COVID-19 Herbs: German Study Shows Green Tea, Chokeberry And Pomegranate Juices Inhibit SARS-Cov-2 In Vitro, But Beware Of Vitro Studies!
: German researchers from the Institute of Molecular Virology, Ulm University Medical Center, Technische Universitaet Dresden and CogniVerde GmbH in a new study report the effects of green tea and black chokeberry, pomegranate, and elderberry juices on preventing SARS-CoV-2 viral infections in cells.
The study team said that respiratory viruses initially infect the naso- and oropharyngeal regions, where they amplify, cause symptoms and may also be transmitted to new hosts. Preventing initial infection or reducing viral loads upon infection might soothe symptoms; prevent dissemination into the lower airways, or transmission to the next individual. The study team here analyzed the potential of plant derived products to inactivate SARS-CoV-2 and influenza virus. The team found that black chokeberry (Aronia melanocarpa) juice, pomegranate (Punica granatum) juice, and green tea (Camellia sinensis) had virucidal activity against both viruses, suggesting that oral rinsing may reduce viral loads in the oral cavity thereby lowering virus transmission.
However the elderberry juice did not have any effect on the SARS-CoV-2 coronavirus.
The study results were published on a preprint server and have yet to be peer reviewed. https://www.biorxiv.org/content/10.1101/2020.10.30.360545v1
Thailand Medical News had already reported on the antiviral properties of green tea since May 2020. https://www.thailandmedical.news/news/covid-19-therapeutics-computational-screenings-show-a-variety-of-natural-phytochemicals-could-have-efficacy-against-sars-cov-2-including-egcg-from-gre
This new vitro study showed that green tea, chokeberry juice, and pomegranate juice killed flu and SARS-CoV-2 viruses when incubated with the viruses in vitro
. Thus, oral rinsing using these might be effective in preventing COVID-19.
The SARS-CoV-2 virus that is causing the global pandemic COVID-19, affects the respiratory tract. It has high transmissibility even before symptoms are seen, making for extremely rapid spread.
The SARS-CoV-2 coronavirus initially infects the upper respiratory tract, entering the body mainly via the nose and throat, causing respiratory symptoms such as sore throat and coughing. A few recent studies have reported gargling with commercial mouthwashes may reduce infection and virus spread. https://onlinelibrary.wiley.com/doi/10.1002/jmv.26514
In reality many herbs and natural products have also been purported to have antiviral activity. For example, pomegranate and black chokeberry extracts have been reported to have in vitro
activity against the flu virus, and gargling with green tea lowered flu infections. Thus, it would be useful to investigate broad-spectrum antiviral activity of natural products that could curb the spread of respiratory viruses and are inexpensive and easy to adopt.
For the study, researchers used Vero E6 cells to test vaccinia virus, influenza A virus,
adenovirus type 5, and SARS-CoV-2.
The study team mixed the herbal substances with the viruses, incubated them at room temperature, and determined infectivity using tissue culture infectious dose 50 (TCID50) endpoint titration.
Importantly after a 5-minute incubation with the herbal substances, they found that chokeberry juice decreased infectivity almost 3,000 times compared to a control with only a buffer. The elderberry juice, pomegranate juice, and green tea decreased infectivity by about ten times. An increase in incubation time to 20 min increased the activity only marginally, indicating the antiviral activity is rapid. This suggests that the herbal extracts are generally active against enveloped viruses.
Interestingly when the study team tested the swine flu virus (IAV) and SARS-CoV-2, they found the four herbal substances inactivated more than 99% of IAV after 5 minutes.
It was found that Chokeberry juice inactivated about 97% of SARS-CoV-2 after 5 min, while green tea and pomegranate juice inactivated about 80% of the virus. Elderberry juice had no effect on SARS-CoV-2. The naked AdV 5, used as a control, was resistant to all except chokeberry juice.
The swine flu virus (IAV) was the most susceptible to the food products, which showed virucidal activity similar to those of typical disinfectants, indicating the low resistance of this virus family, which is also representative of other influenza strains.
Also SARS-CoV-2 was more resistant, although chokeberry juice was quite effective, with pomegranate juice and green tea also reducing virus amounts.
It should be noted that the activity of herbal products could be because of their acidic pH, which can directly inactivate viruses, or because of the presence of polyphenols such as catechins, tannins, and flavonoids, which can affect viral proteins.
Past studies have showed that polyphenols in pomegranates have been shown to inhibit flu virus by affecting the surface glycoproteins and damaging the structural proteins. https://www.sciencedirect.com/science/article/abs/pii/S0166354210006686?via%3Dihub
Catechins, which are found in green tea, can affect both the virus particles and their binding to host cells. Computer simulations have suggested theaflavins might prevent SARS-CoV-2 infection by binding to the angiotensin-converting enzyme 2 (ACE2), the receptor that binds to SARS-CoV-2. https://pubmed.ncbi.nlm.nih.gov/32434254/
In the case of respiratory viruses, since the infection and transmission occurs via the nose and throat, reducing viral loads early may be an effective strategy for reducing and preventing spread.
Hence herbal products, like the ones discussed which are commonly available and are used as foods, could be used as “oral rinses.” In contrast to antiseptic oral rinses that have agents (i.e. ethanol, chlorhexidine, cetylpyridinium chloride, hydrogen peroxide and povidone-iodine) that damage membranes, these juices and tea can be used more frequently without any adverse effect and can be simply swallowed.
Past studies have shown that gargling with tea, tea extracts, or plant juices can lower flu infections and viral symptoms. Similarly, chokeberry or pomegranate juices could be used against SARS-CoV-2, in addition to teas. https://pubmed.ncbi.nlm.nih.gov/15080016/
The study team suggested that continued gargling and rinsing the mouth with juices and teas followed by swallowing could be an effective preventive strategy for SARS-CoV-2, write the authors, particularly for people at high risk of infection healthcare workers and the elderly. Swallowing the “oral rinse” is also practical in situations like on planes, trains, and schools, apart from being healthy in general.
The study team said although the amounts of the different antiviral compounds in natural products may vary with different produce batches, natural products with their mix of compounds may be a powerful method of curbing viral infections and there is a need for further clinical investigations.
The study team concluded, ”In the case of SARS-CoV-2, the virus may be passed before symptom onset, which is particularly treacherous. Oral rinsing and gargling with the tested juices and tea are largely unproblematic in long term use and might be a suitable pre- and post-exposure prophylaxis against SARS-CoV-2 during the current COVID-19 pandemic for any individual. Furthermore, it would be helpful to reduce the risk of transmission in school classes and children by using nutritionally valuable and healthy food products instead of aggressive disinfectants or obstructive measures. Thus, the administration of chokeberry juice, pomegranate juice or green tea may offer a possibility to minimize the spread of enveloped respiratory viruses, ease symptoms and potentially contribute to disease prevention and clinical investigation of their benefits is warranted.
Thailand Medical News would like to warn all readers that all in vitro studies should be taken lightly and until proper vivo and human clinical trials are conducted, the efficacy of these products tested in vitro should never be trusted.
Over the last few months in our various drug repurposing studies and also herbal tea projects https://www.thailandmedical.news/news/new-therapeutic-teas-
, we have discovered that in vitro studies are not really reliable and the gold standard still has to be vivo studies followed by human trials and also if possible detailed studies showing the mechanisms and cellular pathways involved in terms of how the inhibition takes place.
Furthermore in the case of the SARS-CoV-2 coronavirus, all researchers should identify the strains that were tested on and if possible test the candidates against a panel of at least 60 strains that are predominantly in circulation.
We have found that different mutated strains also react different to drug candidates and also therapeutics and chemicals.
To even complicate things but to be more accurate, drug candidates or therapeutics should even be tested against the human genes that play a role in the virus pathogenesis.(that is the current protocols that we at Thailand Medical News are adopting as our standards including the above)
Furthermore in in vitro studies, researchers have to be clear to mention conditions including temperatures of research conditions, pH of mediums, cell lines and also status of cell lines at time of research, concentrations used etc .
From experience we have seen that researchers can manipulate conditions to achieve results! We have seen demonstrations where literally anything from distilled water to urine to simply salt water, sugar water etc can be manipulated to show positive study results in terms of inhibiting the SARS-CoV-2 coronavirus! Hence our warnings on in vitro studies.
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