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

doi:10.3389/fchem.2020.598095

Quinazolinones as Competitive Inhibitors of Carbonic Anhydrase-II (Human and Bovine): Synthesis, in-vitro, in-silico, Selectivity, and Kinetics Studies

Front Chem. 2020 Dec 1:8:598095. doi: 10.3389/fchem.2020.598095. eCollection 2020.

Authors

Ajmal Khan¹, Majid Khan^{1

2}, Sobia Ahsan Halim¹, Zulfiqar Ali Khan³, Zahid Shafiq⁴, Ahmed Al-Harrasi¹

Affiliations

¹ Natural and Medical Sciences Research Center, University of Nizwa, Nizwa, Oman.
² International Center for Chemical and Biological Sciences, H. E. J. Research Institute of Chemistry, University of Karachi, Karachi, Pakistan.
³ Department of Chemistry, Government College University, Faisalabad, Pakistan.
⁴ Institute of Chemical Sciences, Bahauddin Zakariya University, Multan, Pakistan.

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 (bCA-II) and human carbonic anhydrase-II (hCA-II), and compounds displayed moderate to significant inhibition with IC₅₀ 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 bCA-II and hCA-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 bCA-II and hCA-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 hCA-II. The binding mode of these compounds within the active sites of bCA-II and hCA-II was investigated by structure-based molecular docking. The docking results are in complete agreement with the experimental findings.

Keywords: bovine carbonic anhydrase-II; human carbonic anhydrase-II; kinetics; molecular docking; quinazolinones; structure-activity relationship.