Simultaneous Grafting of 3,4,5-Trihydroxypiperidine Iminosugars Onto Multivalent Scaffolds via Double Reductive Amination Provides New GCase Inhibitors

Low-valency multivalent iminosugars have recently emerged as promising inhibitors of the therapeutically relevant enzyme β-glucocerebrosidase (GCase). A new synthetic strategy has been developed to simultaneously build more than one trihydroxypiperidine iminosugar unit onto a polyamine scaffold via double reductive amination (DRA) of a d-mannose derived dialdehyde. Five divalent derivatives, using both aliphatic and aromatic diamines and a trivalent compound based on an aromatic scaffold have been synthesized and evaluated as GCase inhibitors. Only oligomers with an aromatic core (26, 31, and 37) strongly inhibit GCase with IC50 values in the low micromolar range and activity enhancements, when compared to the monovalent counterpart, that confirm the occurrence of a positive multivalent effect. Kinetic analysis for divalent 31 and trivalent 37 revealed a mixed-type inhibition. To rationalize the unexpected behavior of 37, an integrated biophysical and computational approach based on STDNMR, docking, and MD simulations was employed, allowing to clarify the structural basis for its inhibitory profile and paving the way to the rational design of novel inhibitors able to bridge multiple interaction sites of the target enzyme.