Design and Synthesis of Potent and Selective Urea-linked Benzenesulfonamide Analogs as Carbonic Anhydrase II Inhibitors

The development of isoform-selective carbonic anhydrase (CA) inhibitors is an essential strategy for enhancing therapeutic efficacy, reducing off-target interactions, and minimizing side effects. Non-selective CA inhibitors like acetazolamide target multiple isoforms found in various tissues, often causing side effects such as fatigue, GI disturbances, and renal dysfunction. In contrast, selective inhibition of hCA II-the predominant isoform in the ocular ciliary body-effectively lowers intraocular pressure with improved safety, making it a targeted strategy for glaucoma treatment. Herein, we report highly selective human CA II (hCA II) inhibitors with urea-linked benzenesulfonamide scaffolds that exhibit potent and selective inhibitory activities over other isoforms. Compound 8c with 3-chlorophenyl tail group demonstrated the most potent inhibitory activity with a K_i value of 4.3 nM, whereas compound 8f with 3-trifluoromethylphenyl tail group displayed high potency (K_i = 8.2 nM) and exceptional selectivity toward hCA II. This selectivity was achieved through strategic elongation of the tail moiety, as determined through detailed analysis of isoform-specific residues at the outer rim of the active site. Docking studies and molecular dynamics simulations further validated the stable binding and selective recognition of these compounds by hCA II. This approach provides valuable insight and a promising foundation for the development of selective hCA II inhibitors with potential clinical applications, particularly in anti-glaucoma therapies.