Investigating the Inhibitory Properties of Diazo and Pyrazole‐Carboxamide‐Linked Benzenesulfonamides Against Carbonic Anhydrase Isoforms I, II, IX, and XII

A novel library of diazo and pyrazole‐carboxamide‐linked molecules containing the sulfonamide pharmacophore was developed and synthesized, yielding selective inhibitors of clinically relevant carbonic anhydrase (CA) isoforms. The synthesis method involved the production of diazonium salts from 4‐ and 3‐aminobenzenesulfonamide precursors, followed by cyclization and further functionalization to yield structurally diverse pyrazole derivatives. All compounds were evaluated for their inhibitory efficacy against hCA I and II (cytosolic isoforms) and the tumor‐associated isoenzymes hCA IX and XII; also, cytotoxicity and molecular modeling studies were conducted for the compounds. The newly synthesized hybrid compounds displayed extensive inhibitory activity, with most derivatives showing significant potency and selectivity for cancer‐associated isoforms. More specifically, para‐substituted analogs exhibited enhanced inhibitory properties relative to their meta‐substituted counterparts. Compound 5f , with a 3,4‐dichloro motif, exhibited the highest activity with a very low K I value of 1.8 nM against hCA IX, greatly surpassing the reference drug acetazolamide. Electron‐withdrawing substituents improved inhibitory efficacy, whereas electron‐donating groups often reduced activity. Furthermore, compounds 5f (A549: 41.17 μM; HCT116: 4.47 μM) and 6c (A549: 14.64 μM; HCT116: 4.03 μM) showed the lowest IC 50 values in both cell lines. The findings emphasize diazo‐ and pyrazole‐carboxamide‐linked benzenesulfonamides as promising scaffolds for advancing isoform‐selective carbonic anhydrase inhibitors.