New Zn(II) Complexes of Pyrazole-Based Ligands: Synthesis, Characterization, and Inhibition of the Activity of Isoenzymes of Carbonic Anhydrase

Two new Zn(II) complexes of (4-benzoyl-1-(3-nitrophenyl)-5-phenyl-1H-pyrazole-3-carbonyl)(5-sulfamoyl- 1,3,4-thiadiazol-2-yl)amide (L1) and (4-(ethoxycarbonyl)-1,5-diphenyl-1H-pyrazole-3-carbonyl)(5-sulfa- moyl-1,3,4-thiadiazol-2-yl)amide (L2) were synthesized. Characterization of the structure of complexes was performed using spectroscopic methods, elemental analysis, and magnetic moments. The inhibitory effects of acetazolamide (AAZ) as the control compound, free ligands (L1 and L2), and newly synthesized Zn(II) (1 and 2) complexes on hCA I and hCA II isoenzymes were investigated in vitro and IC50 values (the concentration of inhibitor producing a 50% inhibition of carbonic anhydrase activity) were compared. It was found that the in- hibitory effects of the synthesized complexes against hCA I and hCA II were greater than AAZ but slightly lower than free ligands.