Quinazolinones as Competitive Inhibitors of Carbonic Anhydrase-II (Human and Bovine): Synthesis, in-vitro, in-silico, Selectivity, and Kinetics Studies
Ajmal Khan, Majid Khan, Sobia Ahsan Halim, Zulfiqar Ali Khan, Zahid Shafiq, Ahmed Al‐Harrasi
Abstract
Carbonic anhydrase-II (CA-II) is associated with glaucoma, malignant brain tumors, and renal, gastric, and pancreatic carcinomas and is mainly involved in the regulation of the bicarbonate concentration in the eyes. CA-II inhibitors can be used to reduce the intraocular pressure usually associated with glaucoma. In search of potent CA-II inhibitors, a series of quinazolinones derivatives ( 4a-p ) were synthesized and characterized by IR and NMR spectroscopy. The inhibitory potential of all the compounds was evaluated against bovine carbonic anhydrase-II ( b CA-II) and human carbonic anhydrase-II ( h CA-II), and compounds displayed moderate to significant inhibition with IC 50 values of 8.9–67.3 and 14.0–59.6 μM, respectively. A preliminary structure-activity relationship suggested that the presence of a nitro group on the phenyl ring at R position contributes significantly to the overall activity. Kinetics studies of the most active inhibitor, 4d , against both b CA-II and h CA-II were performed to investigate the mode of inhibition and to determine the inhibition constants (Ki). According to the kinetics results, 4d is a competitive inhibitor of b CA-II and h CA-II with Ki values of 13.0 ± 0.013 and 14.25 ± 0.017 μM, respectively. However, the selectivity index reflects that the compounds 4g and 4o are more selective for h CA-II. The binding mode of these compounds within the active sites of b CA-II and h CA-II was investigated by structure-based molecular docking. The docking results are in complete agreement with the experimental findings.