Title:Inhibitory Efficacy of Thiosemicarbazones for Carbonic Anhydrase II (Bovine and
Human) as a Target of Calcification and Tumorigenicity
Volume: 28
Issue: 36
Author(s): Majid Khan, Sobia Ahsan Halim, Zahid Shafiq, Muhammad Islam, Muhammad Tariq Shehzad, Aliya Ibrar, Farhan A. Khan, Najat Marraiki, Jalal Uddin, Ajmal Khan*Ahmed Al-Harrasi*
Affiliation:
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman
- Natural and Medical Sciences Research Center, University of Nizwa, PO Box 33, 616 Birkat Al Mauz, Nizwa, Oman
Keywords:
Thiosemicarbazone, carbonic anhydrase II, bovine, human, kinetics studies, molecular docking.
Abstract:
Background: Carbonic anhydrase II (CA-II) is associated with calcification, tumorigenicity, epilepsy,
osteoporosis, and several other physiological or pathological processes. CA-II inhibitors can be used to
reduce the intraocular pressure usually associated with glaucoma.
Objective: In search for potent CA-II inhibitors, a series of thiosemicarbazone derivatives (3a-u) was synthesized.
Methods: This series was evaluated against bovine and human carbonic anhydrase II (bCA-II and hCA-II) and
their docking studies were carried out.
Results: In the preliminary screening, most of the compounds exhibited significant inhibition of bCA-II and
hCA-II. The predictive structure-activity relationship suggested that the thiosemicarbazide moiety plays a key
role in the inhibition of enzyme activity and substitution at R position and has a remarkable contribution to the
overall activity. The kinetic studies of the most active inhibitors of bCA-II (3d, 3e, 3l, 3f, and 3p) and hCA-II
(3g) were performed against bCA-II and hCA-II, respectively to investigate their mode of inhibition and dissociation
constants (Ki).
Conclusion: Subsequently, (3e, 3f, 3l and 3p) were identified as competitive inhibitors of bCA-II with Ki values
of 5.02-14.70 μM, while (3d) as a noncompetitive inhibitor of bCA-II (Ki = 2.5 ± 0.015 μM), however, (3g)
demonstrated competitive inhibition of hCA-II with a Ki value of 5.95 ± 0.002 μM. The selectivity index
reflects that compound (3g) is more selective for hCA-II. The binding modes of these compounds with bCA-II
and hCA-II were investigated by structure-based molecular docking, and the docking results are in complete
agreement with the experimental findings.
