Virtual Screening Identifies Novel Sulfonamide Inhibitors of <i>ecto</i>-5′-Nucleotidase

We aimed to identify inhibitors of <i>ecto</i>-5′-nucleotidase (<i>ecto</i>-5′-NT, CD73), a membrane-bound metallophosphoesterase that is implicated in the control of purinergic receptor signaling and a number of associated therapeutically relevant effects. Currently, only very few compounds, including ADP, its more stable analogue α,β-methylene-ADP, ATP, and anthraquinone derivatives are known to inhibit this enzyme. In the search for inhibitors with more drug-like properties, we applied a model structure-based virtual screening approach augmented by chemical similarity searching. On the basis of this analysis, 51 candidate compounds were finally selected for experimental evaluation. A total of 13 of these molecules were confirmed to have competitive inhibitory activity. The most potent inhibitor, 6-chloro-2-oxo-<i>N</i>-(4-sulfamoylphenyl)-2<i>H</i>-chromene-3-carboxylic acid amide (<b>17</b>), showed an IC₅₀ value of 1.90 μM. In contrast to the nucleotide- and anthraquinone-derived antagonists, the newly identified competitive inhibitors are uncharged at physiological pH values, possess a drug-like structure, and are structurally distinct from known active compounds