In silico exploration of potent flavonoids for dengue therapeutics

Dengue poses a persistent and widespread threat with no effective antiviral drug available till now. Several inhibitors have been developed by targeting the viral non-structural proteins including methyl transferase (NS5) of the dengue virus with possible therapeutic values. In this work, virtual screening, molecular docking, molecular dynamics simulations (200 ns), and assessments of free energy changes to identify potential candidates from a database of flavonoids (ca. 2000) that may have good curative potential from the disease. The binding affinity of flavonoids, namely Genistein-7-glucoside (FLD1), 6-O-Acetylgenistin (FLD2), 5,6-dihydroxy-2-(4-hydroxyphenyl)-7-[3,4,5-trihydroxy-6-(hydroxymethyl)oxane-2-yl]oxychromen-4-one (FLD3), Glucoliquiritigenin (FLD4), and Chrysin-7-O-glucoronide (FLD5) showed the binding affinities of -10.2, -10.2, -10.1, -10.1, -9.9 kcal/mol, respectively, and possessed better values than that of the native ligand with showed (-7.6 kcal/mol) and diclofenac sodium (-7.3 kcal/mol). Drug-likeness of these compounds was acceptable and no toxicity was hinted by ADMET predictions. The stability of the protein-ligand complexes was accessed from 200 ns molecular dynamics simulation in terms of various geometrical parameters; RMSD, RMSF of residues, Rg, SASA, and H-bond of the protein-ligand complexes. The binding free energy changes of these compounds were calculated by the MM-PBSA solvation model with negative values (less than -38.01{+/-}7.53 kcal/mol) indicating the spontaneity of the forward reaction and favorability of the product formation. The geometrical and thermodynamic parameters infer that the flavonoid binds at the orthosteric site of the target protein of DENV-2 and could inhibit its functioning resulting in the prevention of the disease. Overall, this study highlights the anti-DENV activity of five flavonoids, positioning them as promising candidates for further development as antiviral agents against dengue infection.