Table 4.

Interactions of COVID-19 Spike Protein (PDB ID:6LZG) amino acid residues with ligands at receptor sites.

Ligands	Binding affinity, ΔG (kcal/mol)	Amino acids involved and Distance (A°)
		Hydrogen binding interactions	Hydrophobic interactions	Electrostatic interactions
Luteolin-7-glucoside-3′-glucuronide	−10.1	TYR A:196 (6.05), GLU A:564 (5.23), LYS A:562 (4.36), GLY A:395 (4.95), ASN A:397 (2.98), ARG A:514 (5.03), GLU A:398 (4.76)	TYR A: 202 (6.27), GLY A:205 (5.85)	–
Melitric acid A	−10	TYR A:196 (6.76), LYS A:562 (4.27), ASN A:210 (3.14, 4.84), GLU A:564 (5.97), SER A:511 (3.69), GLU A:398 (4.77, 5.23)	LEU A:95 (5.34), VAL A:209 (4.10), PRO A:565 (4.29)	ASP A:206 (5.09)
Quadranoside III	−9.2	LEU A:391 (3.25, 5.17), ASN A:394 (3.73, 5.10)	PHE A:40 (4.71), HIS A:401 (4.42)	–