Journal of Carbohydrate Chemistry最新文献

Synthesis, structural features, and paramagnetic properties of manganese-containing nanocomposites based on polysaccharides arabinogalactan, sulfated arabinogalactan, and κ-carrageenan have been studied. All compounds have been investigated by physical and chemical methods including electron paramagnetic resonance, transmission electron microscopy, infrared spectroscopy, and atomic absorption analysis. It is shown that manganese-containing nanoparticles of 3–6 nm in size were stabilized in the polysaccharide mass by coordination with Mn²⁺, and the resulting particles have a complex structural organization and are highly EPR active with a spin concentration of about 10²⁰ spin/g. The obtained nanocomposites possess aggregative stability and conserve their properties for a long time.

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Oligosaccharides are one of the major bioactive components in Codonopsis pilosula. The present study was to investigate the protective effect of C. pilosula oligosaccharides (CPO) on d-galactose (D-Gal)-induced aging and to illuminate the underlying mechanisms. The results indicated that CPO effectively increased the growth rate as indicated by body weight, attenuated the decline of thymus and liver indexes, and mitigated the pathological liver injury compared with model group rats. CPO could elevate the activities of anti-oxidative enzymes, including CAT, GSH-Px, and SOD, and reduce MDA level in serum, improve SOD and GSH-Px activities in liver, down-regulate the phosphorylation of MAPK cascade signal transduction components – ERK, JNK, and p38, and inhibit the activation of downstream NF-κB signaling. In addition, CPO treatment noticeably prevented the overexpression of inflammatory factors such as TNF-α, IL-6, and IL-1β in serum, inhibited the expression of apoptosis-related proteins caspase-3, caspase-9, and the ratio of Bax/Bcl-2 in liver caused by the inflammatory cascade, reduced cell apoptosis, and improved liver damage. The above studies suggested that CPO could effectively mitigate the D-Gal-induced aging, and the underlying mechanism might be closely related to ROS-induced oxidative stress, inflammation, and apoptosis.

Radical glycosylation has gradually become a powerful and effective method to synthesize carbohydrate mimetics as reactions via radical intermediates usually provide excellent functional group compatibility and good anomeric selectivity. Novel glycosyl radical precursors have been identified as glycosyl donors in radical glycosylation to access C-, S- and Se-glycosides. This review aims at summarizing the remarkable advances in radical glycosylation reactions to illuminate potential future research directions. Herein, the most recent literature concerning radical glycosylation is covered with a specific emphasis on radical precursor design along with discussions of consequential mechanisms.

The conversion of D-ribose into its 2,3-O-isopropylidene derivative using ultrasonic irradiation is described. The ultrasound proved to be an excellent alternative as the energy source for the reaction. Different reaction times were investigated, and shorter reaction times and high yield were achieved without the need for purification of the acetonide. The compound was then applied as the starting material in the synthesis of 23 new glycoconjugates of 1,2,3-triazole that are tethered together in different ways. The synthesized compounds were characterized by FTIR, ¹H NMR, ¹³C NMR, and HRMS techniques.

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N-glycans in eukaryotic proteins are commonly attached to asparagine residues via β-N-glycosidic linkages, which are susceptible to glycosidases, such as PNGase. Here we report the preparation of α-N-glycosylated peptides based on the solid-phase peptide synthesis strategy using an α-N-GlcNAc-containing asparagine building block, and a transglycosylation reaction of oligosaccharide oxazoline promoted by endoglycosidases CC^N180H. The resultant glycopeptide, bearing the complex-type α-N-sialyl undecasaccharide, exhibits resistance against PNGase F, which may be of potential use in studying the catabolism of N-glycans and glycoengineering those peptide-based therapeutics.

Glycoclusters with high glycan density accessible through grouping of monosaccharide units in multimeric forms are important due to their high affinity and capability in recognition with protein receptors as a result of multivalent effect. In this report, we have achieved the assembly of glycoclusters in dimeric to tetrameric forms using efficient light initiated free radical mediated thiol-ene click reaction. Bacterium (UTI89) inhibition study by yeast agglutination assay demonstrated that these multivalent glycoclusters showed more efficient inhibition of bacteria when compared to monovalent sugar units.

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Seasonal allergic rhinitis (SAR) is an inflammatory process. In this pilot study, matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS)-based analyses were conducted to investigate the effects of SAR on serum N-glycome in a small dataset (n = 10 for both SAR patients and controls). It was detected that two N-glycan compositions (H6N5E2L1 and H6N5E1L2) were down-regulated in SAR patients. Additionally, five tri-antennary N-glycan traits, including both galactosylated and sialylated (A3GS and A3GL) and non-fucosylated (A3F0GE, A3F0GL, A3F0GS) ones, were decreased. Furthermore, three high-antennary and fucosylated N-glycan traits (A3F, A3EF and A4F) were increased in SAR patients compared to controls.

Two photoreactions for the synthesis of 1- and 2-deoxysugars from thioglycosides were developed. In the presence of Hantzsch ester as an additive, a wide range of 1-deoxysugars were synthesized in moderate to excellent yields under irradiation with UV light without an exogenous photosensitizer. On the other hand, the utilization of 2,4,6-tri-tert-butylpyrimidine (TTBP) as the additive furnished a variety of 2-deoxysugars as the main products from their corresponding thioglycosides. The reported methodology has a broad substrate scope and high functional group tolerance and is scalable to gram-scale reaction.

An alginate (molecular weight [Mw] = 64.8 × 10³, F_M = 0.505) was extracted from brown seaweed Turbinaria ornata, and were separated into three fractions, G-blocks (Mw = 8.0 × 10³, F_M = 0.141), M-blocks (Mw = 4.0 × 10³, F_M = 0.952), and MG-blocks (Mw = 8.0 × 10³, F_M = 0.279). According to biological evaluations in terms of antimicrobial, antioxidant, and cytotoxic activities, the native alginate was not a high bioactive compound, but its two main fractions, G-blocks and M-blocks especially M-blocks, showed higher activities. The native alginate and two main fractions were found to have a linear single-chain conformation in saline solution as observed by small-angle X-ray scattering (SAXS) measurements.

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