in silico binding studies with b-sitosterol and some of its fatty acid esters to 3C-like protease of SARS-CoV-2

COVID-19, a coronavirus (SARS-CoV-2) caused disease has turned into a pandemic with no therapeutics in the form of drugs or vaccines yet in sight. The objective of this study was to evaluate in molecular docking studies the binding energies of b-sitosterol (a phytosterol) and some of its fatty acid esters to the main protease of COVID-19, otherwise known as the 3C-like protease or 3CLpro, (PDB ID: 6LU7) in an attempt to discover possible lead compounds or drugs against the virus as a means to contain the pandemic. Molecular docking (blind) was done with the help of Autodock Vina. Seven fatty acid esters of b-sitosterol (a major phytosterol) were evaluated. While b-sitosterol gave a binding energy of -7.0 kcal/mol, b-sitosterol-acetate and b-sitosteryl-ferulate gave binding energies of -6.9 and -7.8 kcal/mol, respectively. The other esters gave lower binding energies. As a result, the ferulic acid ester of b-sitosterol has a greater probability of being a COVID-19 therapeutic.