Synthesis and Evaluation of Amide and Thiourea Derivatives as Carbonic Anhydrase (CA) Inhibitors

Abstract

Series of sulfonamide-substituted amide (<b>9</b>-<b>11</b>), benzamide (<b>12</b>-<b>15</b>), and 1,3-disubstituted thiourea (<b>17</b>-<b>26</b>) derivatives were synthesized from a common precursor, i.e., substituted benzoyl chlorides. Structures of all of the synthesized compounds were characterized by spectroscopic techniques (¹H nuclear magnetic resonance (NMR),¹³C NMR, and Fourier transform infrared spectroscopy (FTIR)). All of the amide (<b>9</b>-<b>15</b>) and thiourea (<b>17</b>-<b>26</b>) derivatives were screened against human carbonic anhydrases, <i>h</i>CA-II, <i>h</i>CA IX, and <i>h</i>CA-XII. Sulfonamide-substituted amides <b>9</b>, <b>11</b>, and <b>12</b> were found to be excellent selective inhibitors with IC₅₀ values of 0.18 ± 0.05, 0.17 ± 0.05, and 0.58 ± 0.05 μM against <i>h</i>CA II, <i>h</i>CA IX, and <i>h</i>CA XII, respectively. Compound <b>9</b> was found to be highly selective for hCA II and about 6-fold more potent as compared to the standard antagonist, acetazolamide. Safe toxicity profiling of the most potent and selective compounds was determined against normal BHK-21 and HEK-293 T cells. Molecular docking studies were performed, which described the type of interactions between the synthesized compounds and enzyme proteins. In addition, <i>in silico</i> absorption, distribution, metabolism, and excretion (ADME) studies were performed, which showed that all of the synthesized molecules fulfilled the druggability criteria.