Neoglycopolymers produced by aqueous ring-opening metathesis polymerization: Decreasing saccharide density increases activity

Non-natural carbohydrate-bearing polymers are emerging as important materials for the investigation of multivalent carbohydrate-protein interactions. In the present study, neoglycopolymers were generated via aqueous ring-opening metathesis polymerizations. A procedure employing a ruthenium catalyst, preformed by treating a small quantity of the monomer with RuCl₃, reduced metal contamination in the products. To examine the effect of sugar residue density on polymer function, materials bearing one or two sugar ligands per repeat unit were synthesized. These polymers were tested for their ability to inhibit the erythrocyte agglutinating activity of the carbohydrate-binding protein, concanavalin A. The polymers with lower sugar density were found to be more potent inhibitors than polymers with higher density, a result that can be rationalized by analysis of the protein and polymer structures.