Benzilydene and thiourea derivatives as new classes of carbonic anhydrase inhibitors: an in vitro and molecular docking study

Carbonic anhydrase-II (CA-II) catalyzes reversible hydration of carbon dioxide leading to the formation of bicarbonate and a proton. CA-II inhibitors act as biomarkers and therapeutic targets for various diseases such as epilepsy, glaucoma, leukemia, and cystic fibrosis. In the present work, a number of thiourea and benzylidene derivatives were evaluated as CA-II inhibitors. For this, detection of CA-II inhibition was tested through high throughput biochemical mechanism-based assay. Results indicated that thiourea derivatives exhibit remarkable inhibition activity with IC₅₀ values ranging from 1.90 ± 1.30 to 25.90 ± 2.05 µM, when compared with the standard inhibitor acetazolamide IC₅₀ = 0.13 ± 0.05. On the other hand, bezylidene derivatives showed weak inhibition potential with IC₅₀ values in the range of 52.68 ± 0.47 to 348.57 ± 3.32 µM when compared with the thiourea derivatives; the Ez-Fit enzyme kinetics software was used for IC₅₀ calculations from the percentage inhibition. In addition, 3T3 normal cell line was employed to determine the toxicity profile of identified inhibitors of CA-II. In silico modeling was performed to decipher the molecular nature of thiourea and benzylidene derivatives with key residues of carbonic anhydrase; results were in agreement with experiments related to inhibition of carbonic anhydrase.