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


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Axe de recherche : Chimie pour le Développement Durable

Description des travaux de recherche

Mise au point de nouvelles méthodes de modifications chimiques régio et stéréosélectives de glucides. Synthèse d'analogues d'alcaloïdes indolizidines et pyrrolizidines polyhydroxylés inhibiteurs potentiels de glycosidases. Utilisation d'intermédiaires sulfates cycliques pour la transformation régiosélective d'aldoses application à la synthèse de pseudo-oligosaccharides.Modification chimique régiosélective d'oligosaccharides mettant en jeu des procédés plus respectueux de l’environnement, notamment par voie micro-onde et par mécanochimie.

Mots clés : N.C.

Sélection de publications

Physicochemical, foaming and biological properties of lowly irritant anionic sugar-based surfactants
Bois, R.; Abdellahi, B.; Mika, B.; Golonu, S.; Vigneron, P.; Chagnault, V.; Drelich, A.; Pourceau, G.; Wadouachi, A.; Vayssade, M.; Pezron, I.; Nesterenko, A.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2020, 607, 125525.
Surface-active compounds derived from biomass, especially sugar-based amphiphiles, have received wide attention regarding their biodegradability, low toxicity and ecological acceptability. Compared to nonionic sugar-based surfactants, the anionic ones show significantly better solubility, higher surface activity and foaming performance. Thus they are largely used in personal care formulations and many technological applications. However, anionic surfactants are well known to induce skin and eye irritation. In this study, three sugar-based anionic surfactants, bearing a lipidic chain grafted to the anomeric position of a monosaccharide (glucose or xylose) and a sulfate group on the primary hydroxyl, were synthesized: 6-O-sulfo-N-(β-d-glucopyranosyl) dodecanamide (GlcNC12S), N-dodecyl-6-O-sulfo-d-gluconamide (GlcCC12S) and N-dodecyl-6-O-sulfo-d-xylonamide (XylCC12S). These molecules were investigated in details for their self-assembling behavior, foaming properties and biological effects. All their properties were compared to those of two commercially available anionic surfactants, sodium laureth sulfate (SLES) and sodium dodecylsulfate (SDS). Results revealed that the three anionic glycolipids show surface properties and foaming behavior comparable to those of SDS. Furthermore, their cytotoxic and irritation potentials are significantly lower compared to commercial molecules, which make these renewable molecules potential candidates for replacement of petroleum-based compounds.

Insight on the Contribution of Plasmons to Gold-Catalyzed Solar-Driven Selective Oxidation of Glucose under Oxygen
Golonu, S.; Pourceau, G.; Quéhon, L.; Wadouachi, A.; Sauvage, F.
Solar RRL 2020, 4, 2000084.
With the increasing concerns about pollution and reduction of energy demands, the use of solar energy to drive chemical transformations is becoming increasingly attractive. Within the context of sustainability, sunlight-driven organic transformation of biomass feedstock, such as free carbohydrates, to obtain high added-value products is an important topic in which the recent progress should contribute to the development of solar biorefineries. Among the variety of photocatalysts, gold nanoparticles (NPs) loaded onto large bandgap semiconductors represent the state of the art. Such catalysts are known to accelerate the targeted reaction upon plasmonic excitation. In addition, as noble metal NPs, they also hold an additional role related to surface catalysis, which has been exploited for aerobic oxidation of free sugars. Nevertheless, the respective contribution of each role during transformation is not well established. Herein, the enhancement of the O2-mediated oxidation of free sugars using Au NPs on CeO2 under standard air mass 1.5G illumination conditions is reported. The results highlight that the plasmonic contribution of Au NPs is totally annihilated and this enhancement stems solely from a thermal activation process induced by NIR radiation from standard white-light conditions.

Nitroxide-Grafted Nanometric Metal Oxides for the Catalytic Oxidation of Sugar
Omri, M.; Becuwe, M.; Courty, M.; Pourceau, G.; Wadouachi, A.
ACS Applied Nano Materials 2019, 2, 5200-5205.
A new series of ([2,2,6,6-tetramethylpiperidin-1-yl]oxy) (TEMPO) catalysts supported on nanometric metal oxides (TiO2, AlO2, CeO2) and their efficiency for sugar oxidation are herein described. The preparation of such hybrid catalysts was carried out by modification of a metal oxide surface with a monolayer of phosphonic linker bearing a TEMPO radical. All prepared catalysts were carefully characterized by diffuse reflectance Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy. The efficiency of these new hybrid TEMPO supported materials for sugar oxidation was evaluated on methyl α-d-glucoside, as a model carbohydrate. The three hybrid catalysts showed high selectivity, activity, and stability, suggesting a promising potential for rapidly obtaining acid sugar derivatives.

Impact of the chemical structure on amphiphilic properties of sugar-based surfactants: A literature overview
Gaudin, T.; Lu, H.; Fayet, G.; Berthauld-Drelich, A.; Rotureau, P.; Pourceau, G.; Wadouachi, A.; Van Hecke, E.; Nesterenko, A.; Pezron, I.
Adv. Colloid Interface Sci. 2019, 270, 87-100.
In this review, structure-property trends are systematically analyzed for four amphiphilic properties of sugar-based surfactants: critical micelle concentration (CMC), its associated surface tension (γCMC), efficiency (pC20) and Krafft temperature (TK). First, the impact on amphiphilic properties of the alkyl chain size and the presence of branching and/or unsaturation is investigated. Then, various polar head parameters are explored, such as the degree of polymerization of the sugar unit (mono- or oligosaccharides), the chemical nature of the linker and the sugar configuration. Some systematic comparisons between ethoxylated surfactants and sugar-based surfactants are also carried out. While some structural trends with the impact of alkyl chain length or the polar head size are now well understood, this analysis points out that systematic studies of more specific effects of alkyl chain (e.g. branching, unsaturation, presence of rings, position on the polar head) and polar head (e.g. linker, anomeric configuration, internal stereochemistry, cyclic vs. acyclic sugar residues) were scarcer or not available to date. This work encourages the use of these structural trends in the perspective of developing new bio-based surfactants and their consideration in predictive models. It also highlights the need of further experimental tests to fill remaining gaps notably to explore some specific structural features (such as the introduction of rings in the alkyl chain or the position of the alkyl chain on the polar head) and towards applicative properties (like foaming capacity or wettability).

Lactose derivatives as potential inhibitors of pectin methylesterases
L'Enfant, M.; Kutudila, P.; Rayon, C.; Domon, J.-M.; Shin, W.-H.; Kihara, D.; Wadouachi, A.; Pelloux, J.; Pourceau, G.; Pau-Roblot, C.
Int. J. Biol. Macromol. 2019, 132, 1140-1146.
The discovery of molecules that can inhibit the action of phytopathogens is essential to find alternative to current pesticides. Pectin methylesterases (PME), enzymes that fine-tune the degree of methylesterification of plant cell wall pectins, play a key role in the pathogenicity of fungi or bacteria. Here we report the synthesis of new lactoside derivatives and their analysis as potential PME inhibitors using three plants and one fungal PME. Because of its structure, abundance and reduced cost, lactose was chosen as a case study. Lactoside derivatives were obtained by TEMPO-mediated oxidation of methyl lactoside, followed by an esterification procedure. Three derivatives were synthesized: sodium (methyl-lactosid)uronate, methyl (methyl-lactosid)uronate and butyl (methyl-lactosid)uronate. The inhibition of the plant and pathogen enzyme activities by lactoside derivatives was measured in vitro, showing the importance of the substitution on lactose: methyl (methyl-lactosid)uronate was more efficient than butyl (methyl-lactosid)uronate. These results were confirmed by docking analysis showing the difference in the interaction between lactoside derivatives and PME proteins. In conclusion, this study identified novel inhibitors of pectin remodeling enzymes.

Photocatalyzed Transformation of Free Carbohydrates
Omri, M.; Sauvage, F.; Golonu, S.; Wadouachi, A.; Pourceau, G.
Catalysts 2018, 8, 672.
In the growing context of sustainable chemistry, one of the challenges of organic chemists is to develop efficient and environmentally friendly methods for the synthesis of high-added-value products. Heterogeneous photocatalytic transformations have brought revolution in this regard, as they take advantage of an unlimited source of energy (solar light) or artificial UV light to onset organic chemical modifications. The abundance of free carbohydrates as chemical platform feedstock offers a great opportunity to obtain a variety of industrial interest compounds from biomass. Due to their chirality and polyfunctionality, the conversion of sugars generally requires multi-step protocols with protection/deprotection steps and hazardous chemical needs. In this context, several selective and eco-friendly methodologies are currently under development. This review presents a state of art of the recent accomplishments concerning the use of photocatalysts for the transformation and valorization of free carbohydrates. It discusses the approaches leading to the selective oxidation of free sugars, their degradation into organic chemicals, or their use for hydrogen production.

Nitroxide supported on nanometric metal oxides as new hybrid catalysts for selective sugar oxidation
Omri, M.; Becuwe, M.; Davoisne, C.; Pourceau, G.; Wadouachi, A.
J. Colloid Interface Sci. 2019, 536, 526-535.
A new series of supported organocatalysts, prepared by a simple method, were used for selective sugar oxidation. This approach is based on the immobilization of a nitroxide derivative through a carboxylic function on nanometric metal oxides (TiO2, Al2O3 and CeO2), allowing the recovery of the catalyst. These hybrid materials were carefully characterized by Diffuse Reflectance FT-IR spectroscopy (DRIFT), ThermoGravimetric Analysis (TGA), X-Ray Diffraction (XRD), Brunauer-Emmet-Teller surface area measurements (B.E.T.), elemental and electrochemical analyses, showing different characteristics and behaviors depending on the nature of the metal oxide used. The activity of the supported nitroxide catalyst was evaluated on methyl α-d-glucoside oxidation, used as model reaction. In all cases, high catalytic activity was highlighted, with up to 25 times less nitroxyl radical required for complete conversion than under homogeneous conditions. The influence of several experimental conditions such as the use of phosphate buffer and recyclability of the catalyst were also investigated.

The influence of chloride and hydrogen sulfate anions in two polymerised ionic liquids based on the poly(1-(hydroxyethyl)-3-vinylimidazolium cation, synthesis, thermal and vibrational studies
Chaker, Y.; Debdab, M.; Belarbi, E. H.; Ilikti, H.; Haddad, B.; Moumene, T.; Wadouachi, A.; Van Nhien, A. N.; Abassi, H. B.; Abbas, O.; Bresson, S.
Eur. Polym. J. 2018, 108, 138-149.
The chemical reaction of 2-chloroethanol with 1-vinylimidazol as precursor led to the corresponding compound 1-hydroxyethyl-3-vinylimidazolium chloride [EtOHVIM+] [Cl−]. In the next step, treatment of [EtOHVIM+][Cl−] with 2,2-azobisisobutyronitril (AIBN) afforded the poly1-(hydroxyethyl)-3-vinylimidazolium chloride (poly[EtOHVIM+][Cl−]), Finally, the reaction of (poly[EtOHVIM+][Cl−]) and sulfuric acid led to poly 1-(hydroxyethyl)-3-vinylimidazolium hydrogen sulfate (poly[EtOHVIM+][HSO4−]) by replacing the [Cl−] halide by an [HSO4−] anion. The structure of these compounds was identified by 1H NMR, 13C NMR as preliminary spectroscopic characterization. To obtain information on the structure and vibrational behavior in these compounds, vibrational spectroscopy measurements were investigated by Fourier Transform-Infrared-Attenuated Total Reflectance and Fourier Transform Raman spectroscopy in the spectral range 600–4000 cm−1 and 4000–500 cm−1, respectively. The Polymerization of IL gave rise to specific marks in the Raman and IR spectra and enhanced its vibrational property. Also, in order to understand the thermal stability in these compounds, the results concerning the melting point, glass transition and decomposition were determined by thermogravimetric analysis (TGA), differential thermal (DTG), and differential scanning calorimetry (DSC). The results indicated that the poly [EtOHVIM+][HSO4−] compound showed interesting thermal properties like high temperature of degradation and low temperature of glass transition compared to poly[EtOHVIM+][Cl−].

Gold Catalysis and Photoactivation: A Fast and Selective Procedure for the Oxidation of Free Sugars
Omri, M.; Sauvage, F.; Busby, Y.; Becuwe, M.; Pourceau, G.; Wadouachi, A.
ACS Catalysis 2018, 1635-1639.
A fast and efficient methodology for the selective oxidation of sugars into corresponding sodium aldonates is herein reported. Hydrogen peroxide was used as a cheap oxidant and electron scavenger, in the presence of only 0.003-0.006 mol % of gold in basic conditions. Three photocatalysts were studied, namely Au/Al2O3, Au/TiO2 and Au/CeO2, the latter being the most efficient (TOF > 750 000 h-1) and perfectly selective. Only 10 minutes exposition under standard incident sunlight irradiation (A.M.1.5G conditions - 100 mW/cm2) affords total conversion of glucose into the corresponding sodium gluconate. Demonstrating its versatility, this methodology was successfully applied to a variety of oligosaccharides leading to the corresponding aldonates in quantitative yield and high purity (>95%) without any purification step. The photocatalyst was recovered by simple filtration and re-used 5 times leading to the same conversion and selectivity after 10 min of illumination.

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.

Measurement of cytotoxicity and irritancy potential of sugar-based surfactants on skin-related 3D models
Lu, B.; Miao, Y.; Vigneron, P.; Chagnault, V.; Grand, E.; Wadouachi, A.; Postel, D.; Pezron, I.; Egles, C.; Vayssade, M.
Toxicol. in Vitro 2017, 40, 305-312.
Sugar-based surfactants present surface-active properties and relatively low cytotoxicity. They are often considered as safe alternatives to currently used surfactants in cosmetic industries. In this study, four sugar-based surfactants, each with an eight carbon alkyl chain bound to a glucose or a maltose headgroup through an amide linkage, were synthesized and compared to two standard surfactants. The cytotoxic and irritant effects of surfactants were evaluated using two biologically relevant models: 3D dermal model (mouse fibroblasts embedded in collagen gel) and reconstituted human epidermis (RHE, multi-layered human keratinocytes). Results show that three synthesized surfactants possess lower cytotoxicity compared to standard surfactants as demonstrated in the 3D dermal model. Moreover, the IC50s of surfactants against the 3D dermal model are higher than IC50s obtained with the 2D dermal model (monolayer mouse fibroblasts). Both synthesized and standard surfactants show no irritant effects after 48h of topical application on RHE. Throughout the study, we demonstrate the difficulty to link the physico-chemical properties of surfactants and their cytotoxicity in complex models. More importantly, our data suggest that, prior to in vivo tests, a complete understanding of surfactant cytotoxicity or irritancy potential requires a combination of cellular and tissue models.

Efficient Synthesis of N-Alkyl Polyhydroxylated Pipecolamide Compounds from d-Glucurono-6,3-lactone
Kaddour, A.; Toumieux, S.; Wadouachi, A.
Synlett 2017, 28, 2174-2178.
N-Alkyl pipecolamides were efficiently synthesized from d-glucurono-6,3-lactone via a key 5-azido N-alkylamide intermediate that can be used as a scaffold for the synthesis of 4-amino and N-sulfonated pipecolamide derivatives.

Structural characterization and rheological properties of a galactomannan from Astragalus gombo Bunge seeds harvested in Algerian Sahara
Chouana, T.; Pierre, G.; Vial, C.; Gardarin, C.; Wadouachi, A.; Cailleu, D.; Le Cerf, D.; Boual, Z.; Ould El Hadj, M. D.; Michaud, P.; Delattre, C.
Carbohydr. Polym. 2017, 175, 387-394.
A water soluble polysaccharide (WSP) was extracted and purified from Astragalus gombo seeds (Fabaceae) harvested in Septentrional Sahara (Ouargla, Algeria) with a yield of 6.8% (w/w of the dry seed ground). It was characterized by gas chromatography coupled to the mass spectrometry (GC–MS), size exclusion chromatography with Multi-Angle Light Scattering analysis (SEC-MALLS), high–resolution 1H and 13C NMR, and rheological measurements. The structural characterization indicated that this WSP fraction is a galactomannan with a mannose/galactose ratio of 1.7 formed by a backbone of β-(1,4)-d-mannopyranosyl residues (63%) substituted at O-6 position by a single α-galactopyranose residue (37%). SEC-MALLS analysis revealed that this galactomannan has an average molecular mass (Mw) of 1.1×106g/mol, an intrinsic viscosity of 860mL/g and, a random coil conformation structure. Rheological analysis in semi diluted regimes shown pseudo-plastic and viscoelastic behaviour.

Structural characterization and rheological behavior of a heteroxylan extracted from Plantago notata Lagasca (Plantaginaceae) seeds
Benaoun, F.; Delattre, C.; Boual, Z.; Ursu, A. V.; Vial, C.; Gardarin, C.; Wadouachi, A.; Le Cerf, D.; Varacavoudin, T.; Ould El-Hadj, M. D.; Michaud, P.; Pierre, G.
Carbohydr. Polym. 2017, 175, 96-104.
Plantago notata (Plantaginaceae) is a spontaneous plant from Septentrional Algerian Sahara currently used by traditional healers to treat stomach disorders, inflammations or wound healing. A water-soluble polysaccharide, called PSPN (PolySaccharide fraction from Plantago Notata), was extracted and purified from the seeds of this semi-arid plant. The structural features of this mucilage were evaluated by colorimetric assays, Fourier transformed infrared spectroscopy (FT-IR), gas chromatography coupled to mass spectrometry (GC/MS) and 1H/13C Nuclear Magnetic Resonance (NMR) spectroscopy. PSPN is a heteroxylan with a backbone composed of β-(1,3)-d-Xylp and β-(1,4)-d-Xylp highly branched, through (O)-2 and (O)-3 positions of β-(1,4)-d-Xylp by various side chains and terminal monosaccharides such as α-l-Araf-(1,3)-β-d-Xylp, β-d-Xylp-(1,2)-β-d-Xylp, terminal Xylp or terminal Araf. The physico-chemical and rheological analysis of this polysaccharide in dilute and semi diluted regimes showed that PSPN exhibites a molecular weight of 2.3×106g/mol and a pseudoplastic behavior.

Improvement of Gold-Catalyzed Oxidation of Free Carbohydrates to Corresponding Aldonates Using Microwaves
Omri, M.; Pourceau, G.; Becuwe, M.; Wadouachi, A.
ACS Sustainable Chemistry & Engineering 2016, 4, 2432-2438.
An efficient microwave-assisted methodology for the oxidation of free carbohydrates to corresponding aldonates is described. Supported gold catalyst, hydrogen peroxide and a mineral base were used to perform the oxidation reaction in water under microwave irradiation. These conditions combined with Au/Al2O3 catalyst allowed to reach in 10 minutes a quantitative conversion of glucose.The catalyst was highly selective and reusable and only 0.004 mol % of gold compared to sugar was used. The reaction was performed using a variety of substrates (mono or oligosaccharides, neutral or acidic sugars) and good to excellent conversion yields and selectivity to corresponding aldonates were obtained. After filtration and freeze-drying, sodium or potassium aldonates were obtained without any purification. Thanks to very high turn-over frequencies (up to 438 000 h-1), this methodology improves significantly the previously described methods for the gold-catalyzed oxidation of carbohydrates.

Catalytic Synthesis of a New Series of Alkyl Uronates and Evaluation of Their Physicochemical Properties
Lu, H.; Drelich, A.; Omri, M.; Pezron, I.; Wadouachi, A.; Pourceau, G.
Molecules 2016, 21, 1301-1315.
Large quantities (>3 g) of a new series of alkyl uronates were synthesized in two steps from commercial methyl hexopyranosides. Firstly, several tens of grams of free methyl α-d-glucopyranoside were selectively and quantitatively oxidized into corresponding sodium uronate using 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO)-catalyzed oxidation. Hydrophobic chains of different length were then introduced by acid-mediated esterification with fatty alcohols (ethyl to lauryl alcohol) leading to the desired alkyl glucuronates with moderate to good yields (49%–72%). The methodology was successfully applied to methyl α-d-mannopyranoside and methyl β-d-galactopyranoside. Physicochemical properties, such as critical micelle concentration (CMC), equilibrium surface tension at CMC (γcmc), solubility, and Krafft temperature were measured, and the effect of structural modifications on surface active properties and micelle formation was discussed.

Physico-chemical properties and cytotoxic effects of sugar-based surfactants: Impact of structural variations
Lu, B.; Vayssade, M.; Miao, Y.; Chagnault, V.; Grand, E.; Wadouachi, A.; Postel, D.; Drelich, A.; Egles, C.; Pezron, I.
Colloids Surf B Biointerfaces 2016, 145, 79-86.
Surfactants derived from the biorefinery process can present interesting surface-active properties, low cytotoxicity, high biocompatibility and biodegradability. They are therefore considered as potential sustainable substitutes to currently used petroleum-based surfactants. To better understand and anticipate their performances, structure-property relationships need to be carefully investigated. For this reason, we applied a multidisciplinary approach to systematically explore the effect of subtle structural variations on both physico-chemical properties and biological effects. Four sugar-based surfactants, each with an eight carbon alkyl chain bound to a glucose or maltose head group by an amide linkage, were synthesized and evaluated together along with two commercially available standard surfactants. Physico-chemical properties including solubility, Krafft point, surface-tension lowering and critical micellar concentration (CMC) in water and biological medium were explored. Cytotoxicity evaluation by measuring proliferation index and metabolic activity against dermal fibroblasts showed that all surfactants studied may induce cell death at low concentrations (below their CMC). Results revealed significant differences in both physico-chemical properties and cytotoxic effects depending on molecule structural features, such as the position of the linkage on the sugar head-group, or the orientation of the amide linkage. Furthermore, the cytotoxic response increased with the reduction of surfactant CMC. This study underscores the relevance of a methodical and multidisciplinary approach that enables the consideration of surfactant solution properties when applied to biological materials. Overall, our results will contribute to a better understanding of the concomitant impact of surfactant structure at physico-chemical and biological levels.

Triterpenes and steroids from the stem bark of Gambeya boiviniana Pierr
Rasoanaivo, L. H.; Wadouachi, A.; Andriamampianina, T.; Andriamalala, S.; Razafindrakoto, E.; Raharisololalao, A.
J Pharmacogn Phytochem 2014, 3, 68-72.
A chemical study was done on the stem bark of Gambeya boiviniana Pierre. This plant has been used in traditional medicine for treatment of different kinds of inflammation disorders. In the present study, anti- inflammatory activities of ethanolic, dichloromethane, ethyl acetate and butanolic extracts were assayed in mice using carrageenan-induced paw edema. Ethyl acetate extract was found to possess the most significant anti-inflammatory effect (67, 78%). These results are in accordance with the folk use of this plant. However, more research is needed for its use in clinical studies. The separations of the chemical compounds of ethyl acetate extract were carried out by different chromatographic technics and their structures were elucidated by spectroscopic method including nuclear magnetic, mass spectrometry, IR spectrometry, GC/MS. Nine compounds were identified during this investigation. There are lupeol acetate 3, β amyrin acetate 4, α amyrin acetate 6, taraxasterol acetate 5, fatty acid ester of lupeol 2 and fatty acid ester of β-amyrin 1, chondrillasterol 7, β-sitosterol 8, β-sitosterol-3-O-glucoside 9.

The synthesis of a glucoconjugate of the peptidic fragment of cryptophycin-24
Mezrai, A.; Lesur, D.; Wadouachi, A.; Pilard, F.; Mulengi, J. K.
Mediterranean Journal of Chemistry 2014, 3, 935-946.
A novel glucoconjugate of the peptidic fragment of cryptophycin-24 was prepd. through the replacement of the leucic acid residue with L-leucine and the functionalisation of tyrosine residue with glucose. Those modifications lead to a novel protected tripeptide fragment of cryptophycin-24.

The Synthesis of an Aziridinyl Analogue of Unit A of Cryptophycin-1
Mezrai, A.; Drici, W.; Lesur, D.; Mulengi, J.; Wadouachi, A.; Pilard, F.
Lett. Org. Chem. 2014, 11, 259-267.
A novel analog of unit A of cryptophycin-1 was prepd. starting from com. trans-cinnamaldehyde. The modifications introduced into the new structure related to the replacement of the epoxide with an aziridine moiety, and the inclusion of the 1,3-enone moiety into an arom. ester frame through the synthesis of a key arom. ketone. Asymmetry was induced during the later steps of the synthetic pathway. The optical purity of compds. was monitored by chiral HPLC and polarimetric measurements.

Efficient synthesis of glycosylamines in solventless conditions promoted by mechanical milling
Lingome, C. E.; Pourceau, G.; Gobert-Deveaux, V.; Wadouachi, A.
RSC Advances 2014, 4, 36350.
A mecanosynthesis of glycosylamines under solventless conditions was established. This environmentally friendly approach optimized with L-rhamnose, was investigated using a variety of amines and other carbohydrates. High reaction yields and simple work-up allow the clean and fast synthesis of a variety of glycosylamines and glycosyl-(di)-amines.

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.

Anti-biofilm activity: a function of Klebsiella pneumoniae capsular polysaccharide
Goncalves Mdos, S.; Delattre, C.; Balestrino, D.; Charbonnel, N.; Elboutachfaiti, R.; Wadouachi, A.; Badel, S.; Bernardi, T.; Michaud, P.; Forestier, C.
PLoS One 2014, 9, e99995.
Competition and cooperation phenomena occur within highly interactive biofilm communities and several non-biocides molecules produced by microorganisms have been described as impairing biofilm formation. In this study, we investigated the anti-biofilm capacities of an ubiquitous and biofilm producing bacterium, Klebsiella pneumoniae. Cell-free supernatant from K. pneumoniae planktonic cultures showed anti-biofilm effects on most Gram positive bacteria tested but also encompassed some Gram negative bacilli. The anti-biofilm non-bactericidal activity was further investigated on Staphylococcus epidermidis, by determining the biofilm biomass, microscopic observations and agglutination measurement through a magnetic bead-mediated agglutination test. Cell-free extracts from K. pneumoniae biofilm (supernatant and acellular matrix) also showed an influence, although to a lesser extend. Chemical analyses indicated that the active molecule was a high molecular weight polysaccharide composed of five monosaccharides: galactose, glucose, rhamnose, glucuronic acid and glucosamine and the main following sugar linkage residues [--> 2)-alpha-L-Rhap-(1 -->]; [--> 4)-alpha-L-Rhap-(1 -->]; [alpha-D-Galp-(1 -->]; [--> 2,3)-alpha-D-Galp-(1 -->]; [--> 3)-beta-D-Galp-(1 -->] and, [--> 4)-beta-D-GlcAp-(1 -->]. Characterization of this molecule indicated that this component was more likely capsular polysaccharide (CPS) and precoating of abiotic surfaces with CPS extracts from different serotypes impaired the bacteria-surface interactions. Thus the CPS of Klebsiella would exhibit a pleiotropic activity during biofilm formation, both stimulating the initial adhesion and maturation steps as previously described, but also repelling potential competitors.

5-O-caffeoylshikimic acid from Solanum somalense leaves: advantage of centrifugal partition chromatography over conventional column chromatography
Chideh, S.; Pilard, S.; Attoumbre, J.; Saguez, R.; Hassan-Abdallah, A.; Cailleu, D.; Wadouachi, A.; Baltora-Rosset, S.
J. Sep. Sci. 2014, 37, 2331-9.
Solanum somalense leaves, used in Djibouti for their medicinal properties, were extracted by MeOH. Because of the high polyphenol and flavonoid contents of the extract, respectively, determined at 80.80 +/- 2.13 mg gallic acid equivalent/g dry weight and 24.4 +/- 1.01 mg quercetin equivalent/g dry weight, the isolation and purification of the main polyphenols were carried out by silica gel column chromatography and centrifugal partition chromatography. Column chromatography led to 11 enriched fractions requiring further purification, while centrifugal partition chromatography allowed the easy recovery of the main compound of the extract. In a solvent system composed of CHCl3/MeOH/H2O (9.5:10:5), 21.8 mg of this compound at 97% purity was obtained leading to a yield of 2.63%. Its structure was established as 5-O-caffeoylshikimic acid by mass spectrometry and NMR spectroscopy. This work shows that S. somalense leaves contain very high level of 5-O-caffeoylshikimic acid (0.74% dry weight), making it a potential source of production of this secondary metabolite that is not commonly found in nature but could be partly responsible of the medicinal properties of S. somalense leaves.