The production and consumption of tea has a history of more than 4,000 years. At present, more than 2 billion cups of tea are consumed every day in the world, which is second only to water in terms of global consumption. Previously published research has shown that regular consumption of green tea and coffee has health benefits because these beverages contain a variety of bioactive compounds. However, little is known about green tea's antiviral properties.
On March 17, 2021, a study by researchers at Jinan University on the bioRxiv preprint platform reports that green tea has antiviral activity, adding to its long-term health benefits. In the new study, epigallocatechin gallate (EGCG), one of the components of green tea, prevented severe SARS-CoV-2 from binding to the human angiotensin-converting enzyme 2 (ACE2) receptor, thereby preventing infection in humans lung cells, and inhibitory effects were also observed in SARS-CoV-2 variants.
The main active ingredients in green tea are catechins, including epigallocatechin gallate (EGCG), epigallocatechin (EGC), epigallocatechin gallate (ECG), and epigallocatechin (EC), of which EGCG is the most abundant catechin in green tea.
The researchers created several pseudoviruses containing complete mutations (B.1.1.7, B.1.351 and B.1.429) with single mutations (K417N, E484K, N501Y, D614G) or emerging variants. S protein, and pseudoviruses were then transfected into HEK293T-hACE2 cells.
Through experiments, the researchers found that green tea effectively prevented the infection of wild-type, D614G, B.1.429 and B.1.351 in a dose-dependent manner.
The researchers also found that when tested against HCoV OC43 in HCT-8 cells, green tea beverages were also observed to protect against infection by other coronaviruses.
Next, the researchers looked for the substances in green tea that cause these antiviral effects. The active components of green tea catechins EGCG, EGC, ECG and EC were studied.
The results showed that three catechins: EGCG, EGC and ECG dose-dependently blocked pseudovirus infection caused by the wild-type SARS-CoV-2 strain.
Upon closer inspection, the researchers concluded that EGCG was the most potent inhibitor of viral infection. EGCG accounts for more than 50% of the catechins in green tea beverages.
Then, after exposure of EGCG to mutants such as D614G, K417N, E484K and N501Y, its ability to cause infection was also inhibited.
The researchers also found that EGCG inhibited viral infection of cells containing interesting variants, including B.1.17, B.1.351 and B.1.429.
Testing EGCG on infected human lung epithelial cells, the researchers found that it inhibited SARS-CoV-2 before and after infection. However, the inhibitory activity was greater when cells were pretreated with EGCG prior to SARS-CoV-2 infection.
Further studies identified the mechanism of action of EGCG against SARS-CoV-2, and the researchers found that it blocked the entry of the virus by blocking the S1 subunit with the highest binding affinity with ACE2. EGCG also reduced the binding of the S2 subunit, although it had little binding affinity to ACE2.
In conclusion, studies suggest that consumption of green tea or its active ingredient EGCG may help prevent or reduce the spread and infection of SARS-CoV-2, given its low toxicity, anti-inflammatory, antioxidant and anti-SARS-CoV-2 variant properties, drinking Green tea may minimize the spread of SARS-CoV-2 and improve symptoms and disease severity.
Paper link：https://doi.org/10.1101/2021.03.17.435637
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