A novel QSAR model for designing, evaluating,and predicting the anti-MES activity of new 1H-pyrazole-5-carboxylic acid derivatives

Abstract

A quantitative structure–activity relationship (QSAR) study was performed to develop a model that relates the structures of 62 compounds, which have activity against maximal electroshock induced seizure (MES), with their anti-MES activity. Molecular structures of the compounds were geometrically optimized and energetically minimized using a combination of modified Merck force field (MMFF) molecular mechanics, Austin model 1 (AM1) semi-empirical quantum mechanical and density functional theory (DFT) quantum mechanical method using the Becke’s three parameter exchange functional (B3) hybrid with Lee, Yang and Parr correlation functional (LYP) and basis set of the double zeta split valence plus polarization quality 6-31G** i.e. B3LYP/6-31G**. Theoretically derived descriptors were obtained from the optimized structures, a genetic function approximation (GFA) algorithm was also applied to select the optimal descriptors and multiple linear regression (MLR) was used to establish a relationship between the anti-MES activity of the compounds and the optimal molecular descriptors. A six-parametric equation containing dipole moment (μ), energy of the lowest unoccupied molecular orbital ( ϵ LUMO), polar surface area (PSA), accessible surface area derived from wave function (WAA), sum of the square root of square of the charge on all atom of the molecule (QA) and sum of the square root of square of the charge on all fluorine atom in the molecule was obtained as the QSAR model in the present study with good statistical qualities (R 2 =0.937, R 2 adj =0.928, F=104.11, R 2 pred =0.929 and Q 2 =0.913). The QSAR model was used to study estimate the anti-MES activities of 1H-pyrazole-5-carboxylic acid derivatives not yet synthesized. 10 out of the 101 screened compounds had improved anti-MES activity when compared to the template (i.e. ethyl 4-(4-chlorophenyl)-3-morpholino-1H-pyrrole-2-carboxylate, which is compound number 61 in the dataset) used to design the 101 derivatives. These 10 compounds were docked with voltage-gated sodium channel (PDB code: 2KaV) and there binding affinity were found to were found to be comparable to that of phenytoin (a standard drug known to possess anti-MES activity).