Molecular docking and density functional theory studies of potent 1,3-disubstituted-9H-pyrido[3,4-b]indoles antifilarial compounds

Abstract

The interaction of three potent antifilarial compounds (4C, 4F, and 3F) with filarial proteins thioredoxin, glutathione s-transferase and cyclophilin were investigated using molecular docking and density functional theory (DFT) studies. Molecular docking was performed using YASARA tool, Hex 8.0.0 Cuda tool and PatchDock server and docked complex were visualized by Discovery Studio 3.0. The predicted binding energy of antifilarial compounds 4C (−247.6, −243.8, −256.8 kcal mol−1), 4F (−242.6, −246.4, −232.4 kcal mol−1) and 3F (−272.4, −248.5, −277.7 kcal mol−1) with filarial protein 4FYU, 5D73, and 1A33, respectively. Docking results were strongly supported by molecular dynamics data and molecular mechanics-generalized born surface area (MM-GBSA) calculations. The optimized geometries of all three compounds were used for calculating the energies of the frontier molecular orbitals highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The lowest HOMO–LUMO energy gap in compound 3F suggested that it is the most bioactive molecule among all these three compounds, which is in accordance with the docking results of these compounds. The interaction energies between ligand and protein are mainly due to hydrogen bonds, hydrophobic interactions, and van der Waals interactions which give the stability to the complex. The structural information and docking studies of different filarial proteins with antifilarials obtained from this study could aid in screening and designing new antifilarial or selective inhibitors for chemotherapy against filariasis. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.