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Unusual triflic acid-promoted oligomerization of arabinofuranosides during glycosylation. Carbohydr Res 2024; 540:109141. [PMID: 38740000 DOI: 10.1016/j.carres.2024.109141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/27/2024] [Accepted: 05/01/2024] [Indexed: 05/16/2024]
Abstract
We discovered an unusual triflic acid-promoted oligomerization of arabinofuranosides during glycosylation of the primary hydroxy group of α-(1 → 5)-linked tetraarabinofuranoside bearing 4-(2-chloroethoxy)phenyl aglycone with α-(1 → 5), β-(1 → 2)-linked tetraarabinofuranoside containing N-phenyltrifluoroacetimidoyl leaving group, which led to octa-, dodeca- and hexadecaarabinofuranosides. The possible mechanism of triflic acid-promoted oligomerization was proposed. The choice of promoter was found to be a critical factor for the discovered oligomerization of arabinofuranosides. The obtained octa-, dodeca- and hexadecaarabinofuranosides may serve as useful blocks in the synthesis of oligosaccharide fragments of polysaccharides of Mycobacterium tuberculosis.
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2
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Synthesis of sialyl halides with various acyl protective groups. Carbohydr Res 2024; 536:109033. [PMID: 38295530 DOI: 10.1016/j.carres.2024.109033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/31/2023] [Accepted: 01/05/2024] [Indexed: 02/02/2024]
Abstract
Glycosyl halides are historically one of the first glycosyl donors used in glycosylation reactions, and interest in glycosylation reactions involving this class of glycosyl donors is currently increasing. New methods for their activation have been proposed and effective syntheses of oligosaccharides with their participation have been developed. At the same time, the possibilities of using these approaches to the synthesis of sialosides are restricted by the limited diversity of known sialyl halides (previously, mainly sialyl chlorides, less often sialyl bromides and sialyl fluorides, with acetyl (Ac) groups at the oxygen atoms and AcNH, Ac2N and N3 groups at C-5 were used). This work describes the synthesis of six new N-acetyl- and N-trifluoroacetyl-sialyl chlorides and bromides with O-chloroacetyl and O-trifluoroacetyl protective groups. Preparation of N,O-trifluoroacetyl protected derivatives was made possible due to development of the synthesis of sialic acid methyl ester pentaol with N-trifluoroacetyl group.
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Synthesis and study of the glycosyl-donor properties of 2-(2,2,2-trichloroethoxy)-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-galactopyrano)-[2,1-d]-2-oxazoline. Carbohydr Res 2024; 536:109040. [PMID: 38232542 DOI: 10.1016/j.carres.2024.109040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/09/2024] [Accepted: 01/09/2024] [Indexed: 01/19/2024]
Abstract
A synthesis of 2-(2,2,2-trichloroethoxy)-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-galactopyrano)-[2,1-d]-2-oxazoline - a previously unknown 2-alkoxy glyco-[2,1-d]-2-oxazoline derivative with d-galacto configuration was carried out. Glycosylating activity of the obtained galactooxazoline has been studied and it has been shown that in the presence of a weak protic acid, such as sym-collidinium triflate, this substance exhibits properties of a reactive and 1,2-trans-stereoselective glycosyl donor. The homopolymerization reaction of oxazoline derivatives of sugars has been found to proceed under the same conditions, leading to the formation of pseudo-oligosaccharide products. It has been found that this undesirable side reaction could be suppressed by changing the acid catalyst concentration, resulting in the development of efficient methods for the synthesis of glycoside and oligosaccharide derivatives of β-d-galactosamine using the synthesized 2-(2,2,2-trichloroethoxy)-2-oxazoline glycosyl donor under very mild conditions.
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TIPS group-assisted isomerization of benzyl protected d-manno- and d-glucopyranose to d-fructofuranose derivatives. Carbohydr Res 2023; 534:108942. [PMID: 37769375 DOI: 10.1016/j.carres.2023.108942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 09/30/2023]
Abstract
Base-promoted (MeONa in MeOH or imidazole in DMF) isomerization of a series of 3,4,6-tri-O-benzyl-d-gluco- and d-mannopyranose derivatives with triisopropylsilyl (TIPS) substituents was studied. The presence of a bulky TIPS group at O-1 or O-2 was shown to be favorable for the isomerization of benzyl protected d-gluco- and d-mannopyranose derivatives to d-fructofuranose derivatives, in which the bulky silyl group occupies less sterically hindered primary position. The highest yield (33%) of the fructofuranose derivative was achieved when 3,4,6-tri-O-benzyl-2-O-triisopropylsilyl-d-mannopyranose was treated with MeONa in MeON at 50 °C.
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Five Triisopropylsilyl Substituents in Ara‐β‐(1→2)‐Ara Disaccharide Glycosyl Donor Make Unselective Glycosylation Reaction Stereoselective. European J Org Chem 2022. [DOI: 10.1002/ejoc.202201110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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6
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New methods for the synthesis of 2-(2,2,2-trichloroethoxy)-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-D-glucopyrano)-[2,1-d]-2-oxazoline and its use for stereo-, chemo- and regioselective glycosylation. Carbohydr Res 2022; 520:108633. [PMID: 35868150 DOI: 10.1016/j.carres.2022.108633] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 11/02/2022]
Abstract
New methods for the synthesis of the title oxazoline 2 from the corresponding 2-deoxy-2-(2,2,2- trichloroethoxycarbonylamino)glucosyl bromide were developed. The target 2-(2,2,2-trichloroethoxy) gluco-[2,1-d]-2-oxazoline 2 can be synthesized under conditions of halide ion catalysis, using triethylamine as a base. The synthesized 2-(2,2,2-trichloroethoxy)-2-oxazoline glycosyl donor was used for stereo-, regio-, and chemoselective glycosylation reactions under extremely mild conditions. The undesirable side reaction of intermolecular aglycone transfer between an ethyl thioglycoside glycosyl acceptor and the 2-(2,2,2-trichloroethoxy)-2-oxazoline glycosyl donor occurred to a relatively small extent. Regio-, and chemoselectivity of the disaccharide synthesis with the oxazoline glycosyl donor depended on the reaction conditions.
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7
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Stereocontrolling Effect of a Single Triisopropylsilyl Group in 1,2‐cis‐Glucosylation. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Black Swan in Phase Transfer Catalysis: Influence of Mixing Mode on the Stereoselectivity of Glycosylation. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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Black swan in phase transfer catalysis: influence of mixing mode on the stereoselectivity of glycosylation. European J Org Chem 2022. [DOI: 10.1002/ejoc.202101377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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The Influence of Anomeric Configuration and Aglycone Structure on the Outcome of Acid‐Promoted Ring Contraction in 2,3‐Di‐
O
‐Silylated S‐Galactopyranosides. ChemistrySelect 2021. [DOI: 10.1002/slct.202101441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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11
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The study of the acid-catalyzed reaction between 2-methyl and 2-(2,2,2-trichloroethoxy) gluco-[2,1-d]-2-oxazolines. Synthesis of macrocyclic pseudo-tetrasaccharide derivative of d-glucosamine. Carbohydr Res 2020; 499:108230. [PMID: 33429169 DOI: 10.1016/j.carres.2020.108230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 12/22/2020] [Accepted: 12/24/2020] [Indexed: 11/26/2022]
Abstract
The formation of macrocyclic pseudo-tetrasaccharide derivative of d-glucosamine as a result of the acid-catalyzed reaction between 2-methyl- and 2-(2,2,2-trichloroethoxy)-substituted oxazoline derivatives of sugars was discovered. The structure of the obtained product was determined using NMR spectroscopy and mass spectrometry. An explanation of the obtained results based on the mechanism of the reaction of electrophilic polymerization of 2-substituted glyco-[2,1-d]-2-oxazolines and the principle of hard and soft acids and bases (HSAB) was proposed.
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12
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Azidation of Partially Protected Carbohydrate Derivatives: Efficient Suppression of Acyl Migration. Synlett 2020. [DOI: 10.1055/s-0040-1707137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Although azidation by nucleophilic substitution is widely used in organic chemistry, it has a limitation for partially protected carbohydrate derivatives under typical reaction conditions used for azidation (heating with NaN3, phase-transfer catalyst (optional), DMF or DMSO) as it can cause substantial migration (70%) of O-acyl protective groups. Several approaches, including the use of a temporary protective group for the unprotected hydroxyl group, to avoid acyl migration have been compared. Addition of excess of ethyl trifluroacetate effectively suppressed benzoyl migration but inhibited substitution of the chlorine atom with the azido group. The most robust procedure involved addition of excess n-butyl formate to the reaction mixture. When this protocol was followed, migration of benzoyl groups in lactose derivatives with free hydroxy group at C-3′ or C-4′ was reduced to 4%, with the yield of the target, partially protected derivatives with an azido group in the aglycone approaching 92%.
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Unusual Outcome of Glycosylation: Hydrogen‐Bond Mediated Control of Stereoselectivity by
N
‐Trifluoroacetyl Group? European J Org Chem 2020. [DOI: 10.1002/ejoc.202000520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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14
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Catalyst-free regioselective acetylation of primary hydroxy groups in partially protected and unprotected thioglycosides with acetic acid. RSC Adv 2020; 10:36836-36842. [PMID: 35517942 PMCID: PMC9057154 DOI: 10.1039/d0ra07360a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 09/24/2020] [Indexed: 12/24/2022] Open
Abstract
Highly regioselective acetylation of primary hydroxy groups in thioglycoside derivatives with gluco- and galacto-configurations was achieved by treatment with aqueous or anhydrous acetic acid (60–100% AcOH) at elevated temperatures (80–118 °C), avoiding complex, costly and time-consuming manipulations with protective groups. Acetylation of both 4,6-O-benzylidene acetals and the corresponding diols as well as the unprotected tetraol with AcOH was shown to lead selectively to formation of 6-O-acetyl derivatives. For example, the treatment of phenyl 1-thio-β-d-glucopyranoside with anhydrous AcOH at 80 °C for 24 h gave the corresponding 6-O-acetylated derivative in 47% yield (71% based on the reacted starting material) and unreacted starting tetraol in 34% yield, which can easily be recovered by silica gel chromatography and reused in further acetylation. Highly regioselective acetylation of primary hydroxy groups in thioglycoside derivatives was achieved by treatment with aqueous or anhydrous acetic acid (60–100%) at elevated temperatures (80–118 °C), avoiding manipulations with protective groups.![]()
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The use of the novel glycosyl acceptor and supramer analysis in the synthesis of sialyl-α(2-3)-galactose building block. Carbohydr Res 2018; 470:27-35. [PMID: 30343245 DOI: 10.1016/j.carres.2018.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 10/02/2018] [Accepted: 10/02/2018] [Indexed: 12/20/2022]
Abstract
A new glycosyl acceptor to be used in sialylation was designed as a 3-hydroxy derivative of 4-methoxyphenyl β-d-galactopyranoside with 2-O-acetyl group and O-4 and O-6 protected as benzylidene acetal. Two alternative syntheses of this compound were compared. Sialylation of 3-OH group of the glycosyl acceptor with O-chloroacetylated N-trifluoroacetylneuraminic acid phenyl thioglycoside (NIS, TfOH, MeCN, MS 3 Å, -40 °C) was studied in a wide concentration range (5-150 mmol L-1). The outcome of sialylation generally followed the predictions of supramer analysis of solutions of sialyl donor in MeCN, which was performed by polarimetry and static light scattering and revealed two concentration ranges differing in solution structure and the structures of supramers of glycosyl donor. The optimized conditions of sialylation (C = 50 mmol L-1) were used to synthesize protected Neu-α(2-3)-Gal disaccharide (78%, α:β = 13:1), which was then converted to sialyl-α(2-3)-galactose imidate building block useful for the synthesis of complex sialo-oligosaccharides.
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A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions. Org Lett 2018; 20:6051-6054. [DOI: 10.1021/acs.orglett.8b02424] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Application of a Janus aglycon with dual function in benzyl-free synthesis of spacer-armed oligosaccharide fragments of polysaccharides from rhizobacterium Azospirillum brasilense sp7. Carbohydr Res 2018; 464:28-43. [PMID: 29803733 DOI: 10.1016/j.carres.2018.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/11/2018] [Accepted: 05/11/2018] [Indexed: 11/16/2022]
Abstract
Both protective and pre-spacer features of 4-(2-chloroethoxy)phenyl (CEP) aglycon, which belong to the class of Janus aglycons, were engaged in a benzyl-free synthesis of oligosaccharide fragments of polysaccharides from rhizobacterium Azospirillum brasilense sp7. Introduction of α-1,4-linked L-fucose residue was performed using 3,4-di-O-benzoyl-2-O-triisopropylsilyl-α-L-fucopyranosyl N-phenyltrifluoroacetimidate in excellent stereoselectivity and high yields. The obtained deprotected di-, tri- and tetrasaccharides contain 4-(2-azidoethoxy)phenyl (AEP) spacer aglycon, which allows straightforward preparation of neoglycoconjugates that will be used for the study of the role of lipopolysaccharide of rhizobacterium A. brasilense sp7 in plant-microbe symbiosis. The intermediate protected oligosaccharide building blocks with cleavable CEP/AEP aglycons have a strong potential for further application in the synthesis of more complex oligosaccharides.
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18
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Stereoselective sialylation with O-trifluoroacetylated thiosialosides: hydrogen bonding involved? Carbohydr Res 2017; 451:12-28. [PMID: 28934626 DOI: 10.1016/j.carres.2017.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 09/05/2017] [Accepted: 09/05/2017] [Indexed: 01/05/2023]
Abstract
A series of novel sialyl donors containing O-trifluoroacetyl (TFA) groups at various positions was synthesized. The choice of protecting groups in sialyl donors was based on hypothesis that variations in ability of different acyl groups to act as hydrogen bond acceptors would influence the supramolecular structure of reaction mixture (solution structure), hence the outcome of sialylation. These glycosyl donors were examined in the model glycosylation of the primary hydroxyl group of 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose in comparison with sialyl donors without O-TFA groups. The presence of O-TFA groups in a sialyl donor strongly affected the outcome of sialylation. Several sialyl donors studied showed promising results: yields of disaccharides can be as high as 86% as can be the stereoselectivities (α/β up to 15:1). The results obtained suggest that varying acyl O-protecting groups in sialyl donor may result in dramatic changes in the outcome of sialylation although further studies are required to dissect the influence of intermolecular hydrogen bonding and intramolecular substituent effects related to variations of electron-withdrawing properties of different acyl groups.
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19
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Free Trehalose Accumulation in Dormant Mycobacterium smegmatis Cells and Its Breakdown in Early Resuscitation Phase. Front Microbiol 2017; 8:524. [PMID: 28424668 PMCID: PMC5371599 DOI: 10.3389/fmicb.2017.00524] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/13/2017] [Indexed: 01/13/2023] Open
Abstract
Under gradual acidification of growth medium resulting in the formation of dormant Mycobacterium smegmatis, a significant accumulation of free trehalose in dormant cells was observed. According to 1H- and 13C-NMR spectroscopy up to 64% of total organic substances in the dormant cell extract was represented by trehalose whilst the trehalose content in an extract of active cells taken from early stationary phase was not more than 15%. Trehalose biosynthesis during transition to the dormant state is provided by activation of genes involved in the OtsA-OtsB and TreY-TreZ pathways (according to RT-PCR). Varying the concentration of free trehalose in dormant cells by expression of MSMEG_4535 coding for trehalase we found that cell viability depends on trehalose level: cells with a high amount of trehalose survive much better than cells with a low amount. Upon resuscitation of dormant M. smegmatis, a decrease of free trehalose and an increase in glucose concentration occurred in the early period of resuscitation (after 2 h). Evidently, breakdown of trehalose by trehalase takes place at this time as a transient increase in trehalase activity was observed between 1 and 3 h of resuscitation. Activation of trehalase was not due to de novo biosynthesis but because of self-activation of the enzyme from the inactive state in dormant cells. Because, even a low concentration of ATP (2 mM) prevents self-activation of trehalase in vitro and after activation the enzyme is still sensitive to ATP we suggest that the transient character of trehalase activation in cells is due to variation in intracellular ATP concentration found in the early resuscitation period. The negative influence of the trehalase inhibitor validamycin A on the resuscitation of dormant cells proves the importance of trehalase for resuscitation. These experiments demonstrate the significance of free trehalose accumulation for the maintenance of dormant mycobacterial viability and the involvement of trehalose breakdown in early events leading to cell reactivation similar to yeast and fungal spores.
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Convenient Synthesis and Purification ofN-Trifluoroacetylated Neuraminic Acid Tetraol: A Key Precursor for the Synthesis of New Sialyl Donors Containing LabileO-Acyl Protecting Groups. J Carbohydr Chem 2014. [DOI: 10.1080/07328303.2014.913058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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21
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Polarimetry as a tool for the study of solutions of chiral solutes. Chemphyschem 2013; 15:195-207. [PMID: 24357041 DOI: 10.1002/cphc.201300894] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Indexed: 11/06/2022]
Abstract
Optical rotation of aqueous solutions of D-levoglucosan was studied experimentally in the 0.03-4.0 mol L(-1) concentration range and a nonlinear concentration dependence of specific optical rotation (SR) was revealed. Discontinuities observed in the concentration plot of SR (at 0.1, 0.3, 0.5, 1.0, and 2.0 mol L(-1)) are well correlated with those found by static and dynamic light scattering and identify concentration ranges in which different solution domains (supramers) may exist. The average SR experimental value for a D-levoglucosan aqueous solution ([α]D(28) -58.5±8.7 deg dm(-1) cm(-3) g(-1)) was found to be in good agreement with values obtained by theoretical calculation (TD-DFT/GIAO) of SR for 15 different conformers revealed by conformational sampling at the PCM/B3LYP/6-311++G(2d,2p)//B3LYP/6-31+G(d,p) level, which were shown to be strongly affected by the solvation microenvironment (0, 1, 2, and 3 explicit solvent molecules considered) due to local geometrical changes induced in the solute molecule. This exceptionally high sensitivity of SR makes polarimetry a unique method capable of sensing changes in the structure of supramers detected in this study.
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Influence of oxidative and nitrosative stress on accumulation of diphosphate intermediates of the non-mevalonate pathway of isoprenoid biosynthesis in corynebacteria and mycobacteria. BIOCHEMISTRY (MOSCOW) 2012; 77:362-71. [PMID: 22809155 DOI: 10.1134/s0006297912040074] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Artificial generation of oxygen superoxide radicals in actively growing cultures of Mycobacterium tuberculosis, Myc. smegmatis, and Corynebacterium ammoniagenes is followed by accumulation in the bacterial cells of substantial amounts of 2-C-methyl-D-erythritol-2,4-cyclodiphosphate (MEcDP) - an intermediate of the non-mevalonate pathway of isoprenoid biosynthesis (MEP) - most possibly due to the interaction of the oxygen radicals with the 4Fe-4S group in the active center and inhibition of the enzyme (E)-4-oxy-3-methylbut-2-enyl diphosphate synthase (IspG). Cadmium ions known to inhibit IspG enzyme in chloroplasts (Rivasseau, C., Seemann, M., Boisson, A. M., Streb, P., Gout, E., Douce, R., Rohmer, M., and Bligny, R. (2009) Plant Cell Environ., 32, 82-92), when added to culture of Myc. smegmatis, substantially increase accumulation of MEcDP induced by oxidative stress with no accumulation of other organic phosphate intermediates in the cell. Corynebacterium ammoniagenes'', well-known for its ability to synthesize large amounts of MEcDP, was also shown to accumulate this unique cyclodiphosphate in actively growing culture when NO at low concentration is artificially generated in the medium. A possible role of the MEP-pathway of isoprenoid biosynthesis and a role of its central intermediate MEcDP in bacterial response to nitrosative and oxidative stress is discussed.
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Synthesis of some 2-alkoxy glyco-[2,1-d]-2-oxazolines and evaluation of their glycosylation reactivity. Carbohydr Res 2012; 356:172-9. [DOI: 10.1016/j.carres.2012.03.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 03/21/2012] [Accepted: 03/23/2012] [Indexed: 10/28/2022]
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25
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[Affect of deoxynojirimycin derivatives on hepatitis C virus morphogenesis]. Mol Biol (Mosk) 2012; 46:644-653. [PMID: 23113354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Viral hepatitis C is one of the wide-spread and dangerous human diseases. The choice of drugs for treatment of chronic hepatitis C virus (HCV) infection is limited and prophylactic vaccines do not exist. Thus, the development of new antiviral strategies and substances are of great importance. The targeting of viral morphogenesis might be used as an alternative approach to existing strategies of HCV blocking. The glycosylation of viral envelope proteins is an important step of viral particle morphogenesis that determines the correct assembly of HCV virions. The derivatives of glucose analog deoxynojirimycin (DNJ)--inhibitors of alpha-glucosidase can impair the assembly of structural proteins and HCV particle formation. In the present work the affect of alkylated derivatives of DNJ N-pentyl-DNJ and N-benzyl-DNJ to HCVmorphogenesis in a model system insect cells producing three viral structural proteins with formation of virus-like particles was studied. Intracellular N-glycosylation of HCV envelope glycoproteins was shown to be impaired by DNJ derivatives. At 1 mM concentrations of these substances the level of gpE1 and gpE2 glycoproteins increase and their electrophoretic mobility decrease which seems to be due to inhibition of a-glucosidase in endoplasmic reticulum and accumulation of hyperglycosylated N-glycans in HCV glycoproteins. The interaction of the latters with calnexin leads to formation of unproductive dimers and bloks productive assembly of virus-like particles.
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26
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Concentration Dependence of Glycosylation Outcome: A Clue to Reproducibility and Understanding the Reasons Behind. European J Org Chem 2012. [DOI: 10.1002/ejoc.201101613] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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27
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Formation of orthoester-linked d-arabinofuranose oligosaccharides and their isomerization into the corresponding glycosides. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.02.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Ring opening of acylated β-d-arabinofuranose 1,2,5-orthobenzoates with nucleophiles allows access to novel selectively-protected arabinofuranose building blocks. Carbohydr Res 2011; 346:7-15. [DOI: 10.1016/j.carres.2010.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 10/25/2010] [Accepted: 11/01/2010] [Indexed: 10/18/2022]
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29
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Use of methanesulfonic acid in the reductive ring-opening of O-benzylidene acetals. Carbohydr Res 2007; 342:627-30. [PMID: 17118348 DOI: 10.1016/j.carres.2006.10.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Revised: 10/06/2006] [Accepted: 10/06/2006] [Indexed: 11/24/2022]
Abstract
Methanesulfonic acid was shown to be an efficient and convenient substitute for ethereal HCl in reductive 4,6-O-benzylidene acetal ring-opening reaction with sodium cyanoborohydride in THF. Normal regioselectivity was observed, the 6-O-benzyl ethers with free 4-OH group being the major products of the reaction.
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Synthesis of two lipopentasaccharides related to the nodulation factors of the nitrogen-fixing bacterium Rhizobium sp. NGR 234. MENDELEEV COMMUNICATIONS 2007. [DOI: 10.1016/j.mencom.2007.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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A universal approach to the synthesis of carbohydrate conjugates of polyhedral boron compounds as potential agents for boron neutron capture therapy. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2006; 32:632-42. [PMID: 17180914 DOI: 10.1134/s1068162006060100] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A uniform approach to the synthesis of carbohydrate conjugates with polyhedral boron compounds (PBCs) was developed. Oligosaccharide derivatives with an aglycone moiety amino group can be coupled with PBC carboxyl derivatives using N-methyl-N-(4,6-dimethoxy-1,3,5-triazin-2-yl)morpholinium chloride as a coupling agent. Both N- and O-glycosides differing in the conformational mobility around the glycoside bond were shown to be useful as oligosaccharides with a functional group in the aglycone moiety. This allows the application of this approach to the synthesis of PBC conjugates with a wide range of oligosaccharides. For example, not only oligosaccharides obtained by chemical synthesis but also reducing oligosaccharides isolated from natural sources can be transformed into N-glycosides. The approach was tested by the example of conjugation of the carboxyl derivatives of ortho-carborane and dodecaborate anion with lactose as a model oligosaccharide. Lactose, an easily available disaccharide, is a ligand for lectins expressed on the surface of melanoma cells. The approach suggested is the first example of the synthesis of such conjugates that does not require protective groups for the carbohydrate residue. It is especially important for obtaining dodecaborate-carbohydrate conjugates for which the removal of protective groups is often a non-trivial task.
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Conjugates of polyhedral boron compounds with carbohydrates. 2. Unexpected easy closo- to nido-transformation of a carborane–carbohydrate conjugate in neutral aqueous solution. J Organomet Chem 2005. [DOI: 10.1016/j.jorganchem.2005.03.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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1-O-Acetyl-beta-D-galactopyranose: a novel substrate for the transglycosylation reaction catalyzed by the beta-galactosidase from Penicillium sp. Carbohydr Res 2002; 337:635-42. [PMID: 11909597 DOI: 10.1016/s0008-6215(02)00027-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
1-O-Acetyl-beta-D-galactopyranose (AcGal), a new substrate for beta-galactosidase, was synthesized in a stereoselective manner by the trichloroacetimidate procedure. Kinetic parameters (K(M) and k(cat)) for the hydrolysis of 1-O-acetyl-beta-D-galactopyranose catalyzed by the beta-D-galactosidase from Penicillium sp. were compared with similar characteristics for a number of natural and synthetic substrates. The value for k(cat) in the hydrolysis of AcGal was three orders of magnitude greater than for other known substrates. The beta-galactosidase hydrolyzes AcGal with retention of anomeric configuration. The transglycosylation activity of the beta-D-galactosidase in the reaction of AcGal and methyl beta-D-galactopyranoside (1) as substrates was investigated by 1H NMR spectroscopy and HPLC techniques. The transglycosylation product using AcGal as a substrate was beta-D-galactopyranosyl-(1-->6)-1-O-acetyl-beta-D-galactopyranose (with a yield of approximately 70%). In the case of 1 as a substrate, the main transglycosylation product was methyl beta-D-galactopyranosyl-(1-->6)-beta-D-galactopyranoside. Methyl beta-D-galactopyranosyl-(1-->3)-beta-D-galactopyranoside was found to be minor product in the latter reaction.
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