Development of carbohydrate functionalized magnetic nanoparticles for aminoglycosides magnetic solid phase extraction.

Magnetic nanoparticles decorated with d-galactose and galactitol (Fe3O4@SiN-galactose and Fe3O4@SiN-galactitol) were synthesized and employed as sorbent in a magnetic solid phase extraction (MSPE) procedure prior the analysis of aminoglycosides (AGs) in honey samples by LC-MS/MS. AGs are broad spectrum antibiotics, characterized by aminosugars, widespread used in therapeutic and veterinary applications. AGs can be found in the environment and food of animal origin. Fe3O4@SiN-galactose and Fe3O4@SiN-galactitol were synthesized via copper catalyzed alkyne azide cycloaddition and the synthesis was efficiently followed by infrared spectroscopy. They were characterized by electron microscopy, thermogravimetric analysis and magnetization curves. The nature of the loading (acetonitrile:water, 50:50 v/v) and elution solution (formic acid 190 mM) were studied in order to optimize the MSPE. Quantitative difference between MSPE with Fe3O4@SiN-galactose and MSPE with Fe3O4@SiN-galactitol in terms of recovery was found. The final optimized method using Fe3O4@SiN-galactose and Fe3O4@SiN-galactitol was applied in the determination of AGs in honey. The MSPE performance of Fe3O4@SiN-galactitol was found to be superior to that of MSPE with Fe3O4@SiN-galactose. The limits of quantification were between 2 and 19 µg kg-1 for amikacin, dihydrostreptomycin, tobramicyn and gentamycin. A good correlation between predicted and nominal values of AGs in honey was found (trueness from 84% to 109%). This MSPE procedure not only requires a minimum amount of sorbent (1 mg) and sample (0.2 g), but it can also be accomplish in a rather short time.

The Structural Signs of Sweetness in Artificial Sweeteners: A Rotational Study of Sorbitol and Dulcitol.

A gas-phase study on the artificial sweeteners sorbitol and dulcitol has been carried out for the first time by using a combination of chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy and laser ablation (LA). The isolation conditions provided by the supersonic expansion reveal the intrinsic conformational structures of these sweeteners. The three and five observed conformers for sorbitol and dulcitol, respectively, are stabilized by networks of cooperative intramolecular hydrogen bonds between vicinal hydroxyl groups in clockwise or counterclockwise arrangements. Suitable places in the structure of seven out of eight conformers identified for both polyalcohols meet the requirements of the glucophore proposed by Shallenberger and Acree's molecular theory of sweet taste. Present results provide the first linkage between sweetness and structure in sugar alcohols.

Asymmetric routes toward polyhydroxylated pyrrolidines: Synthesis of 1,4-dideoxy-1,4-imino-d-galactitol and 1,4-dideoxy-1,4-imino-d-glucitol.

Herein the total synthesis of the pyrrolidine alkaloids 1,4-dideoxy-1,4-imino-d-galactitol and its diastereoisomer 1,4-dideoxy-1,4-imino-d-glucitol is described, starting from a common optically active precursor. The key step in our approach was the double diastereoselection in the asymmetric dihydroxylation of chiral vinyl azido alcohols, obtained by means of two different regio- and stereoselective nucleophilic openings of the corresponding chiral vinyl epoxide.

Tailoring the degradation rate and release kinetics from poly(galactitol sebacate) by blending with chitosan, alginate or ethyl cellulose.

Despite significant advances in recent times, the investigation of discovering a perfect biomaterial is perennial. In this backdrop, blending of natural and synthetic polymers is gaining popularity since it is the easiest way to complement the drawbacks and attain a superlative material. Based on this, the objective of this study was to synthesize a novel polyester, poly(galactitol sebacate), and subsequently blend this polymer with one of the three natural polymers such as alginate, chitosan or ethyl cellulose. FT-IR showed the presence of both the polymers in the blends. 1H NMR confirmed the chemical structure of the synthesized poly (galactitol sebacate). Thermal characterization was performed by DSC revealing that the polymers were amorphous in nature and the glass transition temperatures increased with the increase in ratio of the natural polymers in the blends. SEM imaging showed that the blends were predominantly homogeneous. Contact angle measurements demonstrated that the blending imparted the hydrophilic nature into poly (galactitol sebacate) when blending with alginate or chitosan and hydrophobic when blending with ethyl cellulose. In vitro hydrolytic degradation studies and dye release studies indicated that the polymers became more hydrophilic in alginate and chitosan blends and thus accelerated the degradation and release process. The reverse trend was observed in the case of ethyl cellulose blends. Modeling elucidated that the degradation and dye release followed first order kinetics and Higuchi kinetics, respectively. In vitro cell studies confirmed the cytocompatible nature of the blends. It can be proposed that the chosen natural polymers for blending showed wide variations in hydrophilicity resulting in tailored degradation, release and cytocompatibility properties and thus are promising candidates for use in drug delivery and tissue engineering.

Efficient method for the conversion of agricultural waste into sugar alcohols over supported bimetallic catalysts.

Promoter effect of Sn in the PtSn/γ-Al2O3 (AL) and PtSn/C bimetallic catalysts is studied for the conversion of variety of substrates such as, C5 sugars (xylose, arabinose), C6 sugars (glucose, fructose, galactose), hemicelluloses (xylan, arabinogalactan), inulin and agricultural wastes (bagasse, rice husk, wheat straw) into sugar alcohols (sorbitol, mannitol, xylitol, arabitol, galactitol). In all the reactions, PtSn/AL showed enhanced yields of sugar alcohols by 1.5-3 times than Pt/AL. Compared to C, AL supported bimetallic catalysts showed prominent enhancement in the yields of sugar alcohols. Bimetallic catalysts characterized by X-ray diffraction study revealed the stability of catalyst and absence of alloy formation thereby indicating that Pt and Sn are present as individual particles in PtSn/AL. The TEM analysis also confirmed stability of the catalysts and XPS study disclosed formation of electron deficient Sn species which helps in polarizing carbonyl bond to achieve enhanced hydrogenation activity.

Proton fingerprints portray molecular structures: enhanced description of the 1H NMR spectra of small molecules.

The characteristic signals observed in NMR spectra encode essential information on the structure of small molecules. However, extracting all of this information from complex signal patterns is not trivial. This report demonstrates how computer-aided spectral analysis enables the complete interpretation of 1D (1)H NMR data. The effectiveness of this approach is illustrated with a set of organic molecules, for which replicas of their (1)H NMR spectra were generated. The potential impact of this methodology on organic chemistry research is discussed.

Reversible and efficient inhibition of UDP-galactopyranose mutase by electrophilic, constrained and unsaturated UDP-galactitol analogues.

A series of UDP-galactitols were designed as analogues of high-energy intermediates of the UDP-galactopyranose mutase (UGM) catalyzed furanose/pyranose interconversion, an essential step of Mycobacterium tuberculosis cell wall biosynthesis. The final compounds structurally share the UDP and the galactitol substructures that were connected by four distinct electrophilic connections (epoxide, lactone and Michael acceptors). All molecules were synthesized from a common perbenzylated acyclic galactose precursor that was derivatized by alkenylation, alkynylation and cyclopropanation. The inhibition study against UGM could clearly show that slight changes in the relative orientation of the UDP and the galactitol moieties resulted in dramatic variations of binding properties. Compared to known inhibitors, the epoxide derivative displayed a very tight, reversible, inhibition profile. Moreover, a time-dependent inactivation study showed that none of these electrophilic structures could react with UGM, or its FAD cofactor, the catalytic nucleophile of this still intriguing reaction.

The triterpenes 3ß-lup-20(29)-en-3-ol and 3ß-lup-20(29)-en-3-yl acetate and the carbohydrate 1,2,3,4,5,6-hexa-O-acetyl-dulcitol as photosynthesis light reactions inhibitors.

Three compounds were isolated from Maytenus acanthophylla Reissek (Celastraceae): the pentacyclic triterpenes lup-20(29)-en-3ß-ol (lupeol, 1) and 3ß-lup-20(29)-en-3-yl acetate (2) and the carbohydrate 1,2,3,4,5,6-hexa-O-acetyldulcitol (3); lupeol was also isolated from Xylosma flexuosa. The compounds' structures were elucidated by spectroscopic and spectrometric analysis. Compound 1 acts as an energy transfer inhibitor, interacting with isolated CF1 bound to thylakoid membrane, and dulcitol hexaacetate 3 behaves as a Hill reaction inhibitor and as an uncoupler, as determined by polarography. Chlorophyll a (Chl a) fluorescence induction kinetics from the minimum yield F0 to the maximum yield F(M )provides information of the filling up from electrons coming from water to plastoquinone pool with reducing equivalents. In this paper we have examined the effects of compounds 1 and 3 on spinach leaf discs. Compound 1 induces the appearance of a K-band, which indicates that it inhibits the water splitting enzyme. In vivo assays measuring the fluorescence of chl a in P. ixocarpa leaves sprayed with compound 1, showed the appearance of the K-band and the PSII reaction centers was transformed to "heat sinks" or silent reaction centers unable to reduce Q(A). However, 3 also induced the appearance of a K band and a new band I appears in P. ixocarpa plants, therefore it inhibits at the water splitting enzyme complex and at the PQH2 site on b6f complex. Compounds 1 and 3 did not affect chlorophyll a fluorescence of L. perenne plants.

A fluorescent probe for GM1 gangliosidosis related ß-galactosidase: N-(dansylamino)hexylaminocarbonylpentyl-1,5-dideoxy-1,5-imino-D-galactitol.

N-(Dansylamino)hexylaminocarbonylpentyl-1,5-dideoxy-1,5-imino-D-galactitol, a strong competitive inhibitor of ß-galactosidase, enhances residual ß-galactosidase activities in fibroblasts and serves as lead en route to diagnostic compounds for tracking the fate of mutant ß-gal as well as aberrant GM1 gangliosides by live cell imaging.

Ultrasonic-assisted liquid-liquid extraction and HILIC-ELSD analysis of ginsenoside Rb(1), astragaloside IV and dulcitol in sugar-free "Fufangfufangteng Heji".

A simple method for the extraction and determination of ginsenoside Rb(1), astragaloside IV and dulcitol in sugar-free "Fufangfufangteng Heji" was developed using an ultrasonic-assisted liquid-liquid extraction (UALLE) coupled with Hydrophilic Interaction Liquid Interface Chromatography and Evaporative Light Scattering Detector (HILIC-ELSD) analysis. Good chromatographic separation was achieved using a Phenomenex Luna HILIC column (250mm×4.6mm i.d., 5µm), and a mobile phase consisting of acetonitrile-water at a flow rate of 1.0ml/min with a gradient elution within 25min was also used. Compared to the conventional analysis method, the proposed method had the advantages of a longer column life, shorter analysis time, lower baseline noise, short sample pretreatment time and low consumption of organic solvent. The linear ranges for ginsenoside Rb(1), astragaloside IV and dulcitol were 0.0256-0.179, 0.110-0.770, 0.105-0.630mg/ml, respectively. The recoveries of ginsenoside Rb(1), astragaloside IV and dulcitol during the pharmaceutical preparation were within the range of 97.2-100.3%, and their relative standard deviations were 1.2-3.1%.

Interactions between metal ions and carbohydrates. Syntheses and spectroscopic studies of several lanthanide nitrate-D-galactitol complexes.

Two complexes of neutral D-galactitol (C(6)H(14)O(6), G) with terbium nitrate, TbGN(I) and TbGN(II), and one complex with samarium nitrate SmGN were synthesized and characterized. From IR, FIR, THz and luminescence spectra the possible coordinations were suggested, and the single-crystal X-ray diffraction results confirm the spectroscopic conclusions. In TbGN(I) (Tb(NO(3))(3)·C(6)H(14)O(6)·3H(2)O), the Tb(3+) is 9-coordinated with three water molecules and six OH groups from two D-galactitol molecules. Nitrate ions do not coordinate to metal ions, which is different from other reported lanthanide nitrate-D-galactitol complexes. In TbGN(II) and SmGN (Ln(NO(3))(3)·C(6)H(14)O(6)), Ln(3+) is 10-coordinated with six OH groups from two D-galactitol molecules and four oxygen from two bidentate nitrate ions, and one nitrate ion is hydrogen bonded. No water exists in the structures. D-Galactitol molecules provide their 1-, 2- and 3-hydroxyl groups to coordinate with one metal ion and their 4-, 5- and 6-hydroxyl groups to coordinate with another metal ion in the three structures. There is still a new topological structure that can be observed for lanthanide-d-galactitol complexes, which indicates that the coordinations between hydroxyl groups and metal ions are complicated.

Two new compounds from the dried tender stems of Cinnamomum cassia.

Two new compounds, cinnamic aldehyde cyclic d-galactitol 3'R,4'S-acetal (1) and cinnamomumolide (2), along with six known compounds, syringaresinol (3), lyoniresinol (4), 5,7,3'-trimethoxyl-( - )-epicatechin (5), 5,7-dimethoxyl-3',4'-di-O-methylene-( +/- )-epicatechin (6), 2-methoxyl-4-hydroxy cinnamyl aldehyde (7), and glucosyringic acid (8), have been isolated from the dried tender stems of Cinnamomum cassia. Their structures were elucidated based on spectroscopic data. Compound 2 was elucidated as 8-methoxyl-9-hydroxy-3',4'-methylenedioxy-3S,4R-diphenyl butyrolactone, named cinnamomumolide, which exhibited activity in protecting against the injury caused by hydrogen peroxide oxidation on human umbilical vein endothelial cells, with an EC(50) value of 10.7 microM. Compounds 3-8 were isolated from the title plant for the first time.

DFT/MM modeling of the five-membered ring in 3,6-anhydrogalactose derivatives and its influence on disaccharide adiabatic maps.

Different conformations of methyl 3,6-anhydro-4-O-methyl-alpha-d-galactoside (1) and 3,6-anhydro-4-O-methylgalactitol (2) were studied by molecular mechanics (using the program mm3) and by quantum mechanical (QM) methods at the B3LYP/6-31+G( * *) and MP2/6-311++G( * *) levels, with and without solvent emulation. In 2, where the five-membered ring is free to move, two main stable conformations of this ring were found, identified as North (N) and South (S). The latter appears to be more stable, by either calculation, though the energy difference is reduced when emulating solution behavior. In order to find out the possible influence of a glycosidic bond over its shape, and to explain the marked NMR chemical shift displacements observed by opening of the ring, the adiabatic maps of two disaccharides carrying an analog of beta-galactoside linked to O-4 of 1 and 2 were generated. It was shown that the characteristics of the 3,6-AnGal terminal influence the characteristics of the map, especially at lower dielectric constants. On the other hand, different glycosidic angles also promote distinct stable conformations of the five-membered ring, changing from N to S, or even variants. Comparison with experimental results leads to the idea of highly flexible disaccharides, with variable values for both the five-membered ring and the glycosidic angles.

Synthesis and X-ray crystal structures of two transition metal complexes based on functionalised 1,5-anhydro-2-deoxy-D-galactitol and methyl 2-deoxy-alpha-D-galactopyranoside.

Two new ligands of transition metal cations based on galactose-derived scaffolds were synthesised: 1,5-anhydro-2-deoxy-3,4,6-tri-O-(2-picolyl)-D-galactitol and methyl 2-deoxy-3,4,6-tri-O-(2-picolyl)-alpha-D-galactopyranoside. These ligands permitted the isolation as single crystals of a Co(II) and a Ni(II) complex, respectively. The structures of both complexes were determined by X-ray crystallography showing a coordination sphere including sugar-bound oxygen atoms. The sugar-derived ligands were found to be in both cases in high energy conformations in the crystal structures of the complexes. These conformations contain an arrangement of sugar-bound oxygen atoms similar to those observed in polyol-metal and carbohydrate-metal complexes.

Terahertz absorption spectra of some saccharides and their metal complexes.

In this work, THz absorption spectra of some saccharides and their metal complexes were measured. The main purpose of this work is to investigate the M-O vibrations, intermolecular and intramolecular hydrogen bonds and other vibrations in the FIR region using powerful spectroscopic techniques adopting the metal-sugar complexes prepared in our laboratory. The M-O vibrations in the FIR spectra of metal-sugar complexes indicate the formation of metal complexes. The THz spectrum of glucose below 100cm(-1) was measured at first to confirm the THz experimental method. Characteristic absorption bands in the spectra of various samples are observed. THz spectra of saccharides below 100cm(-1) often have several absorption bands, and different saccharides have various absorption peaks in the THz region, which may be used to distinguish different saccharides. The differences in the number of bands observed are related to different structures of the samples, and these absorption bands are related to the collective motion of molecules. But the THz spectra of their metal complexes are different from the ligands, and no band appears in the region below 50cm(-1) at the present experimental condition, which indicates that THz spectroscopy may also be helpful to identify the formation of metal-sugar complexes, and the changes after complexation in the THz spectra below 100cm(-1) may be related to different metal ions. The metal-sugar complexes with similar crystal structures resemble mid-IR spectra, but their THz spectra may have some differences.

Structural and functional characterization of galactooligosaccharides in Nostoc commune: beta-D-galactofuranosyl-(1-->6)-[beta-D-galactofuranosyl-(1-->6)]2-beta-D-1,4-anhydrogalactitol and beta-(1-->6)-galactofuranosylated homologues.

A new class of galactooligosaccharides has been identified from the terrestrial cyanobacterium Nostoc commune by MS and NMR techniques. These consist of beta-D-galactofuranosyl-(1-->6)-[beta-D-galactofuranosyl-(1-->6)]n-beta-d-1,4-anhydrogalactitols with n ranging from 2 to 8, corresponding to compounds designated 1 through 7. In total these saccharides amounted to approximately 0.35% of the dry thallus of N. commune, while in several other cyanobacteria they were not detected. Possibly they play some role in protection from damage by heat and desiccation as suggested by experiments with heterologous systems. For example, phosphoglucomutase (EC 2.7.5.1) from rabbit muscle was protected against heat inactivation by these oligosaccharides, and alpha-amylase (EC 3.2.1.1) from porcine pancreas by the oligosaccharides 6 and 7. The homologues of lower molecular mass, however, enhanced heat sensitivity of alpha-amylase. The viability of Escherichia coli was completely abolished by desiccation, whereas in the presence of 4 survival rates were approximately 50% of controls not subjected to desiccation. The newly identified saccharides are compared with known galactofuranose-based oligo- and polysaccharides and possible biological functions of them are discussed.

Interaction between metal nitrates and carbohydrates: the topology coordination behavior of galactitol with trivalent lanthanide and divalent alkaline earth ions.

It has long been known that metal ions and saccharides are involved in many biochemical processes. In this paper, metal nitrates were used as reactants to detect the coordination structures of the hydroxyl groups of galactitol in different environments. Three novel crystal structures and FT-IR spectra of metal nitrate-galactitol complexes of La(NO3)3.C6H14O6.(4)H2O, 2Ca(NO3)2.C6H14O6.H2O, and Sr(NO3)2.C6H14O6 were examined in an effort to clarify the structural factors that control metal ion interactions with saccharides in aqueous and biological systems. The coordination structures of galactitol with alkaline earth and lanthanide nitrates in the solid state were compared using FT-IR, Raman, and X-ray diffraction techniques to extensively discuss the coordination rules of different kinds of metal ions. Results provided a model of the coordination sites found in sugars and showed that the introduction of NO3- made the coordination modes of galactitol more diverse and complex than those of the corresponding chloride complexes. Specifically, new coordination modes of galactitol and complicated topology networks were found in 2Ca(NO3)2.C6H14O6.H2O and Sr(NO3)2.C6H14O6. FT-IR results are consistent with the crystal structures and thus provide the possibility of using the similarity of IR spectra to speculate about unknown structures when the compounds are difficult to prepare as single crystals.

Stereoselective synthesis of alpha-C-Substituted 1,4-dideoxy-1,4-imino-D-galactitols. Toward original UDP-Galf mimics via cross-metathesis.

[reaction: see text] Various alpha-C-substituted 1,4-dideoxy-1,4-imino-d-galactitols were prepared efficiently from 1-O-acetyl-2,3,5,6-tetra-O-benzyl-d-glucofuranose by a four-step sequence involving as the key step the highly syn-selective TMSOTf-catalyzed addition of silylated nucleophiles to a glycofuranosylamine. Cross-metathesis of the alpha-C-allylated iminogalactofuranose derivative with an original uridin-5'-yl vinylphosphonate led to novel UDP-galactofuranose mimics. Such compounds are of interest as potential inhibitors of the mycobacterial galactan biosynthesis pathway.

Crystal structures and spectroscopic characterization of galactitol complexes of trivalent lanthanide and divalent alkaline earth chlorides.

Crystal structures and FT-IR spectra of metal ion-galactitol (C6H14O6, the ligand here abbreviated as L) complexes: 2LaCl3*C6H14O6*10H2O and SrCl2*C6H14O6 complexes are reported. Crystal data of lanthanide chlorides (La3+, Nd3+, Sm3+, Eu3+, Tb3+)-galactitol complexes and alkaline earth chlorides (Ca2+, Sr2+)-galactitol complexes published earlier are summarized. Unlike other lanthanide ion-galactitol complexes (2MCl3*C6H14O6*14H2O), lanthanum ions give rise to two different structures: LaCl3*C6H14O6*6H2O (LaL1) and 2LaCl3*C6H14O6*10H2O (LaL2). Sr2+-galactitol complexes also crystallized with two structures: SrCl2*C6H14O6*4H2O (SrL1) and SrCl2*C6H14O6 (SrL2). These metal ions thus give different coordination structures with galactitol. The crystal structures and FT-IR spectra of lanthanide ion and alkaline earth ion-galactitol complexes were integrated to interpret the coordination modes of different metal ions. Similar IR spectra demonstrate the same coordination modes of the complexes.

[Study on the chemical constituents of Buddleja purdomii].

OBJECTIVE: To study the chemical constituents of Buddleja purdomii W. W Smith. METHODS: The constituents were isolated and purified by various chromatographic methods and structurally identified by spectral analysis. RESULTS: 4 compounds were obtained as cryptomeridiol (I), aucubin (II), galactilol (III), daucosterol (IV). CONCLUSION: All these compounds are obtained from this plant for the first time.