- Temporary Protection and Activation in the Regioselective Synthesis of Saccharide Sulfates
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Regioselective sulfation with Et3N*SO3 of partially protected or unprotected glycosides via stannanediyl acetals or stannyl ethers, combined with persistent or temporary protecting groups is described.Stannylation of phenylboronates, followed by sulfation and aqueous workup, is an efficient way for the synthesis of monosulfated monosaccharides.The stannanediyl acetal 2 led in high yields to 3a, while sulfation of the diol 1 proceeded more slowly and led in lower yield to a mixture 1/3a/4a/5a (Scheme 1).The trehalose disulfate 8a was obtained in high yields from 7; reducing the amount of sulfating agent led to a mixture 6/8a/9a.Stannylation and sulfation of the galactoside 11 afforded 13a, while direct sulfation of 11 gave a mixture of the 2- and 3-sulfates 13a/14a besides some disulfate 15a.Sulfation of the lactose derivative 16 and the stannanediyl acetal 17 gave the 3-sulfate 18a, with some disulfate 19a being formed from 16.The mannopyranoside 21 was selectively sulfated at OH-C(2), leading to 22a, while the corresponding diol 20 yielded mostly the isomer 23a and some disulfate 24a.Sulfation of the stannyl ethers derived from the gluco- and galactopyranosides 25 and 28 and (Bu3Sn)2O afforded high yields of the 2,6-disulfate 26a and the 3,6-disulfate 29a, respectively.Stannylation of 25 and 28 with Bu2SnO and sulfation proceeded less satisfactorily.Stannylation of the phenylboronate 32 (Bu2SnO) and sulfation gave good yields of the 2-sulfate 27a; stannylation and benzoylation yielded the 2-benzoate 34 (Scheme 2).Similarly, the galactose-derived 37 provided high yields of the 3-sulfate 30a and of the 3-benzoate 39.Direct sulfation of the phenylboronates 32 and 37 proceeded in lower yields and gave mixtures.
- Langston, Steven,Bernet, Bruno,Vasella, Andrea
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- Operationally simple and efficient workup procedure for TBAF-mediated desilylation: Application to halichondrin synthesis
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An operationally simple and efficient workup method for tetrabutylammonium fluoride (TBAF)-mediated t-butyldimethylsilyl (TBS) deprotection has been developed. The procedure includes addition of a sulfonic acid resin and calcium carbonate, followed by filtration and evaporation. This method eliminates the tedious aqueous-phase extraction process to remove excess TBAF and materials derived from TBAF, thereby making the protocol highly amenable to multiple TBS deprotections. Its efficiency and usefulness were demonstrated by using the transformation of 1 a to 3a in the halichondrin synthesis.
- Kaburagi, Yosuke,Kishi, Yoshito
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- Preliminary 1H NMR investigation of sialic acid transfer by the trans-sialidase from Trypanosoma cruzi
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1H NMR spectroscopy has been used to investigate the transfer of sialic acid from sialic acid donor molecules to acceptor molecules using the trans-sialidase from Typanosoma cruzi. It is clearly demonstrated that NMR spectroscopy is an efficien
- Wilson, Jennifer C,Kiefel, Milton J,Albouz-Abo, Samia,Von Itzstein, Mark
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- STEROIDAL ALKALOIDS FROM SOLANUM CAPSICASTRUM
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From the rootbark of Solanum capsicastrum, in addition to etioline and isoteinemine, a new 22,26-epiminocholestene glycoside named capsicastrine was isolated and its structure elucidated as isoteinemine O(3)-β-D-galactopyranoside by physical and chemical
- Lin, Chun-Nan,Chung, Mei-Ing,Lin, Son-Yuan
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- Catalytic Consequences of Experimantal Evolution. Part 1. Catalysis by the Wild-type Second β-Galactosidase (ebg0) of Escherichia coli: a Comparison with the lacZ Enzyme
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β-D-Galactopyranose is the initial product of the hydrolysis of β-D-galactopyranosyl fluoride by ebg0 enzyme.Transfer to methanol of a β-D-galactopyranosyl residue from either m-nitrophenol or 3-bromopyridine is seven times more favourable than
- Burton, John,Sinnott, Michael L.
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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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- 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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- 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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- 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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- IMPROVED PROCESS FOR PREPARATION OF 2,3,4,6-TETRA-O-BENZYL-D-GALACTOSE
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Provided herein is an improved process for the preparation of benzylated derivative of D-galactose, particularly 2,3,4,6-tetra-O-benzyl-D-galactose that gives higher yield and better purity being cost effective with reduced impurities.
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Page/Page column 22
(2020/01/08)
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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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- 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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- 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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- 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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- 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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- 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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- New secondary metabolites from croton sparsiorus morong
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Sparsioamide (1), a new sphingolipid, and sparsioside (2), a new diglyceride galactoside, have been isolated from the ethyl acetate soluble fraction of the 80% ethanolic extract of the whole plant of Croton sparsiorus Morong. Their structures were assigned by 1 H- and 13C-NMR spectra and DEPT, COSY, NOESY, HMQC, HMBC, and ESI-MS experiments. TUeBITAK.
- Mehmood, Rashad,Bibi, Amna,Malik, Abdul
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p. 111 - 118
(2013/05/08)
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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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- 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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- An exo-β-(1→3)-d-galactanase from Streptomyces sp. provides insights into type II arabinogalactan structure
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An exo-β-(1→3)-d-galactanase (SGalase1) that specifically cleaves the β-(1→3)-d-galactan backbone of arabinogalactan-proteins (AGPs) was isolated from culture filtrates of a soil Streptomyces sp. Internal peptide sequence information was used to clone and recombinantly express the gene in E. coli. The molecular mass of the isolated enzyme was ～45 kDa, similar to the 48.2 kDa mass predicted from the amino acid sequence. The pI, pH and temperature optima for the enzyme were ～7.45, 3.8 and 48 °C, respectively. The native and recombinant enzymes specifically hydrolysed β-(1→3)-d- galacto-oligo- or poly-saccharides from the upstream (non-reducing) end, typical of an exo-acting enzyme. A second homologous Streptomyces gene (SGalase2) was also cloned and expressed. SGalase2 was similar in size (47.9 kDa) and enzyme activity to SGalase1 but differed in its pH optimum (pH 5). Both SGalase1 and SGalase2 are predicted to belong to the CAZy glycosyl hydrolase family GH 43 based on activity, sequence homology and phylogenetic analysis. The K m and Vmax of the native exo-β-(1→3)-d- galactanase for de-arabinosylated gum arabic (dGA) were 19 mg/ml and 9.7 μmol d-Gal/min/mg protein, respectively. The activity of these enzymes is well suited for the study of type II galactan structures and provides an important tool for the investigation of the biological role of AGPs in plants. De-arabinosylated gum arabic (dGA) was used as a model to investigate the use of these enzymes in defining type II galactan structure. Exhaustive hydrolysis of dGA resulted in a limited number of oligosaccharide products with a trisaccharide of Gal2GlcA1 predominating.
- Ling, Naomi X.-Y.,Lee, Joanne,Ellis, Miriam,Liao, Ming-Long,Mau, Shaio-Lim,Guest, David,Janssen, Peter H.,Ková?, Pavol,Bacic, Antony,Pettolino, Filomena A.
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experimental part
p. 70 - 81
(2012/05/04)
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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.
-
experimental part
p. 537 - 546
(2012/06/15)
-
- One-pot preparation of methyl levulinate from catalytic alcoholysis of cellulose in near-critical methanol
-
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
-
p. 37 - 39,3
(2020/07/31)
-
- 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.
-
experimental part
p. 504 - 511
(2012/05/19)
-
- Kinetic products under thermal conditions: Rapid entry into α/β-D-galactofuranosides using microwave irradiation and selective Lewis acids
-
A modified Fischer-Lubineau reaction, employing microwave irradiation and selected Lewis acids such as Mn(ClO4)2, Mn(C 2H3O2)3, FeCl3, CoCl 2, and AgF as independent a
- Santra, Soumava,Jonas, Emily,Bourgault, Jean-Paul,El-Baba, Tarick,Andreana, Peter R.
-
experimental part
p. 27 - 40
(2012/01/17)
-
- Transformation of cellulose into biodegradable alkyl glycosides by following two different chemical routes
-
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
-
experimental part
p. 508 - 513
(2012/03/08)
-
- Structural determination of cerebrosides isolated from Asterias amurensis starfish eggs using high-energy collision-induced dissociation of sodium-adducted molecules
-
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)
-
- 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
-
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
-
scheme or table
p. 3877 - 3886
(2011/11/07)
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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
-
experimental part
p. 1389 - 1396
(2011/11/06)
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- Flavusides A and B, antibacterial cerebrosides from the marine-derived fungus Aspergillus flavus
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Flavusides A (1) and B (2), two new antibacterial cerebroside derivatives, and the previously described phomaligol A (3), kojic acid (4), methyl kojic acid (5), and dimethyl kojic acid (6) have been isolated from the extract of a marine isolate of the fungus Aspergillus flavus. The structure and absolute stereochemistry of two cerebrosides were assigned on the basis of NMR and Tandem FAB-MS/MS experiments. Compounds 1, 2, and 3 exhibited a mild antibacterial activity against Staphylococcus aureus, methicillin-resistant S. aureus, and multidrug-resistant S. aureus. The minimum inhibitory concentration (MIC) values for each strain are as follows: compounds 1 and 2 showed 15.6 μg/ml for S. aureus and 31.2 μg/ml for methicillin-resistant S. aureus and multidrug-resistant S. aureus, and compound 3 exhibited 31.2 μg/ml for S. aureus and methicillin-resistant S. aureus and 62.5 μg/ml for multidrug-resistant S. aureus.
- Yang, Guohua,Sandjo, Louis,Yun, Keumja,Leutou, Alain Simplice,Kim, Gun-Do,Choi, Hong Dae,Kang, Jung Sook,Hong, Jongki,Son, Byeng Wha
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experimental part
p. 1174 - 1177
(2011/10/17)
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- Chemical properties and antiulcerogenic activity of a galactomannoglucan from Syagrus oleracea
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A galactomannoglucan (GMG) with an estimated weight-average molar mass of 415,000. g/mol was obtained from an aqueous extract of the mesocarp of fruits of Syagrus oleracea (Mart.) Becc. by fractionation by Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that GMG has a chain of (1 → 4)-linked β-d-mannopyranosyl residues attached to an initial chain of (1 → 3)-linked β-d-galactopyranosyl residues and a terminal chain of (1 → 4)-linked α-d-glucopyranosyl residues which comprised galactose, mannose and glucose in the molar ratio of 30:33:37. Results of the present study indicated that the polysaccharide GMG of S. oleracea significantly inhibited gastric lesions induced by ethanol, showing a gastroprotective property.
- da Silva, Bernadete Pereira,Parente, José Paz
-
experimental part
p. 1076 - 1080
(2011/12/03)
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- Substrate specificity in hydrolysis and transglucosylation by family 1 β-glucosidases from cassava and Thai rosewood
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Thai rosewood (Dalbergia cochinchinensis Pierre) dalcochinase and cassava (Manihot esculenta Crantz) linamarase are glycoside hydrolase family 1 β-glucosidases with 47% amino acid sequence identity. Each enzyme can hydrolyze its natural substrate, dalcochinin-8′-O-β-d-glucoside and linamarin, respectively, but not the natural substrate of the other enzyme. Linamarase can transfer glucose to primary, secondary and tertiary alcohols with high efficiency, while dalcochinase can transglucosylate primary and secondary alcohols at moderate levels. In this study, eight amino acid residues in the aglycone binding pocket of dalcochinase were individually replaced with the corresponding residues of linamarase, in order to identify residues that may account for their catalytic differences. The residues I185 and V255 of dalcochinase appeared important for its substrate specificity, with their respective mutations resulting in 24- and 12-fold reductions in k cat/Km for the hydrolysis of dalcochinin-8′-O- β-d-glucoside. Transglucosylation activity was improved when I185, N189 and V255 of dalcochinase were replaced with A201, F205 and F271 of linamarase, respectively, suggesting these residues support transglucosylation in linamarase. Among these three mutants, only the N189F mutant showed significant increases in the rate constants for the reactivation of trapped glucosyl-enzyme intermediates by all alcohols. Together, our results suggest that both hydrophobicity and geometry are important determinants for substrate specificity in hydrolysis and transglucosylation by these family 1 β-glucosidases.
- Kongsaeree, Prachumporn T.,Ratananikom, Khakhanang,Choengpanya, Khuanjarat,Tongtubtim, Nusra,Sujiwattanarat, Penporn,Porncharoennop, Chompoonuth,Onpium, Amornrat,Svasti, Jisnuson
-
experimental part
p. 257 - 265
(2011/02/22)
-
- Glycocerebroside bearing a novel long-chain base from Sagina japonica (Caryophyllaceae)
-
A new glycocerebroside (1), along with one reported one (2), was isolated from the ethanol extract of Sagina japonica (Caryophyllaceae) and was fully characterized. The structures of two compounds were identified as (2S, 3S, 4R, 8E)-1-(β-D-glucopyranosyl-3, 4-dihydroxy-2-[(R)-2′- hydroxypalmitoyl]amino-8-heptadecaene (1) and (2S, 3R, 8E)-1-(β-D- glucopyranosyl-3-hydroxy-2-[(R)-2′-hydroxypalmitoyl]amino-8-octadecaene (2) by using spectroscopic methods (1H, 13C, and 2D NMR, MS) and chemical degradation.
- Jia, Ai-Qun,Yang, Xu,Wang, Wei-Xin,Jia, Yong-Hong
-
scheme or table
p. 540 - 545
(2010/11/04)
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- Synthesis of the steroidal glycoside (25R)-3β,16β-diacetoxy-12, 22-dioxo-5α-cholestan-26-yl β-d-glucopyranoside and its anti-cancer properties on cervicouterine HeLa, CaSki, and ViBo cells
-
The synthesis of the new glycoside (25R)-3β,16β-diacetoxy-12,22- dioxo-5α-cholestan-26-yl β-d-glucopyranoside starting from hecogenin is described. This compound showed anti-cancer activity against cervicouterine cancer cells HeLa, CaSki and ViBo in the micromolar range. Its effect on cell proliferation, cell cycle and cell death is also described. The cytotoxic effect of the title compound on HeLa, CaSki and ViBo cells and human lymphocytes was evaluated through the LDH released in the culture supernatant, indicating that the main cell death process is not necrosis; the null effect on lymphocytes implies that it is not cytotoxic. The ability of this novel glycoside to induce apoptosis was investigated; several apoptosis events like chromatin condensation, formation of apoptotic bodies, as well as the increase in the expression of active caspase-3 and the fragmentation of DNA confirmed that the compound induced apoptosis in cervicouterine cancer cells. Significantly, the antiproliferative activity on tumor cells did not affect the proliferative potential of normal fibroblasts from cervix and peripheral blood lymphocytes. The glycoside showed selective antitumor activity and greater antiproliferative activity than its aglycon; it therefore serves as a promising lead candidate for further optimization.
- Fernández-Herrera, María A.,Mohan, Sankar,López-Mu?oz, Hugo,Hernández-Vázquez, José M.V.,Pérez-Cervantes, Esmeralda,Escobar-Sánchez, María L.,Sánchez-Sánchez, Luis,Regla, Ignacio,Pinto, B. Mario,Sandoval-Ramírez, Jesús
-
experimental part
p. 4827 - 4837
(2010/11/20)
-
- X-ray crystal structure determinations of galactosylacetylene building blocks
-
We report the crystal structures of two galactosylacetylenes: 3,7-anhydro-4,5,6,8-tetra-O-benzyl-1,1,2,2-tetradehydro-1,2-dideoxy-1-C- (trimethylsilyl)-D-glycero-L-mann ooctitol (7) and 3,7-anhydro-4,5,6,8-tetra-O- benzyl-1,1,2,2-tetradehydro-1,2-D-glycero-L-mannooctitol (8). A short overview of the synthetic chemistry used to obtain these targets is mentioned. Copyright Taylor & Francis Group, LLC.
- Leaver, David J.,Hughes, Andrew B.,Polyzos, Anastasios,White, Jonathan M.
-
scheme or table
p. 379 - 385
(2012/06/01)
-
- Purification of seminolipid and its cleavage to lyso-seminolipid. interaction of seminolipid with phospholipase A2
-
Seminolipid was purified from boar sperm and characterized by chemical, chromatographical and spectroscopical (IR, NMR) means. Phospholipase A2 from two sources were used in this experiment: from viper (Vipera ammodytes) venom, and bull seminal vesicle. It was proved that seminolipid cannot constitute a biochemical substrate for the two phospholipases. Two substrates were used for the two enzymes, egg yolk lecithin for viper venom phospholipase A2 and [ 14C-linoleoyl]phosphatidyl ethanolamine for bull seminal vesicle phospholipase A2. The action of seminolipid on the latter enzyme, in quantitative terms, is presented. A small portion of seminolipid was submitted to mild alkaline hydrolysis and lyso-seminolipid recovered from the mixture was peracetylated and its 1H and 13C NMR spectra registered.
- Iga, Silvia,Iga, Dumitru Petru
-
experimental part
p. 383 - 387
(2011/06/25)
-
- A sugar aminoacid for the development of multivalent ligands for Escherichia coli 0157 verotoxin
-
Functionalised carbohydrates for incorporation into multivalent ligands for the Escherichia coli 0157 verotoxin are highly desirable. Here, we report the synthesis of a sugar aminoacid based on the known Gal-α-1,4-Gal ligand for verotoxin in eight steps a
- Gibson, Darren,Homans, Steven W.,Field, Robert A.
-
body text
p. 730 - 732
(2009/10/10)
-
- Cerebrosides of the halotolerant fungus Alternaria raphani isolated from a sea salt field
-
In order to search for structurally novel and bioactive natural compounds from marine-derived fungi, a halotolerant fungal strain (THW-18) identified as Alternaria raphani was isolated from sediment collected in the Hongdao sea salt field. From the ethyl
- Wang, Wenliang,Wang, Yi,Tao, Hongwen,Peng, Xiaoping,Liu, Peipei,Zhu, Weiming
-
experimental part
p. 1695 - 1698
(2010/03/31)
-
- Ceramide and cerebrosides from the octocoral sarcophyton ehrenbergi
-
Chemical investigation of the octocoral Sarcophyton ehrenbergi, collected at the Dongsha Islands, Taiwan, has led to the isolation of a known ceramide (1) and two new cerebrosides, sarcoehrenosides A (2)andB(4), along with three known cerebrosides (3, 5,
- Cheng, Shi-Yie,Wen, Zhi-Hong,Chiou, Shu-Fen,Tsai, Chung-Wei,Wang, Shang-Kewi,Hsu, Chi-Hsin,Dai, Chang-Feng,Chiang, Michael Y.,Wang, Wei-Hsien,Duh, Chang-Yih
-
experimental part
p. 465 - 468
(2009/12/24)
-
- Facile synthesis of methyl α- and β-d-[6-3H]galactofuranosides from d-galacturonic acid. Substrates for the detection of galactofuranosidases
-
Galactofuranose metabolism is a good target for the development of novel chemotherapeutic agents for the treatment of some microbial infections. A simple procedure for the synthesis of methyl (methyl α,β-d-galactopyranosid)uronate followed by NaB3H4 reduction gave a straightforward access to radiolabeled substrates for galactofuranosidases.
- Bordoni, Andrea,Lima, Carlos,Marino, Karina,de Lederkremer, Rosa M.,Marino, Carla
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p. 1863 - 1869
(2008/12/22)
-
- Montmorillonite K-10 as a reusable catalyst for fischer type of glycosylation under microwave irradiation
-
Montmorillonite K-10-catalyzed Fischer type glycosylation was studied for various monosacharides with different alcohols under microwave irradiation. The method was found to be efficient, economic, simple, and time saving and the catalyst montmorillonite K-10 was reused three times without loss of catalytic activity and anomeric selectivity. With glycerol, the method gave products glycosylated at primary alcohols only.
- Bordoloi, Manobjyoti
-
p. 300 - 308
(2008/12/21)
-
- Corrugoside, a new immunostimulatory α-galactoglycosphingolipid from the marine sponge Axinella corrugata
-
Corrugoside (1a), a new immunostimulatory triglycosilated α-galactoglycosphingolipid, was isolated from the marine sponge Axinella corrugata, and its structure determined by spectral analysis and chemical degradation. Compound 1a activated murine NKT cells in vitro, with a potency of about 2 logs lower than that of αGalCer. Four stereoisomeric glycosphingolipids (2a-2d) were also obtained, β-glucosylceramides bearing unusual endoperoxide and allylic hydroperoxide functionalities on the sphinganine chain. They were shown to be photooxidation artifacts of the known glycosphingolipids 3, also present in the sponge. A possible role of compound 3 as a singlet oxygen scavenger to protect the organism from oxidative damage is proposed.
- Costantino, Valeria,Fattorusso, Ernesto,Imperatore, Concetta,Mangoni, Alfonso,Freigang, Stefan,Teyton, Luc
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p. 2077 - 2085
(2008/12/21)
-
- General synthesis route to benanomicin-pradimicin antibiotics
-
A general approach to the regio- and stereoselective total synthesis of the benanomicin-pradimicin antibiotics (BpAs) is described. Construction of the aglycon has been achieved by 1)the diastereoselective ring-opening of a biaryl lactone by using (R)-val
- Tamiya, Minora,Ohmori, Ken,Kitamura, Mitsuru,Kato, Hirohisa,Arai, Tadamasa,Oorui, Mami,Suzuki, Keisuke
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p. 9791 - 9823
(2008/09/18)
-
- S-benzoxazolyl as a stable protecting moiety and a potent anomeric leaving group in oligosaccharide synthesis
-
(Chemical Equation Presented) As a part of a program for developing new versatile building blocks for stereoselective glycosylation and convergent oligosaccharide synthesis, we demonstrated that S-benzoxazolyl (SBox) glycosides are stable toward major protecting group manipulations employed in carbohydrate chemistry. On the other hand, they can be glycosidated under relatively mild reaction conditions to afford either 1,2-trans or 1,2-cis-linked disaccharides. Selective and chemoselective activations of the SBox moiety were also proved to be feasible, which was demonstrated by synthesizing a number of oligosaccharide sequences.
- Kamat, Medha N.,De Meo, Cristina,Demchenko, Alexei V.
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p. 6947 - 6955
(2008/02/11)
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- Structure and absolute stereochemistry of syphonoside, a unique macrocyclic glycoterpenoid from marine organisms
-
(Figure Presented) The glycoterpenoid syphonoside (1) is the main secondary metabolite of both the marine mollusk Syphonota geographica and the sea-grass Halophila stipulacea, two Indo-Pacific species migrated to the Mediterranean Sea through the Suez Canal. The structure and the absolute stereochemistry of 1, which displays unique structural features, has been accomplished by using a combination of spectroscopic techniques, degradation reactions, and conformational analysis methods. Compound 1 was able to inhibit high density induced apoptosis in a number of human and murine carcinoma cell lines.
- Gavagnin, Margherita,Carbone, Marianna,Amodeo, Pietro,Mollo, Ernesto,Vitale, Rosa Maria,Roussis, Vassilios,Cimino, Guido
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p. 5625 - 5630
(2008/02/09)
-
