Laboratoire de Glycochimie, des Antimicrobiens
et des Agroressources UMR 7378 CNRS


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Axe de recherche : Chimie pour le Vivant

Description des travaux de recherche

Synthèse et fonctionnalisation d’oligosaccharides sulfatés
Nous obtenons des oligosaccharides anioniques, en particulier sulfatés, par différents voies : la synthèse chimique, la modification d’oligosaccharides naturels, et la dégradation contrôlée des polysaccharides. Nous développons les outils nécessaires à leur fractionnement, purification et l’analyse (HPAEC, ESI-MQS, MALDI).
Tensioactifs pour la flottation des métaux
La contamination des sols et des eaux par les métaux causant à la fois de graves problèmes d’environnement et de santé publique, il est nécessaire de traiter les zones contaminées. Parmi les nombreux procédés de dépollution existants, nous nous sommes intéressés à la flottation. Nous avons synthétisé tout un panel de tensioactifs à base de glucose, comportant une chaîne hydrocarbonée et une fonction complexante.
Ligands Multivalents
Nous avons développé une méthodologie de synthèse pour la fonctionnalisation de saccharides qui vont nous servir de charpente pour l’obtention des ligands multivalents. Cette méthodologie nous à permit d’obtenir un panel de charpentes oligosaccharidiques portant des azotures sur lesquelles nous avons ensuite « clické » des éléments de reconnaissance. Nous avons également étudié l’effet de la multivalence sur les inhibiteurs de glycosidases et obtenu des ligands multivalents de haute affinité pour les galectines.

Mots clés : N.C.

Sélection de publications

Sulfated Galactans from Gracilaria fisheri with Supplementation of Octanoyl Promote Wound Healing Activity In Vitro and In Vivo
Rudtanatip, T.; Somintara, S.; Sakaew, W.; El-Abid, J.; Cano, M. E.; Jongsomchai, K.; Wongprasert, K.; Kovensky, J.
Macromol. Biosci. 2022, n/a, 2200172.
Abstract Sulfated galactans (SG) isolated from Gracilaria fisheri was partially degraded (DSG), and subsequentially supplemented with octanoyl (DSGO) and sulfate (DSGS) groups. The molecular weights of DSG, DSGO, and DSGS were 7.87, 152.79, and 97.07?kDa, respectively. The modification was confirmed using FTIR and NMR, whilst in vitro wound healing activity was assessed using scratched wound fibroblasts. The results revealed that DSGO exhibited highest percentage of wound closure in scratched fibroblast L929 cells. Furthermore, DSGO was able to promote proliferation and accelerate migration of scratched fibroblasts, which corresponded to the regulation of proteins and mRNA (Ki67, p-FAK, vimentin and E-cadherin) determined by Western blotting and qPCR analysis. The superior wound healing activity of DSGO was also confirmed in excision wound of rats. The results demonstrated that DSGO significantly enhanced the percentage of wound closure, re-epithelialization, and collagen arrangement, increased α-SMA and vimentin expression, and decreased that of TNF-α at the wound site. The results suggest that degraded SG supplemented with medium-chain fatty acids of octanoyl group might pass through the membrane, subsequently activating the mediators associated with proliferation and migration of fibroblasts, which could potentially lead to the promotion of wound healing activity. This article is protected by copyright. All rights reserved

Using NMR to Dissect the Chemical Space and O-Sulfation Effects within the O- and S-Glycoside Analogues of Heparan Sulfate
Meneghetti, M. C. Z.; Naughton, L.; O’Shea, C.; Koffi Teki, D. S. E.; Chagnault, V.; Nader, H. B.; Rudd, T. R.; Yates, E. A.; Kovensky, J.; Miller, G. J.; Lima, M. A.
ACS Omega 2022.
Heparan sulfate (HS), a sulfated linear carbohydrate that decorates the cell surface and extracellular matrix, is ubiquitously distributed throughout the animal kingdom and represents a key regulator of biological processes and a largely untapped reservoir of potential therapeutic targets. The temporal and spatial variations in the HS structure underpin the concept of “heparanome” and a complex network of HS binding proteins. However, despite its widespread biological roles, the determination of direct structure-to-function correlations is impaired by HS chemical heterogeneity. Attempts to correlate substitution patterns (mostly at the level of sulfation) with a given biological activity have been made. Nonetheless, these do not generally consider higher-level conformational effects at the carbohydrate level. Here, the use of NMR chemical shift analysis, NOEs, and spin–spin coupling constants sheds new light on how different sulfation patterns affect the polysaccharide backbone geometry. Furthermore, the substitution of native O-glycosidic linkages to hydrolytically more stable S-glycosidic forms leads to observable conformational changes in model saccharides, suggesting that alternative chemical spaces can be accessed and explored using such mimetics. Employing a series of systematically modified heparin oligosaccharides (as a proxy for HS) and chemically synthesized O- and S-glycoside analogues, the chemical space occupied by such compounds is explored and described.

Synthesis of novel S- and O-disaccharide analogs of heparan sulfate for heparanase inhibition
Koffi Teki, D. S. E.; Coulibaly, B.; Bil, A.; Vallin, A.; Lesur, D.; Fanté, B.; Chagnault, V.; Kovensky, J.
Org. Biomol. Chem. 2022.
Heparan sulfate (HS), a glycosaminoglycan related to heparin, is a linear polysaccharide, consisting of repeating disaccharide units. This compound is involved in multiple biological processes such as inflammation, coagulation, angiogenesis and viral infections. Our work focuses on the synthesis of simple HS analogs for the study of structure–activity relationships, with the aim of modulating these biological activities. Thioglycoside analogs, in which the interglycosidic oxygen is replaced by a sulfur atom, are very interesting compounds in terms of therapeutic applications. Indeed, the thioglycosidic bond leads to an improvement of their stability and can allow the inhibition of enzymes involved in physiological and pathological processes. In our previous work, we developed a synthetic sequence which led to a non-sulfated thiodisaccharide analog of HS. In this paper, we report our results of the development of a new synthetic method allowing access to the novel sulfated S-disaccharide, as well as to their oxygenated analogues (O-disaccharide and sulfated O-disaccharide). These 4 compounds were also tested for the inhibition of heparanase, an enzyme involved in biological processes like tumor growth and inflammation. The obtained IC50 values in the micromolar range showed the impact of the interglycosidic sulfur atom and the 6-sulfate group.

Ring-Opening of Cyclodextrins: An Efficient Route to Pure Maltohexa-, Hepta-, and Octaoses
Pélingre, M.; Koffi Teki, D. S.-E.; El-Abid, J.; Chagnault, V.; Kovensky, J.; Bonnet, V.
Organics 2021, 2, 287-305.
Many preparations of maltooligosaccharides have been described in literature, essentially using enzymatic or biotechnological processes. These compounds, derived from starch, are well-known as prebiotic agents. The use of maltohexa-, hepta-, and octaoses as synthons in organic synthesis was also well documented in literature. They can indeed be obtained as single compounds by the cyclodextrins’ ring-opening. This reaction has been studied for many years, varying the protecting and functional groups and the reaction conditions, leading to functionalized oligomaltoses. These compounds are of wide interest in various fields. They have a strong potential as scaffolds for multivalence in chemobiology, as building blocks for the production of biomimetic pseudo-glycopeptides, as well as monomers for the preparation of materials. In view of the importance of these oligomaltoses, this review focuses on the different methodologies allowing access to them via chemical and enzymatic ring-opening of cyclodextrins.

Effects of CoCl2 on the regioselective tosylation of oligosaccharides
El-Abid, J.; Moreau, V.; Kovensky, J.; Chagnault, V.
J. Mol. Struct. 2021, 130609.
The tosyl functional group is commonly used in carbohydrate chemistry as a nucleofuge. Tosylation of the primary hydroxyls of carbohydrates are generally performed after orthogonal protection/deprotection reactions. However, it can be done regioselectively from unprotected sugars. Several examples have been described in the literature starting from free monosaccharides. Yields are generally good but may vary according to the nature of the sugar. Starting from free oligosaccharides, the regioselectivity and the yields generally drop significantly. The use of catalysts, such as DMAP or NEt3, improves the conversion but to the detriment of the regioselectivity. In our current work, we developed a tosylation reaction of the primary positions of several oligosaccharides with improved regioselectivity, using cobalt II chloride in catalytic amounts. Adaptability of this methodology has been tested on cellobiose, maltose, lactose, sucrose and maltotriose.

One-Pot Synthesis of Asymmetrically Difunctionalized Oligomaltosides by Cyclodextrin Ring Opening
Pélingre, M.; Smadhi, M.; Bil, A.; Bonnet, V.; Kovensky, J.
ChemistryOpen 2021, 10, 493-496.
Abstract The synthesis of pure difunctionalized hexa-, hepta- and octamaltosides was performed by one-pot chemical reaction from perbenzoylated cyclodextrin. Oligomaltosides with azide, propargyl or allyl on reducing end and an unprotected hydroxyl group on non-reducing end were obtained from perbenzoylated α-, β- and γ-cyclodextrin with 12 to 48 % yields.

Synthesis of new sulfated disaccharides for the modulation of TLR4-dependent inflammation
Naitaleb, R.; Denys, A.; Allain, F.; Ausseil, J.; toumieux, s.; Kovensky, J.
Org. Biomol. Chem. 2021.
Natural sulfated glycans are key players in inflammation through TLR4 activation, and therefore synthetic exogenous sulfated saccharides can be used to downregulate inflammation processes. We have designed and synthesized new sulfated compounds based on small and biocompatible carbohydrates able to cross the BBB. Suitable protected donor and acceptor, obtained from a unique precursor, have been stereoselectively glycosylated to give an orthogonally protected cellobiose disaccharide. Selective deprotection and sulfation allowed to synthesize four differentially sulfated disaccharides, which have been characterized by NMR, HRMS and MS/MS. Together with their partially protected precursors, the new compounds were tested on HEF-TLR4 cells. Our results show the potential of small oligosaccharides to modulate TLR4 activity, confirming the need of sulfation and the key role of the 6-sulfate groups to trigger TLR4 signalization.

A simple procedure to obtain a medium-size oligogalacturonic acids fraction from orange peel and apple pomace wastes
Cano, M. E.; García-Martín, A.; Ladero, M.; Lesur, D.; Pilard, S.; Kovensky, J.
Food Chem. 2021, 346, 128909.
Pectin oligosaccharides, which can be obtained from fruit wastes, have proven their potential as plant immune-system elicitors. Although the precise size of active species is still under investigation, medium size oligosaccharides have been reported as the most active. Three defined oligogalacturonic acid (OGAs) mixtures were produced from commercial pectin, orange peel and apple pomace residues. The methodology developed involves two sequential acid treatments followed by stepwise ethanol precipitation. Without the need of chromatographic separations, three different fractions were obtained. The fractions were analyzed by high performance anion exchange chromatography (HPAEC) and were completely characterized by mass spectrometry, showing that the small size, medium size and large size fractions contained OGAs of degree of polymerization 3 to 9, 6 to 18, and 16 to 55, respectively.

Synthesis of defined oligohyaluronates-decorated liposomes and interaction with lung cancer cells
Cano, M. E.; Lesur, D.; Bincoletto, V.; Gazzano, E.; Stella, B.; Riganti, C.; Arpicco, S.; Kovensky, J.
Carbohydr. Polym. 2020, 248, 116798.
In this work hyaluronic acid (HA) oligosaccharides with degree of polymerization (DP) 4, 6 and 8, obtained by enzymatic depolymerization of HA, were conjugated to a PEG-phospholipid moiety. The products (HA-DP4, HA-DP6 and HA-DP8) were used to prepare decorated liposomes. The cellular uptake of HA-DP4, HA-DP6 and HA-DP8-decorated fluorescently labelled liposomes was significantly higher (12 to 14-fold) in lung cancer cell lines with high CD44 expression than in those with low CD44 expression, suggesting a receptor-mediated entry of HA-conjugated formulations. Competition assays showed that the uptake followed this rank order: HA-DP8>HA-DP6>HA-DP4 liposomes. Moreover, they are capable of a faster interaction with CD44, followed by phagocytosis, than HA liposomes obtained from HA of higher molecular weight (4800 and 14800 Da). HA-DP4, HA-DP6 and HA-DP8-liposomes did not show cytotoxicity or inflammatory effects. Overall, we propose our new HA-DP oligosaccharides as biocompatible and effective tools for a potential drug delivery to CD44-positive cells.

Production of Oligosaccharides from Agrofood Wastes
Cano, M. E.; García-Martin, A.; Comendador Morales, P.; Wojtusik, M.; Santos, V. E.; Kovensky, J.; Ladero, M.
Fermentation 2020, 6, 31.
The development of biorefinery processes to platform chemicals for most lignocellulosic substrates, results in side processes to intermediates such as oligosaccharides. Agrofood wastes are most amenable to produce such intermediates, in particular, cellooligo-saccharides (COS), pectooligosaccharides (POS), xylooligosaccharides (XOS) and other less abundant oligomers containing mannose, arabinose, galactose and several sugar acids. These compounds show a remarkable bioactivity as prebiotics, elicitors in plants, food complements, healthy coadyuvants in certain therapies and more. They are medium to high added-value compounds with an increasing impact in the pharmaceutical, nutraceutical, cosmetic and food industries. This review is focused on the main production processes: autohydrolysis, acid and basic catalysis and enzymatic saccharification. Autohydrolysis of food residues at 160–190 °C leads to oligomer yields in the 0.06–0.3 g/g dry solid range, while acid hydrolysis of pectin (80–120 °C) or cellulose (45–180 °C) yields up to 0.7 g/g dry polymer. Enzymatic hydrolysis at 40–50 °C of pure polysaccharides results in 0.06–0.35 g/g dry solid (DS), with values in the range 0.08–0.2 g/g DS for original food residues.

Uncommon Strong Inhibition of α-Glucosidase by Multivalent Glycoclusters built on Cyclodextrins Scaffolds
Alali, U.; Vallin, A.; Bil, A.; Khanchouche, T.; Mathiron, D.; Przybylski, C.; Beaulieu, R. R.; Kovensky, J.; Benazza, M.; Bonnet, V.
Org. Biomol. Chem. 2019, 17, 7228-7237.
The homeostasis disruption of D-glucose causes diabetes, a dramatic world wide chronic disease. The type 1 diabetes is a succesfully treatable form, where the blood D-glucose is regulated by insulin treatement. In contrast the type 2 diabetes , the non Insulin dependent one, is problematic. The control of the D-glucose blood level via intestinal α-D-glucosidase inactivation can be achieved by using competitive inhibitors as iminosugars (e.g. acarbose) or sulfonium sugar derivatives (e.g. salacinol). Recently, an unprecedented result showed that multivalent diamond nanoparticules grafted with unmodified sugars displayed α-glucosidase inhibition at low micromolar concentrations. We describe herein the synthesis of multivalent glycoclusters using cyclodextrines (CDs) as scaffolds and their assessment as inhibithors of α-D-glucosidase. The glycoclusters were efficiently obtained from per-azido α, β and γ-CDs derivatives and propargyl glycosides using click-chemistry under microwave irradiation. The methodology was successfully applied to various protected and non-protected propargylated monosaccharides, including both O- and S- glycosides, giving clear evidences of its versatility. The targeted 6-per-glycosylated CDs were isolated in moderate to excellent yields (30-90 %) by silica gel chromatography. The results showed inhibition of α-glucosidase from Saccharomyces cerevisiae with IC50 values in a 32-132 µM range, lower than that of acarbose (IC50 ~250µM), a well knowm competitive inhibitor used in clinical treatment of type 2 diabetes. Preliminary experiments suggest a mixed-type non-competitive inhibition mode of these new glycoclusters.

Synthesis of multivalent S-glycosides analogs of a heparan sulfate sequence
Koffi Teki, D. S.-E.; Bil, A.; Moreau, V.; Chagnault, V.; Fanté, B.; adjou, a.; Kovensky, J.
Organic Chemistry Frontiers 2019.
Glycosaminoglycans (GAGs) are involved in the regulation of a large number of biological processes such as inflammation, cell signalling, angiogenesis, viral infection and coagulation. Unlike molecules isolated from tissues, pure molecules, derived from organic synthesis, can prevent side effects and are very useful tools for understanding the structure-activity relationships of many biological and pharmacological activities. In our research group, we focus particularly on the synthesis of multivalent thioglycoside analogs. In this article, we report the synthesis of new glycoclusters with thiodisaccharide units, S-analogs of heparan sulfate. The thiodisaccharide analog was obtained by nucleophilic displacement of a 4-triflate galactoside derivative, by an anomeric thiol of a glucuronic acid precursor. After modifying the aglycone part to introduce an azide, the thiodisaccharide was coupled to maltotriose scaffolds carrying one, two or three propargyl groups by CuAAC.

High resolution MALDI-TOF-MS and MS/MS: Application for the structural characterization of sulfated oligosaccharides
Lesur, D.; Duhirwe, G.; Kovensky, J.
Eur. J. Mass Spectrom. 2019, 0.
Sulfated oligosaccharides are involved in important biological events that are often modulated by specific sequences and sulfation patterns, but their structural analysis remains challenging. Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) analysis of three different sulfated oligosaccharides (Fondaparinux, the octasulfated pentasaccharide, a disulfated heparin-derived tetrasaccharide 1, and an octasulfated maltoheptaose) 2 was performed using the 2-(4-hydroxyphenylazo)benzoic acid-tetramethylguanidinium (HABA-TMG2) matrix. High resolution mass spectrometry of the main ions observed was successful, and this was complemented by tandem mass spectrometry (MS/MS) analysis for structural assessment. Despite sulfate losses, fully sulfated molecular ions were observed and these allowed the determination of oligosaccharide structures: UA-GlcNAc-UA(2S)-AnhMan(6S) for compound 1 and (Glc6S)6-Glc (1S,6S) for compound 2.

Solid-phase synthesis of molecularly imprinted polymer nanolabels: Affinity tools for cellular bioimaging of glycans
Medina Rangel, P. X.; Laclef, S.; Xu, J.; Panagiotopoulou, M.; Kovensky, J.; Tse Sum Bui, B.; Haupt, K.
Scientific Reports 2019, 9, 3923.
Hyaluronic acid (HA) is a glycosaminoglycan that plays many roles in health and disease and is a key biomarker of certain cancers. Therefore, its detection at an early stage, by histochemical methods, is of importance. However, intracellular HA can be masked by other HA-binding macromolecules, rendering its visualization somehow problematic. We show that fluorescent molecularly imprinted polymer nanogels (MIP-NPs), can localize and detect intracellular HA. MIP-NPs were synthesized by solid-phase synthesis on glass beads (GBs). GBs were functionalized with terminal alkyne groups on which an azide derivative of the template molecule glucuronic acid was immobilized via click chemistry. Immobilization via the anomeric carbon left the template’s carboxyl moiety free to enable strong stoichiometric electrostatic interactions with a benzamidine-based functional monomer, to confer selective recognition to the MIP-NPs. Due to the two-point orientation of the template, the resulting MIP-NPs were endowed with improved binding site homogeneity and specificity, reminiscent of monoclonal antibodies. These synthetic antibodies were then applied for probing and staining HA, of which glucuronic acid is a substructure (epitope), on human epidermal cells. Their excellent sensitivity, small size and water compatibility, enabled the MIP-NPs to visualize HA, as evidenced by confocal fluorescence micrographs.

Biological impact of octyl D-glucopyranoside based surfactants
Zdarta, A.; Pacholak, A.; Smułek, W.; Zgoła-Grześkowiak, A.; Ferlin, N.; Bil, A.; Kovensky, J.; Grand, E.; Kaczorek, E.
Chemosphere 2018.
Development of many branches of industry has stimulated the search for new, effective surfactants with interesting properties. Potential use of alkyl glucose derivatives on a large scale, raises questions about the possible risks associated with their entry into the natural environment. To be able to evaluate this risk, the aim of the study was to determine the physicochemical properties of octyl D-glucopyranoside and its three derivatives: N-(octyl D-glucopyranosiduronyl)aspartic acid, N-(octyl D-glucopyranosiduronyl)glicyne and octyl D-glucopyranosiduronic acid. Moreover, their biodegradability by pure bacterial strains and biocenosis present in river water was examined. While descriptions of sugar-based surfactants on microbial cells are limited, the essential element of the study was to determine the effect of surfactants on cell surface properties of microorganisms isolated from activated sludge and compare it to the effects of the petroleum based surfactants and the surfactants produced from renewable materials. The results obtained indicate that physicochemical properties of surface active agents differ depending on the presence of functional groups in the surfactants molecules. What is more, the presence of amino acid substituent in the derivatives of octyl D-glucopyranoside resulted in a slight decrease in the surfactants biodegradation efficiency, in comparison to the compounds that did not contain such a substituent, prolonging this process from 5 to 10 days. Interestingly, even relatively slightly different derivatives modified the cell surface properties in a different way. Importantly, the surfactants based on octyl D-glucopyranoside have less negative impact on environmental microorganism and better biodegradability than the surfactant synthesized from petroleum products.

Synthesis and Insecticidal Activities of Novel Solanidine Derivatives
Beaulieu, R.; Grand, E.; Stasik, I.; Attoumbre, J.; Chesnais, Q.; Gobert, V.; Ameline, A.; Giordanengo, P.; Kovensky, J.
Pest Manag Sci 2018, 0.
Potato (Solanum tuberosum) is the fourth culture in the world and is widely used in the agri-food industries. They generate by-products where alpha-chaconine and alpha-solanine, the two major solanidine based glycoalkaloids of potato, are present. As secondary metabolites, they play an important role in the protecting system of potato and are involved in plant protection against insects. To add value to these by-products, we described herein new glycoalkaloids that could have phytosanitary properties. RESULTS: Solanidine, as a renewable source, was modified with an azido linker and coupled by Copper catalyzed alkyne azide cycloaddition (CuAAC) to alkynyl derivatives of the monosaccharides found in the natural potato glycoalkakoids: D-glucose, D-galactose and L-rhamnose. The efficacy of our compounds was evaluated on the potato aphid Macrosiphum euphorbiae. The synthetic compounds have stronger aphicidal properties against nymphs than unmodified solanidine. They also showed strong aphicidal activities on adults and a negative impact on fecundity. CONCLUSION: Our synthetic neoglycoalkaloids affected Macrosiphum euphorbiae survival at the nymphal stage as well as at the adult stage. Furthermore, they induced a decrease of fecundity. Our results show that chemical modifications of by-products may afford new sustainable compounds for crop and plant protection. This article is protected by copyright. All rights reserved.

Kinetics of the incorporation of the main phenolic compounds into the lignan macromolecule during flaxseed development
Ramsay, A.; Fliniaux, O.; Quero, A.; Molinie, R.; Demailly, H.; Hano, C.; Paetz, C.; Roscher, A.; Grand, E.; Kovensky, J.; Schneider, B.; Mesnard, F.
Food Chem. 2017, 217, 1-8.
The main flax lignan, secoisolariciresinol diglucoside, is stored in a macromolecule containing other ester-bound phenolic compounds. In this study, NMR and HPLC-UV analyses were performed on flaxseeds harvested at different developmental stages to identify and quantify the main phenolic compounds produced during seed development. Extraction was carried out with or without alkaline hydrolysis to determine if these molecules accumulate in the lignan macromolecule and/or in a free form. Monolignol glucosides accumulate in a free form up to 9.85mg/g dry matter at the early developmental stages. Hydroxycinnamic acid glucosides and flavonoid accumulate (up to 3.18 and 4.07mg/g dry matter, respectively) in the later developmental stages and are ester-bound in the lignan macromolecule. Secosiolariciresinol diglucoside accumulates (up to 28.65mg/g dry matter) in the later developmental stages in both forms, mainly ester-bound in the lignan macromolecule and slightly in a free form.

La chimie en Région Hauts-de-France : Chimie de la biomasse
Philippe Zinck, J.-M. A., Rémi Beaulieu, Fanny Bonnet, Thierry Delaunay, Franck Dumeignil, Cédric Epoune Lingome, Audrey Favrelle, Régis Gauvin, Frédéric Hapiot, Nicolas Jacquel, José Kovensky, Raphaël Lebeuf, Christophe Len, Éric Monflier, Véronique Nardello-Rataj, Jesus F. Ontiveros, Sébastien Paul, René Saint-Loup, Mathieu Sauthier, Isabelle Suisse, Marc Visseaux, Anne Wadouachi et Patrice Woisel
Actualité Chimique 2017, 40-45.
Cet article présente un tour d’horizon de quelques-unes des thématiques de recherche développées en région Hauts-de-France dans les domaines de la chimie de la biomasse.

Applications of Glycosaminoglycans in the Medical, Veterinary, Pharmaceutical, and Cosmetic Fields
Kovensky, J.; Grand, E.; Uhrig, M. L.
Industrial Applications of Renewable Biomass Products: Past, Present and Future 2017, 135-164.
Glycosaminoglycans (GAGs) are complex polysaccharides ubiquitously present in the extracellular matrix of mammalian tissues, where they constitute the gelatinous material responsible for maintaining the cells together, in an intimate association with a variety of proteins. Although their structures are not strictly regular, they are composed of a repeating unit of a hexosamine-containing disaccharide. Most of them possess uronic acid residues, and with the exception of hyaluronic acid, they also carry sulfate groups. As a consequence of their high negative charge, they have an extraordinary capacity to absorb water. GAGs participate in many relevant biological processes by interaction with a plethora of proteins, and thus, a large number of applications in different fields have been conceived for GAGs and their derivatives.

Oligogalacturonic Acid Inhibits Vascular Calcification by Two Mechanisms: Inhibition of Vascular Smooth Muscle Cell Osteogenic Conversion and Interaction With Collagen
Hodroge, A.; Trecherel, E.; Cornu, M.; Darwiche, W.; Mansour, A.; Ait-Mohand, K.; Verissimo, T.; Gomila, C.; Schembri, C.; Da Nascimento, S.; Elboutachfaiti, R.; Boullier, A.; Lorne, E.; Courtois, J.; Petit, E.; Toumieux, S.; Kovensky, J.; Sonnet, P.; Massy, Z. A.; Kamel, S.; Rossi, C.; Ausseil, J.
Arterioscler Thromb Vasc Biol 2017, 37, 1391-1401.
OBJECTIVE: Cardiovascular diseases constitute the leading cause of mortality worldwide. Calcification of the vessel wall is associated with cardiovascular morbidity and mortality in patients having many diseases, including diabetes mellitus, atherosclerosis, and chronic kidney disease. Vascular calcification is actively regulated by inductive and inhibitory mechanisms (including vascular smooth muscle cell adaptation) and results from an active osteogenic process. During the calcification process, extracellular vesicles (also known as matrix vesicles) released by vascular smooth muscle cells interact with type I collagen and then act as nucleating foci for calcium crystallization. Our primary objective was to identify new, natural molecules that inhibit the vascular calcification process. APPROACH AND RESULTS: We have found that oligogalacturonic acids (obtained by the acid hydrolysis of polygalacturonic acid) reduce in vitro inorganic phosphate-induced calcification of vascular smooth muscle cells by 80% and inorganic phosphate-induced calcification of isolated rat aortic rings by 50%. A specific oligogalacturonic acid with a degree of polymerization of 8 (DP8) was found to inhibit the expression of osteogenic markers and, thus, prevent the conversion of vascular smooth muscle cells into osteoblast-like cells. We also evidenced in biochemical and immunofluorescence assays a direct interaction between matrix vesicles and type I collagen via the GFOGER sequence (where single letter amino acid nomenclature is used, O=hydroxyproline) thought to be involved in interactions with several pairs of integrins. CONCLUSIONS: DP8 inhibits vascular calcification development mainly by inhibition of osteogenic marker expression but also partly by masking the GFOGER sequence-thereby, preventing matrix vesicles from binding to type I collagen.

Chirality inversion, supramolecular hydrogelation and lectin binding of two thiolactose amphiphiles constructed on a di-lauroyl-l-tartaric acid scaffold
Cano, M. E.; Di Chenna, P. H.; Lesur, D.; Wolosiuk, A.; Kovensky, J.; Uhrig, M. L.
New J. Chem. 2017, 41, 14754-14765.
Herein we report the synthesis, characterization and self-assembly properties of two new thiolactose based amphiphiles constructed on a di-lauroyl-l-tartaric acid scaffold that only differ in the length of the spacer by an ethylene glycol unit. Upon dissolution in hot water the amphiphiles give rise to different colloidal systems at 25 [degree]C: the one with the shorter linker forms a supramolecular thermoreversible hydrogel at a concentration of 0.1 w/v% while the other renders a colloidal system at high dilution (0.005 w/v%). Dynamic Light Scattering, Electron Microscopy (TEM, SEM and E-SEM), fluorescence CMC determination, SAXS and Circular Dichroism experiments were used to characterize both systems. The experiments indicate that only the amphiphile carrying the shorter linker is able to form a crossed-linked network of micellar fibers and thus, a stable hydrogel is observed. The difference of an ethylene glycol unit in the spacer also causes the adoption of a different molecular assembly evidenced by the inversion of the self-assembled chiral arrangement. In addition, the amphiphiles were evaluated for their ability to bind to the PNA lectin using a turbidimetric method. Agglutination was observed in both cases, a process that was disrupted upon the addition of an excess of the disaccharide lactose.

Glycochemical Applications of Diels-Alder Reaction
Laclef, S.; Toumieux, S.; Kovensky, J.
Curr. Org. Chem. 2016, 20, 2379-2392.
Carbohydrates and their analogs are key molecules with a wide range of biological activities. These bioactive compounds are usually synthesized through derivatization of naturally occurring carbohydrates. Nevertheless, this strategy suffers from a limited range of naturally available monosaccharide building blocks and the necessity of laborious steps of protection and deprotection. Consequently new methods began to emerge and Diels-Alder reaction appeared to be a method of choice for their de novo production. The synthesis of carbohydrates and their analogs by means of cycloaddition reactions will be reviewed here. Moreover the potentiality of the use of monosaccharides to induce chirality in Diels-Alder reaction will be presented. Efficient methods for the synthesis of di- and tri-saccharides using the developments shown previously will be also introduced.

Chapter 5 Recent Advances in the Synthesis of Sugar-based Surfactants
Kovensky, J.; Grand, E.
Biomass Sugars for Non-Fuel Applications 2016, 159-204.

Multivalent sialylation of β-thio-glycoclusters by Trypanosoma cruzi trans sialidase and analysis by high performance anion exchange chromatography
Agustí, R.; Cano, M. E.; Cagnoni, A. J.; Kovensky, J.; de Lederkremer, R. M.; Uhrig, M. L.
Glycoconjugate J. 2016, 1-10.
The synthesis of multivalent sialylated glycoclusters is herein addressed by a chemoenzymatic approach using the trans-sialidase of Trypanosoma cruzi (TcTS). Multivalent β-thio-galactopyranosides and β-thio-lactosides were used as acceptor substrates and 3′-sialyllactose as the sialic acid donor. High performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was shown to be an excellent technique for the analysis of the reaction products. Different eluting conditions were optimized to allow the simultaneous resolution of the sialylated species, as well as their neutral precursors. The TcTS efficiently transferred sialyl residues to di, tri, tetra and octa β-thiogalactosides. In the case of an octavalent thiolactoside, up to six polysialylated compounds could be resolved. Preparative sialylation reactions were performed using the tetravalent and octavalent acceptor substrates. The main sialylated derivatives could be unequivocally assigned by MALDI mass spectrometry. Inhibition of the transfer to the natural substrate, N-acetyllactosamine, was also studied. The octalactoside caused 82 % inhibition of sialic acid transfer when we used equimolar concentrations of donor, acceptor and inhibitor.

Octyl glucoside derivatives: A tool against metal pollutants
Ferlin, N.; Grassi, D.; Ojeda, C.; Castro, M. J. L.; Cirelli, A. F.; Kovensky, J.; Grand, E.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015, 480, 439-448.
Derivatives of octyl glucoside modified by the introduction of a chemical function (carboxylic acid, hydroxamic acid) able to enhance the complexing properties of the surfactants toward metallic cations have been used as flotation collectors to remove various metallic cations from a water phase. Flotation experiments at the laboratory scale were performed on Fe(III), Cu(II), Cr(III), Cd(II), Zn(II), Ni(II) and As(III) aqueous solutions. The most interesting results were obtained in the extraction of Fe(III) and Cu(II). Interfacial properties were studied, and the effect of the polar head structure and anomeric configuration was analyzed. Structural variations have an influence on the efficiency and the foaming ability of these compounds. The introduction of a chelating functionality preserves the interfacial performances of these surfactants. Complexes equilibrium constants and species distribution diagrams for Fe(III) and the best flotation agents 2a and 2b were determined from multi-wavelength spectrophotometric pH titration. Both compounds showed analogous values for log β1, log β2 and log β3. The bidentanted Fe(III)-hydroxamate species (2:1 surfactant-metal ratio) reached a maximum concentration in the pH range of 5.5-6.5. At this pH, the best results in the flotation experiments were obtained for both compounds.

Cholesteryl and diosgenyl glycosteroids: synthesis and characterization of new smectic liquid crystals
Beaulieu, R.; Gottis, S.; Meyer, C.; Grand, E.; Deveaux, V.; Kovensky, J.; Stasik, I.
Carbohydr. Res. 2015, 404, 70-78.
While present in large numbers in nature, studies on the physical chemical aspects of glycosteroids are quite rare and focused on cholesterol, and all compounds studied thus far have shown liquid crystalline properties in a narrow temperature range. New glycosteroids composed by cholesterol or diosgenin and different glycosidic moieties have been synthesized here in order to analyze the influence of the structure on the formation of mesophases. These compounds have been studied by crossed polarized optical microscopy. These studies have revealed that these new glycosteroids form Smetic A liquid crystals in a broad temperature range.

Preparation of solanidine-derived glycosides and oligosaccharides as insecticides
Beaulieu, R.; Attoumbre, J.; Gobert-Deveaux, V.; Grand, E.; Stasik, I.; Kovensky, J.; Giordanengo, P.
2015, 56pp.; Chemical Indexing Equivalent to 162:219449 (FR).
The claimed synthesized solanidine derivs. I, where X = O or S and R1 = saccharidic or thiosaccharidic side-chain with 1-10 pentose and/or hexose units (esp. glucosyl, galactosyl and rhamnosyl units). The solanidine derivs. can be synthesized starting from the compd. II. Thus, glycoside I (X = O, R1 = β-glucopyranosyl) was prepd. and tested as insecticide agent against Macrosiphum euphorbiae. The compds. have toxic and/or repellent effects on aphids and other properties, including insecticidal, nematicidal, antiviral, antibacterial, and antifungal activities in agrochem. and pharmaceutical sense. The solanidine derivs. may be used as plant protective agents esp. against aphid pests.

Development of an NMR metabolomics-based tool for selection of flaxseed varieties
Ramsay, A.; Fliniaux, O.; Fang, J.; Molinie, R.; Roscher, A.; Grand, E.; Guillot, X.; Kovensky, J.; Fliniaux, M.-A.; Schneider, B.; Mesnard, F.
Metabolomics 2014, 10, 1258-1267.
Flaxseed is an important source of lignans and ω-3 fatty acids, compounds which present interest in human health with many applications in food industry. It is therefore necessary to precisely know the metabolite content in flaxseed. A metabolomic approach using NMR was developed to achieve this goal. Due to particular characteristics of flaxseed (high level in oil, high amount in mucilage, and integration of the phenolics into a macromolecule), the extraction procedure had first to be optimized using an experimental design, based on the extraction time, in a water bath or an ultrasound bath, alkaline treatment, defatting, and centrifugation temperature. This methodology was then applied to several flaxseed varieties classified in function of their content in ω-3 fatty acid. The main differences in semi-polar metabolites between these varieties concern compounds of the phenylpropanoid pathway. Hydroxycinnamic acid glucoside and lignan content increase when ω-3 fatty acid content decrease whereas flavonoid content increase in the same way of ω-3 fatty acids.

Chapter 11 Anionic oligosaccharides: synthesis and applications
Grand, E.; Kovensky, J.; Pourceau, G.; Toumieux, S.; Wadouachi, A.
Carbohydrate Chemistry: Volume 40 2014, 40, 195-235.

Synthesis of divalent ligands of β-thio-and β-N-galactopyranosides and related lactosides and their evaluation as substrates and inhibitors of Trypanosoma cruzi trans-sialidase
Cano, M. E.; Agusti, R.; Cagnoni, A. J.; Tesoriero, M. F.; Kovensky, J.; Uhrig, M. L.; de Lederkremer, R. M.
Beilstein J. Org. Chem. 2014, 10, 3073-3086.
In this work we describe the synthesis of mono- and divalent beta-N- and beta-S-galactopyranosides and related lactosides built on sugar scaffolds and their evaluation as substrates and inhibitors of the Trypanosoma cruzi trans-sialidase (TcTS). This enzyme catalyzes the transfer of sialic acid from an oligosaccharidic donor in the host, to parasite betaGalp terminal units and it has been demonstrated that it plays an important role in the infection. Herein, the enzyme was also tested as a tool for the chemoenzymatic synthesis of sialic acid containing glycoclusters. The transfer reaction of sialic acid was performed using a recombinant TcTS and 3'-sialyllactose as sialic acid donor, in the presence of the acceptor having betaGalp non reducing ends. The products were analyzed by high performance anion exchange chromatography with pulse amperometric detection (HPAEC-PAD). The ability of the different S-linked and N-linked glycosides to inhibit the sialic acid transfer reaction from 3'-sialyllactose to the natural substrate N-acetyllactosamine, was also studied. Most of the substrates behaved as good acceptors and moderate competitive inhibitors. A di-N-lactoside showed to be the strongest competitive inhibitor among the compounds tested (70% inhibition at equimolar concentration). The usefulness of the enzymatic trans-sialylation for the preparation of sialylated ligands was assessed by performing a preparative sialylation of a divalent substrate, which afforded the monosialylated compound as main product, together with the disialylated glycocluster.

Design and Synthesis of Hydrolytically Stable Multivalent Ligands Bearing Thiodigalactoside Analogues for Peanut Lectin and Human Galectin-3 Binding
Cagnoni, A. J.; Kovensky, J.; Uhrig, M. L.
J. Org. Chem. 2014, 79, 6456-6467.
Herein, we describe the design and synthesis of a novel family of hydrolytically stable glycoclusters bearing thiodigalactoside (TDG) analogues as recognition elements of β-galactoside binding lectins. The TDG analogue was synthesized by thioglycosylation of a 6-S-acetyl-α-d-glucosyl bromide with the isothiouronium salt of 2,3,4,6-tetra-O-acetyl-β-d-galactose. Further propargylation of the TDG analogue allowed the coupling to azido-functionalized oligosaccharide scaffolds through copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) under microwave activation. The final mono-, di-, and tetravalent ligands were resistant to enzymatic hydrolisis by Escherichia coli β-galactosidase. Binding affinities to peanut agglutinin and human galectin-3 were measured by isothermal titration calorimetry which showed Ka constants in the micromolar range as well as a multivalent effect. Monovalent ligand exhibited a binding affinity higher than that of thiodigalactoside. Docking studies performed with a model ligand on both β-galactoside binding lectins showed additional interactions between the triazole ring and lectin amino acid residues, suggesting a positive effect of this aromatic residue on the biological activity.