13343-67-4

Peptidoglycan (PG) is the core structural motif of the bacterial cell wall. Fragments released from the PG serve as fundamental recognition elements for the immune system. The structure of the PG, however, encompasses a variety of chemical modifications among different bacterial species. Here, the applicability of organic synthetic methods to address this chemical diversity is explored, and the synthesis of cross-linked PG fragments, carrying biologically relevant amino acid modifications and peptide cross-linkages, is presented using solution and solid phase approaches.

The Carbohydrate Esterase family 4 contains virulence factors which modify peptidoglycan and biofilm-related exopolysaccharides. Despite the importance of this family of enzymes, a potent mechanism-based inhibition strategy has yet to emerge. Based on the postulated tridentate binding mode of the tetrahedral de-N-acetylation intermediate, GlcNAc derivatives bearing metal chelating groups at the 2 and 3 positions were synthesized. These scaffolds include 2-C phosphonate, 2-C sulfonamide, 2-thionoacetamide warheads as well as derivatives bearing thiol, amine and azide substitutions at the 3-position. The inhibitors were assayed against a representative peptidoglycan deacetylase, Pgda from Streptococcus pneumonia, and a representative biofilm-related exopolysaccharide deacetylase, PgaB from Escherichia coli. Of the inhibitors evaluated, the 3-thio derivatives showed weak to moderate inhibition of Pgda. The strongest inhibitor was benzyl 2,3-dideoxy-2-thionoacetamide-3-thio-β-D-glucoside, whose inhibitory potency showed an unexpected dependence on metal concentration and was found to have a partial mixed inhibition mode (Ki = 2.9 ± 0.6 μM).

Lipo-chitotetrasaccharide analogues where one central GlcNAc residue was replaced by a triazole unit have been synthesized from a derivative obtained by chitin depolymerization and a functionalized N-acetyl-glucosamine via the copper-catalyzed azide-alkyn

Unnatural uridine diphosphate (UDP)-sugar donors, UDP-4-deoxy-4-fluoro-N-acetylglucosamine (4FGlcNAc) and UDP-4-deoxy-4-fluoro-N-acetylgalactosamine (4FGalNAc), were prepared using both chemical and chemoenzymatic syntheses relying on N-acetylglucosamine-

6-Sulfo-6-deoxy-D-glucosamine (GlcN6S), 6-sulfo-6-deoxy-D-glucosaminitol (ADGS) and their N-acetyl and methyl ester derivatives have been synthesized and tested as inhibitors of enzymes catalyzing reactions of the UDP-GlcNAc pathway in bacteria and yeasts

The invention discloses a method used for catalytic reduction of imine with saccharide-derivatized amino alcohol. According to the method, imine is taken as a substrate. The method comprises following steps: 1) imine and saccharide-derivatized amino alcohol are dissolved in an organic solvent I, wherein molar ratio of imine to saccharide-derivatized amino alcohol ranges from 100:1-20; 2) trichlorosilane with 1.5 to 5 times equivalent weights is added into a solution obtained via step 1) dropwise, an obtained mixture is stirred and reacted for 12 to 36h at a temperature of -20 to 40 DEG C, and a saturated sodium bicarbonate solution is used for quenching; 3) a material obtained via step 2) is extracted with an organic solvent II, and is subjected to column chromatography isolation so as to obtain amine compounds.

The formation of diastereopure α-substituted GlcNAc derivatives in a simple and straightforward way is a challenging task. Herein, we report the chemical synthesis of diastereomeric α/β-substituted GlcNAc derivatives under non-anhydrous atmosphere using u

A novel synthetic route leading to N-glycolyl muramyl dipeptide (MDP), a bacterial glycopeptide of particular interest in studies of nucleotide-binding oligomerization domain-containing protein 2 (NOD2), is described. The synthetic strategy hinges on the alkylation of benzylidene-protected glucal with 2-bromopropionic acid and thus circumvents a challenging and non-reproducible SN2 step at the C-3 position of glucosamine derivatives. The subsequent sequence includes an azidonitration and an unusual azide reduction/acylation step via an aza ylide/oxaphospholidine intermediate. This approach generates a protected N-glycolyl MDP that can be either subjected to a one-step global deprotection or differentially deprotected to obtain further derivatives.

The order of reactivity of OH and NH groups of glucosamine hydrochloride (GlcNH2HCl) and N-acetyl glucosamine (GlcNAc) toward benzylation with NaH/BnBr in DMF was investigated. For GlcNH2.HCl, benzyl groups were introduced in the order of N-Bn > N-Bn2 > 1-O-Bn > 6-O-Bn > 4-O-Bn > 3-O-Bn; for GlcNAc, benzyl groups were introduced in the order of 1-O-Bn > 6-O-Bn > 4-O-Bn > 3-O-Bn > N-Bn. A range of partially benzylated 2-N,N′-dibenzyl glucopyranosides and GlcNAc derivatives were obtained in a single step. Taylor & Francis Group, LLC.

Bacterial sulfatases can be good tools to increase the molecular diversity of glycosaminoglycan synthetic fragments. A chondroitin 4-O-sulfatase from the human commensal bacterium Bacteroides thetaiotaomicron has recently been identified and expressed. In order to use this enzyme for synthetic purposes, the minimal structure required for its activity has been determined. For that, four 4-O-sulfated monosaccharides and one 4-O-sulfated disaccharide have been synthesized and used as substrates with the sulfatase. The minimum structure was shown to be a disaccharide but in contrast to the natural substrate, which must have a 4,5-insaturation, the enzyme accepts as substrate, a disaccharide with a saturated glucuronic acid at the non-reducing end and even a glucopyranosyl moiety without the carboxylic acid functionality.

Neuroprotective agents have been in the focus of attention in the treatment of ischemic stroke. Salidroside, a phenylpropanoid glycoside isolated from Rhodiola rosea L., possessed a wide range of biological activities, especially neuroprotection. In an at

Triazole linked heparosan and chondroitin disaccharide and tetrasaccharide building blocks were synthesized in a stereoselective manner by applying a very efficient copper catalyzed azide-alkyne cycloaddition (CuAAC) reaction of appropriately substituted

A new type of phosphate-pyridine (P, N) ligand derived from d-glucosamine and BINOL was synthesized and successfully applied in Cu-catalyzed enantioselective conjugate addition of diethylzinc to chalcones for the first time, high yields and enantioselectivities were obtained when the ligand 10a which contains (S)-BINOL was used. The results also showed that the configuration of BINOL at the ligand backbone had remarkable effects on the activities and enantioselectivities.

The structural rationale, synthesis and evaluation of an inhibitor designed to block glucosamine synthesis by competitively inhibiting the action of glutamine: fructose-6-phosphate amidotransferase and subsequently reducing the transformation of any gluco

Trypanosoma cruzi, the agent of Chagas disease, expresses a unique enzyme, the trans-sialidase (TcTS) involved in the transfer of sialic acid from host glycoconjugates to mucins of the parasite. The enzyme is shed to the medium and may affect the immune system of the host. We have previously described that lactose derivatives effectively inhibited the transfer of sialic acid to N-acetyllactosamine. Lactitol also prevented the apoptosis caused by the TcTS, although it is rapidly eliminated from the circulatory system. In this paper we report covalent conjugation of polyethylene glycol (PEG) with lactose, lactobionolactone and benzyl β-D-galactopyranosyl-(1→6)-2-amino-2- deoxy-α-D-glucopyranoside (1) with the hope to improve the bioavailability, though retaining their inhibitory properties. Different conjugation methods have been used and the behavior of the PEGylated products in the TcTS reaction was studied.

A direct, mild and efficient protocol for the preparation of β-glycosides of N-acetyl glucosamine (GlcNAc) and N-acetyl galactosamine (GalNAc) has been developed using peracetylated β-GlcNAc and β-GalNAc as donors. All rare Earth metal triflate promoters

Lipid-linked sugar pyrophosphates, such as GlcNAc-pyrophosphoryl undecaprenol, are important intermediates in the biosynthesis of cell-surface bacterial polysaccharides. It was recently demonstrated that much simpler lipids could substitute for undecaprenol while retaining biological activity, thus making efficient synthetic access to this class of compounds highly desirable. In order to facilitate the synthesis of pure substrates for bacterial glycosyltransferases, we have developed a simple 'two-pot' synthesis which we demonstrate here for GlcNAc-α-pyrophosphoryl-decanol (4). GlcNAc pyrophosphate, produced by mild periodate oxidation/β-elimination of commercial UDP-GlcNAc, is alkylated using 1-iododecane to yield the target compound 4 in 39% yield. Compound 4 is shown to be an efficient acceptor for a bacterial galactosyltransferase.

UDP-N-acetylmuramic acid (UDP-MurNAc) is a substrate of MurC, an important enzyme in the intracellular pathway of bacterial peptidoglycan biosynthesis. Various approaches towards preparation of UDP-Mur/VAc have been published but these synthetic preparations were shown to include many problematic steps. An optimization study with the focus on muramyl phosphate and UMP-morpholidate coupling was performed, resulting in a synthetic procedure enabling robust and easily reproducible production on a multi-gram scale.

(Figure Presented) N-Glycopyranosylsulfonohydrazides are introduced as glycosyl donors for protecting group free synthesis of O-glycosides, glycosyl azides, and oxazolines. Mono- and disaccharides containing a reducing terminal N-acelylglucosamine residue were condensed with p-toluenesulfonylhydrazide to give the desired β-D-pyranose donors. These donors can be activated with NBS and then glycosidated with the desired alcohol or transformed to the oxazoline or glycosyl azide.

We report the application of the phosphoramidate ProTide approach, developed by us for antiviral nucleosides, to sugar derivatives with potential chondroprotection against osteoarthritis. In particular, N-acetylglucosamine was converted to a series of 06

A novel acceptor substrate for galactosyltransferase was synthesized containing GlcNAcα-pyrophosphate, covalently bound to a hydrophobic phenoxyundecyl moiety (GlcNAc α-O-PO3-PO3-(CH 2)11-O-Phenyl). The new subs

Fischer glycosylation has been used for decades for the synthesis of simple alkyl and aryl glycosides from free sugars. The reaction proceeds under reflux in the presence of catalytic acid with the alcohol as solvent. The main deficiency of this reaction is the long reaction time required. In this study microwave heating has been utilised for the Fischer glycosylation reaction of N-acetyl-d-glucosamine, N-acetyl-d-galactosamine, d-glucose, d-galactose and d-mannose with a variety of alcohols (methanol, ethanol, benzyl alcohol and allyl alcohol). Remarkable acceleration of the glycosylation reactions (minutes compared to hours) over conventional reflux heating was observed with good yields and production of the α-glycoside as the dominant product.

(Chemical Equation Presented) A concise and convenient route that may be easily scaled is reported for the preparation of unprotected β-glucopyranosides of N-acetyl-D-glucosamine. Reaction of a wide variety of alcohols with a reactive, readily prepared furanosyl oxazoline under acidic conditions affords the corresponding β-D-glucopyranosides in good to high yields. Primary alcohols gave only β-D-glucopyranosides. A mechanism is proposed for this transformation.

Successful glycosynthase-mediated reactions have been performed on 6-O-benzyl-, 6-O-(4-nitrobenzyl)-, and 6-O-benzoyl-D-glucopyranose to give 1,2-β- and 1,3-β-D-glycosylated products; 4-O-benzyl-D-xylopyranose gave only a 1,2-β-glycosylated product. A rat

Several N-acyl and ester derivatives of 2-amino-2-deoxy-D-glucitol-6-phosphate (ADGP) have been synthesised and tested as inhibitors of fungal enzymes involved in early steps of chitin biosynthesis and for antifungal activity. All the tested derivatives w

Chondroitin AC lyase from Flavobacterium heparinum degrades chondroitin sulfate glycosaminoglycans via an elimination mechanism resulting in disaccharides or oligosaccharides with Δ4,5-unsaturated uronic acid residues at their nonreducing end. Mechanistic details concerning the ordering of the bond-breaking and -forming steps of this enzymatic reaction are nonexistent, mainly due to the inhomogeneous nature of the polymeric substrates. The creation of a new class of synthetic substrates for this enzyme has allowed the measurement of defined and reproducible kcat and Km values and has expanded the range of mechanistic studies that can be performed. The primary deuterium kinetic isotope effect upon kcat/Km for the abstraction of the proton α to the carboxylic acid was measured to be 1.67 ± 0.07, showing that deprotonation occurs in a rate-limiting step. Using substrates with leaving groups of differing reactivity, a flat linear free energy relationship was produced, indicating that the C4-O4 bond is not broken in a rate-determining step. Taken together, these results strongly suggest a stepwise mechanism. Consistent with this was the measurement of a secondary deuterium kinetic isotope effect upon kcat/Km of 1.01 ± 0.03 on a 4-{2H}-substrate, indicating that no sp2 character is developed at C4 during the rate-limiting step, thereby ruling out a concerted syn-elimination.

N-Acetyl glucosamine and chitooligosaccharides are selectively converted into β-glycosides without protection of the other hydroxyl groups by alkylation of the anomeric alkoxides in N,N-dimethylformamide containing lithium bromide. Addition of the lithium salt notably improves the stereoselectivity of the glycosylation of the monomer and the efficiency of the process with higher oligomers.

Glycosaminoglycans (GAGs), linear sulfated oligosaccharides, are involved in numerous biological events ranging from tissue structure to protein activity regulation. The combinatorial nature of their oligosaccharidic framework and sulfatation pattern (sul

Rhizobial bacteria synthesize lipo-chitin oligosaccharide signal molecules (Nod factors) that are essential for the formation of symbiotic organs on the roots of host plants, a process known as nodulation. Biosynthesis of the chitin oligosaccharide moiety

A cyclic 2,3-sulfamidate derived from N-acetyl-D-allosamine has been treated with a variety of S-. N-, O-. and C-nucleophiles, leading to nucleophilic displacement at C-3, elimination, or deacetylation reactions depending on the type of nucleophile used. Nucleophilic displacement is achieved with thio-nucleophiles and NaN3. allowing the preparation of 3-thio- or 3-azido glucosamine derivatives difficult to obtain by use of sulfonates.

Cell surface carbohydrates and their analogs may be used to study the cellular interactions responsible for adhesion to pathogenic bacteria, viruses, and other cells and may represent leads for drug discovery. We have generated 12 C-trisaccharides (7-18) as potential inhibitors for the cell surface proteins of the bacterium Helicobactor pylori. The strategy used has resulted in the generation of C-trisaccharides structures that are represented by the formula Fuc-α(1-2)-hexose-(1-3)-GlcNAc where each of the 12 compounds possesses a central sugar that has been systematically replaced with stereochemically diverse structures, including D and L sugars, through de novo synthesis. This aroach relies upon an organometallic coupling of terminal monosaccharides 19 and 20 to prepare a "disaccharide" in a convergent manner. This intermediate is then divergently derivatized to form a variety of structural analogs about the central hexose. For the separable compounds, the assignment of stereochemistry was done using standard NMR techniques. In cases where inseparable diastereomeric mixtures were generated, we have described a novel recursive stereochemical deconvolution strategy. This recursive strategy is demonstrated in the diastereoselective synthesis of trisaccharides 14, subsequent to its initial rapid synthesis as a component of a diastereomeric mixture. Biological assays of these compounds should provide an insight into the binding requirements of carbohydrate receptors.

Several polyhydroxyperhydroazepines have been obtained either by chemoenzymatic or chemical synthesis. Condensation of (±)-3-azido-2-hydroxypropanaldehyde and dihydroxyacetone phosphate (DHAP) in the presence of a DHAP dependent aldolase followed by treat

The title disaccharide Manp(β1-4)GlcpNAcβ1-OCD3 has been prepared by a short synthetic sequence through the inversion of configuration from gluco to manno involving benzyl Glcp(β1-4)GlcpNAc.The disaccharide was subjected to detailed high-field 1H and 13C NMR study.First, conventional and 2D spectra were run to afford a complete set of assigned spectral parameters.Next, steady-state 1H- NOE and 1H, 13C spin lattice relaxation experiments were performed to infer dynamic spectral data related to molecular conformation.Owing to tight couplings and signal overlaps in the 1H spectrum, proton relaxation and selected NOE data were obtained via 13C NMR after transfer of the actual, non-equilibrium, proton magnetization to the 13C frequency domain.Using this experimental approach it has been found that T1's for Manp H-4 and GlcpNAc H-2 were substantially longer than those of the other sugar ring protons, and that the principal interresidue dipolar contact in Manp(β1-4)GlcpNAcβ1-OCD3 takes place between Manp H-1 and GlcpNAc H-4.Subsequently, a conformational analysis of the disaccharide was executed by means of a semiempirical method comparing Boltzman-averaged computed observables with experimental T1 and NOE values.The results suggest that the disaccharide has substantial conformational flexibility.Its exo-anomeric-stabilized conformational minimum at approximately Φ = +50 deg (Ψ = 0 +/- 10 deg) of the glycosidic rotational angle is significantly populated but this global minimum does not represent the only rotational form available to the molecule.

1,3,4,6-Tetra-O-acetyl-2-chloroacetamido-2-deoxy-β-D-glucopyranose was tested as a glycosyl donor for oligosaccharide synthesis via ferric chloride-catalyzed coupling reaction.Glycosyl acceptors tried (6 in all) were O-benzyl-protected D-galactosides having free OH groups at positions 3 and 4, respectively, and similarly protected glycosides of D-glucose and 2-acetamido-2-deoxy-D-glucose unsubstituted on O-4.Existing syntheses of all the acceptors were improved, in four instances by exploitation of Garegg and Hultberg's cyanoborohydride procedure for the conversion 4,6-O-benzylidene -> 6-O-benzyl .Good to excellent yields of β-linked disaccharides were obtained from the galactoside and glucoside acceptors, but with allyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside, stereoselectivity was lost (α:β-ratio 1:2).Allyl and benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranosides gave, respectively, the allyl and benzyl β-glycosides of the donor as major products.A mechanism is proposed for this transglycosidation reaction.The N-chloroacetyl groups in the disaccharide products were readily converted into N-acetyl by reduction with zinc-acetic acid.

Under catalytic condicions, Pd(II) salts effect the clean conversion of aminodeoxyhex-5-enopyranosides 7 into the corresponding 3-hydroxy cyclohexanones 8.

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