Background: COVID-19 is a pandemic respiratory contagious viral (SARS-CoV-2) disease
associated with high morbidity and mortality worldwide. Currently, there are no effective preventive
or treatment strategies for COVID-19 and it has been declared as a global health emergency
by WHO. In silico molecular docking studies can be useful to predict the binding affinity between
the phytocompound and the target protein and play a vital role in finding an inhibitor
through structure-based drug design.
Objective: In this aspect, our objective was to screen essential flavonoids against possible protein
targets such as SARS-CoV-2 spike glycoprotein receptor binding domain (RBD-S) and host Angiotensin
Converting Enzyme-2 protease domain (PD-ACE-2) using in silico molecular docking
Methods: Approximately 49 flavonoids were identified and were evaluated for their drug-likeness
based on Lipinski rule, bioactivity scores, antiviral and toxicity profiles using SwissADME, Molinspiration,
PASS and GUSAR online tools. The flavonoids that passed Lipinski rule were subjected
to in silico analysis through molecular docking on RBD-S and PD-ACE-2 using Molegro Virtual
Results: The bioactive flavonoids that showed NIL violations and were found in compliance with
Lipinski rule were selected for docking studies. In silico analysis reported that biochanin A and silymarin
bind significantly at the active sites of RBD-S and PD-ACE-2 with a MolDock score of
-78.41and -121.28 kcal/mol respectively. Bioactivity scores, antiviral potential and toxicity profiles
were predicted for the top interacting phytocompounds and substantial relevant data was reported.
Conclusion: The current outcomes created a new paradigm for understanding biochanin A and silymarin
bioflavonoids as potent inhibitors of RBD-S and PD-ACE-2 targets respectively. Further
work can be extended to confirm their therapeutic potential for COVID-19.