Table 1 Herbal constituents with possible mechanisms to combat SARS-CoV-2 (Adopted and updated from [75, 76])

Fruit and Vegetables

Quercetin

Inhibits 3CL^pro and interacts with viral HA protein to inhibit virus entry into the cell

Wu et al. [207]; Nguyen et al. [125]; Ryu et al. [151]

Green Chiretta; Andrographis paniculate (Acanthaceae)

Andrographolide

Inhibits 3CL^pro and virus-induced activation of RLRs signaling pathway

Yu et al. [216]; Enmozhi et al. [44]

Licorice

Glycyrrhizin

Inhibits replication, adsorption, and penetration of the virus

Cinatl et al. [29]

Scutellariabaicalensis Georgi.(Lamiaceae)

Baicalin

Inhibits 3CLpro and HIV-1 Env protein-mediated fusion with cells expressing CD4/CXCR4 or CD4/CCR5

Su et al. [171]; Li et al. [104]

Mint or deadnettle; Patchouli spp. (Lamiaceae)

Patchouli alcohol

Inhibits activation of PI3K/Akt and ERK/MAPK signaling pathways to block viral infection and replication

Yu et al. [217]

Vegetables and fruits such as celery, parsley, broccoli, onion leaves, carrots, peppers, cabbages, apple skins, and Chrysanthemum flowers

Luteolin

Inhibits 3CL^pro and the expression of the coat protein I complex and interferes with viral replication at an early stage of infection

Ryu et al. [151]; Yan et al. [212]

Citrus fruits such as oranges and tangerines

Hesperidin

Inhibits 3CL^pro

Lin et al. [111]; Joshi et al. [85]

Rhubarb, Buckthorn, Aloe, Japanese knotweed and many species of fungi.

Emodin

Blocks the SARS-CoV spike protein and ACE2 interaction and inhibits 3a protein to reduces virus release

Ho et al. [71]; Schwarz et al. [160]

Grapes, wine, grape juice, peanuts, cocoa, and berries of Vaccinium spp.including blueberries, bilberries and cranberries

Resveratrol

Inhibits RNA and nucleocapsid expression

Lin et al. [112]

Grapes, tomatoes, broccoli, tea, and Ginkgo biloba leaves

Kaempferol

Inhibits 3a channel protein

Schwarz et al. [159]

Grains, nuts, seeds, vegetables, and drinks such as tea, coffee or wine

Lignan

Inhibits virus replication and 3CL^pro

Wen et al. [196]

The bark of several species of plants principally the white birch

Betulinic acid

Inhibits virus replication and 3CL^pro

Wen et al. [196]

Salvia spp.

Tanshinone

Inhibits 3CL^pro and PL^pro

Park et al. [128]

The root of the Asian medicinal plantSalvia spp.

Cryptotanshinone

Inhibits 3CL^pro and PL^pro

Park et al. [128]

Salvia miltiorrhiza Bunge (Chinese sage, red sage root, and the Chinese herbal;Danshen)

Dihydrotanshinone I

Inhibits 3CL^pro and PL^pro [128]

Park et al. [128]

Salvia miltiorrhiza Bunge (Chinese sage, red sage root, and the Chinese herbal;Danshen)

Tanshinone IIA

Inhibits 3CL^pro and PL^pro

Park et al. [128]

Turmeric; Curcuma longa (Zingiberaceae)

Curcumin

Inhibits virus replication and 3CL^pro

Wen et al. [196]

Died root of the Lithospermumerythrorhizon (Boraginaceae), Alkannatinctorial (Boraginaceae)

Shikonin

Inhibits 3CL^pro

Jin et al. [84]

Sophora spp. (Fabaceae)

Matrine

Improves abnormal laboratory parameters and clinical symptoms inpatients, and significantly shortens the time to nucleic acid conversion

Yang et al. [213]