Plain language summary
Some individuals who have contracted Covid-19 experience an extreme inflammatory reaction known as cytokine storm syndrome. This review paper of 129 studies aimed to review the use of epigallocatechin 3-gallate (EGCG), a green tea derived chemical reported to reduce inflammation with a view to be used in individuals with Covid-19. Conventional therapies used in diseases known to induce extreme inflammation were discussed focusing on steroid based drugs. However, results in Covid-19 patients have shown increased mortality and decreased viral clearance. Several other drugs are being trialled in Covid-19. The use of EGCG and green tea extract (GTE) in several diseases such as rheumatoid arthritis, Sjogrens syndrome, multiple sclerosis, human immunodeficiency virus, dengue virus and inflammatory bowel disease was discussed and beneficial effects such as being anti-inflammatory, antiviral, antimicrobial, and having anti-cancer properties were outlined. The possible mechanisms involved were extensively discussed. The use of EGCG and GTE in a clinical setting was reported to have favourable outcomes and be a potentially safe natural supplement. It was concluded that given the safety and many benefits shown by EGCG in viruses and inflammatory diseases, EGCG/GTE may be effective in Covid-19, and clinical trials are needed. This study could be used by healthcare professionals to justify the recommendation of EGCG/GTE in individuals with Covid-19 and many other inflammatory and viral diseases.
Abstract
Some coronavirus disease 2019 (COVID-19) patients develop acute pneumonia which can result in a cytokine storm syndrome in response to Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) infection. The most effective anti-inflammatory drugs employed so far in severe COVID-19 belong to the cytokine-directed biological agents, widely used in the management of many autoimmune diseases. In this paper we analyze the efficacy of epigallocatechin 3-gallate (EGCG), the most abundant ingredient in green tea leaves and a well-known antioxidant, in counteracting autoimmune diseases, which are dominated by a massive cytokines production. Indeed, many studies registered that EGCG inhibits signal transducer and activator of transcription (STAT)1/3 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcription factors, whose activities are crucial in a multiplicity of downstream pro-inflammatory signaling pathways. Importantly, the safety of EGCG/green tea extract supplementation is well documented in many clinical trials, as discussed in this review. Since EGCG can restore the natural immunological homeostasis in many different autoimmune diseases, we propose here a supplementation therapy with EGCG in COVID-19 patients. Besides some antiviral and anti-sepsis actions, the major EGCG benefits lie in its anti-fibrotic effect and in the ability to simultaneously downregulate expression and signaling of many inflammatory mediators. In conclusion, EGCG can be considered a potential safe natural supplement to counteract hyper-inflammation growing in COVID-19.
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