Carbonic anhydrases (CAs) are known as a drug-target enzymes. The inhibitors of the enzyme are important compounds for discovering new therapeutic agents and understanding in detail protein-drug interactions at the molecular level. For this purpose, the in vitro effects of some anti-inflammatory agents such as tenoxicam, fluorometholone acetate, and dexamethasone were investigated on esterase activity of human erythrocyte CA-I and CA-II in this study. hCA-I and hCA-II were purified by affinity chromatography with a yield of 47.25% and 87%, and a specific activity of 642.8 EU/mg proteins and 5576.9 EU/mg proteins, respectively. SDS-PAGE was performed to determine the purity of the enzymes. Inhibitory effects of the drugs on hCA-I and hCA-II were determined by spectrophotometric method. IC50 values for hCA-I and hCA-II were 0.198, 2.18, 11.7, 0.11, 17.5 and 14 μm using tenoxicam, fluorometholone acetate, and dexamethasone, respectively. For fluorometholone acetate and dexamethasone, Ki values from Lineweaver-Burk plots were obtained as 1.044 and 21.2 μm (noncompetitive) for hCA-I and 9.98 and 8.66 μm (non-competitive) for hCA-II. In conclusion, tenoxicam, fluorometholone acetate, and dexamethasone showed potent inhibitory effects on esterase activity of hCA-I and hCA-II isozymes under in vitro conditions.
In this study a series of pyrazole-3,4-dicarboxamide (3-10) derivatives bearing sulfonamide moiety were synthesized starting from 1-(3-nitrophenyl)-5-phenyl-1H-pyrazole-3,4-dicarboxylic acid (1). The structures of synthesized molecules were characterized by FT-IR, 1 H NMR, 13 C NMR, and elemental analysis methods. Human carbonic anhydrase isoenzymes (hCA I and hCA II) were purified separately from erythrocyte cells by the Sepharose-4B-L-tyrosine-sulfa nilamide affinity column chromatography and inhibitory effects of newly synthesized sulfonamides on esterase activities of these isoenzymes have been studied as in vitro. The K i values of compounds were found in the range of 0.056-110.400 lM for hCA I and 0.057-533.400 lM for hCA II. Compound 4 has the highest inhibitory effect for hCA I and hCA II while compound 5 showed lowest inhibition. The structure-activity relationships for the inhibition of these isoforms with the pyrazole-sulfonamides reported here were also elucidated. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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