Discovery of curcumin inspired sulfonamide derivatives as a new class of carbonic anhydrase isoforms I, II, IX, and XII inhibitors

A series of curcumin inspired sulfonamide derivatives was prepared from various chalcones and 4-sulfamoyl benzaldehyde via Claisen-Schmidt condensation. All new compounds were assayed as inhibitors of four human isoforms of the metalloenzyme carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I, II, IX and XII. Interesting inhibitory activities were observed against all these isoforms. hCA I, an isoform involved in several eye diseases was inhibited moderately with KIs in the range of 191.8-904.2 nM, hCA II, an antiglaucoma drug target was highly inhibited by the new sulfonamides, with KIs in the range of 0.75-8.8 nM. hCA IX, a tumor-associated isoform involved in cancer progression and metastatic spread was potently inhibited by the new sulfonamides, with KIs in the range of 2.3-87.3 nM, whereas hCA XII, and antiglaucoma and anticancer drug target, was inhibited with KIs in the range of 6.1-71.8 nM. It is noteworthy that one of the new compounds, 5d, was found to be almost 9 times more selective against hCA II (KI = 0.89 nM) over hCA IX and hCA XII, whereas 5e was 3 and 70 times more selective against hCA II (KI = 0.75 nM) over hCA IX and hCA XII, respectively.