Table 8.  Binding energies of WS phytoconstituents with papain like protease of SARS-CoV-2 (PDB ID: 6W9C) in comparison to the FDA approved standard reference drugs (Procainamide and Cinacalcet).
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S. No.  Ligands  BE (kcal/mol)   K d  Interacting amino acids  BE(kcal/mol)   K d  Interacting amino acids  TE(kcal/mol)  VDW  HB  EI  Interacting amino acids
1.  Withaferin A  –8.74  393.84 nM   Asn109, Leu162, Gly160, Gln269, Glu161, Val159, His89, Thr158  –9.8  61.88 nM   His89, Val159, Gly160, Glu161,Leu162, Gln269, Asn109, Thr158  –101.80  –86.23  –15.57  0  Trp106, Ala107, Asn267, Asp108, Leu162, Gly163, Lys157, Asp164, Glu167, Tyr264, Pro248, Pro247
2.  Withanolide A  –10.19  34.04 nM   Gln269, Asn109, Leu162, Glu161, Gly160, Val159, Thr158  –10.2  32.78 nM  Asp286, Asn267, Asp164, Tyr264, Tyr273, Pro248, Gly163, Leu162, Lys157, Asp108, Ala107, Trp106, Gly266, Ala288, Lys105, Tyr268, Leu289  –103.61  –84.71  –18.90  0   Asn109, Val159, Thr158, Glu161, Gly160, Gln269, Leu162
3.  Withanolide B  –10.3  28.32 nM   Gln269, Asn109, Leu162, Glu161, Gly160, Val159, His89, Thr158  –10.4  22.51 nM   His89, Thr158, Gly160, Asn109,Gln269, Leu162, Val159  –104.57  –96.14  –8.43  0  Thr158, Leu162, Glu161, Gly160, His89, Asp108, Ser85, Ala86, Gly160, Val159, Asn109
4.  Withanolide D  –9.56  98.21 nM  Gly160, Glu161, Asn109, Gln269, Cys270, Leu162, Cys160, Val159, Thr158, His89  –10.1  38.9 nM   Thr158, His89, Glu161, Gly160, Asn109, Gln269, Leu162, Val159  –99.07  –91.72  –7.35  0  Pro59, Ala68, Arg65, Phe69, Thr74, Thr75, Pro77, Ile44, Lys45, Pro46, Met23, His47, Asn48
5.  Withanolide E  –9.05  231.88 nM   Asn109, Gln269, Leu162, Gly160, Asp108, Glu161, His89  –10.6  15.57 nM   Asp108, Thr158, Glu161, Val159, His89, Gly160, Leu162, Asn109, Gln269  –107.44  –76.48  –30.96  0   Thr158, Asn109, Gly160, Glu161, Leu162, Asp108, Val159, His89
6.  Withanone  –9.09  218.4 nM   Val159, Gly160, Glu161, Asn109, Leu162, Gln269, Gln269  –10.1  38.83 nM  Trp106, Glu167, Ala107, Trp93, Lys92, His89, Asp108, Lys157, Asp164, Tyr264, Gly163, Tyr273, Val165, Thr301, Pro248  –109.36  –87.06  –22.31  0  Asn109, Thr158, Gly160, Gln269,Glu161, Leu162, Val159,His89
7.  Viscosalactone B  –9.02  243.41 nM  Ser85, Ala86, His89, Va159, Gly160, Asp108, Asn109, Gln269, Leu162,Glu161  –9.7  70.23 nM  Lys92, His89, Val159, Trp93, Asp108, Leu162, Gly163, Tyr273, Tyr264, Pro248, Pro247, Thr301, Asp164, Lys105, Glu167, Trp106, Ala107, Glu161, Lys157  –102.08  –86.12  –15.96  0  Leu162, Glu161, Gly160, Val159, Thr158,Asn109, Asp108, Ala107, Trp106
8.  Anaferine  –6.43  19.24 µM  Gly160, Asp108, Ala107, Trp93, Leu162, Glu161, Lys157  –6.0  39.69 µM  Thr301, Tyr273, Tyr264, Trp106, Asp164, Pro248, Pro247, Met208, Arg166  –75.28  –68.35  –6.93  0  Ala68, Thr74, Phe79, Asp76, Pro77, Lys43, Arg65, Pro59, Leu58
9.  Withasomnine  –5.56  84.41 µM  Asn109, Gln269, Cys270, Leu162, Gly160, Cys270  –7.2  4.50 µM  Asp76, Pro59, Phe79, Leu80, Thr74, Ala68, Thr75, Arg65, Pro77, Leu58  –69.24  –69.24  0  0   Asp76, Pro77, Thr75, Leu80, Leu58, Pro59, Arg65
10.  Procainamide  –5.03  206.96 µM   Glu161, Asn109, Leu162, Asp108, Gly160, Gln269, Cys270  –6.3  24.06 µM  Asn109, Gln269, Leu162, Val159, His89, Asp108, Glu161, Gly160  –76.81  –66.66  –10.15  0   Leu162, Glu161, Gly160, Gln269,Asp108, Asn109,Cys270
11.  Cinacalcet  –6.44  19.17 µM   Val159, Asp108, Gly160, Glu161, Leu162, His89, Val159  –8.8  344.50 nM   Gly160, Asn109, Leu162, Gln269, Cys270, Glu161, Asp108  –81.40  –81.40  0  0  Thr158, Leu162, Glu161, Gly160, His89, Ser85, Ala86, Asn109, Val159, Asn108