Benzamide sulfonamide derivatives: potent inhibitors of carbonic anhydrase-II

Synthesis, Bioactivity Assessment, and Molecular Docking of Non-sulfonamide Benzimidazole-Derived N-Acylhydrazone Scaffolds as Carbonic Anhydrase-II Inhibitors

This research reports the synthesis of new benzimidazole-derived N-acylhydrazones (NAH), their characterization using various spectroscopic methods, and in vitro evaluation as potent carbonic anhydrase-II inhibitors. Among the target compounds (9-29), few showed higher inhibition than the standard acetazolamide (IC50: 18.6 ± 0.43 μM), for example, compound 9 (IC50: 13.3 ± 1.25 μM), 10 (IC50: 17.2 ± 1.24 μM), 12 (IC50: 14.6 ± 0.62 μM), and 15 (IC50: 14.5 ± 1.05 μM). Molecular docking was performed on the most active compounds, which revealed their binding interactions with the active site of the enzyme, thus supporting the experimental findings.

Synthesis of benzamide derivatives with thiourea-substituted benzenesulfonamides as carbonic anhydrase inhibitors

The novel compounds with the chemical structure of N-({4-[N'-(substituted)sulfamoyl]phenyl}carbamothioyl)benzamide (1a-g) and 4-fluoro-N-({4-[N'-(substituted)sulfamoyl]phenyl}carbamothioyl)benzamide (2a-g) were synthesized as potent and selective human carbonic anhydrase (hCA) I and hCA II candidate inhibitors. The aryl part was changed to sulfacetamide, sulfaguanidine, sulfanilamide, sulfathiazole, sulfadiazine, sulfamerazine, and sulfametazine. The K_i values of compounds 1a-g were in the range of 20.73 ± 4.32 to 59.55 ± 13.07 nM (hCA I) and 5.69 ± 0.43 to 44.81 ± 1.08 nM (hCA II), whereas the K_i values of compounds 2a-g were in the range of 13.98 ± 2.57 to 75.74 ± 13.51 nM (hCA I) and 8.15 ± 1.5 to 49.86 ± 6.18 nM (hCA II). Comparing the K_i values of the final compounds and acetazolamide, compound 1c with the sulfanilamide moiety (K_i  = 5.69 ± 0.43 nM, 8.8 times) and 2f with the sulfamerazine moiety (K_i  = 8.15 ± 1.5 nM, 6.2 times) demonstrated promising and selective inhibitory effects against the hCA II isoenzyme, the main target protein in glaucoma. Furthermore, compounds 1d (K_i  = 20.73 ± 4.32, 4 times) and 2d (K_i  = 13.98 ± 2.57, 5.9 times), which have the sulfathiazole moiety, were found as potent hCA I inhibitors. Compounds 1c and 2f can be considered as the lead compounds determined in the present study, which can be investigated further to alleviate glaucoma symptoms.

Pharmacophores Modeling in Terms of Prediction of Theoretical Physicochemical Properties and Verification by EXPERIMENTAL correlations of Carbacylamidophosphates (CAPh) and Sulfanylamidophosphates (SAPh) Tested as New Carbonic Anhydrase Inhibitors

Background:

The function of Carbonic anhydrase is to facilitate the physiological process i.e. interconversion of CO2 to HCO3 - by hydration. Carbonic anhydrase enzyme plays a vital role in different physiological processes to regulate pH as well as regulate the inner environment of CO2 and secretion of electrolytes.

Methods:

Six representatives of amidophosphate derivatives (L1-L6) were synthesized and evaluated for their biological activities against carbonic anhydrase enzyme.

Results:

Out of six derivatives, L1 (IC50 = 12.5 ± 1.35 µM), and L2 (IC50 = 3.12 ± 0.45 µM) showed potent activity against BCA-II. While (L3, L4 and L5) showed weak inhibitory activity with IC50 values of 24.5 ± 2.25, 55.5± 1.60, and 75.5 ± 1.25 µM, respectively and were found to be weak inhibitors of carbonic anhydrase as compared to acetazolamide (IC50 =0.12± 0.03µM), used as standard inhibitor. A computational Petra/Osiris/Molinspiration/DFT (POM/DFT) based model has been expanded for the determination of physicochemical parameters governing the bioactivity amidophosphate derivatives (L1-L6) containing (O1 --- O2) pharmacophore site. The six compounds (L1-L6) analyzed here were previously experimentally and now virtually screened for their anti-carbonic anhydrase activity.

:

A computational Petra/Osiris/Molinspiration/DFT (POM/DFT) based model has been expanded for the determination of physicochemical parameters governing the bioactivity amidophosphate derivatives (L1-L6) containing (O1 --- O2) pharmacophore site. The six compounds (L1-L6) analyzed here were previously experimentally and now virtually screened for their anti-carbonic anhydrase activity.

Conclusion:

The highest anti-carbonic anhydrase activity was obtained for compound L2, which exhibited excellent bioactivity (% of inhibition = 95%), comparable to acetazolamide (% of inhibition = 89%). The compound L3 represents increased activity as compared to its analogues (L4-L6). The increase of bioactivity from L3 to L4-L6 could be attributed to the presence of a minimum of steric effect of substituents of P=O moiety which plays a decisive template part in the organization of anti-carbonic anhydrase (O1---O2) phramacophore site. Moreover, it is inexpensive, has little side effects and possible inclusions in selective anti-carbonic anhydrase agents design.