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1.
Biochem Soc Trans ; 48(5): 2283-2293, 2020 10 30.
Artículo en Inglés | MEDLINE | ID: mdl-32897293

RESUMEN

Butanol is an important chemical and potential fuel. For more than 100 years, acetone-butanol-ethanol (ABE) fermentation of Clostridium strains has been the most successful process for biological butanol production. In recent years, other microbes have been engineered to produce butanol as well, among which Escherichia coli was the best one. Considering the crude oil price fluctuation, minimizing the cost of butanol production is of highest priority for its industrial application. Therefore, using cheaper feedstocks instead of pure sugars is an important project. In this review, we summarized butanol production from different renewable resources, such as industrial and food waste, lignocellulosic biomass, syngas and other renewable resources. This review will present the current progress in this field and provide insights for further engineering efforts on renewable butanol production.


Asunto(s)
Biocombustibles , Butanoles/metabolismo , Ingeniería Metabólica/métodos , Eliminación de Residuos/métodos , Acetona/metabolismo , Biomasa , Biotecnología/métodos , Butanoles/química , Carbono/química , Clostridium/metabolismo , Electrones , Escherichia coli/metabolismo , Etanol/metabolismo , Fermentación , Alimentos , Hexosas/química , Hidrólisis , Modelos Biológicos , Pentosas/química , Petróleo , Sacarosa/química , Biología Sintética
2.
Molecules ; 24(10)2019 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-31091775

RESUMEN

A chemical investigation on 70% EtOH extract from the bark of Phellodendron chinense Schneid (Rutaceae) led to six new methyl apiofuranosides (1-6), and ten known compounds (7-16). All these compounds were characterized by the basic analysis of the spectroscopic data including extensive 1D-, 2D-NMR (HSQC, HMBC), and high-resolution mass spectrometry, and the absolute configurations were determined by both empirical approaches and NOESY. Inhibitory effects of compounds 1-9 and 11-16 on nitric oxide production were investigated in lipopolysaccharide (LPS)-mediated RAW 264.7 cells, as a result, most of these isolates inhibited nitric oxide (NO) release, and among them 9, 11, and 12 displayed the strongest inhibition on NO release at the concentration of 12.5 µM.


Asunto(s)
Lipopolisacáridos/efectos adversos , Óxido Nítrico/metabolismo , Pentosas/farmacología , Phellodendron/química , Animales , Ratones , Estructura Molecular , Pentosas/química , Corteza de la Planta/química , Extractos Vegetales/química , Extractos Vegetales/farmacología , Células RAW 264.7
3.
Carbohydr Polym ; 112: 48-55, 2014 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-25129715

RESUMEN

Aiming to investigate the possible occurrence of transglycosylation reactions between galactomannans and side chains of arabinogalactans during coffee roasting, mixtures of ß-(1 → 4)-D-mannotriose and α-(1 → 5)-L-arabinotriose were subjected to dry thermal treatments at 200 °C. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis allowed identifying polysaccharides composed by pentose and hexose residues with a degree of polymerization up to 18 residues. Methylation analysis showed the occurrence of new types of glycosidic linkages in all thermally treated mixtures, as well as the occurrence of terminally and 5-linked ribose, possibly formed from arabinose isomerization. Also, xylose and lyxose were identified and proposed to be formed from mannose. These results support the occurrence of transglycosylation reactions promoted by roasting involving both oligosaccharides in the starting mixtures, resulting in arabinan and mannan chimeric polysaccharides. These structural features were also found in roasted coffee polysaccharide samples.


Asunto(s)
Café/química , Galactanos/química , Mananos/química , Trisacáridos/química , Conformación de Carbohidratos , Manipulación de Alimentos/métodos , Galactosa/análogos & derivados , Glicosilación , Calor , Hidrólisis , Oligosacáridos/química , Oxidación-Reducción , Pentosas/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción
4.
J Chromatogr A ; 1293: 100-6, 2013 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-23623367

RESUMEN

The behavior of the flavonoid diglycosides, relevant constituents of parsley (Petroselinum crispum) fruit (PFr) and leaf (PLe) samples was characterized upon their enzymatic hydrolyses applying complementary liquid chromatography-ultraviolet (LC-UV) and gas chromatography mass selective (GC-MS) detections. Analyses were performed in quantitative manner, from the same extracts as a function of hydrolysis times. Both in fruit and leaf tissue extracts, in intact and in enzyme hydrolyzed ones, apigenin, chrysoeriol, their glycosides, sugars, sugar alcohols, carboxylic acids and phytosterols, in total 17 constituents were identified and quantified. Based primarily on the selective mass fragmentation properties of the trimethylsilyl (oxime) ether/ester derivatives of constituents, we confirmed several novelties to the field. (i) It was shown for the first time that in parsley tissues different types of glycosidase enzyme are active. In PFr samples, both the stepwise and disaccharide specific endogenous mechanisms were certified, quantifying simultaneously the continuous release of apigenin, chrysoeriol, 2-O-apiosyl-apiose, apiose and glucose. (ii) 2-O-Apiosyl-glucose was demonstrated as disaccharide due to its formation under derivatization conditions from parsley glycosides. (iii) Both in PFr and in PLe samples even the invertase enzyme activity was attainable: sucrose decomposition in both tissues was going on with the same intensity. Three different types of enzymatic glycosidase processes were followed with their specific hydrolysis products by means of HPLC-UV and GC-MS, simultaneously.


Asunto(s)
Flavonoides/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Glicósidos/química , Petroselinum/química , Flavonoides/análisis , Flavonoides/metabolismo , Frutas/química , Glicósido Hidrolasas/metabolismo , Glicósidos/análisis , Glicósidos/metabolismo , Oximas/química , Pentosas/química , Petroselinum/enzimología , Fitosteroles/química , Extractos Vegetales/química , Hojas de la Planta/química
5.
Carbohydr Res ; 362: 47-55, 2012 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-23079239

RESUMEN

The structure of acidic fraction gum (AFG) from flaxseed hulls was elucidated by methylation analysis and 1D/2D NMR spectroscopy. This acidic fraction was separated from water-soluble flaxseed gum using anion-exchange chromatography. AFG consisted of a rhamnogalacturonan-I (RG-I) backbone that features diglycosyl repeating units, →2)-α-l-Rhap-(1→4)-α-d-GalpA-(1→. Rhamnosyl residues (38.2%) were the most abundant neutral sugar component. It was present mainly as unbranched (16.5%) and branched (19.5%) →2)-α-l-Rhap-(1→ at O-3. Most of its branches were terminated by monosaccharides, α/ß-d-Galp-(1→ (19.6%), α-l-Fucp-(1→ (4.5%) or ß-d-Xylp-(1→ (3.1%). However, when this branching site was occasionally appended with →4)-α-d-GalpA-(1→ or →2)-α-l-Rhap-(1→, side chains may consist of rhamnogalacturonan-I (RG-I), homorhamnan (HR) or a mixture of both. AFG was highly branched as indicated by its high degree of branching (0.55). A possible structure of AFG was proposed: (HR, RG-I, and HG refer to homorhamnan, rhamnogalacturonan-I, and homogalacturonan, respectively. The locations of HR, RG-I, and HG are interchangeable; (m+n)/(n+i)≈1.5. The substitution rate of R(1) is ∼54%. R(1) is mostly monosaccharide (α/ß-d-Galp-(1→, α-l-Fucp-(1→ or ß-d-Xylp-(1→). R(1) may also occasionally be a longer side chain with more than two residues beginning with →4)-α-GalpA-(1→ or →2)-α-l-Rhap-(1→, wherein the side-chain structure may be similar to part of the main chain.).


Asunto(s)
Lino/química , Pectinas/química , Gomas de Plantas/química , Ácidos , Secuencia de Carbohidratos , Cromatografía por Intercambio Iónico , Hexosas/química , Espectroscopía de Resonancia Magnética , Metilación , Datos de Secuencia Molecular , Pectinas/aislamiento & purificación , Pentosas/química , Residuos
6.
Org Biomol Chem ; 9(19): 6670-84, 2011 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-21847487

RESUMEN

Fragments of pectic polysaccharides rhamnogalacturonan-II (RG-II) and apiogalacturonan were synthesised using p-tolylthio apiofuranoside derivatives as key building blocks. Apiofuranose thioglycosides can be conveniently prepared by cyclization of the corresponding dithioacetals possessing a 2,3-O-isopropylidene group, which is required for preservation of the correct (3R) configuration of the apiofuranose ring. The remarkable stability of this protecting group in apiofuranose derivatives requires its replacement with a more reactive protecting group, such as a benzylidene acetal which was used in the synthesis of trisaccharide ß-Rhap-(1→3')-ß-Apif-(1→2)-α-GalAp-OMe. The X-ray crystal structure of the protected precursor of this trisaccharide has been elucidated.


Asunto(s)
Araceae/química , Pectinas/síntesis química , Pentosas/química , Zosteraceae/química , Araceae/citología , Conformación de Carbohidratos , Cristalografía por Rayos X , Modelos Moleculares , Pectinas/química , Zosteraceae/citología
7.
Carbohydr Res ; 346(10): 1202-11, 2011 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-21550024

RESUMEN

The nitrone 4 (4,5-dideoxy-4-hydroxylamino-3,4-O-isopropylidene-L-lyxofuranose) was synthesised from D-ribose and used as key intermediate for the preparation of fucosidase inhibitors. We describe two transformations of 4. Hydrolysis with aqueous sulfur dioxide gave the known potent nanomolar inhibitor 4-amino-4,5-dideoxy-L-lyxofuranose (3). 1,3-Dipolar cycloaddition with enol ethers led to the related 1,2,5,6-tetradeoxy-2,5-imino-L-altroheptonic ester 2a, acid 2b and the corresponding heptitol 2c. The new iminosugars have been evaluated for their inhibitory activity against α-L-fucosidase from bovine kidney. The alcohol 2c turned out to be a potent inhibitor in the same range as the amino-sugar 3 (K(i)=8 vs 10nM).


Asunto(s)
Amino Azúcares/síntesis química , Inhibidores Enzimáticos/síntesis química , Pirrolidinas/síntesis química , alfa-L-Fucosidasa/antagonistas & inhibidores , Amino Azúcares/química , Amino Azúcares/farmacología , Animales , Bovinos , Evaluación Preclínica de Medicamentos , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Furanos/química , Riñón/efectos de los fármacos , Riñón/enzimología , Riñón/metabolismo , Modelos Químicos , Pentosas/química , Pirrolidinas/farmacología , Ribosa/química , Relación Estructura-Actividad
8.
Carbohydr Res ; 340(10): 1689-98, 2005 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-15927171

RESUMEN

A good yield mild fractionation procedure was developed for the purification of mannans from green and roasted coffee infusions that included anion-exchange chromatography and phenylboronic acid immobilized Sepharose chromatography of the dialyzed and ethanol precipitated material. Enzymatic hydrolysis with endo-beta-mannanase and ESIMS allowed finding that the mannans from roasted coffee infusions, as well as those from green coffee, are acetylated (8 mol% and 11 mol%, respectively). Fragmentation pattern obtained by ESIMS/MS analysis of the acetylated oligosaccharide ions indicates that the acetylation also occurs at O-2 of the mannose residues. Doubly acetylated and contiguously acetylated hexose residues were also found. Arabinose residues, as side chains, were also found as structural features of hot water soluble green (2%) and roasted (<0.9 mol) coffee galactomannans. Methylation analysis, hydrolysis with specific glycosidases and GC-EIMS analysis of the reduced and methylated oligosaccharides allowed to conclude that beta-(1-->4)-linked glucose residues are also structural features of green and roasted coffee galactomannans (6 and 1 mol%, respectively). In hot water soluble green coffee mannans, glucose residues are a constituent of the mannan backbone, and in the roasted coffee they were detected only at the reducing end of the mannan backbone.


Asunto(s)
Arabinosa/química , Café/química , Glucosa/química , Mananos/química , Té/química , Acetilación , Secuencia de Carbohidratos , Cromatografía en Gel , Cromatografía por Intercambio Iónico , Galactosa/análogos & derivados , Glicósidos/química , Hidrólisis , Mananos/metabolismo , Datos de Secuencia Molecular , Pentosas/química , Espectrometría de Masa por Ionización de Electrospray
9.
Appl Biochem Biotechnol ; 113-116: 937-49, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-15054243

RESUMEN

Approximately 9% of the 9.7 billion bushels of corn harvested in the United States was used for fuel ethanol production in 2002, half of which was prepared for fermentation by dry grinding. The University of Illinois has developed a modified dry grind process that allows recovery of the fiber fractions prior to fermentation. We report here on conversion of this fiber (Quick Fiber [QF]) to ethanol. QF was analyzed and found to contain 32%wt glucans and 65%wt total carbohydrates. QF was pretreated with dilute acid and converted into ethanol using either ethanologenic Escherichia coli strain FBR5 or Saccharomyces cerevisiae. For the bacterial fermentation the liquid fraction was fermented, and for the yeast fermentation both liquid and solids were fermented. For the bacterial fermentation, the final ethanol concentration was 30 g/L, a yield of 0.44 g ethanol/g of sugar(s) initially present in the hydrolysate, which is 85% of the theoretical yield. The ethanol yield with yeast was 0.096 gal/bu of processed corn assuming a QF yield of 3.04 lb/bu. The residuals from the fermentations were also evaluated as a source of corn fiber oil, which has value as a nutraceutical. Corn fiber oil yields were 8.28%wt for solids recovered following pretreatment.


Asunto(s)
Biotecnología/métodos , Etanol/química , Fermentación , Aceites de Plantas/química , Zea mays/química , Biomasa , Escherichia coli/metabolismo , Hidrólisis , Pentosas/química , Saccharomyces cerevisiae/metabolismo , Factores de Tiempo
10.
Appl Biochem Biotechnol ; 113-116: 1041-58, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-15054252

RESUMEN

A readily fermentable pentose-containing hydrolysate was obtained from Brewery's spent grain by a two-step process consisting of an auto-hydrolysis (converting the hemicelluloses into oligosaccharides) followed by an enzymatic or sulfuric acid-catalyzed posthydrolysis (converting the oligosaccharides into monosaccharides). Enzymatic hydrolyses were performed with several commercial enzymes with xylanolytic and cellulolytic activities. Acid-catalyzed hydrolyses were carried out at 121 degrees C under various sulfuric acid concentrations and reaction times, and the effects of treatments were interpreted by means of a corrected combined severity factor (CS*), which varied in the range of 0.80-2.01. Under the tested conditions, chemical hydrolysis allowed higher pentose yields than enzymatic hydrolysis. Optimized conditions (defined by CS* = 1.10) allowed both complete monosaccharide recovery and low content of inhibitors. Liquors subjected to posthydrolysis under optimal conditions were easily fermented by Debaryomyces hansenii CCMI 941 in semiaerobic shake-flask experiments, leading to xylitol and arabitol as major fermentation products. The bioconversion process was improved by hydrolysate concentration and supplementation of fermentation media with casamino acids.


Asunto(s)
Biotecnología/métodos , Medios de Cultivo/química , Grano Comestible/química , Hidrólisis , Pentosas/química , Bebidas Alcohólicas , Aminoácidos/química , Fermentación , Residuos Industriales , Cinética , Fenol/química , Temperatura , Factores de Tiempo , Xilitol/química
11.
Appl Biochem Biotechnol ; 113-116: 1059-72, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-15054253

RESUMEN

Dilute-acid hydrolysis of brewery's spent grain to obtain a pentose-rich fermentable hydrolysate was investigated. The influence of operational conditions on polysaccharide hydrolysis was assessed by the combined severity parameter (CS) in the range of 1.39-3.06. When the CS increased, the pentose sugars concentration increased to a maximum at a CS of 1.94, whereas the maximum glucose concentration was obtained for a CS of 2.65. The concentrations of furfural, hydroxymethylfurfural (HMF), as well as formic and levulinic acids and total phenolic compounds increased with severity. Optimum hydrolysis conditions were found at a CS of 1.94 with >95% of feedstock pentose sugars recovered in the monomeric form, together with a low content of furfural, HMF, acetic and formic acids, and total phenolic compounds. This hydrolysate containing glucose, xylose, and arabinose (ratio 10:67:32) was further supplemented with inorganic salts and vitamins and readily fermented by the yeast Debaryomyces hansenii CCMI 941 without any previous detoxification stage. The yeast was able to consume all sugars, furfural, HMF, and acetic acid with high biomass yield, 0.68 C-mol/C-mol, and productivity, 0.92 g/(L.h). Detoxification with activated charcoal resulted in a similar biomass yield and a slight increase in the volumetric productivity (11%).


Asunto(s)
Biotecnología/métodos , Medios de Cultivo/química , Grano Comestible/química , Hidrólisis , Pentosas/química , Bebidas Alcohólicas , Aminoácidos/química , Ascomicetos/metabolismo , Carbohidratos , División Celular , Cromatografía por Intercambio Iónico , Fermentación , Concentración de Iones de Hidrógeno , Residuos Industriales , Resinas de Intercambio Iónico , Cinética , Modelos Estadísticos , Fenol/química , Polisacáridos/química , Temperatura , Factores de Tiempo , Xilitol/química
12.
Carbohydr Res ; 339(1): 21-7, 2004 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-14659667

RESUMEN

Beta-rhamnosylation of methyl 2-C-hydroxymethyl-2,3-O-isopropylidene-beta-D-erythrofuranoside and methyl 2,3-O-isopropylidene-beta-D-ribofuranoside was achieved using 4-O-acetyl-2,3-O-carbonyl-alpha-L-rhamnopyranosyl bromide and Ag2O as a promoter. Deprotected disaccharides beta-L-Rhap-(1-->3')-beta-D-Apif-OMe and beta-L-Rhap-(1-->3')-beta-D-Ribf-OMe were compared to their alpha-rhamnosyl isomers which were prepared using conventional Helferich glycosylation.


Asunto(s)
Oligosacáridos/síntesis química , Pectinas/química , Pentosas/química , Conformación de Carbohidratos , Secuencia de Carbohidratos , Galactosa/química , Glicosilación , Isomerismo , Datos de Secuencia Molecular , Estructura Molecular , Ramnosa/química
13.
J Mass Spectrom ; 37(12): 1272-9, 2002 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-12489088

RESUMEN

Mass spectrometric methods have been developed which allow the direct stereochemical assignment of terminal monosaccharide residues in flavonoid O-glycosides without the need for chemical hydrolysis. Standards containing a glucose, galactose, mannose, xylose, arabinose or apiose residue were examined because these monosaccharides are by far the most commonly encountered in flavonoid glycosides. Following acetylation, the major peracetylated sugar related fragments, generated by fast atom bombardment (FAB) or electrospray ionization (ESI), were selected for collisional activation employing a broad range of collision energies. Both FAB and ESI proved to be useful as ionization techniques. Stereoselective fragmentation was achieved and allowed us clearly to differentiate and characterize isomeric monosaccharide residues. The method developed was successfully applied to an unknown flavonoid containing a terminal pentose and hexose residue which was isolated from Farsetia aegyptia.


Asunto(s)
Flavonoides/química , Glicósidos/química , Hexosas/análisis , Hexosas/química , Pentosas/análisis , Pentosas/química , Conformación Molecular , Estructura Molecular , Peso Molecular , Extractos Vegetales/química , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masa Bombardeada por Átomos Veloces
14.
J Am Chem Soc ; 124(35): 10508-18, 2002 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-12197753

RESUMEN

Palladium(0)-catalyzed silane alcoholysis was applied to sugars for the first time using tert-butyldimethylsilane (TBDMS-H) and Ph(3)SiH as the silanes. The catalyst is a colloidal solution of Pd(0) generated in situ from PdX(2) (X = Cl(-), OAc(-)) and TBDMS-H in N,N-dimethylacetamide. The colloid has been characterized by dynamic light scattering and transmission electron microscopy and consists of catalytically highly active nanoparticles of approximately 2 nm diameter. The silane alcoholysis reaction is an effective method for the regioselective silylation of methyl and phenyl glycosides and generates hydrogen gas as the only side product. For many of the sugar substrates investigated, the distribution of regioisomers obtained is complementary to that of the traditional R(3)SiCl/base (base = pyridine, imidazole) methodology and gives convenient access to the 3,6- rather than the 2,6-silylated pyranosides, obtained as the main product by the silyl chloride method. The method also allows a selective axial silylation of levoglucosan and 1,3,5-O-methylidene-myo-inositol. In an attempt to rationalize the observed regioselectivities, ab initio predictions (HF/3-21G) have been made on the relative energies of some of the silylated products. They suggest that the observed regioselectivities do not reflect a kinetic vs thermodynamic product distribution but are induced by the silylation agent employed. Models for the possible origin of the observed regioselectivity in both silylation methods (silane- and silyl chloride-based) are discussed.


Asunto(s)
Carbohidratos/química , Hexosas/química , Silanos/química , Catálisis , Galactosa/química , Glucosa/química , Manosa/química , Nanotecnología , Paladio/química , Tamaño de la Partícula , Pentosas/química , Piranos/química , Silanos/síntesis química , Especificidad por Sustrato
15.
Carbohydr Res ; 329(3): 525-38, 2000 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-11128582

RESUMEN

1,2,5-Tri-O-acetyl-3,6-anhydro-3-thio-D-glucofuranose was synthesised starting from D-glucose and was used as a donor for the glycosidation of 4-cyano- and 4-nitrobenzenethiol. In the latter reaction, besides an anomeric mixture of the 4-nitrophenyl 2,5-di-O-acetyl-3,6-anhydro-1,3-dithio-D-glucofuranosides, the corresponding 2,6-anhydro-1,2-dithio-D-altrofuranosides were also obtained, formed via a rearrangement of the sugar moiety. A similar rearrangement could be observed during the hydrolysis of the glycosidic bond of methyl 3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-3-thio-alpha-D-glucopyranoside with aqueous trifluoroacetic acid, affording after acetylation besides 1-O-acetyl-3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-3-thio-alpha-D-glucopyranose (32alpha), 1,1,5-tri-O-acetyl-3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-3-thio-D-glucose, methyl 3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-3-thio-beta-D-glucopyranoside and 1,5-di-O-acetyl-2,6-anhydro-3-O-(4-nitrobenzoyl)-2-thio-alpha-D-altrofuranose (40). Glycosidation of 4-cyanobenzethiol with 32alpha in the presence of trimethylsilyl triflate as promoter afforded 4-cyanophenyl 3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-1,3-dithio-beta-D-glucopyranoside as a minor component only, besides 4-cyanophenyl 3,6-anhydro-2-S-(4-cyanophenyl)-4-O-(4-nitrobenzoyl)-1,2,3-trithio-beta-D-glucopyranoside. When boron trifluoride etherate was used as promoter in the reaction of 32alpha with 4-cyano- and 4-nitrobenzenethiol, the corresponding beta-thioglycosides were obtained, while 40 gave under identical conditions the alpha anomers exclusively. All thioglycosides obtained after deacylation were submitted to biological evaluation. Among these glycosides, the 4-cyanophenyl 3,6-thioanhydro-1,3-dithio-D-glucofuranoside possessed the strongest oral antithrombotic effect.


Asunto(s)
Fibrinolíticos/síntesis química , Glucósidos/síntesis química , Pentosas/síntesis química , Animales , Evaluación Preclínica de Medicamentos , Fibrinolíticos/química , Fibrinolíticos/farmacología , Glucósidos/química , Glucósidos/farmacología , Espectroscopía de Resonancia Magnética , Estructura Molecular , Pentosas/química , Pentosas/farmacología , Ratas
16.
J Biomol NMR ; 14(3): 253-71, 1999 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10481276

RESUMEN

Rhamnogalacturonan II (RG-II) is a structurally complex pectic mega-oligosaccharide that is released enzymatically from the primary cell wall of higher plants. It contains roughly 30 monosaccharide units (MW approximately 5 kDa) including very unusual residues such as Kdo, Dha, aceric acid and apiose. Previous studies have demonstrated that these monomers are arranged into four structurally well-defined oligosaccharide side chains (A-D), linked to a homogalacturonan mainchain, but the specific attachment sites of these branches on the pectic backbone have not yet been elucidated. In the present work, fairly complete assignments of the 750 MHz 1H NMR spectra and partial assignments of the 13C NMR spectra of the sodium-borohydride-reduced RG-II monomer were obtained for a 5 mM sample isolated from red wine. On the whole, these data corroborate the primary structures of the sidechains previously established by methylation analysis, partial hydrolysis and FAB-MS spectrometry but some heterogeneity has been demonstrated (partial substitution at B5, B6, and A5). The preferred orientations of the majority of the sidechain glycosidic linkages in the RG-II monomer have been determined from the sequential nOe data and the solution structure is generally in good agreement with the stable conformers previously obtained by molecular modeling (MM3) of the disaccharide and sidechain oligosaccharide building blocks. All of a two-residue, a three-residue, and a four-residue segment of the backbone have been tentatively identified from long range interactions between sidechain protons as well as in the mainchain. Taking into account the length of the 9-mer galacturonan mainchain described in prior work, these building blocks constitute almost the complete structure of RG-II (Scheme 2).


Asunto(s)
Pectinas/química , Borohidruros , Secuencia de Carbohidratos , Isótopos de Carbono , Datos de Secuencia Molecular , Resonancia Magnética Nuclear Biomolecular , Oxidación-Reducción , Pentosas/química , Protones , Soluciones , Espectrometría de Masa Bombardeada por Átomos Veloces , Azúcares Ácidos/química , Vino
17.
J Med Chem ; 41(8): 1242-51, 1998 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-9575044

RESUMEN

Several 2-substituted alpha-D- and alpha-L-lyxofuranosyl and 5-deoxylyxofuranosyl derivatives of 5,6-dicholro-2-(isopropylamino)-1-(beta-L-ribofuranosyl) benzimidazole (1263W94) and 2,5,6-trichloro-1(beta-D-ribofuranosyl)benzimidazole (TCRB) were synthesized and evaluated for activity against two herpesviruses (HSV-1 and HCMV) and for their cytotoxicity against HFF and KB cells. Condensation of 1,2,3,5-tetra-O-acetyl-L-lyxofuranose (2a) with 2,5,6-trichlorobenzimidazole (1) yielded the alpha-nucleoside 3a. The 2-bromo derivative and 2-methylamino derivative were prepared by treatment of 3a with HBr followed by deprotection or from methylamine, respectively. Compound 3a was deprotected and the resultant nucleoside used to prepare the 2-cyclopropylamino and 2-isopropylamino derivatives. The 2-alkylthio nucleosides were prepared by condensing 2a with 5,6-dichlorobenzimidazole-2-thione followed by deprotection. Alkylation of this adduct gave the 2-methylthio and 2-benzylthio derivatives. Condensation of 5-deoxy-1,2,3-tri-O-acetyl-L-lyxofuranosyl, prepared from L-lyxose, with 1 or 2-bromo-5,6-dichlorobenzimidazole (15), followed by deprotection, gave the 2-chloro or 2-bromo-5'-deoxylyxo-furanosyl derivative, respectively. The cyclopropylamino derivative was prepared from the 2-chloro derivative. All D-isomers were prepared in an analogous fashion from D-lyxose. Either compounds were inactive against HSV-1 or weak activity was poorly separated from cytotoxicity. In contrast, the 2-halogen derivatives in both the alpha-lyxose and 5-deoxy-alpha-lyxose series were active against the Towne strain of HCMV. The 5-deoxy alpha-L analogues were the most active, IC50's = 0.2-0.4 microM, plaque assay; IC90's = 0.2-2 microM, yield reduction assay. All of the 2-isopropylamino or 2-cyclopropylamino derivatives were less active (IC50's = 60-100 microM, plaque assay; IC90's = 17-100 microM, yield reduction assay) and were not cytotoxic. The methylamino, thio, and methylthio derivatives were neither active nor cytotoxic. The benzylthio derivatives were weakly active, but this activity was poorly separated from cytotoxicity. The alpha-lyxose L-isomers were more active in a plaque assay against the AD169 strain of HCMV compared to the Towne strain, thereby providing additional evidence of antiviral specificity.


Asunto(s)
Antivirales/síntesis química , Bencimidazoles/síntesis química , Diseño de Fármacos , Nucleósidos/síntesis química , Pentosas/síntesis química , Antivirales/química , Antivirales/farmacología , Bencimidazoles/química , Bencimidazoles/farmacología , División Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Citomegalovirus/efectos de los fármacos , Citomegalovirus/crecimiento & desarrollo , Evaluación Preclínica de Medicamentos , Ensayo de Inmunoadsorción Enzimática , Fibroblastos/efectos de los fármacos , Fibroblastos/virología , Herpesvirus Humano 1/efectos de los fármacos , Herpesvirus Humano 1/crecimiento & desarrollo , Humanos , Células KB , Pruebas de Sensibilidad Microbiana , Nucleósidos/química , Nucleósidos/farmacología , Pentosas/química , Pentosas/farmacología , Piel/citología , Piel/efectos de los fármacos , Piel/virología , Estereoisomerismo , Relación Estructura-Actividad , Ensayo de Placa Viral
18.
Carbohydr Res ; 218: 211-22, 1991 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-1802386

RESUMEN

Evidence for the anomeric configurations and attachment sites of 3-deoxy-D-lyxo-2-heptulosaric acid (DHA) and apiosyl residues has been obtained through the characterization of two oligoglycosyl fragments isolated from rhamnogalacturonan II (RG-II). One of the oligoglycosyl fragments, a pentaglycosyl aldonic acid generated by Smith degradation of RG-II, was composed of four D-galactopyranosyluronic acid residues, a DHA residue, and a threonic acid residue (derived from a D-galactopyranosyluronic acid residue). The structural analysis of the pentaglycosyl aldonic acid established the beta-D-configuration for the DHA residue. Furthermore, it established that a previously identified diglycosyl side chain, 5-O-(beta-L-arabinofuranosyl)-DHA was directly attached to O-3 of a D-galactopyranosyluronic acid residue in the backbone of RG-II. The second oligoglycosyl fragment, a peralkylated diglycosyl hex-1-enitol, was generated by hex-5-enose degradation of permethylated and carboxyl-reduced RG-II. The structure of the peralkylated diglycosyl hex-1-enitol, beta-L-Rhap-(1----3')-beta-D-Apif-(1----5)-hex-1-enitol++ +, was determined by a combination of glycosyl-linkage composition analysis and n.m.r. spectroscopy. The n.m.r. data indicated the beta-configuration for the D-apiosyl residue. The isolation and characterization of the diglycosyl hex-1-enitol also established that a previously identified heptaglycosyl side chain was directly attached to O-2 of a D-galactopyranosyluronic acid in the backbone of RG-II.


Asunto(s)
Pared Celular/química , Desoxiazúcares/metabolismo , Mananos/metabolismo , Oligosacáridos/química , Pectinas/metabolismo , Árboles/química , Butiratos/química , Secuencia de Carbohidratos , Células Cultivadas , Desoxiazúcares/química , Glucósidos/química , Mananos/química , Datos de Secuencia Molecular , Pectinas/química , Pentosas/química , Azúcares Ácidos/química , Alcoholes del Azúcar/química
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