Perylenediimide-based glycoclusters as high affinity ligands of bacterial lectins: synthesis, binding studies and anti-adhesive properties.

The synthesis of eight perylenediimide-based glycoclusters was readily performed from hexa- and tetra-propargylated cores through azide-alkyne "click" conjugation. Variations in the carbohydrate epitope (Glc, Gal, Man, Fuc) and the linker arm provided molecular diversity. Interactions with LecA and LecB, two proteins involved in the adhesion of Pseudomonas aeruginosa to host tissues, were evaluated by microcalorimetry (ITC). In both cases high affinities were obtained with Kd values in the nanomolar range. Further evaluation of their anti-adhesive properties using cultured epithelial cells demonstrated their potent anti-adhesive activities against Pseudomonas aeruginosa with only 30-40% residual adhesion observed. The fluorescence properties of the PDI core were then investigated by confocal microscopy on cell-bacteria cultures. However, the red fluorescence signal of the PDI-based glycocluster was too weak to provide significant data. The present study provides another type of anti-adhesive glycocluster against bacterial infection with a large aromatic PDI core.

Supramolecular assembly of fluorogenic glyco-dots from perylenediimide-based glycoclusters for targeted imaging of cancer cells.

Supramolecular self-assembly between perylenediimide-based glycoclusters and a red-emitting fluorophore produces structurally uniform and stable glyco-dots amenable to targeted fluorogenic imaging of liver and triple-negative breast cancer cells.

Pentavalent pillar[5]arene-based glycoclusters and their multivalent binding to pathogenic bacterial lectins.

Anti-adhesive glycoclusters offer potential as therapeutic alternatives to classical antibiotics in treating infections. Pillar[5]arenes functionalised with either five galactose or five fucose residues were readily prepared using CuAAC reactions and evaluated for their binding to three therapeutically relevant bacterial lectins: LecA and Lec B from Pseudomonas aeuruginosa and BambL from Burkholderia ambifaria. Steric interactions were demonstrated to be a key factor in achieving good binding to LecA with more flexible galactose glycoclusters showing enhanced activity. In contrast binding to the fucose-selective lectins confirmed the importance of topology of the glycoclusters for activity with the pillar[5]arene ligand proving a selective ligand for BambL.

Pillar[5]arene-Based Glycoclusters: Synthesis and Multivalent Binding to Pathogenic Bacterial Lectins.

The synthesis of pillar[5]arene-based glycoclusters has been readily achieved by CuAAC conjugations of azido- and alkyne-functionalized precursors. The lectin binding properties of the resulting glycosylated multivalent ligands have been studied by at least two complementary techniques to provide a good understanding. Three lectins were selected from bacterial pathogens based on their potential therapeutic applications as anti-adhesives, namely LecA and LecB from Pseudomonas aeruginosa and BambL from Burkholderia ambifaria. As a general trend, multivalency improved the binding to lectins and a higher affinity can be obtained by increasing to a certain limit the length of the spacer arm between the carbohydrate subunits and the central macrocyclic core.

Antiadhesive properties of glycoclusters against Pseudomonas aeruginosa lung infection.

Pseudomonas aeruginosa lung infections are a major cause of death in cystic fibrosis and hospitalized patients. Treating these infections is becoming difficult due to the emergence of conventional antimicrobial multiresistance. While monosaccharides have proved beneficial against such bacterial lung infection, the design of several multivalent glycosylated macromolecules has been shown to be also beneficial on biofilm dispersion. In this study, calix[4]arene-based glycoclusters functionalized with galactosides or fucosides have been synthesized. The characterization of their inhibitory properties on Pseudomonas aeruginosa aggregation, biofilm formation, adhesion on epithelial cells, and destruction of alveolar tissues were performed. The antiadhesive properties of the designed glycoclusters were demonstrated through several in vitro bioassays. An in vivo mouse model of lung infection provided an almost complete protection against Pseudomonas aeruginosa with the designed glycoclusters.

Fucosylation of triethyleneglycol-based acceptors into 'clickable' α-fucosides.

Design of multivalent glycoconjugates can find applications such as in anti-adhesive therapy against bacterial infections. Nevertheless, the access to such macromolecules requires functionalized building blocks prepared in a minimum number of steps and on a multi-gram scale at least for the laboratory. Fucose is a representative epitope used by several bacteria for adhesion to their host cells. The stereoselective, rapid, and efficient access to two 'clickable' α-fucosides was re-investigated using PPh3/CBr4-promoted glycosylation of chloro- (as precursors of azido-) and alkyne-functionalized triethyleneglycols with fully unprotected l-fucose. The convenient access to such building blocks paves the way to the design of new multivalent glycoconjugates functionalized with fucose epitopes and their applications.