Journal of Carbohydrate Chemistry最新文献

Intramolecular glycosylation with peptides as tethers is attractive for the synthesis of oligosaccharides because conjugation between the amino acids present in the tethers is facile. However, few studies have been published about the effects of the amino acid side chain length and amino acid chirality on the glycosylation process. In this study, we revealed that the chain length of the amino acid can regulate the regioselectivity of the glycosylation process based on our observation that the 1,2-linked products were preferred when tethers were those having aspartic acid residues linked to each other, while 1,3-linked products were preferred for glutamic acid-based tethers. However, the amino acid chirality was found to have no effect on the yield and stereoselectivity of the glycosylation reaction.

Herein, we report a novel method for highly efficient and stereoselective construction 1,2-cis-2-amino-2-deoxy-glycosidic linkages using conformation-constrained 2-nitroglycal donors and bifunctional thiourea catalyst. The method enjoys mild reaction conditions, good to excellent stereoselectivity, broad substrate scope, and good to excellent efficiency.

Morinda officinalis polysaccharides (MOPS) were investigated for their physicochemical properties, monosaccharide composition, and immune-modulating effects in vitro and in vivo. In vitro, MOPS significantly promoted lymphocyte proliferation and increased IFN-γ and IL-4 secretion. In vivo, MOPS acted as adjuvant, which significantly up-regulated HBsAg-specific IgG and IgG isotype levels, promoted antigen-specific T cell proliferation and cytokine (IL-2 and IL-5) production, and induced CTL and NK cytotoxicity. Moreover, MOPS increased DC maturation. Overall, MOPS can serve as an adjuvant to promote humoral and cellular immune responses via promoting DC maturation, suggesting that MOPS may have potentials as a natural immune-enhancing agent.

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TMG-chitotriomycin is a recently discovered β-N-acetylglucosaminidase (GlcNAcase) inhibitor, specific for insect and fungal GlcNAcases. Chemical synthesis is a reliable and effective means to solve the attainability issues of TMG-chitotriomycin, which could facilitate in-depth studies of its biological activities. Thus far, four different synthetic routes toward TMG-chitotriomycin have been reported. Herein, we provide a comprehensive review on the chemical synthesis of TMG-chitotriomycin.

Herein, o-(methoxycarbonyl)phenyl thioglycosides [or (methyl)salicyl 1-thioglycosides] were evaluated as non-malodorous thioglycoside alternatives. The o-methoxycarbonyl group was expected to assist in the departure of leaving group. Salicyl-type thioglycosides exhibited high reactivity and glycosylation yields when N-iodosuccinimide and trifluoromethanesulfonic acid were used as promoters. Glycosylation with these thioglycosides in dichloromethane showed similar reactivity and stereoselectivity as those of phenyl thioglycosides. Glycosylation with per-O-benzyl salicyl-type thioglycosides in dichloromethane showed 1,2-cis-selectivity, while the same reaction in nitriles afforded predominantly 1,2-trans glycosides. In contrast, glycosylation with per-O-benzoyl thioglycosides afforded exclusively 1,2-trans glycosides. These results strongly suggest that salicyl-type thioglycosides can serve as non-malodorous alternatives for phenyl thioglycosides.

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A novel protein-polysaccharide conjugate NFP-A4 was isolated and purified from water extracts of Nervilia fordii. The polysaccharide chain of NFP-A4 was found to contain D-galacturonic acid, D-galactose, D-glucose, L-arabinose, D-glucuronic acid, L-rhamnose, and D-mannose. The protein content of NFP-A4 was determined to be 12.83%, and it was bound to the polysaccharide chain via O-linkages at the serine and threonine residues. NFP-A4 was found to significantly activate macrophages and also induce immunomodulatory responses. These data suggest that NFP-A4 is a major bioactive component of N. fordii and may be responsible for many of its therapeutic properties.

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A series of deoxynojirimycin-triazole hybrid iminosugars had been prepared and investigated against a panel of glucosidases. Compound 10f (IC₅₀ = 0.063 ± 0.006 mM) exhibited improved inhibitory potency against α-glucosidase compared to 1-deoxynojirimycin (IC₅₀ = 0.155 ± 0.015 mM). Moreover, analysis of the kinetics of enzyme inhibition by using Lineweaver–Burk plots indicated that 10f inhibited α-glucosidase in a competitive manner. Compound 10m displayed moderate inhibition of α-glucosidase and β-glucosidase. The structure-activity relationships indicated that the introduction of the phenyl group and the nature of 4-position substituents on the phenyl ring had significant effects on the glucosidase inhibitory potency of the compounds.

Here, we report a highly selective, efficient and rapid method for the selective cleavage of primary acetonide using silica supported polyphosphoric acid (PPA-SiO₂) for various carbohydrate substrates. Corresponding diols were obtained in good to excellent yields within 30 min using PPA-SiO₂. Overall, PPA-SiO₂ was found to be a useful catalyst for selective acetonide cleavage in carbohydrate substrates which may expand its utility in organic synthesis.

In this work, the performances of two ionic liquid matrices (ILMs) with the same ammonium counterpart for mass spectrometric analysis of the insoluble and soluble sucralfate were compared. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) was performed assisted by the butylammonium salts of α-cyano-hydroxycinnamic acid (CHCAB) and 2,5-dihydroxybenzoic acid (DHBB). CHCAB has a higher IE than DHBB, but better optical properties. CHCAB is more suitable for the analysis of sucralfate, although molecular ions of both compounds were detectable only with low intensities. Thus, optical properties of ILMs are crucial to enhance the sensitivity of MALDI MS detection of polysulfated oligosaccharides.