Chalcone-based benzenesulfonamides as potent and selective inhibitors for human carbonic anhydrase II: Design, synthesis, in vitro, and in silico studies

Sulfonamides are promising classical carbonic anhydrase (CA; EC 4.2.1.1) inhibitors, being used for several medical purposes such as diuretics, anticonvulsants, topically acting antiglaucoma agents, for antiobesity and anticancer therapies. Herein, a series of chalcone-based benzenesulfonamides (3a‒m) was synthesized and assessed for its inhibitory activity against a panel of four human carbonic anhydrases (hCA isoforms I, II, IX, and XII). Most compounds displayed single- to double-digit nanomolar inhibition constants (K_is), with some derivatives being more potent and/or selective than the standard drug acetazolamide (AAZ). Among the synthesized compounds, 3g compound demonstrated the highest inhibitory activity against the hCA II isoform (K_i = 2.5 nM) with 30-, 9-, and 11-fold selectivity for hCA II over the I, IX, and XII isoforms, respectively. Structure–activity relationships for different substitution patterns were analyzed. Additionally, a molecular docking study showed that compound 3g bound to hCA II by coordinating with the zinc ion through the deprotonated benzenesulfonamide moiety, in addition to a hydrogen bond formed between an oxygen of the sulfonamide moiety and Thr199. Moreover, the chalcone core participated in van der Waals interactions with some active site residues, such as Ile91, Val121, and Leu198. Consequently, this report introduces a successful approach toward identifying compound 3g as a highly potent and selective chalcone-based benzenesulfonamide inhibitor of hCA II worthy of further investigation.