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The late-onset form of Tay-Sachs disease displays when the activity levels of human β-hexosaminidase A (HexA) fall below 10% of normal, due to mutations that destabilise the native folded form of the enzyme and impair its trafficking to the lysosome. Competitive inhibitors of HexA can rescue disease-causative mutant HexA, bearing potential as pharmacological chaperones, but often also inhibit the enzyme O-glucosaminidase (GlcNAcase; OGA), a serious drawback for translation into the clinic. We have designed sp²-iminosugar glycomimetics related to GalNAc that feature a neutral piperidine-derived thiourea or a basic piperidine-thiazolidine bicyclic core and behave as selective nanomolar competitive inhibitors of human Hex A at pH 7 with a ten-fold lower inhibitory potency at pH 5, a good indication for pharmacological chaperoning. They increased the levels of lysosomal HexA activity in Tay-Sachs patient fibroblasts having the G269S mutation, the highest prevalent in late-onset Tay-Sachs disease. [ABSTRACT FROM AUTHOR]

An efficient synthetic pathway to guanidine-type iminosugars based on the ability of the carbonyl group of an l-idose precursor to act as the electrophilic target for the nitrogen atom of a guanidine substituent located at the C-5 position is described. Biological evaluation of the new glycomimetics confirms a strong influence of the nature of the substituents at the nitrogen atoms on the glycosidase inhibitory properties.

Research has been conducted on the polyhydroxylated 6-oxa-nor-tropanes. The synthesis of these compounds which incorporate the structural features of calystegine B (sub)2 from 5-deoxy-5-thioureido and 5-ureido-L-idofuranose precursors has been carried out and the results are discussed.

Research examines the molecular recognition processes in carbohydrates with reference to the binding properties of the multitopic sugar-thiourea conjugates. Data on the complex stoichiometry and association constant for glutarate and octyl-beta-D-glucopyranoside are discussed in terms of the number of hydrogen bond donating sites and ligand binding efficiency.

Research has been conducted on the synthesis of aminoketalic castanospermine analogues. The analysis of the polyhydroxylated bicyclic system is presented.

Research was conducted to characterize ionic intermediates through a comparative analysis of base- and acid-catalayzed transformations in S-linked thiooligosaccharides and their O-linked counterparts. In this study, the 1-O(S)-D-glucopyranosyl-D-fructose disaccharide model was utilized. Results confirm the important role played by sulfur atom participation reactions in thiooligosaccharide chemistry.

Existing procedures help prepared 3-deoxy-3-isothiocyanato derivatives of D-glucose, D-allose and D-galactose. These derivatives undergo intramolecular cyclization, generating enantiomerically pure 2-thioxotetrahydro-1,3-O,N-heterocycles with chirality at C-4. Configuration of the sugar controls the outcome of the reaction and the fully unprotected D-gluco derivative undergoes a nucleophile addition of the gamma-oxo group to the NCS group, producing 4-(trihydroxypropyl)tetrahydrooxazine-2-thione.

6-deoxydi-O-isopropylidene-6-isothiocyanato-aldoses are deprotected and 6-amino-6-deoxy sugars interact with thiophosgene to synthesize chiral oxazolidine-2-thiones, which are obtained from sugar. Temporary 6-deoxy -6-isothiocyanato- or 6-(chlorothioformamido)-6-deoxy aldoses act as channels for the derivation of intramolecular 6,5-cyclic thiocarbamates due to the complex regioselectivity of the interactions. A pseudo-C-nucleoside geometry is observed in the oxazolidine-2-thiones. Steady compounds of 6-deoxy-6-isothiocyanatoaldopyranosides are formed when 6-amino-6-deoxyladopyranosides interact with thiophosgene. Bicyclic 2-thioxotetrahydro-1,3-oxazines are formed due to base-stimulated extramolecular cyclization.

The preparation of bicyclic carbohydrate mimics related to (+)-castanospermine incorporating a thiohydantoin moiety is described. Biological evaluation of the new [sp.sup.2]-iminosugar-type glycomimetics has shown a strong e ffect of the nature of the substituents at the nitrogen or oxygen atoms on the glycosidase inhibitory properties.

An efficient strategy is described for the synthesis of large-ring cyclodextrin (CD) analogs alternating [alpha],[alpha]E-trehalose disaccharide subunits and pseudoamide segments (cyclotrehalans (CTs)). The higher mobility of the pseudoamide bridges when compared with classical glycosidic linkages has provided these hosts with induced fitting capabilities toward smaller guests.

A modular and efficient method for the synthesis of cyclooligosaccharide receptors consisting of [alpha],[alpha]'-trehalose building blocks linked through pseudoamide segments, namely cyclotrehalans (CTs) is described. The results based on NMR and molecular mechanics and dynamics studies showed that CTs exhibited a convex-shaped hydrophobic cavity in which the [beta]-face of the monosaccharide subunits is oriented toward the inner side.

An efficient strategy is described for the synthesis of multi-valent mannosides based on a selectively functionalized carbohydrate scaffold. Molecular dynamics on representative glyco-conjugates has shown structural features such as rigidity of the scaffold for presenting the ligands and highly flexible mannone counterparts.

The xylylene moiety is employed as a rigid tether in the spacer-mediated synthesis of difructose dianhydrides (DFAs), a unique class of bis-spiroacetal derivatives present in food products. The rigid spacer concept is implemented to favor intermolecular processes leading to higher macrocyclic architectures that incorporate the bis-spiro fructodisaccharide subunit.

The modification of the glycosidase inhibitory properties of pyrolidine homoazasugars through the incorparation of the key ring nitrogen into liner or cyclic pseudoamide functionalities is discussed. This provides a new direction to development of highly selective glycosidase inhibitors.

A practical synthesis of reducing isourea-derived azasugar glycomimetics related to the indolizidine and trehazolin glycosidase inhibitor families with different pKa values is discussed.

Studies the stereocontrolled synthesis of oxazolidine pseudo-C-nucleosides and bicyclic oxazine-2-thiones. Preparation of chiral,sugar-derived oxazolidine-2-thiones; Intramolecular cyclization of 6-deoxy-6-isothiocyanatoaldoses; Protection of the secondary hydroxyl groups.

Retinal diseases linked to inflammation are often accompanied by macrophage/microglial cells activation. However, the dynamics between M1 (pro-inflammatory) and M2 (anti-inflammatory) polarization of microglia during diabetic retinopathy (DR) has not been investigated and it might be therapeutically useful. We assessed microglia polarization in retinas from db / db mice and human diabetic donors and also the microglia-mediated anti-inflammatory effects of the bicyclic nojirimycin derivative (1 R )-1-dodecylsulfinyl-5 N ,6 O -oxomethylidenenojirimycin ( R -DS-ONJ). Visual function in mice was evaluated by electroretinogram (ERG). Expression of pro- and anti-inflammatory markers in the retina was analyzed by immunofluorescence, Western-blot and quantitative real-time PCR. Lipopolysaccharide (LPS)-mediated polarization profile was studied in Bv.2 microglial cells in the absence or presence of anti-inflammatory cytokines (IL4/IL13) or R -DS-ONJ. At 5 weeks of age, reduced ERG amplitude values of rod and mixed waves were detected in db / db compared to db /+ mice that correlated with elevated circulating endotoxemia and pro-inflammatory cytokines. At this early stage of DR, the marker of activated microglia Iba-1 co-localized with the M2 marker arginase-1 in the retina. Conversely, in retinas from 8 weeks old db / db mice Iba-1-colocalized with active caspase-1, a key component of the inflammasome, reflecting an opposite pattern of microglia polarization. Markers of activated microglia were detected in retinas of diabetic donors. Treatment of Bv.2 cells with LPS and IL4/IL13 or R -DS-ONJ switched the M1 response towards M2. In retinal explants from db / db mice, R -DS-ONJ induced a M2 response. In conclusion, the modulation of microglia polarization dynamics towards a M2 status at early stages of DR offers novel therapeutic interventions. [ABSTRACT FROM AUTHOR]

The Tn antigen (GalNAc-α-1- O -Thr/Ser) is a well-known tumor-associated carbohydrate determinant. The use of glycopeptides that incorporate this structure has become a significant and promising niche of research owing to their potential use as anticancer vaccines. Herein, the conformational preferences of a glycopeptide with an unnatural Tn antigen, characterized by a threonine decorated with an sp 2 -iminosugar-type α-GalNAc mimic, have been studied both in solution, by combining NMR spectroscopy and molecular dynamics simulations, and in the solid state bound to an anti-mucin-1 (MUC1) antibody, by X-ray crystallography. The Tn surrogate can mimic the main conformer sampled by the natural antigen in solution and exhibits high affinity towards anti-MUC1 antibodies. Encouraged by these data, a cancer vaccine candidate based on this unnatural glycopeptide and conjugated to the carrier protein Keyhole Limpet Hemocyanin (KLH) has been prepared and tested in mice. Significantly, the experiments in vivo have proved that this vaccine elicits higher levels of specific anti-MUC1 IgG antibodies than the analog that bears the natural Tn antigen and that the elicited antibodies recognize human breast cancer cells with high selectivity. Altogether, we compile evidence to confirm that the presentation of the antigen, both in solution and in the bound state, plays a critical role in the efficacy of the designed cancer vaccines. Moreover, the outcomes derived from this vaccine prove that there is room for exploring further adjustments at the carbohydrate level that could contribute to designing more efficient cancer vaccines., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A series of sp²-iminosugar glycomimetics differing in the reducing or nonreducing character, the configurational pattern (d- gluco or l- ido ), the architecture of the glycone skeleton, and the nature of the nonglycone substituent has been synthesized and assayed for their inhibition properties towards commercial glycosidases. On the basis of their affinity and selectivity towards GH1 β-glucosidases, reducing and nonreducing bicyclic derivatives having a hydroxylation profile of structural complementarity with d-glucose and incorporating an N′ -octyl-isourea or -isothiourea segment were selected for further evaluation of their inhibitory/chaperoning potential against human glucocerebrosidase (GCase). The 1-deoxynojirimycin (DNJ)-related nonreducing conjugates behaved as stronger GCase inhibitors than the reducing counterparts and exhibited potent chaperoning capabilities in Gaucher fibroblasts hosting the neuronopathic G188S/G183W mutation, the isothiourea derivative being indeed one of the most efficient chaperone candidates reported up to date (70% activity enhancement at 20 pM). At their optimal concentration, the four selected compounds promoted mutant GCase activity enhancements over 3-fold; yet, the inhibitor/chaperoning balance became unfavorable at much lower concentration for nonreducing as compared to reducing derivatives.

Fully homogeneous facial amphiphiles consisting in a cyclodextrin (CD) platform onto which a polycationic cluster and a multi-tail hydrophobic moiety have been installed (polycationic amphiphilic CDs; paCDs) self-organized in the presence of plasmid DNA to form nanometric complexes (CDplexes) which exhibit broad-range transfection capabilities. We hypothesized that biorecognizable moieties located at the hydrophilic rim in the CD scaffold would be exposed at the surface of the corresponding nanoparticles after DNA-promoted aggregation, endowing the system with molecular recognition abilities towards cell receptors. This concept has been demonstrated by developing an efficient synthetic strategy for the preparation of multivalent polycationic glyco-amphiphilic CDs (pGaCDs). Self-assembled nanoparticles obtained from mannosylated pGaCDs and pDNA (average hydrodynamic diameter 80 nm) have been shown to be specifically recognized by mannose-specific lectins, including concanavalin A (Con A) and the human macrophage mannose receptor (MMR). Further macrophage adhesion studies indicated that unspecific binding, probably due to electrostatic interactions with negatively charged cell membrane components, can also operate. The relative specific versus non-specific internalization is dependent on the pGaCD:pDNA proportion, being optimal at a protonable nitrogen/phosphate (N/P) ratio of 5. The resulting GlycoCDplexes were shown to specifically mediate transfection in Raw 264.7 (murine macrophage) cells expressing the mannose-fucose receptor in vitro. FACS experiments confirmed that transfection using these nanoparticles is mannose-dependent, supporting the potential of the approach towards vectorized gene delivery., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Concise and efficient strategies toward the synthesis of D2h- and D3h-symmetric cyclodextrin analogues alternating alpha,alpha'-trehalose disaccharide subunits and pseudoamide segments (cyclotrehalans, CTs) are reported. The conformational properties of these cyclooligosaccharides are governed by the rigidity of the alpha,alpha'-trehalose disaccharide repeating unit and the partial double-bond character of the N-(C=X) linkages. In contrast to the typical concave-shaped cavity of cyclodextrins (CDs), CTs feature a convex-shaped hydrophobic cavity in which the beta-face of the monosaccharide subunits is oriented toward the inner side, as supported by NMR and modeling (molecular mechanics and dynamics) studies. In the case of cyclodimeric CTs (CT2s), the existence of intramolecular hydrogen bonds results in collapsed cavities, too small to allow the formation of inclusion complexes with organic molecules. Cyclotrimeric CTs (CT3s) display cavity sizes that are intermediate between those of alphaCD and betaCD, ideally suited for the complexation of complementary guests with ternary symmetry such as adamantane 1-carboxylate (AC). The higher flexibility of the pseudoamide bridges as compared with classical glycosidic linkages endow these glyconanocavities with some conformational adaptability properties, making them better suited than CDs for complexation of angular guests, as seen from comparative inclusion capability experiments against the fluorescent probes 6-p-toluidinonaphthalene-2-sulfonate (TNS; linear) and 8-anilinonaphthalene-1-sulfonate (ANS; angular).