Inhibition of carbonic anhydrase isozymes I, II and IX with benzenesulfonamides containing an organometallic moiety

A novel series of benzenesulfonamides that contain ferrocenyl or ruthenocenyl moieties were synthesized and investigated for their ability to inhibit the enzymatic activity of physiologically relevant carbonic anhydrase (CA) isozymes: hCA I, II and tumour-associated IX (h = human). This manuscript describes the regioselective synthesis of both the 1,4- and 1,5-disubstituted-1,2,3-triazole benzenesulfonamides from ethynylmetallocene substrates. This is the first report describing the covalent attachment of organometallic moieties to the arylsulfonamide (ArSO2NH2) CA recognition pharmacophore. At hCA I these metallocene derivatives were either nanomolar or low micromolar inhibitors, while against hCA II and IX inhibition in the range of 9.7–80 nM and 10.3–85 nM, respectively, was observed. The ruthenocenyl derivatives gave superior CA inhibition compared to the ferrocenyl compounds across all three CA isozymes. These compounds constitute a new organometallic class of CA inhibitors with promising biological activity.