Carbonic anhydrase inhibitors. Synthesis of 2,4,6-trimethylpyridinium derivatives of 2-(hydrazinocarbonyl)-3-aryl-1H-indole-5-sulfonamides acting as potent inhibitors of the tumor-associated isoform IX and XII

KI (hCA I) = 7.6 nM; KI (hCA II) = 65 nM, KI (hCA IX) = 8.3 nM; KI (hCA XII) = 9.5 nM.