Multivalent Presentation of Mannose on Hyperbranched Polyglycerol and their Interaction with Concanavalin A Lectin

We describe the synthesis of multivalent mannose derivatives by using hyperbranched polyglycerols (hPG) as a scaffold with different linker structures. Grafting of protected mannose (Man) units is achieved by using Cu-1-catalyzed Huisgen click chemistry with either an anomeric azide or propargyl ether onto complementarily functionalized alkyne or azido polymer surfaces. NMR spectroscopy, dynamic light scattering (DLS), IR spectroscopy, size-exclusion chromatography (SEC), and elemental analysis have been used to characterize the hPG-Man compounds. The surface availability and bioactivity of Man-modified polymers were evaluated by using a competitive surface plasmon resonance (SPR)-based binding assay by interactions of the glycopolymers with concanavalin A (Con A), a lectin that binds mannose containing molecules. The results indicated that the novel glycoarchitectures presented in this work are efficient inhibitors of Con A-mannose recognition and resulted in inhibitor concentrations (mean IC50) from the micro-to the nanomolar range, whereas the corresponding monovalent mannoside (methyl-Man) requires millimolar concentrations. The results provide an interesting structure-activity relationship for libraries of materials that differ in the linkage of the sugar moiety presented on a biocompatible polyglycerol scaffold.