Inhibition Effects of 5-Amino-1,3,4-thiadiazole Derivatives on Carbonic Anhydrase Enzyme

In this study, new carbonic anhydrase inhibitors's effects on bovine carbonic anhydrase enzyme, to resembling human carbonic anhydrase-II (hCA-II), as candidates for treatment of glaucoma were investigated. Therefore, carbonic anhydrase enzyme was purificated from bovine erythrocyte cells by the affinity column. The inhibition effects of 5-amino-1,3,4-thiadiazole-2-sulfonamide (1), acetazolamide (2) and new synthesized amides (5, 6, 7) on this enzyme have been studied in vitro. The IC50 concentrations (the concentration of inhibitor producing a 50 % inhibition of bovine erythrocyte carbonic anhydrase activity) against hydratase activity values were 0.179, 0.758, 0.978 mu M for bovine erythrocyte carbonic anhydrase. The IC50 values against esterase activity values were 0.225, 0.194 and 0.205 mu M for this enzyme. The K-1 values were observed 0.351, 0.208 and 0.232 mu M for this enzyme. The comparison of new synthesized amides (5, 6, 7) to 1 and 2 indicated that the new synthesized compounds (5, 6, 7) inhibit carbonic anhydrase activity more effectively than parent compounds.