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. 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.