3-Aminobenzenesulfonamides incorporating acylthiourea moieties selectively inhibit the tumor-associated carbonic anhydrase isoform IX over the off-target isoforms I, II and IV

We describe the synthesis of a series of novel 1-aroyl/acyl-3-(3-aminosulfonylphenyl) thioureas (4a-k) acting as human carbonic anhydrase (hCA, EC 4.2.1.1) inhibitors. Reaction of alkyl/aryl isothiocyanates with 3-amino-benzenesulfonamide afforded a series of the title compounds incorporating a variety of short as well as highly lipophilic long tails. The newly synthesized sulfonamides were evaluated against 4 physiologically relevant CA isoforms (hCA I, II, IV, and IX). Several compounds showed interesting inhibitory activity. The tumor-associated hCA IX was the most sensitive isoform to inhibition with these compounds, with K(I)s in the range of 21.5-44.0 nM and selectivity ratios over the major cytosolic isoform hCA II in the range of 3.35-37.3. The sulfonamides incorporating the phenylacetylthioureido and pentadecanoylthioureido moieties were the most hCA IX-selective inhibitors detected in this work, making them of interest for further investigations.