Carbonic anhydrase inhibitors: Inhibition of cytosolic/tumor-associated isoforms I, II, and IX with iminodiacetic carboxylates/hydroxamates also incorporating benzenesulfonamide moieties

The synthesis of a new class of sulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs), also possessing carboxylate/hydroxamate moieties in their molecule, is reported. These compounds may act on dual antitumor targets, the tumor-associated CA isozymes (CA IX) and some matrix metalloproteinases (MMPs). The compounds were prepared by an original method starting from iminodiacetic acid, and assayed as inhibitors of three isozymes, hCA I, II (cytosolic), and IX (transmembrane). The new derivatives showed weak inhibitory activity against isozyme I (KIs in the range of 95–8300 nM), were excellent to moderate CA II inhibitors (KIs in the range of 8.4–65 nM), and very good and selective CA IX inhibitors (KIs in the range of 3.8–26 nM). The primary sulfonamide moiety is a better zinc-binding group in the design of CAIs as compared to the carboxylate/hydroxamate one, but the presence of hydroxamate functionalities in the molecule of CAIs leads to selectivity for the tumor-associated isozyme IX over the ubiquitous, cytosolic isoform II.