Review Article

Novel Drug Design for Treatment of COVID-19: A Systematic Review of Preclinical Studies

Table 2

Summary of studies with in silico method that used natural products for novel drug discovery against COVID-19.

AuthorYearMethodDetail of methodName of compound/drugTargetEfficacyComments

Abdelli et al. [120]2021In silicoMolecular dockingIsothymol, thymol, limonene, P-cymene, and γ-terpinene derived from the essential oil of the antiviral and antimicrobial plant Ammoides verticillata (Desf.) Briq.Inhibition of ACE2 cellular receptorIsothymol, a major component of this plant, gives the best docking scores, as good ACE2 inhibitor
Abouelela et al. [121]2021In silicoMolecular docking, dynamic simulation, and binding free energy calculationAloeMain protease and spike protein132, 134, and 159 were the best scoring compounds against main protease, while compounds 115, 120, and 131 were the best scoring ones against spike glycoprotein. Compounds 120 and 131 were able to achieve significant stability and binding free energies during molecular dynamic simulation
Adem et al. [122]2020In silicoMolecular dockingMedicinal plant-based bioactive compounds (80 flavonoid compounds)Main proteaseHesperidin, rutin, diosmin, apiin, diacetylcurcumin, (E)-1-(2-hydroxy-4-methoxyphenyl)-3-[3-[(E)-3-(2-hydroxy-4-methoxyphenyl)-3-oxoprop-1-enyl]phenyl]prop-2-en-1-one, and beta, beta′-(4-methoxy-1,3-phenylene)bis(2′-hydroxy-4′,6′-dimethoxyacrylophenone have been found as more effective on COVID-19 than nelfinavir
Allam et al. [123]2020In silicoMolecular docking, 3D shape similarity study (rapid overlay chemical similarity-ROCS) to the clinically used drugs in COVID-19 patients3′-Hydroxy-4′-methoxy-chroman-7-O-β-d-glucopyranoside 4, ferulic acid heptyl ester 1, naringenin 2, and 4,2′,4′-trihydroxy-6′-methoxychalcone-4′-O-β-d-glucopyranoside 3, which were isolated from peach (Prunus persica (L.) Batsch) fruitsMain protease, spike proteinNaringenin 2 and 4,2′,4′-trihydroxy-6′-methoxychalcone-4′-O-β-d-glucopyranoside 3 have a strong binding mode to a protease receptor and spike protein and also block the inflammatory stormRecommendation of peach fruits in controlling and managing COVID-19 cases
Al‐Sehemi et al. [124]2020In silicoMolecular docking31000 natural compounds of the natural product activity and species source (NPASS) librarySpike glycoproteinCastanospermine and karuquinone B were shown to be the best-in-class derivatives in silico able to target an essential structure of the virus and to act in the early stage of infection
Attia et al. [125]2021In silicoMolecular docking10 phenolic antiviralAgainst SARS-CoV-2Hesperidin showed the highest docking scoreHesperidin and its mediated ZnO nanoparticles are willing antiviral agents
Azim et al. [126]2020In silicoVirtual screening methods molecular docking27 plant metabolitesMain protease proteins (MPP), Nsp9 RNA-binding protein, spike receptor-binding domain, spike ectodomain, and HR2 domainAsiatic acid, avicularin, guajaverin, and withaferin showed a maximum binding affinity with all key proteins in terms of lowest global binding energy
Bhowmik et al. [39]2021In silicoRepurposing drugs, docking, and molecular dynamic simulationOrientin (phytochemical)Inhibitor of SARS-CoV-2 spike and host cell receptor GRP78 bindingBinding of orientin in the overlapping residues of GRP78 binding region of SARS-CoV-2 spike modelAs a promising precautionary or therapeutic measure for COVID-19
Çakır et al. [127]2021In silicoMolecular dockingPeptides derived from beta-lactoglobulinInhibit the host cell membrane receptorsAla-Leu-Pro-Met-His-Ile-Arg (ALMPHIR) and Ile-Pro-Ala-Val-Phe-Lys (IPAVFK) peptidesβ-Lactoglobulin (BLG) is the major whey protein of cow and sheep’s milk (∼3 g/l)
Chatterjee et al. [128]2021In silicoMolecular dockingHesperidin, kaempferol, quercetin, epigallocatechinPLpro (papain-like protease), RdRp (RNA-dependent RNA polymerase), Mpro or 3cl protease, and spike proteinHesperidin, kaempferol, quercetin, epigallocatechinLead to conclusive data for the treatment of polyphenols, flavonoids, and bioflavonoids against SARS-CoV-2
Chikhale et al. [129]2020In silicoMolecular docking, dynamicsPlant Withania somnifera (Indian ginseng)NSP15 endoribonuclease and receptor-binding domain of prefusion spike proteinWithanoside X and quercetin glucoside from W. somnifera have favorable interactions at the binding site of selected proteinsImmunomodulatory, antioxidant, and anti-inflammatory roles
Chikhale et al. [130]2021In silicoMolecular docking, dynamics, and network pharmacology analysisSaikosaponinsAdjuvant therapy in the treatment of COVID-19Saikosaponins interact with the proteins CAT gene CAT (catalase) and checkpoint kinase 1 (CHEK1)Possible improvement in immune response towards COVID-19
Chikhalet al. [131]2020In silicoMolecular docking, dynamicsAsparagus racemosus (Willd.)NSP15 endoribonuclease and spike receptor-binding domainAsparoside -C and Asparoside -F have good binding with target proteinsAsparagus racemosus holds promise as SARS-CoV-2 (S) and (N) protein inhibitor
Chowdhury [132]2020In silicoMolecular docking, dynamicsTinospora cordifolia (Giloy)Main proteaseBerberine can regulate main protease protein’s function
Dahab et al. [133]2020In silicoMolecular docking10 phenolic compounds of different classes (phenolic acids, flavonoids, and coumarins)Main protease and RNA polymeraseThe top 7 hits are flacourticin [3], sagerinic acid [16], hordatine a [23], hordatine B [134], N-feruloyl tyramine dimer [135], bisavenanthramides B-5 [27], and vulnibactins [38] and have better binding scores than remdesivir, the native ligand in RNA polymerase target (PDB ID: 7bV2)Hordatines are phenolic compounds present in barley and were found to exhibit the highest binding affinity to both protease and polymerase
Das et al. [136]2020In silicoMolecular dockingFlavonoid-based phytochemicals of Calendula officinalisMain proteaseRutin, isorhamnetin-3-O-β-D, calendoflaside, narcissin, calendulaglycoside B, calenduloside, and calendoflavoside have better binding energy than the native ligandRutin and caledoflaside showed better stability, compactness, and flexibility
Debnath et al. [137]2020In silicoSequential E-pharmacophore and structure-based virtual screening (VS)113687 number of commercially available natural compoundsADP-ribose phosphatase6 potential inhibitors having good binding affinity towards active sitesCommercially available
Dev and Kaur [138]2020In silicoMolecular dockingEucalyptus essential oilMain proteaseJensenone may represent potential treatment potential to act as main protease inhibitor
Duru et al. [139]2021In silicoMolecular dockingOil of Nigella sativa seedReplicase polyprotein 1a, RNA-binding protein of NSP9, ADP ribose phosphatase of NSP3, 3-chymotrypsin-like protease 3CLpro, and RNA-dependent RNA polymerase RdRp, and ACE2-angiotensin-converting enzyme from the Homo sapiensThe binding affinity of caryophyllene oxide was the highest on NSP9 and RdRp targets, while α-bergamotene gave the best binding affinity on RPIA target. The binding affinity of β-bisabolene on the ACE2 was almost the same as remdesivir
El-Demerdash et al. [140]2021In silicoMolecular dynamic simulations, molecular docking15 guanidine alkaloidsMain protease (Mpro) (PDB ID: 6lu7), spike glycoprotein (PDB ID: 6VYB), nucleocapsid phosphoprotein (PDB ID: 6VYO), membrane glycoprotein (PDB ID: 6M17), and a nonstructural protein (nsp10) (PDB ID: 6W4H)Crambescidin 786 [5] and crambescidin 826 had the highest binding affinities. The examined 15 alkaloids especially 5 and 13 showed promising docking, ADMET, toxicity, and MD results
Elekofehinti et al. [141]2020In silicoMolecular docking studies, molecular dynamics, and ADME/Tox50,000 natural compounds retrieved from IBS databasePapain-like proteaseSTOCK1N-69160 [(S)-2-((R)-4-((R)-2-amino-3-methylbutanamido)-3-(4-chlorophenyl) butanamido)propanoic acid hydrochloride] has been proposed as a novel inhibitor against COVID-19 PLpro
El‐Hawary et al. [142]2021In silicoMolecular docking (a combination of metabolomics and in silico approaches)A. terreus, the endophytic fungus associated with soybean rootsMain proteaseAspergillide B1 and 3α-hydroxy-3,5-dihydromonacolin L were found to be potent anti-COVID-19 drug candidates
Emirik [143]2020In silicoMolecular docking, MM-GBSA-based predictions, and molecular dynamicsTurmeric contentsSARS-CoV-2 vital proteinsTurmeric spice has the potential to inhibit the SARS-CoV-2 vital proteins and can be used a therapeutic or protective agent against SARS-CoV-2 via inhibiting key protein of the SARS-CoV-2. Compounds 4, 23, and 6 are the most prominent inhibitor for the main protease, the spike glycoprotein, and RNA polymerase of virus, respectively
Fakhar et al. [144]2020In silicoStructure-based pharmacophore modeling, virtual screening-based PHASE screen score, molecular modelingAnthocyanin derivativesMain protease6 best anthocyanin-derived natural compounds, which could be used as promising lead compounds against main protease SARS-CoV-2
Falade et al. [145]2021In silicoMolecular dockingSaponins and tanninsMain proteaseEllagic acid, arjunic acid, theasapogenol B, and euscaphic acid as potential inhibitors of SARS-CoV-2 (Mpro) with better pharmacokinetics and bioavailability compared with remdesivir
Fitriani et al. [146]2020In silicoMolecular dockingPhytochemical compounds (Moringa oleifera, Allium cepa, Cocos nucifera, Psidium guajava, and Eucalyptus globulus)Main proteaseOleanolic acid in Allium cepa, α-tocotrienol in Cocos nucifera, asiatic acid in Psidium guajava, and culinoside in Eucalyptus globulus were the most recommended compound in each medicinal plantOleanolic acid in Allium cepa found as a potential inhibitor of COVID-19 Mpro
Gangadevi et al. [147]2021In silicoMolecular dynamic simulations, molecular dockingLibrary of natural compoundsHost ACE2 receptor with spike RBD domain of SARS-CoV-2Kobophenol A, identified through docking studies, is the first compound that inhibits SARS-CoV-2 binding to cells through blocking S1-RBD to the host ACE2 receptor and thus may serve as a good lead compound against COVID-19
Gangarapu et al. [148]2020In silicoMolecular docking online pkCSM and SwissADME Web serverPhytoconstituents of Siddha official formulation kabasura kudineer and novel herbal preparation—JACOMSpike protein37 compounds were screened, and of these, 9 compounds showed high binding affinity against spike proteinSNACK-V formulations could be used for effective treatment of COVID-19
Ghosh et al. [149]2020In silicoMolecular dynamic simulations, molecular docking8 polyphenols from green teaMain protease3 polyphenols (epigallocatechin gallate, epicatechin gallate, and gallocatechin-3-gallate) interact strongly with one or both catalytic residues (His41 and Cys145) of main protease
Ghosh et al. [150]2021In silicoMolecular dynamic simulations, molecular docking, MM-GBSA analysisJusticia adhatoda alkaloidsMain protease1 alkaloid (anisotine) had interaction with both the catalytic residues (His41 and Cys145) of Mpro and exhibited good binding affinity (−7.9 kcal/mol)More potent Mpro inhibitor than the two previously recommended antiviral drugs (lopinavir and darunavir)
Gorla et al. [151]2020In silicoMolecular dockingEssential flavonoidsSARS-CoV-2 spike glycoprotein receptor-binding domain (RBD-S) and host angiotensin-converting enzyme-2 protease domain (PD-ACE2)Biochanin A and silymarin bind significantly at the active sites of RBD-Sand PD-ACE2
Gurung et al. [152]2020In silicoVirtual screening, molecular dockingAntiviral compounds from plantsMain proteaseBonducellpin D was identified as the best lead molecule, which shows higher binding affinity
Gyebi et al. [153]2021In silicoMolecular docking, ADME/Tox, and Lipinski filter analysisAfrican plants derived alkaloids and terpenoidsMain protease4 nontoxic, druggable plant-derived alkaloids (10-hydroxyusambarensine and cryptoquindoline) and terpenoids (6-oxoisoiguesterin and 22-hydroxyhopan-3-one)
Elwakil et al. [154]2021In silicoGas chromatography/mass spectrometry analysis molecular dockingEgyptian propolisRNA-dependent RNA polymerase, spike protein S1, and main proteaseOctatriacontyl pentafluoropropionate is well oriented inside the enzyme pockets, in addition to an excellent binding manner with the active site of the target macromoleculesMenoufia propolis could be a promising candidate in the combat against the pandemic COVID-19
Hasan et al. [155]2020In silicoMolecular dockingCompounds present in the plant Solanum surattenseMain protease13 phytochemicals were studied, eight showed very strong binding affinities to main protease, and four showed moderate to strong binding affinities
Hashem [156]2020In silicoMolecular dockingHoneybee and propolisMain protease6 main compounds possess high binding energy with the receptor active site of the main protease
Ibrahim et al. [157]2020In silicoMolecular dynamic simulations, molecular docking, MM-GBSA analysisMolPort database that contains over 100,000 natural productsMain protease9 potent natural products with binding affinities (ΔG binding) >−48.0 kcal/mol four bis([1, 3]dioxolo)pyran-5-carboxamide derivatives were identified as potential drug candidatesMolPort-004-849-765, MolPort-000-708-794, MolPort-002-513-915 and MolPort-000-702-646 are bis([1,3]dioxolo)pyran-5-carboxamide derivatives
Ibrahim et al. [158]2020In silicoMolecular dynamic simulations, molecular dockingMetabolites present in several common spicesMain proteaseHigh potency of salvianolic acid A and curcumin as main protease inhibitorsSalvianolic acid A as an in silico natural product inhibitor against the SARS-CoV-2 main protease
Isa et al. [159]2020In silicoDocking and molecular dynamic (MD) simulationExtracts of Zingiber officinale and Anacardium occidentaleMain proteaseSix compounds had good binding energies. CID_9910474 and CID_10503282 had a better stability when compared to other selected phytochemicals
Istifli et al. [160]2020In silicoMolecular dynamics and molecular mechanic Poisson–Boltzmann surface area (MM/PBSA) methods23 phytochemicals belonging to different flavonoid subgroupsSpike glycoprotein cellular proteases (transmembrane serine protease 2 (TMPRSS2), cathepsin B and L (CatB/L)).(−)-Epicatechin gallate interacted strongly with all the proteins studiedEpicatechin gallate can be evaluated as a candidate molecule in drug development studies against 2019-nCoV since it was not the substrate of P-gp (P-glycoprotein), did not inhibit any of the cytochrome Ps, and did not show AMES toxicity or hepatotoxicity on eukaryotic cells
Jan et al. [161]2021In silicoCell-based infection assay molecular modeling2,855 small molecules and 190 traditional herbal medicinesMain protease RNA-dependent RNA polymeraseMefloquine, nelfinavir, and extracts of Ganoderma lucidum (RF3), Perilla frutescens, Mentha haplocalyx
Jo et al. [162]2020In silicoDockingFlavonoidsMain proteaseBaicalin, herbacetin, and pectolinarin have been discovered to block the proteolytic activity. Baicalin showed an effective inhibitory activity against main protease
Joshi et al. [163]2021In silicoDocking7100 moleculesMain proteaseSeveral natural molecules such as δ-viniferin, myricitrin, taiwanhomoflavone A, lactucopicrin 15-oxalate, nympholide A, afzelin, biorobin, hesperidin, and phyllaemblicin B strongly binds to main proteaseThese molecules also showed strong binding with other potential targets of SARS-CoV-2 infection such as viral receptor human angiotensin-converting enzyme 2 (hACE2) and RNA-dependent RNA polymerase (RdRp)
Junior et al. [164]2021In silicoDocking and molecular dynamic (MD) simulationLapachol(1,4-naphthoquinone)SARS-CoV-2 nonstructural proteins (nsps)Lapachol derivatives VI and IX demonstrated the strongest bindingLapachol derivatives are potential ligands for SARS-CoV-2 Nsp9
Kar et al. [165]2020In silicoMolecular docking molecular dynamic simulations and analysis of MM-PBSA energyIndian plants including Justicia adhatoda, Ocimum sanctum, and Swertia chirataSpike protein, main protease enzyme Mpro, and RNA-dependent RNA polymerase (RdRp)Anisotine against SARS-CoV-2 spike and Mpro proteins and amarogentin against RdRp as potential inhibitors
Khalifa et al. [166]2020In silicoMolecular docking modeling structural-relationship activity10 anthocyaninsMain proteasePhacelianin, gentiodelphin, cyanodelphin, tecophilinLeading molecules for further optimization and drug development process to combat COVID-19
Khalifa et al. [167]2020In silicoMolecular operating environment molecular docking19 structural different hydrolysable tanninsMain proteasePedunculagin, tercatain, and castalin
Khan et al. [168]2020In silicoMolecular dockingMarine natural productsMain proteaseC-1 (PubChem CID 11170714) exhibited good activity
Kiran Raj et al. [169]2020In silicoMolecular dockingC-Phycocyanin of Spirulina platensisNonstructural proteins 12C-Phycocyanin inhibits the active site of nsp12
Krupanidhi et al. [170]2020In silicoMolecular docking molecular dynamic simulation ADME along with toxicity analysisPhytochemical constituents of Tinospora cordifoliaMain proteaseTinosponone
Kumar et al. [171]2020In silicoMolecular docking molecular dynamic simulations and analysis of MM-PBSA energyNovel natural metabolitesMain proteaseUrsolic acid, carvacrol, and oleanolic acid could
Kumar et al. [172]2021In silicoMolecular docking, ADMET, and molecular dynamic simulationsPhytoconstituents from natural herbsMain proteaseLaurolitsineLaurolitsine, an active constituent of roots of Lindera aggregata
Kumar et al. [173]2021In silicoMolecular docking molecular dynamic simulations and analysis of MM-PBSA energyStrychnos nux-vomicaMain proteaseDemethoxyguiaflavine, strychnoflavine
Li et al. [174]2021In silicoNetwork pharmacology and in vitro experiment verification molecular dockingMaxing Shigan decoction (MXSGD)ACE2, Mpro, and RdRpThe components with strong potential affinity (top 10) with ACE2, Mpro, and RdRp are mainly from Glycyrrhiza uralensis (Chinese name: Gancao) and Semen armeniacae amarum (Chinese name: Kuxingren). Among them, amygdalin was selected as the optimal candidate component binds to all three key targets, and euchrenone, glycyrrhizin, and glycyrol also exhibited superior affinity interactions with ACE2, Mpro, and RdRp, respectivelyMulticomponent, multitarget, and multi-approach intervention
Maiti and Banerjee [175]2021In silicoBioinformatic molecular dockingTea flavonoid catechin productsSpike glycoproteinsEpigallocatechin gallate and theaflavin gallate interact better than hydroxychloroquine
Mahmud et al. [176]2021In silicoMolecular docking molecular dynamic simulation MM-GBSA scores3063 compounds from more than 200 plants from the Asian regionMain proteaseCurcumin, gartanin, robinetin
Mahmud et al. [177]2020In silicoMolecular docking molecular dynamic simulation MM-GBSA scoresPlant-derived natural compoundsMain proteaseCarinol, albanin, myricetin
Mesli et al. [178]2021In silicoMolecular docking molecular dynamic simulationsLeaves of Corchorus olitorius Linn.Angiotensin-converting enzyme 2Méthyl-1,4,5-tri-O-caféoyl quinate has a stronger bond, high affinity, and gives the best docking scores compared with the co-crystallized inhibitor (PRD_002214) of the enzyme ACE2
Mohammadi et al. [179]2020In silicoMolecular dockingMarine polypeptides were isolated from the hydrolysate of Pacific oysterMain proteaseThe score of Leu-Leu-Glu-Tyr-Ser-Ileu ligand was higher than remdesivirPacific oyster compounds may have the potency to be evolved as an anti-COVID-19 main protease
Murugan et al. [180]2020In silicoMolecular docking molecular dynamic simulation MM-GBSA scoresAndrographis paniculata phytochemicals3 nonstructural proteins (3 L main protease (3CLpro), papain-like proteinase (PLpro) and RNA-directed RNA polymerase (RdRp)), and a structural protein (spike protein (S))Neoandrographolide (AGP3) has shown promising binding affinity towards all the four targets
Naik et al. [181]2020In silicoMolecular docking molecular dynamic simulation ADME propertiesNatural product activity and species source (NPASS) databaseEndoribonuclease exoribonuclease RNA-dependent RNA polymerase (RdRp) methyltransferase and main protease21 compounds showed maximum docking scores NPC214620, NPC52382, and NPC270578 are targeting five, four, and three-drug targets, respectivelyMultitarget-based drug design
Narkhede et al. [182]2020In silicoMolecular docking molecular dynamic simulationsNatural productsMain proteaseGlycyrrhizin, bicyclogermacrene, tryptanthrin, β-sitosterol, indirubin, indican, indigo, hesperetin, chrysophanic acid, rhein, berberine, and β-caryophylleneInteractions with the COVID-19 main protease were highest in the case of glycyrrhizin and rhein
Nivetha et al. [183]2020In silicoMolecular docking molecular dynamic simulation MM-PBSASeselin purified from the leaf extracts of Aegle marmelosSpike protein S2, main protease, and free enzyme of the SARS-CoV-2Seselin had inhibitory potential over multiple SARS-CoV-2 targets
Ogunyemi et al. [184]2020In silicoMolecular docking molecular dynamic simulation ADME properties226 bioactive compounds from African herbs and medicinal plantsRNA-dependent RNA polymeraseDrugable alkaloids (10′-hydroxyusambarensine, cryptospirolepine, strychnopentamine) and flavonoids (usararotenoid A and 12α-epi-millettosin)
Padhi et al. [185]2021In silicoMolecular docking ADME properties415 natural metabolites isolated from several plants, fungi, and bacteriaSpike glycoprotein (S1) and the main proteaseFusaric acid, jasmonic acid, jasmonic acid methyl ester, putaminoxin, putaminoxins B and D, and stagonolide K were predicted to have considerable (ADME) and safety indicesJasmonic acid and putaminoxins B and D bind best to main protease
Pandey et al. [186]2020In silicoMolecular docking molecular dynamic simulation ADME properties10 potential naturally occurring compounds (flavonoids/non-flavonoids)Spike glycoproteinFisetin, quercetin, and kaempferol consist of drug-likeness property
Kumar et al. [187]2020In silicoMolecular dockingKabasura kudineer and thonthasura kudineer are two Siddha formulationsSpike glycoproteinCucurbitacin B (−112.09), cardiofolioside (−111.5), apigenin (−98.84), and pyrethrin (−92.98) were observed as more effective with less bind energiesKabasura kudineer could be a potential Siddha medicine for COVID-19
Rahman et al. [188]2021In silicoMolecular docking ADMET propertiesRutinMain protease (Mpro), RNA-dependent RNA polymerase (RdRp), papain-like protease (PLpro), and spike (S) proteinSignificant binding of rutin with Mpro, RdRp, PLpro, and S proteins. Main protease exhibited the strongest binding affinityOptimal solubility, nontoxic, and noncarcinogenic properties
Rahman et al. [189]2020In silicoMolecular operating environment (MOE) ligand-based pharmacophore approach and a molecular docking-based screeningNatural product activity and species source (NPASS)Type II transmembrane serine protease (TMPRSS2)85 compounds with molecular docking comparable to or greater than that of the standard inhibitor (camostat mesylate) were identified. The top 12 compounds with the most favorable structural features were studied. The low-molecular-weight compound NPC306344 showed significant interaction with the active site residues of TMPRSS2
Rakib et al. [190]2020In silicoMolecular dockingBioactive phytocompounds isolated from Tinospora crispaMain proteaseThe top nine hits might serve as potential anti-SARS-CoV-2 lead molecules, with three of them exerting biological activity
Ramadhan et al. [191]2020In silicoMolecular dockingEtlingera elatior plantMain proteaseErgosterol peroxide sitostenone
Rangsinth et al. [192]2021In silicoMolecular docking ADMET propertiesNatural products isolated from edible and medicinal mushroomsMain protease6 of 25 compounds are the best drug-like property candidates, including colossolactone VIII, colossolactone E, colossolactone G, ergosterol, heliantriol F, and velutin
Rivero-Segura et al. [193]2021In silicoMolecular docking molecular dynamic simulation ADME propertiesMexican natural productsAgainst the SARS-CoV-2Quercetin, riolozatrione, and cichoriin target the key proteins of SARS-CoV-2Cichoriin reaches higher lung levels (100 mg/kg, IV); therefore, it may be considered in developing therapeutic tools
Selvaraj et al. [194]2020In silicoHomology modeling and molecular dynamic (MD) simulation MM/GBSA, MD simulations, and PCA calculationsTraditional Chinese medicine (TCM) databaseNsp 14 guanine-N7 methyltransferase (N7-MTase)TCM 57025, TCM 3495, TCM 5376, TCM 20111, and TCM 31007 are the compounds from the TCM database, which can occupy and interact nicely with the substrate-binding site of N7-MTase
Sharma and Kaur [195]2021In silicoMolecular docking, protein interaction calculator ADME studies12 bioactive molecules present in essential oils of eucalyptus plant leavesSpike (S) proteinToruatone
Sharma [196]2020In silicoMolecular docking, protein interaction calculatorEucalyptol (1,8 cineole), an essential oil component from eucalyptus oilMain proteaseEucalyptol may represent potential treatment potential to act as main protease inhibitorEffective binding of eucalyptol to COVID-19 proteinase
Sharma and Kaur [197]2020In silicoMolecular docking, protein interaction calculatorJensenone, an essential oil component from eucalyptus oilMain proteaseJensenone may represent potential treatment potential to act as main protease inhibitor
Shawan et al. [198]2021In silicoPharmacophore study molecular docking molecular dynamic simulation ADME properties43 flavonoids of 7 different classesAgainst the SARS-CoV-2Luteolin and abyssinone II were found to develop successfully docked complex within the binding sites of target proteins
Sindhu et al. [199]2020In silicoMolecular dockingClerodendrum paniculatum leavesMain proteaseClerodol
Singh et al. [200]2021In silicoMolecular docking and structural dynamic studiesTea (Camellia sinensis) polyphenolsNonstructural protein 16 (NSP16)Theaflavin compound demonstrated lower binding free energy in comparison with the standard molecule sinefungin
Singh et al. [201]2020In silicoMolecular docking and structural dynamic studies molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) ADME propertiesPolyphenolsRNA‐dependent RNA polymerase (RdRp)EGCG, theaflavin (TF1), theaflavin-3′-O-gallate (TF2a), theaflavin-3′-gallate (TF2b), theaflavin 3,3′-digallate (TF3), hesperidin, quercetagetin, and myricetin strongly bind to the active site of RdRpEGCG, TF2a, TF2b, and TF3 can inhibit RdRp and represent an effective therapy for COVID-19
Srimathi et al. [202]2020In silicoMolecular dockingTraditional herbal medicine: apo-quinine, catechin, cinchonidine, cinchonine, cupreidine, epicatechin, epiprocurcumenol, epiquinine, procurcumenol, quinidine, quinine, zedoaronediol, procurcumadiolAgainst the SARS-CoV-2Epicatechin, apo-quine
Subbaiyan et al. [203]2020In silicoMolecular dockingActive constituents present in common herbsSpike (S) proteinEpigallocatechin gallate (EGCG) was found to have the highest binding affinity with the viral S protein, followed by compounds, “F” (curcumin), “D” (apigenin), and “E” (chrysophanol)Green tea
Surti et al. [204]2020In silicoMolecular docking molecular dynamic simulationsIlimaquinone (marine sponge metabolite)Spike receptor-binding domain, RNA-dependent RNA polymerase, Nsp10, Nsp13, Nsp14, Nsp15, Nsp16, main protease, and papain-like proteaseIlimaquinone exhibited promising inhibitory potential against all the SARS-CoV-2 target proteins, as evident from the binding energiesMost promising inhibitory candidate against the SARS-CoV-2 papain-like protease
Tao et al. [205]2020In silicoNetwork pharmacology and molecular docking.Huashi Baidu formula (HSBDF): ChineseAgainst the SARS-CoV-2Baicalein and quercetin were the top two compounds of HSBDF, which had high affinity with ACE2Regulate multiple signaling pathways through ACE2
Umar et al. [206]2021In silicoMolecular docking molecular dynamic simulation ADME propertiesAzadirachta indica, Mangifera indica, and Moringa oleifera: African plantsMain proteaseMost of the active phytocomponents of the study plants exhibited relative inhibitory potentials against main protease and preferred pharmacological features when compared with hydroxychloroquineCaffeic acid, chlorogenic acid, catechin, ellagic acid, gallic acid, etc.
Umesh et al. [207]2021In silicoMolecular docking molecular dynamic simulation ADME propertiesChemical compounds from Indian spicesMain proteaseCarnosol exhibited the highest binding affinity for arjunglucoside-I and rosmanol showed a strong and stable binding affinity with favorable ADME properties
Yang et al. [208]In silico2020High-throughput virtual screeningNatural Products Research Laboratories (NPRL)Main proteaseCurcuminoid derivatives (including NPRL334, NPRL339, NPRL342, NPRL346, NPRL407, NPRL415, NPRL420, NPRL472, and NPRL473) display strong binding affinity to COVID-19 3Lpro polyproteinNPRL-334 revealed the strongest binding affinity
Yu et al. [209]2020In silicoMetascape analysis protein docking molecular dockingMongolian medicineSARS-CoV-2 S protein RBD domain253 active components were predicted. Phillyrin and chlorogenic acid can effectively prevent the combination of SARS-CoV-2 S protein and ACE2 at the molecular level
Zhang et al. [210]2020In silicoMolecular docking molecular dynamic simulation ADME property network pharmacology analysisChinese herbal medicinesAnti-2019-nCoV activity13 compounds that exist in traditional Chinese medicines were found to have potential anti-2019-nCoV activity. 125 Chinese herbs were found to contain 2 or more of these 13 compounds. Of these 125 herbs, 26 are classically cataloged as treating viral respiratory infectionsRegulating viral infection, immune/inflammation reactions, and hypoxia response