Dynamic combinatorial chemistry for the multiplexed identification of glyco-dyn[n]arenes in an anti-adhesive strategy against Pseudomonas aeruginosa

Carbohydrate-protein interactions are of prime importance in cell-cell communication, signal transduction, cancer, bacterial or viral infection. Chemists have designed multivalent systems to mimick these recognition phenomena and provide potent ligands of these proteins with foreseen therapeutic applications. Dynamic combinatorial chemistry provides access to a library of chemical species in equilibrium through reversible covalent bonds. This strategy can be readily applied to the rapid and efficient identification of multivalent glycoclusters by introducing a protein into the equilibrating library for the selection of the fittest glycocluster for this protein. 1,4-Dithiophenols conjugated to monosaccharides were equilibrated into dynamic combinatorial libraries providing a diverse mixture of glycoclusters. Selection of the best ligand for different lectins (ConA, LecA and LecB from Pseudomonas aeruginosa) could increase the concentration of glyco-dyn[3]arenes and glyco-dyn[4]arenes. A key aspect of this strategy is that multiplexing can be readily achieved by using two building blocks (galactosylated and fucosylated 1,4-dithiophenols) to interrogate several lectins at once in a single experiment. These macrocyclic glycoclusters could be synthesized, isolated, then evaluated as ligands of the lectins and displayed nanomolar dissociation constants. Furthermore, while no toxicity could be detected against human cells or bacteria, their evaluation as anti-adhesive agents could be confirmed through a virulence assay on human A549 lung epithelial cells.