454, Tyr523, Val379, His383, Glu384, Val380, His513, Gln281, Thr282, Ser284, Phe457, Asp453 –10.2 31.56 nM Lys449, Val291, Pro297, Ser298, Asp300, Met299, Ser284, Asn285, Asn374, Glu376, Thr302, Leu375, Thr301, Tyr287, Asp288 –100.15 –79.22 –20.92 0 Asn374, Leu375, Thr302, Thr301, Asp300, Met299, Ser298, Pro297, Ala296, Pro294, Val291, Tyr287, Asn285   7. Viscosalactone B –8.83 339.1 nM Ala356, His387, Ser355, Glu384, Ala354, His353, His513, Phe512, Tyr523, Thr282, Asp453, Ser284, Glu376, Val379, Val380, His383, Glu411 –11.1 760 pM Tyr62, Asn85, Asn136, Leu81, Glu143, Leu139, Leu140, Asn66,Asn70, Phe512, Ala356, Ser355, Ala354, His353, Tyr523, His383, His387, Glu411, Arg522, Val518, Arg124 –119.88 –92.25 –27.63 0 Tyr62, Leu81,Asn136, Asn66, Tyr69, Leu139, Leu140, Glu143, Ser516, Asn70, His513, His353, Ala354, Tyr523, Ser355, Ala356, Trp357, His387, Glu411, Glu384, His383   8. Anaferine –8.25 890.86 nM Glu411, Tyr523, His383, His387, Glu384, Val380, Ala356, Ser355, Ala354, His353 –6.7 12.50 µM His383, His387, Ala354, Glu384, Ser355, Ala356, Val518, His513, Phe512, His353, Tyr523, Tyr520, Gln281, Phe457, Phe527 –77.85 –74.35 –3.5 0 Phe570, Met223, Asn406, Glu403, Gly404, Pro407, His410, Phe391, Glu411, His387   9. Withasomnine –4.99 218.08 µM Tyr523, His513, Val380, His383, Glu384, His387, Ala356, Ser355, Ala354, His353 –6.7 12.59 µM Phe291, Tyr394, His410, Arg522, Gly404, Pro407, Glu403, Met223, Phe570, Asn406 –74.24 –64.10 –10.14 0 Leu122, Thr92, Ala125, Arg124, Ala89, Ile88, Asn85, Asn136, Trp59   10. Arbidol –6.69 12.47 µM Ala354, His353, Glu162, Lys511, Trp279, Gln281, Thr282, Phe457, Asp453, Tyr523, Lys454, Phe527, Asp415, His383, Val380, Glu384 –8.3 880.23 nM Phe570, Met223, Asn406, Gly404, Glu403, Arg402, Tyr394, Tyr360, Phe391, Asp358, Trp357, Ala356,His387, His410, Glu411, Arg522, Pro407 –86.22 –73.55 –12.67 0 Phe391, His410, Glu411, His387, Trp357, Ala356, Ser355, Ala354, His353, Asn66, Ala63, Tyr62, Val518, Tyr523   11. Losartan –6.72 11.86 µM Asn406, Met223, Arg522, Pro407, Gly404, Glu403, His410, Glu411, Tyr523, Phe391, His387, Ala356, Val518 –9.4 129.59 nM Met223, Pro519, Arg522, His410, His387, Tyr523, Glu411, Ser355, Val518, Ala356, Asp358, Tyr360, Phe391, Gly404, Glu403, Asn406, Pro407 –101.28 –85.24 –16.04 0 Asp121, Leu122, Thr92, Trp220, Glu123, Arg124, Ala89, Ile88, Pro519, Tyr62, Ser517, Tyr135, Ile204   Table 6. Binding energies of WS phytoconstituents with SARS-CoV spike glycoprotein (PDB ID: 5WRG) in comparison to the FDA approved standard reference drugs (Arbidol and Hydroxychloroquine).   AutoDock v4.2.6 AutoDock vina iGEMDOCK v2.1 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 –8.39 702.21 nM Ile979, Leu983, Thr980, Gly981, Gln984, Tyr738, Leu983, Gln984, Thr980 –10.3 28.30 nM Lys715, Ala753, Ala754, Asp757, Arg761, Leu846, Arg758, Pro651, Ile652, Leu843, Leu597, Gln599, Ala633, Val581, Tyr300, Thr302 –104.25 –83.69 –20.56 0 Arg453, Glu452, Asp454, Ser456, Arg449, Arg441, Val458, Pro459, Arg444, His445, Phe460, Pro466, Gly464, Ser461, Lys465   2. Withanolide A –9.78 67.23 nM Gln984,Leu983, Thr980, Gly981, Arg977, Phe952, Tyr738 –10.5 19.50 nM Ile299, Ala754, Ser750, Thr302, Ala753, Val581, Leu843, Gln599, Ile652, Arg758, Lys715, Gly653, Asp757, Tyr300, Arg761, Pro651, Leu846 –97.67 –85.32 –12.35 0 Ile652, Pro651, Thr302, Tyr300, Ile299, Gln301, Ser750, Ala754, Arg747, Gly751, Lys715   3. Withanolide B –9.4 129.59 nM Gln984, Thr980, Leu983, Gly981, Arg977, Phe952, Tyr738, Asp976 –10.4 23.67 nM Ser950, Asn951, Gly981, Arg977,Thr980, Asp976, Asp976, Phe952,Gln984, Leu983, Gln947, Phe741, Ser985, Tyr738 –100.62 –94.31 –6.32 0 Lys715, Asp757, Ala753, Arg761, Arg758, Ala754, Leu846, Gly653, Ile652, Pro651, Tyr300   4. Withanolide D –9.1 212.78 nM Thr980, Gly981, Leu983, Tyr738, Phe952, Gln984, Asp976, Ile979 –10.7 11.45 nM Ile299, Ala754, Pro651, Arg758, Arg761, Asp757, Leu846, Leu597, Lys715, Val581, Ile652, Ala633, Gln599, Leu843, Tyr300, Ser750, Ala753, Thr302 –103.3 –84.53 –18.77 0 Ala926,Leu927, Ser924, Gly928, Thr925, Gln931, Asn935, Lys297, Asp296, Ile295, Glu294, Val290   5. Withanolide E –7.13 5.93 µM Thr980, Gly981, Gln984, Arg977, Tyr738, Leu983 –9.5 99.21 nM Lys715, Ala753, Ser750, Pro844, Thr302, Leu843, Ala633,Gln599, Ile652, Leu597, Val581, Ile299, Pro651, Ile650, Tyr300, Ala754 –99.34 –93.84 –5.49 0 Leu597,Ala633, Gln599, Ile652, Val581, Pro651, Thr302, Ile650, Tyr300, Ile299, Pro844, Leu843, Lys715, Ser750, Ala753, Ala754   6. Withanone –6.49 17.46 µM Thr980, Gly981, Gln984, Leu983, Phe741,Tyr738 –9.5 99.56 nM Arg747, Gly751, Ala754, Pro651, Ile652, Lys715, Gln599, Val581, Tyr200, Leu843, Ala753, Thr302, Ser750, Ile299, Gln939, Gln301 –104.09 –85.03 –19.07 0 Leu810, Ala938, Asn942, Lys946, Thr943, Gln744, Arg747, Thr743, Ser289, Gln301, Val290, Lys291   7. Viscosalactone B –7.6 2.69 µM Gln987, Gln984, Leu983, Thr980, Asp976, Phe952, Gly981, Gln984, Thr988 –10.2 32.60 nM Leu994, Ile995, Glu999, Ala998, Ile752, Arg1001, Ala997, Glu755, Gln936, Asp932, Ile299, Asp296, Tyr300, Gln301, Gln939, Arg747, Ala748, Gly751, Arg996 –121.82 –89.39 –32.43 0 Arg563, Arg315, Phe551, Gln550, Asn530, Gly531, Asn505, Leu504, Leu503, Ser380, Phe379, Cys378, Arg965, Asn530, Gly551   8. Anaferine –6.94 8.16 µM Gln947, Phe741, Ser985, Gln984, Gly981, Tyr738, Phe952, Leu983, Thr980, Ile979, Asp976 –7.0 6.40 µM Arg747, Thr943, Gln744, Thr988, Gln987, Phe741, Gln947, Ser985, Tyr989, Leu944, Ala940, Gln992 –84.12 –69.13 –14.99 0 Arg965, Leu374, Lys373, Tyr352, Cys378, Leu503, Phe501, Met417, Val369, Ser370   9. Withasomnine –5.87 49.69 µM Gln947, Phe741, Ser985, Gln984, Gly981, Leu983, Phe952, Asn951, Tyr738, Ser950 –7.1 6.25 µM Leu963, Ser728, Cys725, Val958, Leu948, Phe558, Asp557, Phe837, Asn960, Thr535, Thr533, Asp727, Leu959 –80.03 –72.43 –7.60 0 Cys278, Phe262, Met263, Val276, Cys288, Lys287, Ser292   10. Arbidol –4.91 251.65 µM Phe95