TABLE 3.
Natural compounds, their origins, and sites of action showing the antiviral natural compounds, their origin and mechanism of action
| Constituents | Class of constituents | Biological source/origin | Mechanism of action | References |
|---|---|---|---|---|
| Apigenin | Flavone | Matricaria chamomilla | Blocks the proteolytic activity of SARS‐CoV‐2 3CLpro. | (Baumann, 2008; Jo et al., 2020) |
| Baicalin | Flavonoid | S. baicalensis | Prevents viral attachment to the host cell. | (Li‐Weber, 2009) |
| β‐Sitosterol | Phytosterol | Isatis indigotica | Blocks the SARS‐3CLpro enzyme cleavage activity. | (Lin et al., 2005) |
| Dihydrotanshinone | Biterpenoids | Salvia miltiorrhiza | Inhibits virus entry into the cell. | (Kim et al., 2018; Zhang, Wu, Zhang, et al., 2020) |
| Emodin | Anthraquinone | Rheum and polygonum | Inhibits attachment of surface spike protein of SARS‐CoV‐2 with the host cell. | (Alves et al., 2004; Ho et al., 2007) |
| Epigallocatechin gallate | Flavan | C. sinensis | Anti‐SARS 3CLpro enzyme activity. | (Jo et al., 2020; Westbrook et al., 2018) |
| Gallocatechin gallate | Flavan | Litchi chinensis sonn. | Anti‐SARS 3CLpro enzyme activity. | (Jo et al., 2020) |
| Gnidicin | Diterpene esters | Gnidia lamprantha | Inhibit SARS‐CoV‐2 RdRp. | (Bhandurge et al., 2013) |
| Gniditrin | Diterpene esters | Gnidia lamprantha | Inhibit SARS‐CoV‐2 RdRp. | (Bhandurge et al., 2013) |
| Glycyrrhizin | Saponin | G. radix. | Active against viral adsorption and penetration. | (Cinatl et al., 2003; Ong, 2002) |
| Herbacetin | Flavonol | M. paniculata | Anti‐proteolytic activity of SARS‐CoV 3CLpro. | (Harborne, 1969; Jo et al., 2020) |
| Hesperidin | Flavonoid | Citrus spp. | Inhibits helicase of SARS‐CoV‐2. | (Man et al., 2019; Wu, Liu, et al., 2020) |
|
Hesperetin |
Flavonoid | Isatis indigotica | Blocks cell‐based division of SARS‐M pro (3CLpro). | (De Clercq, 2006) |
| Indigo | Glycoside |
Isatis indigotica |
Blocks the SARS‐3CLpro enzyme cleavage activity. | (Lin et al., 2005) |
| Isobavachalcone | Flavonoid | Psoralea corylifolia | Inhibits the enzymatic functioning of MERS‐CoV 3CLpro. | (Jo et al., 2019) |
| Kaempferol | Flavonol | B. oleraceaS. oleracea | Blocks the 3a channel of coronavirus. | (Zakaryan et al., 2017) |
| Luteolin | Flavone | V. linariifolia | Inhibits attachment of spike proteins of SARS‐CoV‐2 with the host cell in an avid manner. | (Yi et al., 2004) |
|
Maco‐flavanone E |
Flavonoid | M. tanarius | Blocks viral assembly and release. | (Gupta et al., 2020) |
| Pectolinarin | Flavone | Cirsium spp. | Anti‐SARS 3CLpro enzyme activity. | (Cho et al., 2016; Jo et al., 2020) |
| Puerarin | Iso‐flavone | Pueraria lobata | Anti‐SARS CoV 3CLpro proteolytic activity. | (Jo et al., 2020; Zhou et al., 2014) |
| Phaithanthrin | Alkaloid | Isatis indigotica | Inhibition of PLpro activity. | (Wu, Liu, et al., 2020) |
| Phyllaemblicin | Terpenoids | P. emblica | Inhibits helicase activity of SARS‐CoV‐2. | (Wu, Liu, et al., 2020; Zhang, Kaunda, et al., 2019) |
| Phyllaemblinol | Terpenoids | P. emblica | Anti‐SARS‐CoV‐2 helicase activity. | (Wu, Liu, et al., 2020; Zhang, Kaunda, et al., 2019) |
| Platycodin D | Triterpenoidal saponin | P. grandiflorum | Inhibit PLpro activity of SARS‐CoV‐2. | (Khan et al., 2016; Wu, Liu, et al., 2020) |
| Quercetin | Flavonol |
C. sinensis |
Inhibition of SARS‐CoV‐2 3CLpro. | (Wu et al., 2015) |
| Rhoifolin | Flavone | Citrus paradisi, Citrus aurantium, Citrus limon | Inhibits the enzymatic action of SARS‐CoV‐2 3CLpro. | (Jo et al., 2020) |
| Rutin | Glycoside | R. graveolens | Inhibits the helicase of SARS‐CoV‐2. | (Ganeshpurkar & Saluja, 2017; Wu, Liu, et al., 2020) |
| Saikosaponin | Terpenoids | R. bupleuri | Impedes early stage of HCOV‐22E9 infection including the attachment and penetration of virus. | (Cheng et al., 2006; Li, Li, et al., 2018) |
| Sinigrin | Glucoside | Isatis indigotica | Blocks the SARS‐3CLpro enzyme cleavage activity. | (Lin et al., 2005) |
| Sugetriol‐3,9‐diacetate | Sesqui‐terpenoids | Cyperus rotundus L. | Anti‐SARS‐CoV‐2 PLpro activity. | (Kim et al., 2013) |
| Tetrandrine | Alkaloid | Stephania tetrandra S. | Blockage of spike and nucleocapsid protein expression in HCOV‐OC43. | (Kim et al., 2019) |
| Tetra‐O‐galloyl‐β‐D‐glucose | Gallate Ester | Galla chinensis | Attaches with the surface spike protein of SARS‐CoV‐2 in an avid manner. | (Yi et al., 2004) |
| Theaflavin | Flavonoid | C. sinensis | Inhibition of SARS‐CoV‐2 RdRp. | (Leung et al., 2001) |
| Vibsanol A | Lignan | V. odoratissimum | Blocks viral assembly and release. | (Gupta et al., 2020) |
Note: SARS‐CoV: Severe acute respiratory syndrome coronavirus, 3CLpro: 3 chymotrypsin‐like protease, M pro: main protease, RdRp: RNA‐dependent RNA polymerase, MERS‐CoV: Middle East respiratory syndrome coronavirus, PLpro: papain‐like protease.