Synthesis of novel sulfonamides under mild conditions with effective inhibitory activity against the carbonic anhydrase isoforms I and II

<p>Novel sulfonamide derivatives <b>6a</b>–<b>i</b>, as new carbonic anhydrase inhibitors which candidate for glaucoma treatment, were synthesized from the reactions of 4-amino-<i>N</i>-(4-sulfamoylphenyl) benzamide <b>4</b> and sulfonyl chloride derivatives <b>5a</b>–<b>i</b> with high yield (71–90%). The structures of these compounds were confirmed by using spectral analysis (FT-IR, <sup>1</sup>H NMR, <sup>13</sup>C NMR, LC/MS and HRMS). The inhibition effects of <b>6a</b>–<b>i</b> on the hydratase and esterase activities of human carbonic anhydrase isoenzymes, hCA I and II, which were purified from human erythrocytes with Sepharose®4B-l-tyrosine-<i>p</i>-aminobenzene sulfonamide affinity chromatography, were studied as <i>in vitro</i>, and IC<sub>50</sub> and <i>K</i><sub>i</sub> values were determined. The results show that newly synthesized compounds have quite powerful inhibitory properties.</p>