Insighting the inhibitory potential of novel modafinil drug derivatives against estrogen alpha (ERα) of breast cancer through a triple hybrid computational methodology

Breast cancer (Bca) is the prominent, most commonly detected, and the leading cause of mortality among women. Estrogen receptor alpha (ERα) is considered an important receptor for the proliferation of this disease and its blockage is necessary for the treatment of Bca. The purpose of the current study is to design novel potential inhibitors against ERα of Bca. We designed modafinil drug derivatives using quantum chemical methods. These newly designed derivatives were put under an in-silico investigation followed by molecular docking simulation, molecular dynamics simulation, and MMPBSA analysis to find novel inhibitors of ERα. Moreover, three reference anticancer drugs; tamoxifen, raloxifene, and toremifene are also studied against ERα of Bca. The spectroscopic and structural features of sulfoxide-based designed derivatives of modafinil drug M1 ((R)-2-(banzhydrylsulfinyl-N,N diethylacetamide) have been evaluated using different quantum chemical analyses. The findings of the current investigation demonstrate that all studied ligands exhibit the binding energy ranges (-5.3 to −5.8 Kcal/mol). The designed compounds showed effective hydrophobic (alkyl, π-alkyl, π-sigma, π-amide stacked, π-π T-shaped) interactions and hydrogen bond formation and are anticipated to be potential inhibitors against ERα. Additionally, designed derivatives have a good ADMET (absorption, distribution, metabolism, excretion, toxicity) profile and drug-likeness properties obeying RO5 without any toxicity. The stability profile of designed derivatives (M1-M6) was further validated by molecular dynamics (MD) simulation and calculate binding free energy by the MM-PBSA approach. All ligand–protein complexes showed structural stability over the 120 ns MD simulation time. The MD simulation of the complex system was carried out by RMSD (root-mean-square deviation) of C α atoms of ERα, RMSF (root mean square fluctuations), Rg (radius of gyration), SASA (solvent accessible surface area), and dynamic behavior of hydrogen bonds. The MD simulation results illustrate that RMSD for trajectories of designed derivative complexes over 120 ns are within the acceptable deviation range of ∼ 3 Å. The calculations of net binding free energy (ΔGbind) between the designed derivatives and their complexes are found to be −8.50 Kcal/mol (M1) at maximum and −5.197 Kcal/mol (M3) at a minimum among all derivatives. The outcomes of our current in-silico investigation will evoke the scientific community to carry out further in vivo and in vitro studies on designed modafinil derivatives that can be potential therapeutic drug candidates against ERα.