In silico validation of potent phytochemical orientin as inhibitor of SARS-CoV-2 spike and host cell receptor GRP78 binding.

The present wellbeing worry to the whole world is the outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also called COVID-19. This global health crisis first appeared in Wuhan, China around December 2019 and due to its extremely contagious nature it had spread to almost 187 countries. Still now no effective method of treatment or vaccine is developed for controlling the disease. Therefore, the sole obliging strategy is to take precautionary measures by repurposing drugs from the pre-existing library of therapeutically potent molecules. In this situation of pandemic this repurposing technique may save the labour-intensive and tiresome process of new drug development. Orientin is a natural flavonoid with several beneficial effects. This phytochemical can be isolated from different plants like tulsi or holy basil, black bamboo, passion flowers etc. It's antiviral, anti-inflammation, vasodilatation, cardioprotective, radioprotective, neuroprotective, anticarcinogenic and antinociceptive effects are already established. In this research, it is intriguing to find out whether this molecule can interfere the interaction of SARS-CoV-2 spike glycoprotein and their host receptor GRP78. Our in silico docking and molecular dynamics simulation results indicate the binding of Orientin in the overlapping residues of GRP78 binding region of SARS-CoV-2 spike model and SARS-CoV-2 spike model binding region of GRP78 substrate-binding domain. Therefore, the results included in this research work provide a strong possibility of using Orientin as a promising precautionary or therapeutic measure for COVID-19.