Investigating Potential Inhibitory Effect of Uncaria tomentosa (Cat’s Claw) against the Main Protease 3CL^pro of SARS-CoV-2 by Molecular Modeling

Table 1

Best binding energy (kcal/mol) based on AutoDock scoring of the main constituents of Cat’s claw into the cleavage site of the novel SARS-CoV-2 main protease (PDB ID: 6LU7).

Main constituents of Cat’s claw	Best binding energy (kcal/mol)
Spiroxindole alkaloids
Speciophylline	−8.1
Isopteropodine	−6.6
Isomitraphylline	−7.6
Uncarine F	−8.2
Mitraphylline	−7.0
Pteropodine	−7.0
Rhynchophylline	−5.9
Isorhynchophylline	−6.1
Indole glycoside alkaloids
Cadambine	−8.6
3-Dihydrocadambine	−8.0
3-Isodihydrocadambine	−8.0
Polyhydroxylated triterpenes
PHT-1	−6.8
Uncaric acid	−7.0
Floridic acid	−7.6
Quinovic acid glycosides
QAG-1	−7.8
QAG-2	−7.4
QAG-3	−7.2
QAG-4	−7.9
QAG-5	−7.8
QAG-6	−7.8
Proanthocyanidins
Chlorogenic acid	−6.8
Epicatechin	−7.2
Proanthocyanidin B2	−9.2
Epiafzelechin-4β-8-epicatechin	−8.9
Proanthocyanidin B4	−9.2
Proanthocyanidin C1	−8.8
References
N3^a	−8.1 (−8.1)^b, (−8.3)^c, (−7.9)^d
Remdesivir^h	−8.5
Ritonavir^h	−8.1 (−7.7)^e, (−7.5)^f, (−8.9)^g
Lopinavir^h	−8.0 (−8.4)^e, (−7.4)^f, (−9.4)^g

^aPotent irreversible inhibitor of SARS-CoV-2 virus 3CL^pro. ^bBinding affinity reported by [47]. ^cBinding affinity reported by [77]. ^dBinding affinity reported by [78]. ^eBinding affinity reported by [79]. ^fBinding affinity reported by [80]. ^gBinding affinity reported by [3]. ^hFDA-approved antiviral drugs promising to treat SARS-CoV-2 [81–83].