Molecular modeling studies on benzimidazole carboxamide derivatives as PARP-1 inhibitors using 3D-QSAR and docking

Poly(ADP-ribose) polymerases (PARPs) play significant roles in various cellular functions including DNA repair and control of RNA transcription. PARP-1 inhibitors have been demonstrated to potentiate the effect of cytotoxic agents or radiation in a number of animal tumor models. To understand the structure-activity correlation of cyclic amine-containing benzimidazole carboxamide-based PARP-1 inhibitors, we have carried out a combined molecular docking and three-dimensional quantitative structure-activity relationship (3D-QSAR) modeling study. Two types of satisfactory substructure-based 3D-QSAR models were built, including the comparative molecular field analysis (CoMFA) model (r(2) , 0.913; q(2) , 0.743) and comparative molecular similarity indices analysis (CoMSIA) model (r(2) , 0.869; q(2) , 0.734), to predict the biologic activity of new compounds. Docking studies were performed to explore the binding mode between all of the inhibitors and the PARP-1 and produce the bioactive conformation of each compound in the whole data set. The docked conformer-based alignment strategy gave the best 3D-QSAR models, CoMFA model (r(2) , 0.899; q(2) , 0.712) and CoMSIA model (r(2) , 0.889; q(2) , 0.744), respectively. The structural insights obtained from both the 3D-QSAR contour maps and molecular docking help to better interpret the structure-activity relationship. The information obtained from molecular modeling studies helped us to predict the activity of new inhibitors and further design some novel and potent PARP-1 enzyme inhibitors.