Journal of Carbohydrate Chemistry最新文献

6′-Sialolactose-modified mono- and bivalent nanobodies were designed and synthesized by a chemoenzymatic strategy. Epidermal growth factor receptor (EGFR)-targeting 7D12 nanobodies, including mono- and bivalent 7D12, were recombinantly expressed in Escherichia coli. Triglycine-modified 6′-sialolactose derivative was synthesized in nine steps. The conjugation of carbohydrates with nanobodies was achieved by Sortase-A mediated ligation with high conversion rates. The obtained glycoengineered nanobodies were finally verified by SDS-PAGE, western blot, and mass spectrometry.

Based on the capability of silyl ethers for efficient glycosylation, the new MTEAN glycosylation protocol utilizing 8-methyltosylaminoethynyl-1-naphthyl (MTEAN) glycosides as donors were extended to one-pot synthesis of nucleosides, late-stage modification of bioactive molecules, and stereoselective construction of 1,2-cis-glucosidic linkages using silyl ethers of the acceptors. Moreover, the reaction mechanism was systematically investigated by control reactions and side product characterizations, leading to the determination of a TfOH-catalyzed ynamide functionality-initiated process, which was further corroborated by identifications of the departure form of leaving group and the real catalyst.

A new route for the synthesis of tetrahydrocortisone 3-glucuronide has been developed with cortisone acetate as a starting material. The key step was using lithium tri-tert-butoxyaluminum hydride to reduce the C-3 carbonyl group of 5β-dihydrocortisone acetate (8) to provide 3α-5β-tetrahydrocortisone acetate (5). Then, Koenig–Knorr method was used for glycosylation with glycosyl bromide as the donor, cadmium carbonate as promoter and 4Å molecular sieves as dehydrating agent to give high yield of the desired product. The new route is shorter and gives higher yield than that reported in the literature.

Extracts of Salacia, which are woody climbers mainly distributed in South Asian countries, have long been used to treat type-2 diabetes. Eight sulfonium-type α-glucosidase inhibitors salacinol, kotalanol, ponkoranol, salaprinol and their corresponding de-O-sulfonated analogues have been isolated so far. The unique structures, as well as distinguished biological activities, made them attractive targets in diverse research disciplines. The development of facile synthetic approaches is critical and fundamental for other extended investigations, including chemical biology and pharmaceutical development. This report provides an overview of the recent synthetic efforts directed toward the assembly of these sulfonium-containing polyhydroxylated natural products. This review will be helpful to gather insights into the development of a novel sulfonium type molecules with potential therapeutic applications.

A novel, straightforward, and environmentally friendly direct coupling procedure to immobilize carbohydrates on solid supports is presented. A characterization study showed that all amino groups on solid supports participated in the linkage with a carbohydrate unit, implicating that the surface load can be easily adjusted by tuning the amination coverage of the surface. Most importantly, the integrity of the cyclic conformation of the linked sugar unit was demonstrated, a feature that is critical for most of the possible applications of carbohydrate-functionalized surfaces. Furthermore, carbohydrate-immobilized submicron particles synthesized by the direct coupling method, on which lectin profiling experiments were conducted, validated the successfulness of our simplistic approach.

Novel 3H-1,5-benzodiazepine-derived aryl C-glycosides were synthesized in good to excellent yields by the coupling of structurally diverse terminal sugar alkynes, aroyl chlorides and 1, 2-phenylenediamine. The protocol is general, mild and efficient. It was suitable for various terminal sugar alkynes and aroyl chlorides, with 37 selected examples. The sugar substrates include pyranosides, furanosides, and acyclic sugars with sensitive and bulky protecting groups. The aroyl chlorides contain electron-donating, electron-withdrawing and electron-neutral substituents.

Several novel benzimidazolium-based ionic liquids (BzIm ILs) with free and acetyl protected glucopyranoside unit were synthesized and used as ligand for Pd-catalyzed environment-friendly Suzuki reaction. The BzIm ILs with the acetyl protection shows the highest activity, probably because the sugar has a large steric hindrance and acetyl groups can coordinate with Pd. The nuclear magnetic resonance spectra of Pd(OAc)₂/Glc-BzIm ILs free glucopyranoside indicate that Pd-C is formed. The Pd nanoparticles protected by ILs with a size of 5.3 (0.6) nm are considered to be real active species. A series of fluorene core arylfluorene derivatives were prepared with isolated yields above 90%.

Sophora flavescens Ait. is a medicinal herb traditionally used to treat inflammatory diseases. In this study, four polysaccharides, SFNP-1, SFNP-2, SFAP-1, and SFAP-2, were isolated from S. flavescens. Both SFNP-1 and SFNP-2 were (1→4)-linked glucans. SFAP-1 and SFAP-2 were identified as pectin-type polysaccharides containing mainly a homo-galacturanan backbone (as shown). NO release inhibition test revealed that the major polysaccharides, SFAP-1 and SFAP-2, did not have a significant anti-inflammatory effect. This result suggests that the anti-inflammatory effect of S. flavescens may not depend on its polysaccharides.

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Carbohydrates, also known as glycans or sugars are the nature’s most abundant biomolecules. Human breast milk contains soluble oligosaccharides that are involved in the biological recognition process. Oligosaccharides occur in numerous conformational states due to their flexible nature at glycosidic linkages. Molecular dynamics simulation is used to investigate the structural flexibility of glycosidic linkage and intramolecular interactions between molecules. The work focused on human milk oligosaccharide (HMOs), lacto-N-fucopentaose (LNFP) I and II, investigated through MD simulation for 250 ns, and its replicate. Possible conformational models for LNFP I and II were determined and deposited in the open-access database 3DSDSCAR. The structural analysis was carried out for the two HMOs with the CPPTRAJ module.

Aromatic diamines are essential components of polyimide and many other thermosetting polymers. Recent attention has been growing on the threading of cyclodextrins (CDs) onto diamine monomers intended to improve the solubility in water and thermal stability of resultant polymers. The co-precipitation method is often used to isolate inclusion complexes (ICs) of aromatic diamines and other sparingly water-soluble aromatic guest molecules with β-CD. To find the viability of other methods, we studied IC formation between β-CD and some aromatic diamines by mixing in hot water, co-precipitation, and solid-state grinding. ICs formation in water was carried out by solid guest dispersion into the β-CD aqueous solution at 80 °C with high-speed magnetic stirring. In contrast, solid-state grinding was employed by adding a small amount of water to promote IC formation. Thus, ICs prepared by mixing in hot water and solid-state grinding methods were crystallized from water by cooling to 4 °C. Structures of the ICs in solution were confirmed by chemical shifts changes of cavity protons of β-CD in ¹H NMR and the cross-peaks between aromatic protons and cavity protons in ¹H-¹H ROESY NMR. Job’s plot and NMR titration experiments were used to determine the stoichiometric ratio of host and guest in solution.