Synthesis, characterization and biological evaluation of pyrazole-based benzene sulfonamides as inhibitors of human carbonic anhydrase II, IX and XII.

The aberrant level of the carbonic anhydrase isozymes is linked with various disorders which include glaucoma, epilepsy, altitude sickness and obesity. In the present study, a series of the pyrazole-based benzene sulfonamides derivatives (4a-4l) were designed, synthesized and evaluated as the inhibitors of the three isoforms of human carbonic anhydrases (hCAII, hCAIX and hCAXII). A number of the derivatives were found more active inhibitors than acetazolamide used as a standard against the human hCAII, hCAIX and hCAXII. Among the series, the compound 4k inhibited the hCAII to a submicromolar level presenting the IC 50 ± SEM concentration of 0.24 ± 0.18 μM, the inhibitor 4j reduced the activity of the hCAIX to the IC 50 ± SEM equals 0.15 ± 0.07 μM, whereas, the molecule 4g blocked the catalytic potential of the isozyme hCAXII with as low as IC 50 concentration of 0.12 ± 0.07 μM. In addition, compounds 4e and 4k were screened as the preferential inhibitors of the isoform hCAXII as compared to the hCAIX and hCAXII with half of the maximal concentrations of 0.75 ± 0.13 μM, and 0.24 ± 0.18 μM, respectively. Moreover, the compounds 4k, 4j and 4g were docked inside the active pocket of the crystallographic structure of the isoforms hCAXII, hCAIX and hCAXII, respectively. The docked inhibitors showed the binding interactions with the important amino acid residues such as Leu1198, Thr1199, His1094, and Phe1131 in hCAXII isozyme; residues Val121, Thr200, Pro203, and Gln71 in hCAIX; the amino acids Val119, Leu197, Gln89, and Asn64 in the case of hCAXII. In addition, structural geometries, reactivity descriptors, optimization energy and electronic parameters were calculated to predict the activity of the synthesized compounds.