Molecular Simulation-Based Investigation of Highly Potent Natural Products to Abrogate Formation of the nsp10-nsp16 Complex of SARS-CoV-2

The SARS-CoV-2 non-structural protein (nsp) nsp10-nsp16 complex is essential for the 2 '-O-methylation of viral mRNA, a crucial step for evading the innate immune system, and it is an essential process in SARS-CoV-2 life cycle. Therefore, detecting molecules that can disrupt the nsp10-nsp16 interaction are prospective antiviral drugs. In this study, we screened the North African Natural Products database (NANPDB) for molecules that can interact with the nsp10 interface and disturb the nsp10-nsp16 complex formation. Following rigorous screening and validation steps, in addition to toxic side effects, drug interactions and a risk /benefit assessment, we identified four compounds (genkwanin-6-C-beta-glucopyranoside, paraliane diterpene, 4,5-di-p-trans-coumaroylquinic acid and citrinamide A) that showed the best binding affinity and most favourable interaction with nsp10 interface residues. To understand the conformational stability and dynamic features of nsp10 bound to the four selected compounds, we subjected each complex to 200 ns molecular dynamics simulations. We then calculated the free binding energies of compounds interacting with nsp10 structure using the molecular mechanics-generalised Born surface area (MMGBSA). Of the four compounds, genkwanin-6-C-beta-glucopyranoside demonstrated the most stable complex with nsp10, in addition to a tighter binding affinity of -37.4 +/- 1.3 Kcal/mol. This potential to disrupt the nsp10-nsp16 interface interaction and inhibit it now sets the path for functional studies.