  Covid-19, a serious respiratory complications caused by SARS-CoV-2 has become
one of the global threat to human healthcare system. The present study
evaluated the possibility of plant originated approved 117 therapeutics against
the main protease protein (MPP), RNA-dependent RNA polymerase (RdRp) and spike
protein (S) of SARS-CoV-2 including drug surface analysis by using molecular
docking through drug repurposing approaches. The molecular interaction study
revealed that Rifampin (-16.3 kcal/mol) were topmost inhibitor of MPP where
Azobechalcone were found most potent plant therapeutics for blocking the RdRp
(-15.9 kcal /mol) and S (-14.4 kcal/mol) protein of SARS-CoV-2. After the
comparative analysis of all docking results, Azobechalcone, Rifampin,
Isolophirachalcone, Tetrandrine and Fangchinoline were exhibited as the most
potential inhibitory plant compounds for targeting the key proteins of
SARS-CoV-2. However, amino acid positions; H41, C145, and M165 of MPP played
crucial roles for the drug surface interaction where F368, L371, L372, A375,
W509, L514, Y515 were pivotal for RdRP. In addition, the drug interaction
surface of S proteins also showed similar patterns with all of its maximum
inhibitors. ADME analysis also strengthened the possibility of screened plant
therapeutics as the potent drug candidates against SARS-C with the highest drug
friendliness.
