Table 2.

Molecular interactions of lead ligands with the amino acid residues in the binding region of SARS-CoV 2’s Main protease

S/N	Compounds	Binding affinity (kcal/mol)	No. of residues involved in H-Bond	Residues involved in hydrogen bond (Distance, Å)	Residues involved in hydrophobic interaction
1	3-O-(6-galloylglucoside)	− 8.6	7	Leu141 (3.00, 2.99), Ser144 (3.01, 3.00), His163 (3.04), Thr26 (3.08, 2.87), Thr24 (3.23), Gly143 (3.10, 2.88) and His41 (3.28)	Met49, Thr25, Asn142, Cys145, Met165 and Gln189
2	C33	− 8.3	4	Ser144 (2.92), Gly143 (2.94), Cys145 (3.15) and Asn142 (2.82)	Asn142, Cys145, Met49, Met165 and Glu166
3	Remdesivir	− 8.2	4	Gly143 (3.08), Leu141 (2.70), Ser144 (2.85) and His163 (3.28, 3.07)	Glu166, Met165, Arg188, Asp187, His41, Met49, Cys145, Leu27, Thr26 and Thr25