Polygoni Cuspidati Radix et Rhizoma is the root and rhizome of Polygonum cuspidatum. The extract of this medicinal plant is commonly used in Traditional Asian Medicine because of its antibacterial, antiviral, anti-inflammatory, analgesic, cardiovascular system protection, liver protection, immunity improving effect . Up to now 13 active components could be identified in the extract of Polygoni Cuspidati Radix et Rhizoma which could be linked to the antiviral, anti-inflammatory and analgesic effect . One compound in the extract of this medicinal plant called Polydatin was shown to be able to bind directly on a protein which is important for the replication of the corona virus and thus might inhibit the spread of the virus in the human body . Based on the pharmacological properties of Polygoni Cuspidati Radix et Rhizoma this medicinal herb is commonly used in Traditional Chinese Medicine prescription to treat viral infection of the respiratory system like common cold, influenza and COVID-19 
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Forsythiae Fructus is the dried fruit of Forsythia suspensa, known as lianqiao in China. It has been widely used both as a single herb and in complex formulas with other medicinal plants in Asia. Modern pharmacological analysis identified 321 single compounds, like phenylethanoid glycosides, lignans, sterols, flavonoids and alkaloids in the extract of Forsythia fructus. Clinical studies revealed that Forsythia Fructus has anti-inflammatory, antioxidant, antiviral, antivomiting, neuroprotective and cardiovascular protective effects [4-9]. Furthermore, it was shown that one active ingredient called digitoxin can bind directly on the spike glycoprotein of SARS-CoV-2 and inhibits the binding of the virus to the human cells .
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Isatidis Radix is the dried roots of Isatis tinctoria, one of the most used medicinal plants in traditional Chinese medicines. For centuries, the herb has been used in clinical practice for treatment of virus infection, like the influenza virus, and inflammation. During the outbreak of the severe acute respiratory syndrome (SARS) in 2003 and H1N1 flu in 2009 this medicinal plant was one of the most important medicinal plants for the production of traditional medicine to fight against the virus [11, 12]. It is also worth mentioning that Isatidis Radix shows its anti-influenza efficacy regardless of the various subtypes of viruses and their rapid mutations . Analysis of the compounds showed that several compounds of Isatidis Radix, like (3H)-quinazolinone, progoitrin, goitrin, epigoitrin, indirubin, isatithioetherin B and isatithioetherin D have a clear anti-viral effect .Additionally it was found that Isatidis Radix contains like Forsythia Fructus digitoxin a inhibitor of the SARS-CoV-2 spike glycoprotein .
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Bupleuri Radix is the dried root of Bupleurum chinense. This medicinal plant has been used widely in the traditional Asian medicine for more than 2000 years. Up to now approximately 349 compounds have be identified in the extract of Bupleuri Radix including essential oils, triterpenoid saponins, polyacetylenes, flavonoids, lignans, fatty acids, and sterols. Results from basic research and clinical studies revealed that the extract of this medical plant exhibited various biological activities, such as anti-inflammatory, anticancer, antipyretic, antimicrobial, antiviral, hepatoprotective, neuroprotective, and immunomodulatory effects . Several studies showed that polysaccharides and saikosaponins isolated from Bupleuri Radix significantly attenuated lung injury and variety of allergic inflammation by regulation of different anti-inflammatory pathways (e.g. inhibiting the level of myeloperoxidase (MPO), tumor necrosis factor-α (TNF-α), regulation of MAPK and NF-κB signals pathways) [16, 17]. Furthermore it was shown that saikosaponins from Bupleuri Radix exerted strong antiviral activity on human coronavirus-229E. The mechanism behind this anti-coronavirus effect might be based on an interference in the early stage of viral replication, such as absorption and penetration of the virus .
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Patriniae Herba is the part of Patrinia scabiosaefolia that grows above the ground. In the traditional Asian medicine this plant is used for the treatment of rheumatoid arthritis, diarrhea, acute hepatitis, pelvic inflammatory disease and ulcerative colitis . Up to now approximately 233 compounds including triterpenoid saponins, flavonoids, organic acids, iridoids, and volatiles have been identified in Patriniae Herba. Basic research data showed that the extract of this plant has a strong anti-inflammatory effect by inhibiting the infiltration of inflammatory cells and attenuation of cytokine as well as pro-inflammatory cytokine production . Research on the anti-viral effect of Patrinia Herba was mainly focused on the respiratory syncytial virus (RSV) and severe acute respiratory syndrome (SARS) virus were the extract of this medicinal plant showed a strong anti-viral effect . Furthermore, it was shown that the extract of Patrinia Herba has a sedative and central nervous system inhibitory effect, which can shorten the falling asleep time and prolong the sleep time which might be beneficial for the recovery of a viral infection [22, 23].
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Verbena Herba is the medical part of Verbena officinalis that grows above the ground. This herb is grown in different regions in Europe and Asia, and is commonly used in folk medicine, for example in the Traditional Chinese Medicine. Traditionally, Verbena Herba has been used to treat melancholia, hysteria, seizures, fever, anxiety, depression, insomnia, , pharyngitis, cough and asthma . Phamaceutical analysis of the extract from Verbena Herba showed that the constituents include verbenin, verbenalin, hastatoside, alpha-sitosterol, ursolic acid, oleanolic acid, kaempferol, luteolin, verbascoside, aucubin, apigenin, scutellarein and essential oils like limonene and cineole . Results from basic research and clinical studies showed that the extract can be used to reduce anxiety and promotes the sleep by a seditative effect, which is relevant for the quick recovery from a viral infection . Furthermore, it was shown that Verbena Herba reduces pain and inflammation by its analgesic and anti-inflammatory effect .
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Phragmitis Rhizoma is the rhizome of Phragmites Phragmites communis, better known as common Reed. Phragmitis Rhizoma has been used in traditional Asian medicine to relieve fever, vomiting and to nourish the body fluid [28-30]. Analysis of the extract from Phragmitis Rhizoma revealed that it comprised mainly of polysaccharides as its main active component . Furthermore, it has ben shown recently that the watery extract of Phragmitis Rhizoma has detoxification properties .
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Glycyrrhizae Radix et Rhizoma ist the root and rhizome of Glycyrrhiza uralensis, better known as licorice. It is used by in many different regions around the world including the USA, Europe and Asia as food and herbal medicine. Known pharmacological effects of the extract of licorice obtained through experimental and clinical studies are antiviral, anti-inflammatory, immunomodulatory, antimicrobial, antitussive, gastroprotective, hepatoprotective, anticonvulsant, antidiabetic, anti-asthma, anti-allergic, antispasmodic and blood cholesterol lowering activities [33, 34]. Analysis of the compounds in the extract of licorice has revealed more than 200 different single compounds. The most active components belonging to the group of flavonoids (e.g. liquiritin and liquiritihenin, 4’,7-dihydroxy-flavone and isoliquiritigenin) and terpenes/saponins (like glycyrrhizic and glycyrrhetinic acid) [33, 34]. Licorice has been used in traditional medicine extensively to treat viral infections like common cold and influenza based on the strong anti-viral, anti-inflammatory and immunomodulatory as well as the antitussive effect . Recently published studies suggest that licorice could be used for the treatment of COVID-19 as well. Several studies showed that active compounds of licorice directly block replication and viral assembly in different stages of the viral replication cycle by inhibition of 3C-like protease, papain-like protease, Mpro and S proteins [36, 37]. Furthermore, it has been shown that COVID-19 patients have developed excessive inflammatory response called cytokine storm. This cytokine storm is caused by an overactivation of immune response caused by the viral infection. High amounts of cytokines and chemokines can lead to damage of organs like the heart, lungs and kidneys. It has been shown previously that the extract of licorice significantly decreases the release of cytokines from macrophages and other inflammatory pathways (e.g. TNF, IL-17), which attenuates the cytokine storm as well as the inflammation and by this protects the lung and other organs from damages caused by the viral infection [38, 39]. Additionally, it´s well known that COVID-19 patients develop respiratory symptoms, including cough and shortness of breath during the cause of the disease. Thus, the antitussive, bronco-relaxant and expectorant activity which was shown for the extract of licorice may be able to attenuate those symptoms and promote a faster recovery .
33. Hosseinzadeh H, Nassiri-Asl M. Pharmacological effects of Glycyrrhiza spp. and its bioactive constituents: update and review. Phytother Res. 2015;29(12):1868–1886.
34. Ming Yang YJ, Li-Ping Y. A systematic summary of natural compounds in radix Glycyrrhizae. Tradit Med Res. 2018;3(2):82–94.
35. Ng SL, Khaw KY, Ong YS, et al. Licorice: A Potential Herb in Overcoming SARS-CoV-2 Infections. J Evid Based Integr Med. 2021;26:2515690X21996662. doi:10.1177/2515690X21996662
36. Tao Z, Zhang L, Friedemann T, Yang G, Li J, Wen Y, Wang J, Shen A. Systematic analyses on the potential immune and anti-inflammatory mechanisms of Shufeng Jiedu Capsule against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)-caused pneumonia. J Funct Foods. 2020 Dec;75:104243. doi: 10.1016/j.jff.2020.104243. Epub 2020 Oct 12. PMID: 33072190; PMCID: PMC7550105.
37. Zhang DH, Wu KL, Zhang X, Deng SQ, Peng B. In silico screening of Chinese herbal medicines with the potential to directly inhibit 2019 novel coronavirus. J Integr Med. 2020;18(2):152–158.
38. Yang R, Liu H, Bai C, et al. Chemical composition and pharmacological mechanism of Qingfei Paidu decoction and ma Xing Shi Gan decoction against coronavirus disease 2019 (COVID-19): in silico and experimental study. Pharmacol Res. 2020;157:104820.
39. Huang YF, Bai C, He F, Xie Y, Zhou H. Review on the potential action mechanisms of Chinese medicines in treating Coronavirus Disease 2019 (COVID-19). Pharmacol Res. 2020;158:104939