to wheat straw from which butyl glycosides and xylosides were produced in good yields. Butyl glycosides and xylosides are important chemicals as they can be used as hydrotropes but also as intermediates in the production of valuable amphiphilic alkyl glycosides.
- Boissou, Florent,Sayoud, Nassim,De Oliveira Vigier, Karine,Barakat, Abdellatif,Marinkovic, Sinisa,Estrine, Boris,Jér?me, Fran?ois
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p. 3263 - 3269
(2015/10/19)
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- Catalytic effect of aluminium chloride on the example of the conversion of sugar model compounds
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Abstract In this work, the catalytic effect of the Bronsted acid hydrochloric acid, the Bronsted base sodium hydroxide and the Lewis acid AlCl3 on the conversion of biomass derived carbohydrates is investigated. On the example of the glycolaldehyde conversion, it is shown that the Lewis acid catalyses the ketol-endiol-tautomerism, the dehydration, the retro-aldol-reaction and the benzilic-acid-rearrangement. The main products are C4- and C6-carbohydrates as well as their secondary products 2-hydroxybut-3-enoic acid 1 and several furans. Under the same reaction conditions hydrochloric acid catalyzes mainly the dehydration and sodium hydroxide the tautomerism and subsequent aldolization.
- Schwiderski, Martin,Kruse, Andrea
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- Productive sugar isomerization with highly active Sn in dealuminated β zeolites
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A water-tolerant Lewis acid catalyst was synthesized by grafting Sn IV in isopropanol under reflux onto dealuminated zeolites with the BEA (β) topology. This synthesis method allows the production of highly active Snβ-type catalysts without the need for long hydrothermal syntheses or hydrogen fluoride, while using cheap Sn-precursors, industrially available β zeolites and standard catalyst synthesis unit operations. Extensive characterization of the best catalyst shows highly dispersed Sn in the zeolite matrix (XRD, 29Si MAS NMR and 1H MAS NMR) without the formation of SnO2 (XRD and UV-Vis). The catalyst was tested for the model isomerization of sugars such as glucose to fructose. The catalytic activity proved to be purely heterogeneous and the catalyst was recycled and reused without significant loss in activity. Isomerization productivities above 4 kg product per kg of catalyst per hour are reported with appreciably low Sn loadings, corresponding to exceptionally high turnover frequencies, viz. 500 cycles per Sn per hour at 110 °C, which surpass the activity per Sn of the original hydrothermally synthesized Snβ.
- Dijkmans, Jan,Gabriels, Dries,Dusselier, Michiel,De Clippel, Filip,Vanelderen, Pieter,Houthoofd, Kristof,Malfliet, Annelies,Pontikes, Yiannis,Sels, Bert F.
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p. 2777 - 2785
(2013/10/08)
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- Development of a chemical strategy to produce rare aldohexoses from ketohexoses using 2-aminopyridine
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Rare sugars are monosaccharides that are found in relatively low abundance in nature. Herein, we describe a strategy for producing rare aldohexoses from ketohexoses using the classical Lobry de Bruyn-Alberda van Ekenstein transformation. Upon Schiff-base formation of keto sugars, a fluorescence-labeling reagent, 2-aminopyridine (2-AP), was used. While acting as a base catalyst, 2-AP efficiently promoted the ketose-to-aldose transformation, and acting as a Schiff-base reagent, it effectively froze the ketose-aldose equilibrium. We could also separate a mixture of Sor, Gul, and Ido in their Schiff-base forms using a normal-phase HPLC separation system. Although Gul and Ido represent the most unstable aldohexoses, our method provides a practical way to rapidly obtain these rare aldohexoses as needed.
- Hasehira, Kayo,Miyanishi, Nobumitsu,Sumiyoshi, Wataru,Hirabayashi, Jun,Nakakita, Shin-Ichi
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experimental part
p. 2693 - 2698
(2011/12/21)
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- COSMETIC COMPOSITION CONTAINING HYDROLYSATES OF ICARIIN
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The present invention relates to a cosmetic composition containing hydrolysates of icariin, and more particularly, a cosmetic composition containing hydrolysates of icariin including icaritin, icariside I and icariside II. The hydrolysates of icariin is prepared by a method comprising the steps of: (a) obtaining an extract from a plant containing icariin using water or an organic solvent; and (b) hydrolyzing the plant extract with an acid, a base, an enzyme or a microorganism producing the enzyme. The cosmetic composition according to the present invention is employed for anti-oxidant, anti-aging, whitening or anti-wrinkling effects.
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Page/Page column 15
(2008/06/13)
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- A new convergent route to aldohexoses from a common chiral building block.
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[reaction in text] A diastereocontrolled route to the eight aldohexoses has been developed starting from a common cyclohexanoid chiral building block.
- Honzumi,Taniguchi,Ogasawara
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p. 1355 - 1358
(2007/10/03)
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- Saponins isolated from Allium chinense G. DON and antitumor-promoting activities of isoliquiritigenin and laxogenin from the same drug
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Investigation of the Chinese crude drug 'Xiebai,' the bulbs of Allium chinense G. DON (Liliaceae), led to the isolation of 2 saponins, xiebai- saponin I (laxogenin 3-O-β-xylopyranosyl (1→4)-[α-arabinopyranosyl (1→6)]-β-glucopyranoside) (1) and laxogenin 3-O-α-arabinopyranosyl (1→6)- β-glucopyranoside (2), and the aglycone, laxogenin (3), together with 2 chalcones, isoliquiritigenin (4) and isoliquiritigenin-4-O-glucoside (5), and β-sitosterol glucoside (6). Compounds 15 were tested in vitro for their inhibitory effect on the 12-O-tetradecanoylphorbol-13-acetate (TPA)- stimulated 32Pi-incorporation into phospholipids of HeLa cells. In addition to this, laxogenin (3) was proven to have an antitumor-promoting activity in a two-stage lung carcinogenesis experiment.
- Baba, Masaki,Ohmura, Masayoshi,Kishi, Naoki,Okada, Yoshihito,Shibata, Shoji,Peng, Jeng,Yao, Shin-Sen,Nishino, Hoyoku,Okuyama, Toru
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p. 660 - 662
(2007/10/03)
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- Total synthesis of the L-hexoses
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Enantiomerically pure polyhydroxylated natural products are synthesized by using a reiterative two-carbon extension cycle consisting of four key transformations. The generality and efficiency of this methodology are demonstrated in the total synthesis of all eight L-hexoses.
- Ko, Soo Y.,Lee, Albert W. M.,Masamune, Satoru,Reed III, Lawrence A.,Sharpless, K. Barry,Walker, Frederick J.
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p. 245 - 264
(2007/10/02)
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- STUDY OF THE EFFECT OF ORGANIC SOLVENTS ON THE SYNTHESIS OF LEVAN AND THE HYDROLYSIS OF SUCROSE BY Bacillus subtilis LEVANSUCRASE
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The equilibrium between the hydrolase and synthetase activities of levansucrase was determined by progressively substituting water with various organic solvents in the enzymic reaction medium.In the presence of high concentrations of these solvents, the enzyme displayed anly synthetase activity.The levan obtained under such conditions had Mr-106 and presented a low molecular dipersity.In the presence of solvent, the Km values for sucrose and raffinose remained unchanged, but the kcat values were five times higher in comparison to the same constants determined for an aqueous medium.
- Chambert, Regis,Petit-Glatron, Marie-Francoise
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p. 117 - 124
(2007/10/02)
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- Glycosyl Nervogenic Acid Esters of Carbohydrates from Anodendron affine (Anodendron. VI)
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Esters of p-O-glucosyl- and p-O-primverosylnervogenic acid with some carbohydrates (including dambonitol, glucose, and sucrose) were isolated from the seeds, unripened fruits, and caules of Anodendron affine DRUCE.The locations of the nervogenic acid moiety on dambonitol and sucrose were determined on the basis of spectral and chemical evidence.Keywords--Anodendron affine; Apocynacea; 3,5-diprenyl-4-hydroxybenzoic acid; nervogenic acid; 1,3-di-O-methyl-myo-inositol; dambonitol; 5-acyldambonitol; 6-acyldambonitol; 6glc-O-(p-O-glucosyl)nervogenoylsucrose; anodendrosin
- Abe, Fumiko,Yamauchi, Tatsuo
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p. 2712 - 2720
(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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- Kinetics of reactions of manganese(III) pyrophosphate with some hexitols
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Alditols are acyclic, polyhydric alcohols that are derived from aldoses and ketoses by reduction.Their wide-spread occurance in Nature, particularly in the lower forms of life, points to their biological importance.Compared to studies of the metal-ion oxidation of sugars, it seems that the oxidation of alditols has received little attention.Earlier, the oxidation of hexitols with cerium(IV) (ref. 1), cobalt(III) (ref. 2), and vanadium(V) (ref. 3) was reported, and we now describe oxidations with manganese(III) pyrophosphate.
- Fadnis, Anand G.,Kulshrestha, Sudhir K.
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p. 137 - 140
(2007/10/02)
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- STRUCTURE D'UN NOUVEL HETEROSIDE D'ISOFLAVONE : LE SAROTHAMNOSIDE
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The structure of sarothamnoside (genistein 7,4'-di-O-4-O-β-D-glucopyranosyl-β-D-apiofuranoside), a new isoflavone glycoside from Sarothamnus scoparius and S. patens, has been established by spectral analysis, mainly 13C NMR.
- Brum-Bousquet, M.,Lallemand, Y.,Tillequin, F.,Delaveau, P.
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p. 1223 - 1226
(2007/10/02)
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- The "formoin reaction" : A promising entry to carbohydrates from formaldehyde
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Formaldehyde condensation catalyzed by the conjugate bases of thiazolium ions, leads to a complex mixture ("formoin mixture") of unbranched aldoses and ketoses, in which glucose, galactose, glyceraldehyde dimer, xylose and arabinose have been identified.
- Castells, Joseph,Geijo, Fernando,Lopez-Calahorra, Francisco
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p. 4517 - 4520
(2007/10/02)
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