Bioorganometallic derivatives of 4-hydrazino-benzenesulphonamide as carbonic anhydrase inhibitors: synthesis, characterisation and biological evaluation.

A series of bio-organometallic-hydrazones of the general formula [{(η-CH)-C(R)=N-N(H)-CH-4-SONH}]MLn(MLn = Re(CO), Mn(CO), FeCp; R=H, CH) were prepared by reaction of formyl/acetyl organometallic precursors with 4-hydrazino-benzenesulphonamide. All compounds were characterized by conventional spectroscopic techniques (infra-red, H and C NMR, mass spectrometry and elemental analysis). Biological evaluation as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors agents was carried out using four human/h) isoforms, hCA I, II, IX and XII. The cytosolic isoforms hCA I and II were effectively inhibited by almost all derivatives with inhibition constants of 1.7-22.4 nM. Similar effects were observed for the tumour-associated transmembrane isoform hCA XII (Ks of 1.9-24.4 nM). hCA IX was less sensitive to inhibition with these compounds. The presence of bio-organometallic or metallo-carbonyl moieties in the molecules of these CAIs makes them amenable for interesting pharmacologic applications, for example for compounds with CO donating properties.