Investigation of carbonic anhydrase inhibitory effects and cytotoxicities of pyrazole-based hybrids carrying hydrazone and zinc-binding benzenesulfonamide pharmacophores.

Pyrazole-based carbohydrazone hybrids have been considered to be a remarkable class of compounds in pharmaceutical chemistry. Here, we reported bioactivities of 4-(3-(2-(arylidene)hydrazin-1-carbonyl)-5-phenyl-1H-pyrazol-1-yl)benzenesulfonamides (1-27) towards CA isoenzymes (hCA I, hCA II, hCA IX) and human oral squamous cell carcinoma cell line. Compounds 19 (Ki = 10.1 nM, hCA I/hCA IX = 749.6), 22 (Ki = 18.5 nM, hCA I/hCA IX = 429.2), 26 (Ki = 14.5 nM, hCA I/hCA IX = 596.9), 27 (Ki = 21.5 nM, hCA I/hCA IX = 413.1) were more potent and selective inhibitors of cancer-associated hCA IX isoenzyme. Compounds 22 and 26 were also found to be approximately three times more selective hCA IX inhibitors over off-target hCA II at low nanomolar. Compounds 19, 22, 23, 24, and 26 with IC50 of 1.6-1.7 μM showed potent cytotoxicity against human oral squamous cell carcinoma cell line as compared with human gingival fibroblast, producing the tumor-specificity value over 100. This was due to its cytostatic growth inhibition accompanied by a slight but significant dose-dependent increase in cell shrinkage and subG1 cell accumulation and marginal activation of caspase 3 substrates. Bioassay results showed that carbohydrazone-based hybrids could be useful candidates to design novel anticancer compounds and selective carbonic anhydrase inhibitors.