4-Dehydroxymethyl-4-C-biphenyl-DAB derivatives: Introduction of a biphenyl group at the C4 position shifts the binding selectivity, resulting in improved affinity for lysosomal acid β-glucocerebrosidase

Pharmacological chaperones can enhance the stability of the three-dimensional structure by reversibly binding to the active site of mutant enzymes, thereby promoting maturation within the cell and transport to the lysosome. This study provides an example of a high-affinity ligand design strategy for lysosomal acid β-glucocerebrosidase (GCase), focusing on introducing a biphenyl substituent at the C4 position of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) in place of the native hydroxymethyl group. The introduction of a p-CF₃-biphenyl group at the C4 position shifted the binding selectivity of DAB from α-glucosidase to β-glucosidase while simultaneously increasing binding affinity by 4289-fold compared to DAB, exhibiting nanomolar affinity (K_i = 0.045 μM). These findings suggest a novel possibility that contradicts the conventional view that modification of the hydroxymethyl group at the C4 position of the pyrrolidine ring inevitably leads to loss of sugar recognition ability and a consequent decrease in binding affinity. The docking models and molecular dynamics simulations showed that para-trifluoromethyl substitution restricts the mobility of the B-ring of the biphenyl moiety within the hydrophobic pocket of GCase. This interaction of the para-trifluoromethyl group and the hydrophobic pocket stabilises the active site architecture and markedly suppresses dynamic fluctuations of loop 1 and loop 2 compared with fluctuations observed in the isofagomine complex, thereby contributing to enhanced thermodynamic stabilisation of the enzyme. 4-Dehydroxymethyl-4-C-(p-CF₃-biphenyl)-DAB (6e) dose dependently increased intracellular GCase activity in V394L and L444P mutant cells. It is noteworthy that the effective dose was about 10-fold lower than that for isofagomine. Therefore, 4-dehydroxymethyl-4-C-(p-CF₃-biphenyl)-DAB (6e) is expected to increase intracellular mutant enzyme activity and may represent a useful therapeutic option for the treatment of Gaucher disease.