Molecular modeling studies of phenoxypyrimidinyl imidazoles as p38 kinase inhibitors using QSAR and docking.

p38 Kinase plays a vital role in inflammation mediated by tumor necrosis factor-alpha (TNFalpha) and interleukin-1beta (IL-1beta) pathways and inhibitors of p38 kinase provide effective approach for the treatment of inflammatory diseases. Pyridinyl and pyrimidinyl imidazoles, selectively inhibit p38alpha MAP kinase, are useful in the treatment of inflammatory diseases like rheumatoid arthritis. Three dimensional quantitative structure-activity relationship studies (3D-QSAR) involving comparative molecular field analysis (CoMFA) and comparative similarity indices analysis (CoMSIA) and molecular docking were performed on 44 phenoxypyrimidinyl imidazole p38 kinase inhibitors to find out the structural relationship with the activity. The best predictive CoMFA model with atom fit alignment resulted in cross-validated r(2) value of 0.553, noncross-validated r(2) value of 0.908 and standard error of estimate 0.187. Similarly the best predictive CoMSIA model was derived with q(2) of 0.508, noncross-validated r(2) of 0.894 and standard error of estimate of 0.197, comprising steric, electrostatic, hydrophobic and hydrogen bond donor fields. These models were able to predict the activity of test set molecules efficiently within an acceptable error range. GOLD and FlexX were employed to dock the inhibitors into the active site of the p38 kinase and these docking studies revealed the vital interactions and binding conformation of the inhibitors. The information rendered by 3D-QSAR models and the docking interactions may afford valuable clues to optimize the lead and design new potential inhibitors.