- Mechanism of Acid-Catalyzed Anomerization of Methyl D-Glucopyranosides
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The anomerization of methyl D-glucopyranosides catalyzed by D2SO4 in Me2SO/CD3OD solvent was monitored by proton magnetic resonance and by changes in optical rotation.The rate of anomerization was found to be zero order in methanol, yet methanol (or a similar nucleophilic species) was required to effect anomerization.It has been shown that the solvent plays a dominant role in controlling the stereochemistry of reactions at the anomeric carbon; however, the transition-state interactions must be between solvent cage molecules and substrate and are thus solvational forces rather than a more direct nucleophilic participation inside the solvent cage.Evidence is presented supporting the notion that glucoside hydroxyls orient solvent cage molecules to assist attaining a suitable transition-state structure.
- Jensen, James L.,Tsuang, Sho-Chein,Uslan, Arif H.
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- Transglycosylation reactions with a crude culture filtrate from Thermoascus aurantiacus
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Some characteristics of regioselectivity and acceptor tolerance in transglycosylation reactions, catalysed by a crude culture filtrate from Thermoascus aurantiacus, were examined by employing methanol and monosaccharides as acceptors. When β-D-mannopyranosyl fluoride was employed as the donor, the anomeric configuration of the newly formed bond was found to depend on the structure of the acceptor used. Copyright (C) 2000 Elsevier Science Ltd.
- Ortner, Joerg,Albert, Martin,Terler, Katherine,Steiner, Walter,Dax, Karl
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- STEROIDAL ALKALOID GLYCOSIDES FROM LILIUM CORDATUM
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Two new steroidal alkaloid glycosides named cordatine A and B were isolated from petals of Lilium cordatum.Their structures were elucidated by spectral data as (25R)- and (25S)-22,26-epimino-5α-cholest-22(N)-en-3β,6β-diol O(3)-β-D-glucopyranoside
- Nakano, Kimiko,Nishizawa, Koji,Murakami, Kotaro,Takaishi, Yoshihisa,Tomimatsu, Toshiaki
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- Two new glycosides from the whole plant of Anemone rivularis var. flore-minore
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Phytochemical investigation on the whole plant of Anemone rivularis var. flore-minore led to the isolation of a new labdane-type diterpene glycoside (1) and a new trihydroxyfuranoid lignanoid glycoside (2), together with three known triterpene and triterpenoid glycosides (3-5). The structures of the two new compounds were elucidated as β-d-glucopyranosyl (13S)-13-hydroxy-7-oxo- labda-8,14-diene-18-oate (1) and (7S,7′R,8R,8′S)-7′-butoxy-7, 9′-epoxy-4,4′,9-trihydroxy-3,3′-dimethoxylignane 9-O-β-d-glucopyranoside (2), on the basis of extensive spectral analysis and chemical evidence. Compound 1 is characterized by a glucose (Glc) esterified C-18 carboxyl group, which is a rarely encountered labdane-type diterpene glycoside in nature. The two new compounds (1 and 2) reported here are the first examples of diterpene glycoside and lignanoid glycoside found in the genus Anemone, and the known triterpene and triterpenoid glycosides (3-5) are identified for the first time from the title plant.
- Ding, Yu,Tian, Xiang-Rong,Tang, Hai-Feng,Feng, Jun-Tao,Zhang, Wei,Hai, Wen-Li,Wang, Xiao-Yang,Wang, Yi
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- Glucolipsin A and B, two new glucokinase activators produced by Streptomyces purpurogeniscleroticus and Nocardia vaccinii
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During the screening of the natural products for their ability to increase the activity of glucokinase by relieving inhibition by long chain fatty acyl CoA esters (FAC), two novel compounds, glucolipsin A (1) and B (2) were isolated from the butanol extracts of Streptomyces purpurogeniscleroticus WC71634 and Nocardia vaccinii WC65712, respectively. The structures of these two compounds were established by spectroscopic methods and chemical degradation. Glucolipsin A (1) and B (2) relieved the inhibition of glucokinase by FAC with RC50 values of 5.4 and 4.6 μM.
- Qian-Cutrone, Jingfang,Ueki,Huang, Stella,Mookhtiar, Kasim A.,Ezekiel, Regina,Kalinowski, Steven S.,Brown, Karen S.,Golik, Jerzy,Lowe, Susan,Pirnik, Dolores M.,Hugill, Robert,Veitch, Judy A.,Klohr, Steven E.,Whitney, Jeffrey L.,Manly, Susan P.
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- Carbon glycoside glycosylated tetravalent platinum compound as well as synthesis method and application thereof
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The invention provides a carbon glycoside glycosylated tetravalent platinum compound, a synthesis method and application thereof. R1 and R2 are independently C1-C4 lower alkanes, R3 is glucose, galactose, mannose and ribose, different sugars are used as raw materials, and a series of carbon glycoside glycosylated tetravalent platinum compounds are synthesized through protection and deprotection reaction and metallization reaction of the sugars. The synthesis method is simple, the used raw materials are cheap and easy to obtain, the glycosylated tetravalent platinum compound has the capacity of targeting glucose transporter protein and has potential application value in the field of cancer treatment, introduction of a C-glucosidic bond enables the series of compounds to have the capacity of resisting hydrolysis of beta-glucosidase, and the compound is expected to be applied to the field of oral antitumor drugs.
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Paragraph 0064-0067
(2021/07/08)
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- Calixanthomycin A: Asymmetric Total Synthesis and Structural Determination
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We report the first asymmetric total synthesis and structural determination of calixanthomycin A. Taking advantage of a modular strategy, a concise approach was developed to assemble the hexacyclic skeleton with both enantiomers of the lactone A ring. Stereoselective glycosylation coupled the angular hexacyclic framework with a monosaccharide fragment to produce calixanthomycin A and its stereoisomers. This enable us to determine and assign the absolute configuration of C-25 (25S) and monosaccharide (derivative of l-glucose).
- Chen, Kuanwei,Xie, Tao,Shen, Yanfang,He, Haibing,Zhao, Xiaoli,Gao, Shuanhu
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supporting information
p. 1769 - 1774
(2021/03/08)
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- Nascent-HBr-Catalyzed Removal of Orthogonal Protecting Groups in Aqueous Surfactants
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Organic reactions in the aqueous environment have recently emerged as a promising research area. The generation of nascent-HBr from the slow hydrolysis of the dispersed catalyst, benzyl bromide, with the interior water present in the hydrophobic core of the confined micellar medium in aqueous surfactant is described for the first time. The sustained-release nascent-HBr enabled the chemoselective cleavages of acid-sensitive orthogonal functionalities present in carbohydrates, amino alcohols, and hydroxylated acyclic compounds in good to excellent yields.
- Bera, Smritilekha,Gupta, Shilpi,Mondal, Dhananjoy
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- Structure of the unusual Sinorhizobium fredii HH103 lipopolysaccharide and its role in symbiosis
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Rhizobia are soil bacteria that form important symbiotic associations with legumes, and rhizobial surface polysaccharides, such as K-antigen polysaccharide (KPS) and lipopolysaccharide (LPS), might be important for symbiosis. Previously, we obtained a mutant of Sinorhizobium fredii HH103, rkpA, that does not produce KPS, a homopolysaccharide of a pseudaminic acid derivative, but whose LPS electrophoretic profile was indistinguishable from that of the WT strain. We also previously demonstrated that the HH103 rkpLMNOPQ operon is responsible for 5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-L-glyc-ero-L-manno-nonulosonic acid [Pse5NAc7(3OHBu)] production and is involved in HH103 KPS and LPS biosynthesis and that an HH103 rkpM mutant cannot produce KPS and displays an altered LPS structure. Here, we analyzed the LPS structure of HH103 rkpA, focusing on the carbohydrate portion, and found that it contains a highly heterogeneous lipid A and a peculiar core oligosaccharide composed of an unusually high number of hexuronic acids containing b-configured Pse5NAc7(3OHBu). This pseudaminic acid derivative, in its a-configuration, was the only structural component of the S. fredii HH103 KPS and, to the best of our knowledge, has never been reported from any other rhizobial LPS. We also show that Pse5NAc7(3OHBu) is the complete or partial epitope for a mAb, NB6-228.22, that can recognize the HH103 LPS, but not those of most of the S. fredii strains tested here. We also show that the LPS from HH103 rkpM is identical to that of HH103 rkpA but devoid of any Pse5NAc7(3OHBu) residues. Notably, this rkpM mutant was severely impaired in symbiosis with its host, Macroptilium atropurpureum.
- Di Lorenzo, Flaviana,Speciale, Immacolata,Silipo, Alba,Alías-Villegas, Cynthia,Acosta-Jurado, Sebastián,Rodríguez-Carvajal, Miguel-ángel,Dardanelli, Marta S.,Palmigiano, Angelo,Garozzo, Domenico,Ruiz-Sainz, José-Enrique,Molinaro, Antonio,Vinardell, José-María
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p. 10969 - 10987
(2021/01/07)
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- Chemical constituents of the aerial parts of Algerian Galium brunneum: Isolation of new hydroperoxy sterol glucosyl derivatives
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The liposoluble extract of Galium brunneum aerial parts from North-eastern Algeria was chemically investigated. The EtOAc soluble portion contained a series of glycosyl cucurbitacins and sterols including three new glucosyl hydroperoxy sterols 1–3 among other phenolic components whereas the BuOH soluble fraction was dominated by glycosyl derivatives of flavonoids, iridoids and lignans, according to the chemistry reported in the literature for the genus Galium. The structure of new oxidized sterols 1–3 was determined by spectroscopic methods as well as by comparison with related known metabolites. Selected main compounds from both extracts, which revealed moderate antibacterial activities, were tested for their growth inhibitory properties against Gram-positive and Gram-negative bacteria. This is the first report of cucurbitacins in plants of genus Galium.
- Bertella, Anis,Bitam, Fatma,Carbone, Marianna,Ciavatta, Maria Letizia,Gavagnin, Margherita,Smadi, Abla
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- Kinetically Controlled Fischer Glycosidation under Flow Conditions: A New Method for Preparing Furanosides
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Kinetically controlled Fischer glycosidation was achieved under flow conditions. β-Hydroxy-substituted sulfonic acid functionalized silica (HO-SAS) was used as an acid catalyst. This reaction directly converted aldohexoses into kinetically favored furanosides to enable the practical synthesis of furanosides. After optimization of the reaction temperature and residence time, glucofuranosides, galactofuranosides, and mannofuranosides were synthesized in good yields.
- Masui, Seiji,Manabe, Yoshiyuki,Hirao, Kohtaro,Shimoyama, Atsushi,Fukuyama, Takahide,Ryu, Ilhyong,Fukase, Koichi
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supporting information
p. 397 - 400
(2019/02/26)
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- Methyl glycosides via Fischer glycosylation: translation from batch microwave to continuous flow processing
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Abstract: A continuous flow procedure for the synthesis of methyl glycosides (Fischer glycosylation) of various monosaccharides using a heterogenous catalyst has been developed. In-depth analysis of the isomeric composition was undertaken and high consistency with corresponding results observed under microwave heating was obtained. Even in cases where addition of water was needed to achieve homogeneity—a prerequisite for the flow experiments—no detrimental effect on the conversion was found. The scalability was demonstrated on a model case (mannose) and as part of the target-oriented synthesis of d-glycero-d-manno heptose, both performed on multigram scale.
- Aronow, Jonas,Stanetty, Christian,Baxendale, Ian R.,Mihovilovic, Marko D.
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- Catalytic glycosylation of glucose with alkyl alcohols over sulfonated mesoporous carbons
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Herein we investigated the catalytic performances of sulfonated mesoporous carbons in the glycosylation of carbohydrates with alkyl alcohols. Catalytic performances were compared to common solid acid catalysts previously reported for this reaction. Under optimized conditions, the targeted alkyl glycosides were obtained in 85% yield, together with a turn over frequency and a space time yield higher than those of the best heterogeneous catalysts reported so far in such reaction. Furthermore, the presence of mesoporous channels significantly lowered the deactivation rate of the catalyst in comparison to a non-porous sulfonated carbon.
- Ramdani, Wahiba Ghezali,Karam, Ayman,De Oliveira Vigier, Karine,Rio, Sébastien,Ponchel, Anne,Jér?me, Fran?ois
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p. 125 - 129
(2019/03/06)
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- From d-to l-Monosaccharide Derivatives via Photodecarboxylation-Alkylation
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Photodecarboxylation-alkylation of conformationally locked monosaccharides leads to inversion of stereochemistry at C5. This allows the synthesis of l-sugars from their readily available d-counterparts. Via this strategy, methyl l-guloside was synthesized from methyl d-mannoside in 21% yield over six steps.
- Wan, I. C. Steven,Witte, Martin D.,Minnaard, Adriaan J.
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supporting information
p. 7669 - 7673
(2019/10/08)
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- Production of lactic acid derivatives from sugars over post-synthesized Sn-Beta zeolite promoted by WO3
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Various metal oxides were used as co-catalysts to improve the production of alkyl lactate over Sn-Beta-P. WO3 exhibited the best promotion effect. The yield of MLA increased from 25% (6.5 g L?1) over Sn-Beta-P (0.2 g) to 52% (13.4 g L?1) over WO3 (0.1 g) and Sn-Beta-P (0.1 g) at 160 °C for 5 h and 3.1 wt% of glucose concentration. MLA yield of 38% was attained even at glucose concentration of 10 wt% and the space-time yield reached 7.1 g L?1 h?1. The action mechanism of WO3 was investigated. Fine WO3 particles adsorbed on surface of Sn-Beta-P in reaction media and decreased the silanol defects of Sn-Beta-P. This promotes retro-aldol of fructose, the rate-determining step of whole reaction, thus facilitated the formation of MLA. Kinetic studies indicate that the presence of WO3 decreased the activation energy of the retro-aldol of fructose. The binary solid WO3 and Sn-Beta-P is recyclable.
- Yang, Xiaomei,Zhang, Yali,Zhou, Lipeng,Gao, Beibei,Lu, Tianliang,Su, Yunlai,Xu, Jie
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p. 285 - 291
(2019/03/21)
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- Facile and high-yield synthesis of methyl levulinate from cellulose
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Efficient production of chemicals from cellulose provides sustainable routes for the utilization of natural renewable resources to meet the requirements of human society. Herein, we reported a highly efficient and simple metal salt catalyst, Al2(SO4)3, for cellulose conversion to methyl levulinate (ML) under microwave conditions. A highest ML yield of 70.6% was obtained at 180 °C within a very short time of 40 min. The introduction of water could reduce humin/coke formation and solvent consumption, and could also switch the reaction pathway via the more reactive intermediate glucose. Kinetic and mechanistic studies of the subreactions showed that both cellulose hydrolysis and alcoholysis pathways were involved in the cellulose conversion to ML, with the former as the main route in the presence of water. The Lewis acid species [Al(OH)x(H2O)y]n+ and the Br?nsted acid species H+, generated by in situ hydrolysis of Al2(SO4)3, were responsible for the reaction conversions. The reaction with microwave heating showed accelerated reaction rates of 25 times the reaction with conventional oil heating, and even more times for the rates of glucose and methyl glucoside (MG) dehydration, resulting in higher reaction selectivity toward ML production. The catalyst was also successfully recycled and applied to the conversion of cellulose to other alkyl levulinates, as well as the conversion of raw biomass to ML with high yields. The homogeneous nature of Al2(SO4)3, together with its high efficiency and excellent recyclability, make it a potential catalyst for the large-scale production of ML in industry.
- Huang, Yao-Bing,Yang, Tao,Lin, Yu-Ting,Zhu, Ying-Zhi,Li, Li-Cheng,Pan, Hui
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supporting information
p. 1323 - 1334
(2018/03/26)
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- Structure elucidation of a novel oligosaccharide (Medalose) from camel milk
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Free oligosaccharides are the third most abundant solid component in milk after lactose and lipids. The study of milk oligosaccharides indicate that nutrients are not only benefits the infant's gut but also perform a number of other functions which include stimulation of growth, receptor analogues to inhibit binding of pathogens and substances that promote postnatal brain development. Surveys reveal that camel milk oligosaccharides possess varied biological activities that help in the treatment of diabetes, asthma, anaemia, piles and also a food supplement to milking mothers. In this research, camel milk was selected for its oligosaccharide contents, which was then processed by Kobata and Ginsburg method followed by the HPLC and CC techniques. Structure elucidation of isolated compound was done by the chemical degradation, chemical transformation and comparison of chemical shift of NMR data of natural and acetylated oligosaccharide structure reporter group theory, the 1H, 13C NMR, 2D-NMR (COSY, TOCSY and HSQC) techniques, and mass spectrometry. The structure was elucidated as under: MEDALOSE[Figure presented]
- Gangwar, Lata,Singh, Rinku,Deepak, Desh
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p. 157 - 161
(2017/10/13)
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- Synthesis of alkyl α- and β-d-glucopyranoside-based chiral crown ethers and their application as enantioselective phase-transfer catalysts
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Chiral monoaza-15-crown-5-type lariat ethers annelated to alkyl 4,6-O-benzylidene-α- and β-d-glucopyranosides have been synthesized. These macrocycles generated significant asymmetric induction as phase-transfer catalysts in a few two-phase reactions. The catalytic effect of the lariat ethers with methoxy, ethoxy, and i-propoxy substituents on C-1 of the sugar unit in both α and β positions was compared. In liquid–liquid two-phase reactions, the nature and position of the substituents did not have much effect. The α-anomers were somewhat more efficient in terms of enantioselectivity than the β forms. In asymmetric Darzens condensations, in the epoxidation of trans-chalcone, in the Michael addition of β-nitrostyrene and diethyl acetamidomalonate, and in the reaction of 2-benzylidene-1,3-indandione with diethyl bromomalonate, maximum enantioselectivities of 73, 94, 78, and 72%, respectively, were obtained in presence of glucopyranoside-based lariat ethers as catalysts.
- Pálv?lgyi, ádám,Rapi, Zsolt,Ozohanics, Olivér,Tóth, Gábor,Keglevich, Gy?rgy,Bakó, Péter
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p. 1627 - 1645
(2017/11/16)
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- Antimycobacterial 1,4-napthoquinone natural products from Moneses uniflora
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A new 1,4-naphthoquinone derivative, 5,8-dihydro-3-hydroxychimaphilin (4) and five known compounds (1, 2 and 5–7) were isolated from an extract of the Canadian medicinal plant Moneses uniflora that significantly inhibited the growth of Mycobacterium tuberculosis H37Ra. The structure of 4 was established through analysis of NMR and MS data and the absolute configuration of the glycone of 5 was determined by chemical transformation and comparison with standards prepared from D- and L-glucose. All compounds isolated were screened against Mycobacterium tuberculosis (H37Ra) and the mammalian HEK 293 cell line and, with the exception of compounds 5 and 7, exhibited marked selectivity in their bioactivity: Compound 1 exhibited potent antimycobacterial activity (IC50 of 5.4 μM) and moderate cytotoxicity (IC50 of 30 μM); compounds 2, 4 and 6 showed moderate antimycobacterial activity (IC50 values from 28 to 47 μM) without affecting the viability of mammalian cells; compound 5 displayed moderate activity in both assays (IC50 values of 44 and 55 μM respectively); and compound 7 was not active in either assay. These data suggest that the Moneses napthaquinone derivatives elicit biological responses in mycobacterial and mammalian cells through disparate modes of action that warrant further investigation.
- Li, Haoxin,Bos, Allyson,Jean, Stéphanie,Webster, Duncan,Robichaud, Gilles A.,Johnson, John A.,Gray, Christopher A.
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p. 229 - 233
(2018/08/21)
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- Synthesis of Rare Deoxy Amino Sugar Building Blocks Enabled the Total Synthesis of a Polysaccharide Repeating Unit Analogue from the LPS of Psychrobacter cryohalolentis K5T
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Lipopolysaccharides (LPSs) play key roles in humoral immunity. Recently, the LPS structure of the Psychrobacter cryohalolentis K5T strain was reported. Due to the presence of unnatural amino sugars and branched linkages, its structure is unique. Herein we report the total synthesis of an LPS analogue of P. cryohalolentis K5T. After overcoming the issues like ring conformation changes and elimination of triflate, we were able to develop a strategy for the synthesis of the newly reported 2,3,4-triacetamido-2,3,4-trideoxy-l-arabinose derivative. Coupling of different donors with suitable acceptors from the nonreducing end to the reducing end and further functional group modifications delivered the protected LPS hexasaccharide repeating unit. After functional group modifications, we were unable to oxidize the hindered primary hydroxyl group to synthesize the target molecule. Alternatively, removal of the permanent protecting groups afforded the LPS hexasaccharide repeating unit analogue of Psychrobacter cryohalolentis K5T.
- Emmadi, Madhu,Kulkarni, Suvarn S.
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p. 14323 - 14337
(2018/11/25)
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- Kinetic analysis of hexose conversion to methyl lactate by Sn-Beta: Effects of substrate masking and of water
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Simple sugars show promise as substrates for the formation of fuels and chemicals using heterogeneous catalysts in alcoholic solvents. Sn-Beta is a particularly well-suited catalyst for the cleavage, isomerization and dehydration of sugars into more valuable chemicals. In order to understand these processes and save resources and time by optimising them, kinetic and mechanistic analyses are helpful. Herein, we study substrate entry into the Sn-Beta-catalysed methyl lactate process using abundant hexose substrates. NMR spectroscopy is applied to show that the formation of methyl lactate occurs in two kinetic regimes for fructose, glucose and sucrose. The majority of methyl lactate is not formed from the substrate directly, but from methyl fructosides in a slow regime. At 160 °C, more than 40% of substrate carbon are masked (i.e. reversibly protected in situ) as methyl fructosides within a few minutes when using hydrothermally synthesised Sn-Beta, while more than 60% methyl fructosides can be produced within a few minutes using post-synthetically treated Sn-Beta. A significant fraction of the substrate is thus masked by rapid methyl fructoside formation prior to subsequent slow release of fructose. This release is the rate-limiting step in the Sn-Beta-catalysed methyl lactate process, but it can be accelerated by the addition of small amounts of water at the expense of the maximum methyl lactate yield.
- Tosi, Irene,Riisager, Anders,Taarning, Esben,Jensen, Pernille Rose,Meier, Sebastian
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p. 2137 - 2145
(2018/05/04)
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- Selective anomeric acetylation of unprotected sugars in water
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High yielding selective acetylation of only the anomeric hydroxyl of unprotected sugars is possible in aqueous solution using 2-chloro-1,3-dimethylimidazolinium chloride (DMC), thioacetic acid, and a suitable base. The reaction, which may be performed on a multi-gram scale, is stereoselective for sugars that possess a hydroxyl group at position-2, exclusively yielding the 1,2-trans products. The use of an iterative reagent addition procedure allows the use of sodium carbonate as the base, avoiding the formation of triethylammonium salts, which may hamper product purification. The glycosyl acetate products may be used as donor substrates for glycosidase-catalysed synthesis. The crude aqueous acetylation reaction mixture may also be used for this purpose.
- Lim, David,Fairbanks, Antony J.
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p. 1896 - 1900
(2017/03/09)
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- Polyvalent effect enhances diglycosidic antiplasmodial activity
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An efficient and facile total synthesis of diglycoside Matayoside D isolated from the root bark of Matayba guianensis with antiplasmodial activity have been accomplished in 11 steps with 5% overall yields starting from commercially available glucose and rhamnose. Furthermore, a class of the diglycosidic derivatives with different lengths of the linker and valences were also prepared and evaluated for their antiplasmodial activities against chloroquine-susceptible (3D7) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Low valent and short linker attached diglycoside show no enhancement of the antiplasmodial activity while polyvalent conjugates showed enhanced antiplasmodial activity with IC50 value at least 20 fold better than that of the corresponding diglycosidic monomer. The polyvalent diglycoside were non-cytotoxic against normal mammalian cells under 50,000 μg/L.
- Zhang, Wen-Qiang,He, Yun,Yu, Qun,Liu, Hai-Peng,Wang, De-Min,Li, Xiao-Bin,Luo, Jian,Meng, Xin,Qin, Hai-Juan,Lucchi, Naomi W.,Udhayakumar, Venkatachalam,Iyer, Suri S.,Yang, Yang,Yu, Peng
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p. 640 - 648
(2016/07/06)
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- Mesoporous H-ZSM-5 as an efficient catalyst for conversions of cellulose and cellobiose into methyl glucosides in methanol
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The alcoholysis of cellobiose, which is a dimer of glucose and a model molecule of cellulose, has been studied in methanol medium in the presence of various solid acids. Zeolite H-ZSM-5 was found to be highly efficient for the conversion of cellobiose into methyl glucosides (including methyl-α-glucoside and methyl-β-glucoside) in methanol. The Br?nsted acidity plays a key role in the catalytic alcoholysis of cellobiose. H-ZSM-5 with a lower Si/Al ratio (20) possessed higher density of acidic sites afforded a higher methyl glucoside yield (53%) for the conversion of cellobiose at 423 K. The introduction of mesoporosity into the zeolite significantly enhanced its catalytic performance. Methyl glucosides with a yield of 73% were achieved from cellobiose over a mesoporous H-ZSM-5 (H-meso-ZSM-5-0.5 M) sample with an average mesopore size of 6.1 nm. The mesoporous ZSM-5 could also catalyze the direct transformation of cellulose in methanol, providing methyl glucosides with yields of 51% at 463 K. Our comparative studies revealed that the alcoholysis of cellulose in methanol proceeded more efficiently than the hydrolysis of cellulose in water under similar reaction conditions.
- Xue, Laiqi,Cheng, Kang,Zhang, Hongxi,Deng, Weiping,Zhang, Qinghong,Wang, Ye
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- Flavonoid glycosides from Siparuna gigantotepala leaves and their antioxidant activity
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Two new flavonol g1lycosides were isolated from the leaves of Siparuna gigantotepala. Their structures were determined to be kaempferol 3-O-β-xylopyranosyl-(1→2)-α-arabinofuranoside (1) and kaempferol 3,7-di-O-methyl-4′-O-α-rhamnopyranosyl-(1→2)-β-glucopy
- Casta?eda, Harlen Gerardo Torres,Dulcey, Ana Julia Colmenares,Martínez, José Hipólito Isaza
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p. 502 - 506
(2016/06/01)
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- Isolation, structure elucidation and DFT study on two novel oligosaccharides from yak milk
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Two novel oligosaccharides were isolated from yak milk. The milk was processed by the method of Kobata and Ginsberg involving deproteination, centrifugation and lyophilization followed by gel filtrate chromatography acetylation and silica gel column chromatography of derivatized oligosaccharides while their homogeneity was confirmed by HPLC. The structures of these isolated oligosaccharides were elucidated by chemical transformation, chemical degradation, 1H, 13C NMR, 2D NMR (COSY, TOCSY and HSQC) and mass spectrometry. The geometry of compound A (Bosiose) and B (Bovisose) have been optimized at B3LYP method and 6-311 + G(d,p) basis set. The difference between the energies of A and B is 1.269 a.u. or 796.309 kcal/mol.
- Singh, Meenakshi,Kumar, Alok,Srivastava, Gaurav,Deepak, Desh,Singh
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- Zemplén transesterification: A name reaction that has misled us for 90 years
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We demonstrated that using NaOH and NaOMe in methanol for deacylation are identical, indicating that the Zemplén condition has been misleading us for almost 90 years. The traditional base-catalyzed mechanism cannot be used to explain our results. We propose that H-bond complexes play key roles in the base-catalyzed process, explaining why deacylation in methanol can be catalyzed by hydroxide.
- Ren, Bo,Wang, Meiyan,Liu, Jingyao,Ge, Jiantao,Zhang, Xiaoling,Dong, Hai
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supporting information
p. 1390 - 1394
(2015/03/18)
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- Application of 2-substituted benzyl groups in stereoselective glycosylation
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The use of 2-O-(2-nitrobenzyl) and 2-O-(2-cyanobenzyl) groups controls stereoselective formation of 1,2-trans-glycosidic linkages via the arming participation effect. The observed stereoselectivity likely arises from the intramolecular formation of cyclic intermediate between the electron-rich substituent and the donor oxacarbenium ion providing the expected facial selectivity for attack of the glycoside acceptor. The stereodirecting effect of the 2-nitro- and 2-cyanobenzyl groups attached at the remote position (C-3, C-4, and C-6) of the donor molecule have also been investigated. To prove the postulated mechanism based on the participation effect of 2-substituted benzyl groups in the glycosylation stereoselectivity we used DFT theoretical calculation methodology.
- Buda, Szymon,Nawj, Miroslaw,Golbiowska, Patrycja,Dyduch, Karol,Michalak, Artur,Mlynarski, Jacek
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p. 770 - 780
(2015/03/03)
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- Quinofuracins A-E, produced by the fungus staphylotrichum boninense PF1444, show p53-dependent growth suppression
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Quinofuracins A-E, novel anthraquinone derivatives containing β-d-galactofuranose that were isolated from the fungus Staphylotrichum boninense PF1444, induced p53-dependent cell death in human tumor cells. The structures of quinofuracins A-E, including absolute configurations, were elucidated by extensive spectroscopic analysis and chemical transformation studies. Quinofuracins were classified into three groups according to the aglycone moieties. 5'-Oxoaverantin was present in quinofuracins A-C, whereas averantin and versicolorin B were identified in quinofuracins D and E, respectively. These quinofuracins induced p53-dependent growth suppression in human glioblastoma LNZTA3 cells.
- Tatsuda, Daisuke,Momose, Isao,Someno, Tetsuya,Sawa, Ryuichi,Kubota, Yumiko,Iijima, Masatomi,Kunisada, Takao,Watanabe, Takumi,Shibasaki, Masakatsu,Nomoto, Akio
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supporting information
p. 188 - 195
(2015/03/18)
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- Effect of metal salts existence during the acid-catalyzed conversion of glucose in methanol medium
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Catalytic effect of various metal salts as co-catalyst of sulfuric acid was examined.The reaction selectivity is a clear function of the type of metal salts.The major product was methyl glucoside in the presence of K2SO4 or Na2SO4.For Fe2(SO4)3 and Al2(SO4)3, methyl levulinate was formed in the highest yields.Alkali metal sulfates can suppress methyl glucoside isomerize to methyl fructoside.
- Peng, Lincai,Li, Hui,Lin, Lu,Chen, Keli
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- Three new glycosides from the whole plant of Clematis lasiandra Maxim and their cytotoxicity
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Phytochemical investigation on the whole plant of Clematis lasiandra Maxim led to the isolation of two new phenolic glycosides (1 and 2), one new lignanoid glycoside (3), together with three known lignanoid glycosides (4-6). The structures of the new comp
- Tian, Xiang-Rong,Feng, Jun-Tao,Ma, Zhi-Qing,Xie, Na,Zhang, Jing,Zhang, Xing,Tang, Hai-Feng
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p. 168 - 172
(2015/02/06)
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- Protecting-group-free O-glysosidation using p-toluenesulfonohydrazide and glycosyl chloride donors
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A range of N′-glycosylsulfonohydrazides (GSHs) display good reactivity but poor stereoselectivity in protecting-group-free O-glycosidations when a moderate excess of the model acceptor n-decanol is employed. This stable, readily-accessed class of donor may be more tractable for the glycosylation of non-volatile acceptors than Fischer's glycosidation conditions. It is possible to generate unprotected glycosyl chlorides from GSHs in situ. In an effort to find conditions to improve glycosidation stereoselectivity, methanolysis of unprotected glucosyl chloride under halide-ion exchange conditions was examined. Relative to its tetra-O-benzyl analogue, this donor displays moderate, inverted stereoselectivity and a significantly faster reaction rate.
- Williams, Rohan J.,Paul, Caroline E.,Nitz, Mark
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- Lipid metabolites with free-radical scavenging activity from Euphorbia helioscopia L.
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The methanolic extract of the plant Euphorbia helioscopia L. exhibited an interesting free-radical scavenging activity. From the aerial parts of Euphorbia helioscopia L. (Euphorbiaceae), a complex mixture of seven cerebrosides together with glucoclionasterol, a digalactosyldiacylglycerol and a diacylmonogalactosylglycerol were identified. The structures of the cerebrosides were characterized as 1-O-β-d-glucosides of phytosphingosines, which comprised (2S, 3S, 4E, 8E)-2-amino-4(E),8(E)-octadecadiene-1,3-diol, (2S, 3S, 4E, 8Z)-2-amino-4(E),8(Z)-octadecadiene-1,3-diol, (2S, 3S, 4R, 8Z)-2-amino-8(Z)-octadecene-1,3,4-triol as long chain bases with seven 2-hydroxy fatty acids of varying chain lengths (C16, C24:1, C 26:1, C24, C26, C28:1) linked to the amino group. The glycosylglycerides were characterized as (2S)-2,3-O-di-(9,12, 15-octadecatrienoyl)-glyceryl-6-O-(α-d-galactopyranosyl) -β-d-galactopyranoside and (2S)-2,3-O-di-(9,12,15-octadecatrienoyl)- glyceryl-1-O-β-d-galactopyranoside. The structures were established on the basis of spectroscopic data and chemical reactions.
- Cateni,Zilic,Altieri,Zacchigna,Procida,Gaggeri,Rossi,Collina
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- Isolation and characterization of the chemical constituents from Plumeria rubra
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Rubranonoside (=7-O-α-l-rhamnopyranosyl-4′-O-β-d- glucopyranosylnaringenin; (1), a new flavanone glycoside, rubranin (=(2S,3S,4R)-2-{[(2R,16E)-2-hydroxyhexaeico-16-en]amino}octadecane-1,3, 4-triol-1-O-β-d-glucopyranoside; (2), a new sphingolipid, rubradoid (plumieridine-1-O-β-d-galactopyranoside; (3), a new iridoid galactoside, rubrajaleelol (4) and rubrajaleelic acid (5), two new nor-terpenoids together with known iridoids: 1-α-plumieride (6), plumieride p-Z-coumarate (7) and plumieride-p-E-coumarate (8) have been isolated from the EtOAc-soluble fraction of the MeOH extract of Plumeria rubra. Their structures were assigned from 1H, 13C NMR spectra and 2D NMR analyses (COSY, NOESY, HMQC and HMBC experiments) in combination with HRMS experiments and comparison with literature data of related compounds. All the isolates (1-8) were tested for their antioxidant, antiurease, cytotoxic and phytotoxic activities and were found almost inactive.
- Akhtar, Nasim,Saleem, Muhammad,Riaz, Naheed,Ali, M. Shaiq,Yaqoob, Asma,Nasim, Faiz-Ul-Hassan,Jabbar, Abdul
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p. 291 - 298
(2013/08/25)
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- Application of the 2-nitrobenzyl group in glycosylation reactions: A valuable example of an arming participating group
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The application of the o-nitrobenzyl (oNBn) group is demonstrated. This practical methodology allows the stereocontrolled synthesis of glucosides with a 1,2-trans linkage. This new ether-type arming group can broadly extend the concept of the use of participating groups in glycosylation reactions. Easy protection and deprotection of the oNBn group further confirms its usefulness in synthesis. The application of o-nitrobenzyl (oNBn) ether as an arming participating group is demonstrated. This practical methodology allows the stereocontrolled synthesis of glucosides with a 1,2-trans linkage. Copyright
- Buda, Szymon,Golebiowska, Patrycja,Mlynarski, Jacek
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p. 3988 - 3991
(2013/07/19)
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- METHOD FOR PRODUCING GLUCOSIDES
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The present invention relates to methods for producing glucosides directly from glucose or a polysaccharide comprising glucose as a structural unit. The present invention provides a method comprising reacting glucose or a polysaccharide comprising glucose as a structural unit with a compound represented by R—OH in the presence of a supercritical or subcritical carbon dioxide to produce glucosides and a method comprising dissolving or suspending glucose or a polysaccharide comprising glucose as a structural unit in an organic solvent containing a compound represent by R—OH and reacting the glucose or polysaccharide with the compound represented by R—OH in the presence of a supercritical or subcritical carbon dioxide to produce glucosides.
- -
-
Paragraph 0071-0103
(2013/03/26)
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- Mode of action of a β-(1→6)-glucanase from Penicillium multicolor
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β-(1→6)-Glucanase from the culture filtrate of Penicillium multicolor LAM7153 was purified by ammonium sulfate precipitation, followed by cation-exchange and affinity chromatography using gentiotetraose (Gen 4) as ligand. The hydrolytic mode of action of the purified protein on β-(1→6)-glucan (pustulan) was elucidated in real time during the reaction by HPAEC-PAD analysis. Gentiooligosaccharides (DP 2-9, Gen 2-9), methyl β-gentiooligosides (DP 2-6, Gen2-6 β-OMe), and p-nitrophenyl β-gentiooligosides (DP 2-6, Gen 2-6 β-pNP) were used as substrates to provide analytical insight into how the cleavage of pustulan (DP? 320) is actually achieved by the enzyme. The enzyme was shown to completely hydrolyze pustulan in three steps as follows. In the initial stage, the enzyme quickly cleaved the glucan with a pattern resembling an endo-hydrolase to produce a short-chain glucan (DP? 45) as an intermediate. In the midterm stage, the resulting short-chain glucan was further cleaved into two fractions corresponding to DP 15-7 and DP 2-4 with great regularity. In the final stage, the lower oligomers corresponding to DP 3 and DP 4 were very slowly hydrolyzed into glucose and gentiobiose (Gen 2). As a result, the hydrolytic cooperation of both an endo-type and saccharifying-type reaction by a single enzyme, which plays a bifunctional role, led to complete hydrolysis of the glucan. Thus, β-(1→6)-glucanase varies its mode of action depending on the chain length derived from the glucan.
- Hattori, Takeshi,Kato, Yasuna,Uno, Shuji,Usui, Taichi
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- Two new sphingolipids from the leaves of Piper betle L.
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Two new sphingolipids, pipercerebrosides A (1) and B (2), were isolated from the leaves of Piper betle L. Their structures, including absolute configurations, were determined by spectroscopic analysis and chemical degradation. These two compounds did not show significant cytotoxic activity against the cancer cell lines K562 and HL-60 in a MTT assay.
- Chen, Duo-Zhi,Xiong, Hua-Bin,Tian, Kai,Guo, Jun-Ming,Huang, Xiang-Zhong,Jiang, Zhi-Yong
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p. 11241 - 11249
(2013/10/22)
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- Novel cerebrosides isolated from the fermentation mycelia of tuber indicum
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The four new cerebrosides 1-4 possessing a unique C18 9-methylsphinga-4,8-dienine-related moiety and a cyclic octapeptide, 5, possessing alternating proline and glycine moietes were isolated from the Tuber indicum fermentation mycelium. Their structures were established on the basis of a spectroscopic analysis including NMR and HR-ESI-MS, as well as an acidic methanolysis experiment. To the best of our knowledge, the cerebrosides identified in the present study are quite different from those isolated from Tuber indicum fruiting bodies. Additionally, it was the first time that a cyclic peptide was isolated from the Tuber genus. Copyright
- Li, Yuan-Yuan,Liu, Ping,Tang, Yang,Li, Hong-Mei,Tang, Ya-Ling,Liang, Xin-Hua,Tang, Ya-Jie
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p. 702 - 709
(2013/06/04)
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- Lipoxygenase inhibitory sphingolipids from Launaea nudicaulis
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Four new sphingolipids: nudicaulin A [(2S,3S,4R,14E)-2-{[octadecanoyl] amino}tetraeicos-14-ene-1,3,4-triol; 1], nudicaulin B [(2S,3S,4R,14E)-2-{[(2R)- 2-hydroxyoctadecanoyl]amino}tetraeicos-14-ene-1,3,4-triol; 2], nudicaulin C [(2S,3S,4R,14E)-2-{[(2R)-2-hydroxyoctadecanoyl]amino}tetraeicos-14-ene-1,3, 4-triol-1-O-β-d-glucopyranoside; 3], and nudicaulin D [(2S,3S,4R)-2-{[(2R, 3S,12E)-2,3-dihydroxyeicos-12-enoyl]amino}octadecane-1,3,4-triol; 4] together with 1-hexatriacontanol,-sitosterol, octadecyl 4-hydroxycinnamate, elaidic acid, cholesta-5,22-diene-3,7-diol, oleanolic acid, apigenin, and-sitosterol 3-O-β-d-glucopyranoside were isolated from the methanolic extract of the whole plant of Launaea nudicaulis. Their structures were elucidated using 1H and 13C NMR spectra and 2D NMR analyses (HMQC, HMBC, and COSY) in combination with mass spectrometry (EI-MS, HR-EI-MS, FAB-MS, and HR-FAB-MS) experiments and comparison with literature data of related compounds. Compounds 1-4 displayed moderate inhibitory potential against enzyme lipoxygenase in concentration-dependent manner with IC50 value ranges 103-193M.
- Riaz, Naheed,Parveen, Shehla,Saleem, Muhammad,Ali, Muhammad Shaiq,Malik, Abdul,Ashraf, Muhammad,Afzal, Iftikhar,Jabbar, Abdul
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experimental part
p. 545 - 554
(2012/09/25)
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- New sphingolipids from Abutilon pakistanicum
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Pakistamides A and B (1 and 2, respectively), two new sphingolipids, have been isolated from the AcOEt-soluble sub-fraction of the MeOH extract of the whole plant of Abutilon pakistanicum. Their structures were assigned by 1 H and 13C NMR spectra, and by DEPT and COSY, NOESY, HMQC, HMBC, EI-MS, and FAB-MS experiments.
- Ali, Bakhat,Mehmood, Rashad,Hussain, Riaz,Malik, Abdul,Imran, Muhammad,Nawaz, Haq,Hussain, Ajaz
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experimental part
p. 433 - 437
(2012/08/14)
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- Spiraeamide, new sphingolipid from Spiraea brahuica
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Spiraeamide (1), a new sphingolipid, has been isolated from the ethyl acetate-soluble fraction of the methanolic extract of the whole plant of Spiraea brahuica, along with marrubiin (2), 19-acetylmarrubenol (3), and 6-acetylmarruenol (4). Their structures were elucidated by 1H and 13C NMR spectra, and COSY, NOESY, HMQC, HMBC, EI-MS, and FAB-MS experiments.
- Mughal, Uzma Rasheed,Mehmood, Rashad,Malik, Abdul,Ali, Bakhat,Safder, Muhammad,Tareen, Rasool Bakhsh
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experimental part
p. 601 - 606
(2012/08/28)
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- Significantly improved equilibrium yield of long-chain alkyl glucosides via reverse hydrolysis in a water-poor system using cross-linked almond meal as a cheap and robust biocatalyst
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An array of ten β-D-glucopyranosides with varied alkyl chain lengths were enzymatically synthesized. It was found that for longer alkyl chains a lower initial rate and final yield of glucoside was obtained except for methyl glucoside because of the severe toxicity of methanol to the enzyme. From a thermodynamics point of view, the equilibrium constant and Gibbs free energy variation of the glucoside syntheses were systematically investigated. To improve the final yields of the glucosides containing long alkyl chains the equilibrium of the enzymatic glucoside synthesis was altered. The equilibrium yield of decyl β-D-glucoside increased from 1.9 to 6.1 when the water content was reduced from 10 to 5 (v/v) using tert-butanol as a cosolvent and 0.10 mol/L of glucose as a substrate. As for the other longer alkyl chain glucosides, heptyl β-D-glucoside was found to have significant surface activity as well.
- Wang, Qinqqin,Yu, Huilei,Zhao, Na,Li, Chunxiu,Shang, Yazhuo,Liu, Honglai,Xu, Jianhe
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p. 275 - 280
(2012/06/29)
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- Significantly Improved Equilibrium Yield of Long-Chain Alkyl Glucosides via Reverse Hydrolysis in a Water-Poor System Using Cross-Linked Almond Meal as a Cheap and Robust Biocatalyst
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An array of ten β-D-glucopyranosides with varied alkyl chain lengths were enzymatically synthesized. It was found that for longer alkyl chains a lower initial rate and final yield of glucoside was obtained except for methyl glucoside because of the severe toxicity of methanol to the enzyme. From a thermodynamics point of view, the equilibrium constant and Gibbs free energy variation of the glucoside syntheses were systematically investigated. To improve the final yields of the glucosides containing long alkyl chains the equilibrium of the enzymatic glucoside synthesis was altered. The equilibrium yield of decyl β-D-glucoside increased from 1.9% to 6.1% when the water content was reduced from 10% to 5% (v/v) using tert-butanol as a cosolvent and 0.10 mol/L of glucose as a substrate. As for the other longer alkyl chain glucosides, heptyl β-D-glucoside was found to have significant surface activity as well.
- Wang, Qinqqin,Yu, Huilei,Zhao, Na,Li, Chunxiu,Shang, Yazhuo,Liu, Honglai,Xu, Jianhe
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p. 275 - 280
(2016/04/10)
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- Cytotoxic ceramides and glycerides from the roots of Livistona chinensis
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A 70% ethanol extract of the roots of Livistona chinensis has been investigated, led to the isolation of 13 compounds, including a new ceramide, (2S,3S,4R,9Z)-2-[(2R)-2-hydroxytricosanoylamino]-9-octadecene-1,3,4-triol (2), a new glycosyl ceramide, 1-O-β-d-glucopyranosyl-(2S,3S,4R,9Z)-2-[(2R)-2- hydroxydocosanoylamino]-9-octadecene-1,3,4-triol (3), three new monoacylglycerols, 1-(34-hydroxytetratriacontanoyl)-sn-glycerol (9), 1-[nonadeca-(9Z,12Z)-dienoyl]-sn-glycerol (10), and 1-[12-hydroxypentatriaconta- (13E,15Z)-dienoyl]-sn-glycerol (11), a new diacylglycerol, 1-(heptadeca-6Z,9Z- dienoyl)-3-(octadeca-6Z,9Z,12Z-trienoyl)-sn-glycerol (12), as well as a new diacylglycerol aminoglycoside, 1-octadecanoyl-2-nonadecanoyl-3-O-(6-amino-6- deoxy)-β-d-glucopyranosyl-sn-glycerol (13). The structures of new compounds were elucidated, based on spectroscopic, zymologic and chemical methods. Among the compounds tested, compounds 3, 4 and 13 showed significantly antiproliferative effects against the human tumor cell lines (K562, HL-60, HepG2, and CNE-1) with the IC50 of 10-65 μM. To our knowledge, this is first report of the occurrence of ceramides and acylglycerols in the genus Livistona.
- Zeng, Xiaobin,Xiang, Limin,Li, Chen-Yang,Wang, Yihai,Qiu, Guofu,Zhang, Zhen-Xue,He, Xiangjiu
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experimental part
p. 609 - 616
(2012/06/04)
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- One-pot preparation of methyl levulinate from catalytic alcoholysis of cellulose in near-critical methanol
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One-pot preparation of methyl levulinate (MLA) from cellulose in near-critical methanol was studied. Acids containing SO3H group were proven to be effective catalysts for the production of MLA from cellulose's catalytic alcoholysis. The effects of different reaction conditions, such as an initial cellulose concentration of 10-30 g/L, a temperature range from 170 to 190 °C, and a sulfuric acid concentration of 0.01-0.03 mol/L, on the production of MLA were investigated. The results showed the reaction temperature and acid concentration significantly affected the process of cellulose alcoholysis and the yield of MLA. A high yield of up to 55% MLA was achieved at 190 °C for 5 h, using 0.02 mol/L H2SO4 as a catalyst.
- Wu, Xiaoyu,Fu, Jie,Lu, Xiuyang
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p. 37 - 39,3
(2020/07/31)
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- Characterization of ulvan extracts to assess the effect of different steps in the extraction procedure
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An effective application development of the polysaccharide ulvan requires a comprehensive knowledge about the influence of the extraction process on composition of the extracts and in ulvan itself. In this context, the two main objectives of the present work are (1) the establishment of an efficient extraction process for ulvan and (2) development of an accurate characterization methodology to evaluate the extract composition and ulvan content. Three ulvan-rich extracts obtained by different schemes of extraction were studied. The methodology for the analysis was improved and a detailed analysis of extracted ulvan was provided. The polysaccharide is rich in ulvanobiuronic acid 3-sulfate type A [→4)-β-d-GlcAp-(1 → 4)-α-l-Rhap 3S-(1→], with minor amounts of ulvanobiuronic acid 3-sulfate type B [→4)-α-l-IdoAp-(1 → 4)-α-l-Rhap 3S-(1→]. The extract with the higher degree of purification is a high molecular weight polysaccharide (790 kDa) composed of rhamnose (22.4%), glucuronic acid (22.5%), xylose (3.7%), iduronic acid (3.1%) and glucose (1.0%). It is highly sulfated (32.2%) and contains 1.3% of proteins and 10.3% of inorganic material. Applying simple extraction scheme it was possible to obtain an extract from green algae with high content of ulvan without affecting the overall chemical structure of the polysaccharide.
- Costa, Carina,Alves, Anabela,Pinto, Paula R.,Sousa, Rui A.,Borges Da Silva, Eduardo A.,Reis, Rui L.,Rodrigues, Alírio E.
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experimental part
p. 537 - 546
(2012/06/15)
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- Steroidal saponins from the roots of Smilax sp.: Structure and bioactivity
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Phytochemical characterization of a commercial herb sample supplied as Smilax ornata Lem. (sarsaparilla) led to the isolation of five steroidal saponins, including two new furostanol saponins sarsaparilloside B (1) and sarsaparilloside C (2), whose structures were elucidated via a combination of multistage mass spectrometry (MSn), 1D and 2D NMR experiments, and chemical degradation. The previously unreported spectroscopic characterization of sarsaparilloside (3), Δ20(22)-sarsaparilloside (4), and parillin (5) is also provided. The antiproliferative activity of the isolated saponins was compared in six human cell lines derived from different tumor types and one of the structures (2) was particularly active against the HT29 colon tumor cell line.
- Challinor, Victoria L.,Parsons, Peter G.,Chap, Sonet,White, Eve F.,Blanchfield, Joanne T.,Lehmann, Reginald P.,De Voss, James J.
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experimental part
p. 504 - 511
(2012/05/19)
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- A new cerebrogalactoside from juglans mandshurica
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A new cerebrogalactoside, Juglans cerebroside A (1), together with five known compounds, quercetin-3-O-β-D-galactopyranoside (2), myricetin-3-O-β-D-galactopyranoside (3), 2''E-quercetin-3-O-β-D- (6''''-O-[3''-(4'''-hydroxyphenyl) propylene acyl]) glucopyranoside (4), gallic acid (5), and 2-methyl-1-hexadecanol (6) were isolated from the leaves of Juglans mandshurica Maxim. The structures of these compounds were determined by 1D, 2D NMR, and MS techniques.
- Sun, Jiaming,Chang, Renlong,Zhang, Hui
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experimental part
p. 254 - 256
(2011/08/09)
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- Cerebrosides and 2-pyridone alkaloids from the halotolerant fungus Penicillium chrysogenum grown in a hypersaline medium
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Five new cerebrosides, chrysogesides A-E (1-5), and two new 2-pyridone alkaloids, chrysogedones A and B (6 and 7), were isolated from the fermentation broth of Penicillium chrysogenum PXP-55, a halotolerant fungus grown in a hypersaline medium. Among them, chrysogesides B-D (2-4) are the first cerebrosides that contain an unsaturated C19-fatty acid. Their structures were identified by spectroscopic and chemical methods, including CD spectroscopy as well as the modified Mosher's method. Compound 2 showed antimicrobial activity against Enterobacter aerogenes with an MIC value of 1.72 μM. (Chemical Equation Presented).
- Peng, Xiaoping,Wang, Yi,Sun, Kunlai,Liu, Peipei,Yin, Xia,Zhu, Weiming
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experimental part
p. 1298 - 1302
(2011/07/30)
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- Synthesis and biological evaluation of the glycoside (25R)-3β, 16β-diacetoxy-22-oxocholest-5-en-26-yl β-d-glucopyranoside: A selective anticancer agent in cervicouterine cell lines
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The synthesis and biological evaluation of the new cholestane glycoside (25R)-3β,16β-diacetoxy-22-oxocholest-5-en-26-yl β-d- glucopyranoside starting from diosgenin is described. This compound showed selective antiproliferative activity against CaSki, ViBo, and HeLa cervicouterine cancer cells. Its effect on the cell-cycle was determined. The cytotoxic effects of the title compound on cervicouterine cancer cell lines and human lymphocytes indicate that the main cell death process is not necrosis; hence it is not cytotoxic. The title compound induced apoptosis in cervicouterine cancer cells. Importantly, the antiproliferative activity on tumor cells did not affect the proliferative potential of peripheral blood lymphocytes. The title compound showed selective antitumor activity and greater antiproliferative activity than its aglycon, and therefore serves as a promising lead candidate for further optimization.
- Fernandez-Herrera, Maria A.,Lopez-Munoz, Hugo,Hernandez-Vazquez, Jose M.V.,Lopez-Davila, Moises,Mohan, Sankar,Escobar-Sanchez, Maria L.,Sanchez-Sanchez, Luis,Pinto, B. Mario,Sandoval-Ramirez, Jesus
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scheme or table
p. 3877 - 3886
(2011/11/07)
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- Transformation of cellulose into biodegradable alkyl glycosides by following two different chemical routes
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The transformation of cellulose into long-chain alkyl glycoside surfactants has been carried out following two different routes: (1) Direct transformation of cellulose to butyl-, hexyl-, octyl-, decyl- and dodecyl-α,β- glycosides in an ionic liquid media and Amberlyst-15Dry as catalysts, with mass yield of up to 82%; and (2) two steps reaction with transformation of cellulose into methyl glucosides, with a procedure described by Zhang et al., followed by transacetalation with 1-octanol and 1-decanol in the presence of Amberlyst-15Dry. A kinetic study for the direct transformation of cellulose using 1-octanol has shown that depolymerisation of cellulose continues during the Fischer glycosidation. Increasing the chain length of the alcohol decreases the global reaction rate owing to an increase in the lipophilicity of the alcohol that decreases its contact with the carbohydrates. Finally, several acid catalysts were tested and the best results were obtained with Amberlyst-15Dry.
- Villandier, Nicolas,Corma, Avelino
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experimental part
p. 508 - 513
(2012/03/08)
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- Structural determination of cerebrosides isolated from Asterias amurensis starfish eggs using high-energy collision-induced dissociation of sodium-adducted molecules
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Six cerebrosides were isolated from the eggs of the starfish Asterias amurensis using solvent extraction, silica gel column chromatography, and reversed-phase high-performance liquid chromatography. This study demonstrated that the structures of cerebrosides could be completely characterized, based on their sodium-adducted molecules, using fast atom bombardment (FAB) tandem mass spectrometry. The high-energy collision-induced dissociation of the sodium-adducted molecule, [M+Na]+, of each cerebroside molecular species generated abundant ions, providing information on the compositions of the 2-hydroxy fatty acids and long-chain sphingoid bases, as well as the sugar moiety polar head group. Each homologous ion series along the fatty acid and aliphatic chain of the sphingoid base was useful for locating the double-bond positions of both chains and the methyl branching position of the long-chain base. The N-fatty acyl portions were primarily long-chain saturated or monoenoic acids (C16 to C24) with an α-hydroxy group. The sphingoid long-chain base portions were aliphatic chains (C18 or C22) with two or three degrees of unsaturation and with or without methyl branching.
- Park, Taeseong,Park, Young Seung,Rho, Jung-Rae,Kim, Young Hwan
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experimental part
p. 572 - 578
(2012/01/14)
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- Cytotoxic and haemolytic steroidal glycosides from the Caribbean sponge Pandaros acanthifolium
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Six new steroidal saponins, pandarosides K-M (1-3) and their methyl esters (4-6), were isolated as minor components, after a careful chemical reinvestigation of the Caribbean sponge Pandaros acanthifolium. Their structures were established on the basis of spectroscopic analyses and comparison with the data obtained from previous metabolites of this family. All new compounds showed moderate to weak activity against four parasitic protozoa. Additionally, these compounds and previously reported pandarosides and acanthifoliosides were tested on three human tumour cell lines, and their haemolytic and liposome permeabilizing activity were assessed. Two pandarosides exhibited moderate to strong cytotoxic effect, while three acanthifoliosides showed strong haemolytic activity.
- Regalado, Erik L.,Turk, Tom,Tasdemir, Deniz,Gorjanc, Manca,Kaiser, Marcel,Thomas, Olivier P.,Fernández, Rogelio,Amade, Philippe
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experimental part
p. 1389 - 1396
(2011/11/06)
-
