New syntheses of thiosaccharides utilizing substitution reactions

Novel synthetic methods published since 2005 affording carbohydrates containing sulfur atom(s) are reviewed. The review is divided to subchapters based on the position of sulfur atom(s) in the sugar molecule. Only those methods that take advantage of substitution are discussed.

The Impact of Nanomaterial Morphology on Modulation of Carbohydrate-Protein Interactions

Carbohydrate-protein interactions (CPIs) play a crucial role in the regulation of various physiological and pathological processes within living systems. However, these interactions are typically weak, prompting the development of multivalent probes, including nanoparticles and polymer scaffolds, to enhance the avidity of CPIs. Additionally, the morphologies of glyco-nanostructures can significantly impact protein binding, bacterial adhesion, cellular internalization, and immune responses. In this review, we have examined the advancements in glyco-nanostructures of different shapes that modulate CPIs. We specifically emphasize glyco-nanostructures constructed from small-molecule amphiphilic carbohydrates, block copolymers, metal-based nanoparticles, and carbon-based materials, highlighting their potential applications in glycobiology.

Visible light-induced functionalization of indazole and pyrazole: a recent update

Indazole and pyrazole are renowned as a prodigious class of heterocycles having versatile uses in medicinal as well as industrial chemistry. Considering sustainable approaches, recently, photocatalysis has become an indispensable tool in organic chemistry due to its application for the activation of small molecules and the use of a clean energy source. In this review, we have highlighted the use of metal-based photocatalysts, organic photoredox catalysts, energy transfer photocatalysts and electron-donor-acceptor complexes in the functionalization of indazole and pyrazole. This perspective is arranged based on the types of functionalization reactions on indazole and pyrazole. A detailed discussion regarding the reaction mechanism of each reaction is given to provide a comprehensive guide to the reader. Finally, a summary of existing challenges and the future outlook towards the development of efficient photocatalytic methods for functionalization of these heterocycles is also presented.

Copper catalyzed reaction of alcohols, alkyl halides and Na2S2O3: An odorless and ligand-free rout to unsymmetrical thioether synthesis

A CuI-catalyzed condensation reaction between alcohols, alkyl halides, and Na2S2O3 leading to structurally diverse thioethers is reported. A variety of alkyl halides and electron-rich benzyl alcohols were employed successfully in...

The disulfide bond as a key motif for the construction of multivalent glycoclusters

S-Glycosylated dendrons having a thioacetate group in their focal points led to multivalent glycoclusters by spontaneous O2-oxidation of sulfides.

Synthesis of Glycodendrimers with Antiviral and Antibacterial Activity

Glycodendrimers are an important class of synthetic macromolecules that can be used to mimic many structural and functional features of cell-surface glycoconjugates. Their carbohydrate moieties perform key important functions in bacterial and viral infections, often regulated by carbohydrate-protein interactions. Several studies have shown that the molecular structure, valency and spatial organisation of carbohydrate epitopes in glycoconjugates are key factors in the specificity and avidity of carbohydrate-protein interactions. Choosing the right glycodendrimers almost always helps to interfere with such interactions and blocks bacterial or viral adhesion and entry into host cells as an effective strategy to inhibit bacterial or viral infections. Herein, the state of the art in the design and synthesis of glycodendrimers employed for the development of anti-adhesion therapy against bacterial and viral infections is described.

Click Chemistry Enabling Covalent and Non-Covalent Modifications of Graphene with (Poly)saccharides

Graphene is a material with outstanding properties and numerous potential applications in a wide range of research and technology areas, spanning from electronics, energy materials, sensors, and actuators to life-science and many more. However, the insolubility and poor dispersibility of graphene are two major problems hampering its use in certain applications. Tethering mono-, di-, or even poly-saccharides on graphene through click-chemistry is gaining more and more attention as a key modification approach leading to new graphene-based materials (GBM) with improved hydrophilicity and substantial dispersibility in polar solvents, e.g., water. The attachment of (poly)saccharides on graphene further renders the final GBMs biocompatible and could open new routes to novel biomedical and environmental applications. In this review, recent modifications of graphene and other carbon rich materials (CRMs) through click chemistry are reviewed.

Recent Advances in Iodine-Promoted C-S/N-S Bonds Formation

Sulfur-containing scaffold, as a ubiquitous structural motif, has been frequently used in natural products, bioactive chemicals and pharmaceuticals, particularly C-S/N-S bonds are indispensable in many biological important compounds and pharmaceuticals. Development of mild and general methods for C-S/N-S bonds formation has great significance in modern research. Iodine and its derivatives have been recognized as inexpensive, environmentally benign and easy-handled catalysts or reagents to promote the construction of C-S/N-S bonds under mild reaction conditions, with good regioselectivities and broad substrate scope. Especially based on this, several new strategies, such as oxidation relay strategy, have been greatly developed and accelerated the advancement of this field. This review focuses on recent advances in iodine and its derivatives promoted hybridized C-S/N-S bonds formation. The features and mechanisms of corresponding reactions are summarized and the results of some cases are compared with those of previous reports. In addition, the future of this domain is discussed.

Gold-Speckled SPION@SiO2 Nanoparticles Decorated with Thiocarbohydrates for ASGPR1 Targeting: Towards HCC Dual Mode Imaging Potential Applications

Efforts are made to perform an early and accurate detection of hepatocellular carcinoma (HCC) by simultaneous exploiting multiple clinically non-invasive imaging modalities. Original nanostructures derived from the combination of different inorganic domains can be used as efficient contrast agents in multimodal imaging. Superparamagnetic iron oxide nanoparticles (SPIONs) and Au nanoparticles (NPs) possess well-established contrasting features in magnetic resonance imaging (MRI) and X-ray computed tomography (CT), respectively. HCC can be targeted by using specific carbohydrates able to recognize asialoglycoprotein receptor 1 (ASGPR1) overexpressed in hepatocytes. Here, two different thiocarbohydrate ligands were purposely designed and alternatively conjugated to the surface of Au-speckled silica-coated SPIONs NPs, to achieve two original nanostructures that could be potentially used for dual mode targeted imaging of HCC. The results indicated that the two thiocarbohydrate decorated nanostructures possess convenient plasmonic/superparamagnetic properties, well-controlled size and morphology and good selectivity for targeting ASGPR1 receptor.

Carbohydrate supramolecular chemistry: beyond the multivalent effect

(Hetero)multivalency acts as a multichannel switch that shapes the supramolecular properties of carbohydrates in an intrinsically multifactorial biological context.

Stereoselective Epimerizations of Glycosyl Thiols

Glycosyl thiols are widely used in stereoselective S-glycoside synthesis. Their epimerization from 1,2-trans to 1,2-cis thiols (e.g., equatorial to axial epimerization in thioglucopyranose) was attained using TiCl₄, while SnCl₄ promoted their axial-to-equatorial epimerization. The method included application for stereoselective β-d-manno- and β-l-rhamnopyranosyl thiol formation. Complex formation explains the equatorial preference when using SnCl₄, whereas TiCl₄ can shift the equilibrium toward the 1,2-cis thiol via 1,3-oxathiolane formation.

Controlling Ligand Spacing on Surface: Polyproline-Based Fluorous Microarray as a Tool in Spatial Specificity Analysis and Inhibitor Development for Carbohydrate-Protein Interactions

Multivalent carbohydrate-protein interactions are essential for many biological processes. Convenient characterization for multivalent binding property of proteins will aid the development of molecules to manipulate these processes. We exploited the polyproline helix II (PPII) structure as molecular scaffolds to adjust the distances between glycan ligand attachment sites at 9, 18, and 27 Å on a peptide scaffold. Optimized fluorous groups were also introduced to the peptide scaffold for immobilization to the microarray surface through fluorous interaction to control the orientation of the helical scaffolds. Using lectin LecA and antibody 2G12 as model proteins, the binding preference to the 27 Å glycopeptide scaffold, matched the distance of 26 Å between its two galactose binding sites on LecA and 31 Å spacing between oligomannose binding sites on 2G12, respectively. We further demonstrate this microarray system can aid the development of inhibitors by transforming the selected surface-bound scaffold into multivalent ligands in solution. This strategy can be extended to analyze proteins that lacking structural information to speed up the design of potent and selective multivalent ligands.

Cu0-Loaded organo-montmorillonite with improved affinity towards hydrogen: an insight into matrix-metal and non-contact hydrogen-metal interactions

Copper-loaded organo-montmorillonite showed improved affinity towards hydrogen under ambient conditions. Clay ion exchange with a propargyl-ended cation followed by thiol-yne coupling with thioglycerol resulted in a porous structure with a 6 fold higher specific surface area, which dramatically decreased after copper incorporation. X-ray diffraction and photoelectron spectrometry, nuclear magnetic resonance (¹H and ¹³C) and CO₂-thermal programmed desorption revealed strong sulfur:Cu⁰ and oxygen:Cu⁰ interactions. This was explained in terms of structure compaction that 'traps' Cu⁰ nanoparticles (CuNPs) and reduces their mobility. Transmission electron microscopy showed predominant 1.0-1.5 nm CuNPs. Hydrogen capture appears to involve predominantly physical interaction, since differential scanning calorimetry measurements gave low desorption heat and almost complete gas release between 20 °C and 75 °C. Possible hydrogen condensation within the compacted structure should hinder gas diffusion inside CuNPs and prevent chemisorption. These results allow safe hydrogen storage with easy gas release to be envisaged even at room temperature under vacuum. The reversible capture of hydrogen can be even more attractive when using natural inorganic supports and commercial plant-derived dendrimers judiciously functionalized, even at the expense of porosity.

Multivalency as an action principle in multimodal lectin recognition and glycosidase inhibition: a paradigm shift driven by carbon-based glyconanomaterials

The last decade has witnessed a series of discoveries that question the traditional paradigm of multivalency as a "safe" strategy to enhance the binding affinity of a lectin receptor to its cognate carbohydrate ligand. Upon following the initial reports on the supplementary effects operating in the presence of a third carbohydrate species (heteromultivalent effect), the observation of functional promiscuity of glyco(mimetic)ligands elicited by (hetero)multivalency, spreading from lectins to glycoprocessing enzymes (inhibitory multivalent effect), has raised concerns about the potential consequences of glyconanomaterials binding to non-cognate proteins and creating messiness or noise in the processes they participate in. Carbon-based glycomaterials, specifically glyconanodiamonds and glycofullerenes, have been instrumental in increasing our awareness of the frequency of these lectin-enzyme crosstalk behaviours elicited by multivalency, driving a reformulation of the rules and concepts in glycoscience towards a "generalized multivalency" scenario.

Synthesis of β-galactosylamides as ligands of the peanut lectin. Insights into the recognition process

The synthesis of mono and divalent β-galactosylamides linked to a hydroxylated chain having a C2 symmetry axis derived from l-tartaric anhydride is reported. Reference compounds devoid of hydroxyl groups in the linker were also prepared from β-galactosylamine and succinic anhydride. After functionalization with an alkynyl residue, the resulting building blocks were grafted onto different azide-equipped scaffolds through the copper catalyzed azide-alkyne cycloaddition. Thus, a family of structurally related mono and divalent β-N-galactopyranosylamides was obtained and fully characterized. The binding affinities of the ligands towards the model lectin PNA were measured by the enzyme-linked lectin assay (ELLA). The IC₅₀ values were significantly higher than that of galactose but the presence of hydroxyl groups in the aglycone chain improved lectin recognition. Docking and molecular dynamics experiments were in accordance with the hypothesis that a hydroxyl group properly disposed in the linker could mimic the Glc O3 in the recognition process. On the other hand, divalent presentation of the ligands led to lectin affinity enhancements.

Chirality inversion, supramolecular hydrogelation and lectin binding of two thiolactose amphiphiles constructed on a di-lauroyl-l-tartaric acid scaffold

The supramolecular self-assembly mode of two diacyl-glycoamphiphiles depends on the length of the flexible achiral ethoxylated linker.

Regioselective thiolation of electron rich arenes and heterocycles in recyclable catalytic media

A convenient and novel approach has been developed for the synthesis of unsymmetrical diaryl sulfides by the reaction of sulfonyl hydrazides with phenols, aromatic amines and heterocycles using a [Bmim][Br] ionic liquid through C–S bonds formation.

Cu-Catalyzed first direct access towards 3-sulfenylindoles from aryl halides

The copper-catalyzed cross-coupling of indole derivatives with aryl halides in the presence of thiourea proceeds to give 3-sulfenylindoles in DMSO at 120 °C.

Assessing the effect of different shapes of glyco-gold nanoparticles on bacterial adhesion and infections

Achieving selective and sensitive carbohydrate-protein interactions (CPIs) using nanotechnology is an intriguing area of research. Here we demonstrate that the different shapes of gold nanoparticles (AuNPs) functionalized with monosaccharides tune the bacterial aggregations. The mechanism of aggregation revealed that the large number of surface interactions of rod shaped mannose-AuNPs with E. coli ORN 178 compared with spherical and star-shaped AuNPs exhibited higher avidity and sensitivity. Moreover, such sensitive binding can be used for effective inhibition of bacterial infection of cells.

Switching of carbohydrate nanofibers for regulating cell proliferation

We report switchable, fluorescent carbohydrate nanofibers formed through the self-assembly of aromatic rod amphiphiles with a combination of mannose epitopes and thermoresponsive oligoether dendrons. The carbohydrate nanofibers undergo reversible switching between carbohydrate-exposed and hidden states on their surface in response to a thermal signal, and have the ability to regulate cell proliferation.

TBAI–HBr system mediated generation of various thioethers with benzenesulfonyl chlorides in PEG400

An efficient procedure was developed for the synthesis of aryl sulfides in good to excellent yields using TBAI–HBr system promoted direct sulfenylation of various compounds, such as phenols, pyrazolones, indoles and related heteroarenes.

Synthesis of 1D-glyconanomaterials by a hybrid noncovalent-covalent functionalization of single wall carbon nanotubes: a study of their selective interactions with lectins and with live cells

To take full advantage of the remarkable applications of carbon nanotubes in different fields, there is a need to develop effective methods to improve their water dispersion and biocompatibility while maintaining their physical properties. In this sense, current approaches suffer from serious drawbacks such as loss of electronic structure together with low surface coverage in the case of covalent functionalizations, or instability of the dynamic hybrids obtained by non-covalent functionalizations. In the present work, we examined the molecular basis of an original strategy that combines the advantages of both functionalizations without their main drawbacks. The hierarchical self-assembly of diacetylenic-based neoglycolipids into highly organized and compacted rings around the nanotubes, followed by photopolymerization leads to the formation of nanotubes covered with glyconanorings with a shish kebab-type topology exposing the carbohydrate ligands to the water phase in a multivalent fashion. The glyconanotubes obtained are fully functional, and able to establish specific interactions with their cognate receptors. In fact, by taking advantage of this selective binding, an easy method to sense lectins as a working model of toxin detection was developed based on a simple analysis of TEM images. Remarkably, different experimental settings to assess cell membrane integrity, cell growth kinetics and cell cycle demonstrated the cellular biocompatibility of the sugar-coated carbon nanotubes compared to pristine single-walled carbon nanotubes.

Structural Insight into Multivalent Galactoside Binding to Pseudomonas aeruginosa Lectin LecA

Multivalent galactosides inhibiting Pseudomonas aeruginosa biofilms may help control this problematic pathogen. To understand the binding mode of tetravalent glycopeptide dendrimer GalAG2 [(Gal-β-OC6H4CO-Lys-Pro-Leu)4(Lys-Phe-Lys-Ile)2Lys-His-Ile-NH2] to its target lectin LecA, crystal structures of LecA complexes with divalent analog GalAG1 [(Gal-β-OC6H4CO-Lys-Pro-Leu)2Lys-Phe-Lys-Ile-NH2] and related glucose-triazole linked bis-galactosides 3u3 [Gal-β-O(CH2)n-(C2HN3)-4-Glc-β-(C2HN3)-[β-Glc-4-(N3HC2)]2-(CH2)n-O-β-Gal (n = 1)] and 5u3 (n = 3) were obtained, revealing a chelate bound 3u3, cross-linked 5u3, and monovalently bound GalAG1. Nevertheless, a chelate bound model better explaining their strong LecA binding and the absence of lectin aggregation was obtained by modeling for all three ligands. A model of the chelate bound GalAG2·LecA complex was also obtained rationalizing its unusually tight LecA binding (KD = 2.5 nM) and aggregation by lectin cross-linking. The very weak biofilm inhibition with divalent LecA inhibitors suggests that lectin aggregation is necessary for biofilm inhibition by GalAG2, pointing to multivalent glycoclusters as a unique opportunity to control P. aeruginosa biofilms.

Biologically Active Heteroglycoclusters Constructed on a Pillar[5]arene-Containing [2]Rotaxane Scaffold

A synthetic approach combining recent concepts for the preparation of multifunctional nanomolecules (click chemistry on multifunctional scaffolds) with supramolecular chemistry (self‐assembly to prepare rotaxanes) gave easy access to a large variety of sophisticated [2]rotaxane heteroglycoclusters. Specifically, compounds combining galactose and fucose have been prepared to target the two bacterial lectins (LecA and LecB) from the opportunistic pathogen Pseudomonas aeruginosa.

Recent advances in click chemistry applied to dendrimer synthesis

Dendrimers are monodisperse polymers grown in a fractal manner from a central point. They are poised to become the cornerstone of nanoscale devices in several fields, ranging from biomedicine to light-harvesting. Technical difficulties in obtaining these molecules has slowed their transfer from academia to industry. In 2001, the arrival of the "click chemistry" concept gave the field a major boost. The flagship reaction, a modified Hüisgen cycloaddition, allowed researchers greater freedom in designing and building dendrimers. In the last five years, advances in click chemistry saw a wider use of other click reactions and a notable increase in the complexity of the reported structures. This review covers key developments in the click chemistry field applied to dendrimer synthesis from 2010 to 2015. Even though this is an expert review, basic notions and references have been included to help newcomers to the field.

Functionalization of a Rigid Divalent Ligand for LecA, a Bacterial Adhesion Lectin

The bacterial adhesion lectin LecA is an attractive target for interference with the infectivity of its producer P. aeruginosa. Divalent ligands with two terminal galactoside moieties connected by an alternating glucose-triazole spacer were previously shown to be very potent inhibitors. In this study, we chose to prepare a series of derivatives with various new substituents in the spacer in hopes of further enhancing the LecA inhibitory potency of the molecules. Based on the binding mode, modifications were made to the spacer to enable additional spacer–protein interactions. The introduction of positively charged, negatively charged, and also lipophilic functional groups was successful. The compounds were good LecA ligands, but no improved binding was seen, even though altered thermodynamic parameters were observed by isothermal titration calorimetry (ITC).

Inhibition of type 1 fimbriae-mediated Escherichia coli adhesion and biofilm formation by trimeric cluster thiomannosides conjugated to diamond nanoparticles

Recent advances in nanotechnology have seen the development of a number of microbiocidal and/or anti-adhesive nanoparticles displaying activity against biofilms. In this work, trimeric thiomannoside clusters conjugated to nanodiamond particles (ND) were targeted for investigation. NDs have attracted attention as a biocompatible nanomaterial and we were curious to see whether the high mannose glycotope density obtained upon grouping monosaccharide units in triads might lead to the corresponding ND-conjugates behaving as effective inhibitors of E. coli type 1 fimbriae-mediated adhesion as well as of biofilm formation. The required trimeric thiosugar clusters were obtained through a convenient thiol-ene "click" strategy and were subsequently conjugated to alkynyl-functionalized NDs using a Cu(I)-catalysed "click" reaction. We demonstrated that the tri-thiomannoside cluster-conjugated NDs (ND-Man3) show potent inhibition of type 1 fimbriae-mediated E. coli adhesion to yeast and T24 bladder cells as well as of biofilm formation. The biofilm disrupting effects demonstrated here have only rarely been reported in the past for analogues featuring such simple glycosidic motifs. Moreover, the finding that the tri-thiomannoside cluster (Man3N3) is itself a relatively efficient inhibitor, even when not conjugated to any ND edifice, suggests that alternative mono- or multivalent sugar-derived analogues might also be usefully explored for E. coli-mediated biofilm disrupting properties.

Dendritic glycopolymers based on dendritic polyamine scaffolds: view on their synthetic approaches, characteristics and potential for biomedical applications

The potential of dendritic glycopolymers based on dendritic polyamine scaffolds for biomedical applications is presented and compared with that of the structurally related anti-adhesive dendritic glycoconjugates.

Major Advances in the Development of Synthetic Oligosaccharide-Based Vaccines

Because of their involvement in a variety of different biological processes and their occurrence onto pathogens and malignant cell surface, carbohydrates have been identified as ideal candidates for vaccine formulation. However, as free oligosaccharides are poorly immunogenic and do not induce immunological memory in the most at risk population (infants and young children, elderly and immunocompromised patients), glycoconjugate vaccines containing the same carbohydrate antigen covalently linked to an immunogenic carrier protein have gained a prominent role. Accordingly, a number of glycoconjugate vaccines mostly directed against infections caused by bacterial pathogens have been licensed and are currently available on the market. However, also glycoconjugate vaccines suffer from significant drawbacks. The challenging procedures required for the isolation and purification of the carbohydrate antigen from its natural source often lead to poor homogeneity and presence of biological contaminants, resulting in batch-to-batch variability. Moreover, in some cases, the overwhelming immunogenicity of the carrier protein may induce the carbohydrate epitope suppression, causing hyporesponsiveness. The development of synthetic oligosaccharide-based vaccine candidates, characterized by the presence of pure and well-defined synthetic oligosaccharide structures, is expected to meet the requirement of homogeneous and highly reproducible preparations.

In the present chapter, we report on the major advances in the development of synthetic carbohydrate-based vaccines. First of all, we describe different strategies developed during the last years to circumvent the inherent difficulties of classical oligosaccharide synthesis, such as the one-pot glycosylation and the solid-phase synthesis, and their application to the preparation of carbohydrate antigens apt to conjugation with protein carriers. Next, we discuss the most representative methodologies employed for the chemical ligation of oligosaccharide structures to proteins. Finally, in the last section, we report significant examples of fully synthetic vaccines exploiting the multivalency effect. These constructs are based on the concept that the conjugation of multiple copies of synthetic oligosaccharide antigens to multivalent scaffolds, such as dendrimers, (cyclo)peptides, gold nanoparticles, and calixarenes, raises cooperative interactions between carbohydrates and immune receptors, leading to strong enhancement of the saccharide antigen immunogenicity.

Glyconanosynthons as powerful scaffolds and building blocks for the rapid construction of multifaceted, dense and chiral dendrimers

The arsenal of available carbohydrates can be manipulated to provide versatile building blocks toward the syntheses of complex and chiral dendrimers.

Iodine-mediated thiolation of phenol/phenylamine derivatives and sodium arylsulfinates in neat water

An efficient and convenient protocol for iodine-mediated thiolation of phenols/phenylamines with sodium benzene-sulfinates in water has been achieved.

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

In this work we describe the synthesis of mono- and divalent β-N- and β-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 βGalp 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 βGalp 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.

Are glycan biosensors an alternative to glycan microarrays?

Complex carbohydrates (glycans) play an important role in nature and study of their interaction with proteins or intact cells can be useful for understanding many physiological and pathological processes. Such interactions have been successfully interrogated in a highly parallel way using glycan microarrays, but this technique has some limitations. Thus, in recent years glycan biosensors in numerous progressive configurations have been developed offering distinct advantages compared to glycan microarrays. Thus, in this review advances achieved in the field of label-free glycan biosensors are discussed.

Expeditive synthesis of trithiotriazine-cored glycoclusters and inhibition of Pseudomonas aeruginosa biofilm formation

Readily accessible, low-valency glycoclusters based on a triazine core bearing D-galactose and L-fucose epitopes are able to inhibit biofilm formation by Pseudomonas aeruginosa. These multivalent ligands are simple to synthesize, are highly soluble, and can be either homofunctional or heterofunctional. The galactose-decorated cluster shows good affinity for Pseudomonas aeruginosa lectin lecA. They are convenient biological probes for investigating the roles of lecA and lecB in biofilm formation.