1,6-epi-Cyclophellitol Cyclosulfamidate Is a Bona Fide Lysosomal α-Glucosidase Stabilizer for the Treatment of Pompe Disease

alpha-Glucosidase inhibitors are potential therapeutics for the treatment of diabetes, viral infections, and Pompe disease. Herein, we report a 1,6-epi-cyclophellitol cyclosulfamidate as a new class of reversible alpha-glucosidase inhibitors that displays enzyme inhibitory activity by virtue of its conformational mimicry of the substrate when bound in the Michaelis complex. The alpha-D-glc-configured cyclophellitol cyclosulfamidate 4 binds in a competitive manner the human lysosomal acid alpha-glucosidase (GAA), ER alpha- glucosidases, and, at higher concentrations, intestinal alpha-glucosi-dases, displaying an excellent selectivity over the human beta- glucosidases GBA and GBA2 and glucosylceramide synthase (GCS). Cyclosulfamidate 4 stabilizes recombinant human GAA (rhGAA, alglucosidase alfa, Myozyme) in cell medium and plasma and facilitates enzyme trafficking to lysosomes. It stabilizes rhGAA more effectively than existing small-molecule chaperones and does so in vitro, in cellulo, and in vivo in zebrafish, thus representing a promising therapeutic alternative to Miglustat for Pompe disease.