Synthesis and Biological Evaluation of 3,5-Diaryl-Substituted 1,2,4-Oxadiazole Sulfamates as Potent Steroid Sulfatase Inhibitors

A novel series of 3,5-disubstituted 1,2,4-oxadiazole sulfamates was synthesized and evaluated as steroid sulfatase (STS) inhibitors. Molecular docking predicted high affinity (binding energies of up to -8.9 kcal·mol^-1), often surpassing the reference Irosustat. Biological evaluation confirmed potent inhibition; compound <b>9n</b> reduced enzymatic STS activity to 3.5% at 10 μM. In JEG-3 cells, the most potent derivative, <b>9j</b>, exhibited an IC₅₀ of 6.64 nM, comparable to that of Irosustat (4.19 nM). Structure-activity relationship analysis revealed that the substitution pattern of the oxadiazole heterocycle plays a decisive role in determining biological activity. Shifting the aryl-sulphamate pharmacophore between positions 3- and 5- of the 1,2,4-oxadiazole heterocycle is crucial for maintaining high biological activity. These findings establish 3,5-disubstituted 1,2,4-oxadiazole sulfamates as promising leads for treating hormone-dependent cancers.