Synthesis of 4-hydroxy-L-proline derivatives as new non-classical inhibitors of human carbonic anhydrase II activity: an in vitro study

Abstract

Carbonic anhydrase (CA) is a zinc metalloenzyme that facilitates the rapid conversion of water and carbon dioxide into proton and bicarbonate ion. CA isozymes have been broadly studied in many pathological/physiological processes. In the current research, a series of 4-hydroxy-L-proline derivatives were designed and chemically synthetized, and interaction of these carboxylic acid-based compounds with hCA II were evaluated. Results indicated that different derivatives had different potencies on hCAII inhibitory activity and among them, compounds 3 b and 3c had the lowest IC50 and K d values than 4-hydroxy-L-proline and other derivatives and therefore had the most affinity to the hCA II enzyme. As a result, compounds 3 b and 3c were chosen for additional testing in this research. The Kinetic data demonstrated that 3 b and 3c inhibit the hCA II esterase activity in a linear competitive way, with K i values in the low micromolar range. Fluorescence tests showed that the hCA II surface hydrophobicity is diminished in the presence of compounds 3 b and 3c, as confirmed by the decrease in ANS binding to hCA II in their presence. Docking results revealed that 3 b and 3c had more binding energy than 4-hydroxy-L-proline. Furthermore, these compounds could occupy the active site of hCA II, where they would interact with critical amino acid residues via non-covalent forces to inhibit hCA II. Overall, the strengthening of inhibitory activity and the binding power of these carboxylic acid derivatives (3 b and 3c) for the hCA II makes these compounds interesting for designing novel hCA II inhibitors. Communicated by Ramaswamy H. Sarma