Nouvelle voie d'accès à des dérivés de l'acide L-iduronique

Accès restreint aux membres de l'Université de Lorraine jusqu'au 2015-07-05The aim of this work is the conception of a new synthetic approach to L-iduronic acid derivatives, a saccharidic sub-unit part of glycosaminoglycans like heparin. The starting materials used for this synthesis are glucose derivatives, a cheap and abundant sugar. The strategy of the synthesis was to obtain an L-ido derivative from a D-gluco one, by performing an inversion of configuration at position 5. The first part of this work deals with the different reactions leading to the inversion of configuration. The second part concerns the way to obtain L-iduronic acid derivatives by the above studied reactions along with synthesis optimisationLe but de ce travail est la mise au point d'une nouvelle voie de synthèse de dérivés de l'acide L-iduronique, une sous-unité saccharidique constitutive des glycosaminoglycanes comme l'héparine. Les substrats de départ utilisés pour cette synthèse sont des dérivés du glucose, un sucre abondant et bon marché. Nous avons étudié, l'inversion de configuration en C-5 permettant de passer d'un dérivé D-gluco à un dérivé L-ido. La première partie de ce travail porte donc sur les différentes étapes conduisant à l'inversion de configuration. La seconde partie est consacrée à l'obtention de divers dérivés d'acide L-iduronique obtenus par la suite de réactions précédemment mises au point, ainsi qu'à une optimisation des rendements de la synthèse mise au point

New route to L-iduronic acid derivatives

Le but de ce travail est la mise au point d'une nouvelle voie de synthèse de dérivés de l'acide L-iduronique, une sous-unité saccharidique constitutive des glycosaminoglycanes comme l'héparine. Les substrats de départ utilisés pour cette synthèse sont des dérivés du glucose, un sucre abondant et bon marché. Nous avons étudié, l'inversion de configuration en C-5 permettant de passer d'un dérivé D-gluco à un dérivé L-ido. La première partie de ce travail porte donc sur les différentes étapes conduisant à l'inversion de configuration. La seconde partie est consacrée à l'obtention de divers dérivés d'acide L-iduronique obtenus par la suite de réactions précédemment mises au point, ainsi qu'à une optimisation des rendements de la synthèse mise au point.The aim of this work is the conception of a new synthetic approach to L-iduronic acid derivatives, a saccharidic sub-unit part of glycosaminoglycans like heparin. The starting materials used for this synthesis are glucose derivatives, a cheap and abundant sugar. The strategy of the synthesis was to obtain an L-ido derivative from a D-gluco one, by performing an inversion of configuration at position 5. The first part of this work deals with the different reactions leading to the inversion of configuration. The second part concerns the way to obtain L-iduronic acid derivatives by the above studied reactions along with synthesis optimisatio

Nouvelle voie d'accès à des dérivés de l'acide L-iduronique

Le but de ce travail est la mise au point d'une nouvelle voie de synthèse de dérivés de l'acide L-iduronique, une sous-unité saccharidique constitutive des glycosaminoglycanes comme l'héparine. Les substrats de départ utilisés pour cette synthèse sont des dérivés du glucose, un sucre abondant et bon marché. Nous avons étudié, l'inversion de configuration en C-5 permettant de passer d'un dérivé D-gluco à un dérivé L-ido. La première partie de ce travail porte donc sur les différentes étapes conduisant à l'inversion de configuration. La seconde partie est consacrée à l'obtention de divers dérivés d'acide L-iduronique obtenus par la suite de réactions précédemment mises au point, ainsi qu'à une optimisation des rendements de la synthèse mise au point.The aim of this work is the conception of a new synthetic approach to L-iduronic acid derivatives, a saccharidic sub-unit part of glycosaminoglycans like heparin. The starting materials used for this synthesis are glucose derivatives, a cheap and abundant sugar. The strategy of the synthesis was to obtain an L-ido derivative from a D-gluco one, by performing an inversion of configuration at position 5. The first part of this work deals with the different reactions leading to the inversion of configuration. The second part concerns the way to obtain L-iduronic acid derivatives by the above studied reactions along with synthesis optimisationNANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Process of preparation of L-iduronic acid comprising a decarboxylation/intramolecular cyclisation tandem reaction

The present invention relates to a process of preparation of L-iduronic acid and derivatives comprising a decarboxylation/intramolecular cyclisation tandem reaction. The present invention also relates to the intermediates of the process as well as their use as intermediates in the preparation of Idraparinux

The Bicyclic Form of galacto-Noeurostegine Is a Potent Inhibitor of β-Galactocerebrosidase.

Competitive inhibitors of galactocerebrosidase (GALC) could be candidates for pharmacological chaperone therapy of patients with Krabbe disease. The known and selective nortropane-type iminosugar galacto-noeurostegine has been found to competitively inhibit GALC with K i = 7 μM at pH 4.6, which is 330-fold more potent than the analogous deoxynoeurostegine. It was shown through X-ray protein crystallography that galacto-noeurostegine binds to the active site of GALC in its bicyclic form

Synthesis of new troglitazone derivatives: Anti-proliferative activity in breast cancer cell lines and preliminary toxicological study

International audienceBreast cancer is the most prevalent cancer in women. The development of resistances to therapeutic agents and the absence of targeted therapy for triple negative breast cancer motivate the search for alternative treatments. With this aim in mind, we synthesised new derivatives of troglitazone, a compound which was formerly used as an anti-diabetic agent and which exhibits anti-proliferative activity on various cancer cell lines. Among the compounds prepared, some displayed micromolar activity against hormone-dependent and hormone-independent breast cancer cells. Furthermore, the influence of the compounds on the viability of primary cultures of human hepatocytes was evaluated. This enabled us to obtain for the first time interesting structure-toxicity relationships in this family of compounds, resulting in 6b and 8b, which show good anti-proliferative activities and poor toxicity towards hepatocytes, compared to troglitazone

Investigation on the Synthesis of Shigella flexneri Specific Oligosaccharides Using Disaccharides as Potential Transglucosylase Acceptor Substrates

International audienceChemo-enzymatic strategies hold great potential for the development of stereo- and regioselective syntheses of structurally defined bioactive oligosaccharides. Herein, we illustrate the potential of the appropriate combination of a planned chemo-enzymatic pathway and an engineered biocatalyst for the multistep synthesis of an important decasaccharide for vaccine development. We report the stepwise investigation, which led to an efficient chemical conversion of allyl α-d-glucopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→3)-2-deoxy-2-trichloroacetamido-β-d-glucopyranoside, the product of site-specific enzymatic α-d-glucosylation of a lightly protected non-natural disaccharide acceptor, into a pentasaccharide building block suitable for chain elongation at both ends. Successful differentiation between hydroxyl groups features the selective acylation of primary alcohols and acetalation of a cis-vicinal diol, followed by a controlled per-O-benzylation step. Moreover, we describe the successful use of the pentasaccharide intermediate in the [5 + 5] synthesis of an aminoethyl aglycon-equipped decasaccharide, corresponding to a dimer of the basic repeating unit from the O-specific polysaccharide of Shigella flexneri 2a, a major cause of bacillary dysentery. Four analogues of the disaccharide acceptor were synthesized and evaluated to reach a larger repertoire of O-glucosylation patterns encountered among S. flexneri type-specific polysaccharides. New insights on the potential and limitations of planned chemo-enzymatic pathways in oligosaccharide synthesis are provided

Computer-Aided Engineering of a Transglycosylase for the Glucosylation of an Unnatural Disaccharide of Relevance for Bacterial Antigen Synthesis

International audienceThe exploration of chemo-enzymatic routes to complex carbohydrates has been hampered by the lack of appropriate enzymatic tools having the substrate specificity for new reactions. Here, we used a computer-aided design framework to guide the construction of a small, diversity-controlled library of amino acid sequences of an α-transglucosylase, the sugar binding subsites of which were re-engineered to enable the challenging 1,2-cis-glucosylation of a partially protected β-linked disaccharide allyl (2-deoxy-2-trichloroacetamido-β-d-glucopyranosyl)-(1→2)-α-l-rhamnopyranoside, a potential intermediate in the synthesis of Shigella flexneri cell-surface oligosaccharides. The target disaccharide is not recognized by the parental wild-type enzyme and exhibits a molecular structure very distinct from that of the natural α-(1→4)-linked acceptor. A profound reshaping of the binding pocket had thus to be performed. Following the selection of 23 amino acid positions from the first shell, mutations were sampled using RosettaDesign leading to a subset of 1515 designed sequences, which were further analyzed by determining the amino acid variability among the designed sequences and their conservation in evolutionary-related enzymes. A combinatorial library of 2.7 × 104 variants was finally designed, constructed, and screened. One mutant showing the desired and totally new specificity was successfully identified from this first round of screening. Impressively, this mutant contained seven substitutions in the first shell of the active site leading to a drastic reshaping of the catalytic pocket without significantly perturbing the original specificity for sucrose donor substrate. This work illustrates how computer-aided approaches can undoubtedly offer novel opportunities to design tailored carbohydrate-active enzymes of interest for glycochemistry or synthetic glycobiology

Azasugar inhibitors as pharmacological chaperones for Krabbe disease.

Krabbe disease is a devastating neurodegenerative disorder characterized by rapid demyelination of nerve fibers. This disease is caused by defects in the lysosomal enzyme β-galactocerebrosidase (GALC), which hydrolyzes the terminal galactose from glycosphingolipids. These lipids are essential components of eukaryotic cell membranes: substrates of GALC include galactocerebroside, the primary lipid component of myelin, and psychosine, a cytotoxic metabolite. Mutations of GALC that cause misfolding of the protein may be responsive to pharmacological chaperone therapy (PCT), whereby small molecules are used to stabilize these mutant proteins, thus correcting trafficking defects and increasing residual catabolic activity in cells. Here we describe a new approach for the synthesis of galacto-configured azasugars and the characterization of their interaction with GALC using biophysical, biochemical and crystallographic methods. We identify that the global stabilization of GALC conferred by azasugar derivatives, measured by fluorescence-based thermal shift assays, is directly related to their binding affinity, measured by enzyme inhibition. X-ray crystal structures of these molecules bound in the GALC active site reveal which residues participate in stabilizing interactions, show how potency is achieved and illustrate the penalties of aza/iminosugar ring distortion. The structure-activity relationships described here identify the key physical properties required of pharmacological chaperones for Krabbe disease and highlight the potential of azasugars as stabilizing agents for future enzyme replacement therapies. This work lays the foundation for new drug-based treatments of Krabbe disease.We thank Stephen Graham for helpful discussions. We acknowledge Diamond Light Source for time on beamline I04-1 and I02 under proposal MX8547. C.H.H. is funded by a Wellcome Trust PhD studentship; S.J.S. is funded by an MRC PhD studentship; and J.E.D. is supported by a Royal Society University Research Fellowship (UF100371). R.J.R. is funded by a Wellcome Trust Principal Research Fellowship (Grant 082961/Z/ 07/Z). We are also grateful for funding from The Lundbeck Foundation to A.H. V, S. S. and H. H. J. The Cambridge Institute for Medical Research is supported by Wellcome Trust Strategic Award 100140. Notes andThis is the final published version. It first appeared at http://pubs.rsc.org/en/Content/ArticleLanding/2015/SC/c5sc00754b#!divAbstract