Spectroscopic Investigations, Computational Analysis and Molecular Docking to SAR-Cov-2 Targets Studies of 5,8-Quinolinedione Attached to Betulin Derivatives

The 5,8-quinolinedione-betulin hybrids were investigated using spectroscopic methods as well as a variety of quantum chemical calculations in order to characterize their molecular structure. We used FT-IR and NMR spectroscopy supplemented by the density functional theory (DFT) calculations, molecular electrostatic potential (MEP) and molecular orbital (HOMO, LUMO) analyses. The experimental and calculated FT-IR spectra showed a good correlation for all compounds. Analysis of carbonyl band showed that the compounds are the 7-mono substituted. The calculated 1H NMR and 13C NMR spectra of hybrids reproduced well the experimental ones. Identification of C-6 and C-7 carbon atoms of 5,8-quinolinedione revealed the position of betulin moiety at the C-7 of 5,8-quinolinedione. Molecular electrostatic potential maps of hybrids allowed to recognize the electrophilic and nucleophilic regions within the molecules. The molecular docking study was used to examine the interaction between the 5,8-quinolinedione-betulin hybrids and the SARS-CoV-2 protein, like: Mpro and PLpro. The obtained results showed that compounds with the highest Dock Score are good anti-SARS-CoV-2 potential drug candidates.