| 1. |
- Dorst, Kevin, 1992-, et al.
(författare)
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On the influence of solvent on the stereoselectivity of glycosylation reactions
- 2024
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 535
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Tidskriftsartikel (refereegranskat)abstract
- Methodology development in carbohydrate chemistry entails the stereoselective formation of C-O bonds as a key step in the synthesis of oligo- and polysaccharides. The anomeric selectivity of a glycosylation reaction is affected by a multitude of parameters, such as the nature of the donor and acceptor, activator/promotor system, temperature and solvent. The influence of different solvents on the stereoselective outcome of glycosylation reactions employing thioglucopyranosides as glycosyl donors with a non-participating protecting group at position 2 has been studied. A large change in selectivity as a function of solvent was observed and a correlation between selectivity and the Kamlet-Taft solvent parameter pi* was found. Furthermore, molecular modeling using density functional theory methodology was conducted to decipher the role of the solvent and possible reaction pathways were investigated.
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| 2. |
- Hsieh, Yves S. Y., et al.
(författare)
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The knowns and unknowns of callose biosynthesis in terrestrial plants
- 2024
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 538, s. 109103-109103
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Tidskriftsartikel (refereegranskat)abstract
- Callose, a linear (1,3)-β-glucan, is an indispensable carbohydrate polymer required for plant growth and development. Advances in biochemical, genetic, and genomic tools, along with specific antibodies, have significantly enhanced our understanding of callose biosynthesis. As additional components of the callose syn- thase machinery emerge, the elucidation of molecular biosynthetic mechanisms is expected to follow. Short-term objectives involve defining the stoichiometry and turnover rates of callose synthase subunits. Long-term goals include generating recombinant callose synthases to elucidate their biochemical properties and molecular mechanisms, potentially culminating in the determination of callose synthase three-dimensional structure. This review delves into the structures and intricate molecular processes underlying callose biosynthesis, emphasizing regulatory elements and assembly mechanisms.
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| 3. |
- Dorst, Kevin, 1992-, et al.
(författare)
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NMR chemical shift prediction and structural elucidation of linker-containing oligo- and polysaccharides using the computer program CASPER
- 2023
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 533
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Tidskriftsartikel (refereegranskat)abstract
- Carbohydrate structures containing alkyl groups as aglycones are useful for investigating enzyme activity and glycan-protein interactions. Moreover, linker-containing oligosaccharides with a spacer group are commonly used to print glycan microarrays or to prepare protein-conjugates as vaccine candidates. The structural accuracy of these synthesized glycans are essential for interpretation of results from biological experiments in which the compounds have been used and NMR spectroscopy can unravel and confirm their structures. An approach for efficient 1H and 13C NMR chemical shift assignments employed a parallel NOAH-10 measurement followed by NMR spin-simulation to refine the 1H NMR chemical shifts, as exemplified for a disaccharide with an azidoethyl group as an aglycone, the NMR chemical shifts of which have been used to enhance the quality of CASPER (http://www.casper.organ.su.se/casper/). The CASPER program has been further developed to aid characterization of linker-containing oligo- and polysaccharides, either by chemical shift prediction for comparison to experimental NMR data or as structural investigation of synthesized glycans based on acquired unassigned NMR data. The ability of CASPER to elucidate structures of linker-containing oligosaccharides is demonstrated and comparisons to assigned or unassigned NMR data show the utility of CASPER in supporting a proposed oligosaccharide structure. Prediction of NMR chemical shifts of an oligosaccharide, corresponding to the repeating unit of an O-antigen polysaccharide, having a linker as an aglycone and a non-natural substituent derivative thereof are presented to exemplify the diversity of structures handled. Furthermore, NMR chemical shift predictions of synthesized polysaccharides, corresponding to bacterial polysaccharides, containing a linker are described showing that in addition to oligosaccharide structures also polysaccharide structures having an aglycone spacer group can be analyzed by CASPER.
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| 4. |
- Norberg, Thomas, 1948-, et al.
(författare)
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N-methyl-O-benzylhydroxylamine derivatives of sialylated oligosaccharides, their synthesis and separation with reversed-phase HPLC
- 2023
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Ingår i: Carbohydrate Research. - : Elsevier. - 0008-6215 .- 1873-426X. ; 533
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Tidskriftsartikel (refereegranskat)abstract
- The human milk trisaccharide 3′- sialyllactose was reacted with an excess of N-methyl-O-benzylhydroxylamine (MBHA) and the product 3′- sialyllactose-MBHA was isolated in high (91%) yield by solid-phase extraction. The isomeric trisaccharide 6′-sialyllactose-MBHA was also prepared, in this case by enzymatic sialylation of lactose-MBHA. A 50/50 mixture of the two sialyllactose-MBHA derivatives was easily separated by reversed-phase HPLC. The free oligosaccharides were recovered from their respective MBHA derivatives by acid hydrolysis.
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| 5. |
- Alexandersson, Elin, et al.
(författare)
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Complete H-1 and C-13 NMR spectral assignment of D-glucofuranose
- 2022
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 511
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Tidskriftsartikel (refereegranskat)abstract
- Although D-glucose is the most common sugar in nature, only a few NMR studies have focused on its minor furanose forms, and they have been limited to the anomeric position. Here, complete H-1 and C-13 NMR spectral analysis of alpha- and beta-D-glucofuranose was performed, including signal assignment, chemical shifts, and coupling constants. Selective and non-selective 1D and 2D NMR experiments were used for the analysis, complemented by spin simulations and iterative spectral analysis.
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| 6. |
- Avetyan, David L., et al.
(författare)
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Scalable total synthesis of natural vanillin-derived glucoside omega-esters
- 2022
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 522, s. 108683-
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Tidskriftsartikel (refereegranskat)abstract
- The first total synthesis of vanilloloside, calleryanin, and a series of naturally occurring omega-esters of vanilloloside was realized through direct glycosylation of vanillin-based aglycones or late-stage derivatization of vanilloloside. All aglycones and their fragments were synthesized from vanillin as the sole aromatic precursor. Subsequently, these intermediates were used to construct various vanillin-derived glucoside omega-esters using a mild acidic deacetylation as the key synthetic step, providing the final products in the total yields of 10-50% and general purity of >95%. Additionally, the first operationally simple and sustainable synthesis of litseafoloside B was realized on large scale, avoiding the use of toxic solvents and reagents, providing an attractive alternative to isolation of this and other similar compounds from plant sources.
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| 7. |
- Duyen, Nguyen Thi, et al.
(författare)
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Steroid glycosides isolated from Paris polyphylla var. chinensis aerial parts and paris saponin II induces G1/S-phase MCF-7 cell cycle arrest
- 2022
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215. ; 519
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Tidskriftsartikel (refereegranskat)abstract
- In our previous research on Vietnamese medicinal plants, we found that the ethanolic extract of the aerial parts of Paris polyphylla var. chinensis exhibited cytotoxic effects in vitro in the MCF-7 human cancer cell line. Here, we used combined chromatographic separations to isolate six compounds including a new steroid glycoside, paripoloside A (3), and five known compounds, from the butanol extract of the aerial parts of P. polyphylla. We unambiguously elucidated their structures based on spectroscopic data (proton and carbon-13 nuclear magnetic resonance, heteronuclear single quantum coherence, heteronuclear multiple bond correlation, correlation spectroscopy, and high-resolution electrospray ionization mass spectroscopy data), and chemical reactions. Among the isolated compounds, paris saponin II (PSII) had the strongest cytotoxic effects against MCF-7 breast cancer cells. Interestingly, PSII significantly increased the expression of p53, p21, p27, and Bax protein levels and significantly suppressed the expression of cyclin D1 and retinoblastoma protein. These data suggest that PSII may induce G1/S phase cell cycle arrest and apoptosis pathway development in MCF-7 cells. Furthermore, the MCF-7 breast cancer cells mechanism of PSII was also investigated using molecular docking. Together, our results demonstrate that isolated compounds from P. polyphylla are promising candidates as breast cancer inhibitors.
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| 8. |
- Furevi, Axel, 1992-, et al.
(författare)
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Complete 1H and 13C NMR chemical shift assignments of mono-to tetrasaccharides as basis for NMR chemical shift predictions of oligo- and polysaccharides using the computer program CASPER
- 2022
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 513
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Tidskriftsartikel (refereegranskat)abstract
- Carbohydrate structure can be elucidated or confirmed by using NMR spectroscopy as the prime technique. Prediction of 1H and 13C NMR chemical shifts by computational approaches makes this assignment process more efficient and the program CASPER can perform this task rapidly. It does so by relying on chemical shift data of mono-, di-, and trisaccharides. In order to improve accuracy and quality of these predictions we have assigned 1H and 13C NMR chemical shifts of 30 monosaccharides, 17 disaccharides, 10 trisaccharides and one tetrasaccharide; in total 58 compounds. Due to different rotamers, ring forms, α- and β-anomeric forms and pD conditions this resulted in 74 1H and 13C NMR chemical shift data sets, all of which were refined using total line-shape analysis for the 1H resonances in order to obtain accurate chemical shifts. Subsequent NMR chemical shift predictions for three sialic acid-containing oligosaccharides, viz., GD1a, a disialyl-LNnT hexasaccharide and a polysialic acid-lactose decasaccharide, and NMR-based structural elucidations of two O-antigen polysaccharides from E. coli O174 were performed by the CASPER program (http://www.casper.organ.su.se/casper/) resulting in very good to excellent agreement between experimental and predicted data thereby demonstrating its utility for carbohydrate compounds that have been chemically or enzymatically synthesized, structurally modified or isolated from nature.
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| 9. |
- Li, Jing, et al.
(författare)
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Structural compositions and biological activities of cell wall polysaccharides in the rhizome, stem, and leaf of Polygonatum odoratum (Mill.) Druce
- 2022
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 521
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Tidskriftsartikel (refereegranskat)abstract
- Polygonatum odoratum is a perennial rhizomatous medicinal plant and different plant parts have been used in the treatment of various ailments. Herein, we have investigated the structural compositions of rhizome, leaf, and stem cell walls. We found 30–44% of polysaccharides in these wall preparations were cyclohexanediaminetetraacetic acid (CDTA) extractable, the proportion of heteromannans (HMs) in the rhizome is nearly three-fold compared to that of the leave and stem. The pectic polysaccharides of the rhizome are also structurally more diverse, with arabinans and type I and type II arabinogalactans being richest as shown by linkage study of the sodium carbonate (Na2CO3) extract. In addition, the 2-linked Araf was rhizome-specific, suggesting the cell walls in the rhizome had adapted to a more complex structure compared to that of the leaf and stem. Water-soluble polysaccharide fractions were also investigated, high proportion of Man as in 4-linked Manp indicated high proportion of HMs. The 21.4 kDa pectic polysaccharides and HMs derived from rhizome cell walls induced specific immune response in mice macrophage cells producing IL-1α and hematopoietic growth factors GM-CSF and G-CSF in vitro.
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| 10. |
- Moe, S. T., et al.
(författare)
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Formation of 5-methylfurfural and 2-acetylfuran from lignocellulosic biomass and by Cr3+-catalyzed dehydration of 6-deoxyhexoses
- 2022
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Ingår i: Carbohydrate Research. - : Elsevier Ltd. - 0008-6215 .- 1873-426X. ; 522
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Tidskriftsartikel (refereegranskat)abstract
- During autocatalyzed steam explosion of lignocellulose, polysaccharides in the cell wall are hydrolyzed and dehydrated to form various furaldehydes. In addition to furfural, 5-methylfurfural and 2-acetylfuran were identified in condensates from autocatalyzed steam explosion of Scandinavian softwood (Norway spruce, Picea abies). The presence of 5-methylfurfural can be explained by an acid-catalyzed dehydration of 6-deoxyaldohexoses, which are known to be present in lignocellulosic biomass. However, the presence of 2-acetylfuran cannot be explained by previously published reaction mechanisms since the required substrate (a 1-deoxyhexose or a 1-deoxyhexosan) is not known to be present in lignocellulosic biomass. In model experiments, it was shown that 2-acetylfuran is formed from rhamnose and fucose upon heating in the presence of the Lewis acid Cr3+. Possible reaction pathways for the formation of 2-acetylfuran from 6-deoxyaldohexoses are suggested. This reaction can potentially enable the targeted production of 2-acetylfuran from renewable biomass feedstocks. © 2022 The Authors
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