Design and synthesis of polyhydroxylated azabicyclo[3.3.1]nonane as selective lysosomal α-glucosidase stabilizers enhancing cellular uptake

This study presents an efficient synthetic strategy for developing polyhydroxylated azabicyclo[3.3.1]nonane derivatives as selective lysosomal α-glucosidase (GAA) stabilizers. We synthesized the target bridged bicyclic iminosugars through an intramolecular [3 + 2] cycloaddition of monocyclic allyl aldonitrones, followed by NO bond cleavage. These iminosugars showed potent and selective inhibition of GAA, and their distinct conformations were closely linked to inhibitory potency. Enzyme-based evaluations demonstrated that iminosugar 15, which adopts a chair-chair conformation, was the most potent inhibitor (Ki = 0.7 μM) and provided superior GAA stabilization, as demonstrated by thermal shift and enzyme inactivation assays. Additionally, cell-based studies confirmed that iminosugars 11 and 15 effectively enhanced GAA uptake, resulting in a 2.2 and 3.7-fold increase, respectively, in Pompe fibroblasts. Our findings reveal that bridged bicyclic iminosugars represent a promising class of enzyme stabilizers for lysosomal storage diseases, particularly Pompe disease, by improving enzyme stability and cellular uptake.