SARS-CoV-2 neutralizing activity of polyphenols in a special green tea extract preparation

Abstract

Background The COVID-19 pandemic will continue to threaten our health care systems in the next years. In addition to vaccination there is a need for effective tools for prevention and treatment. Products from natural sources, like standardized plant extracts offer a wide range of antiviral effects and possible applications. Purpose The aim of this study was to investigate, whether a sorbitol/lecithin-based throat spray containing concentrated green tea extract (sGTE) interacts with SARS-CoV-2 viral particles and additionally is capable to block the virus replication. Study design and methods The antiviral effect was studied in a VeroE6 cell culture model, including concentration/effect correlations and the biological mechanism of virus blockade, using the Wuhan type of SARS CoV-2 beta- and delta-mutations. In addition, the qualitative and quantitative tannin profile present on the oral mucosa after spray application has been investigated by LC-MS/MS and HPLC-DAD analyses of EGCG and related catechin derivatives. Results The findings of this study demonstrate, that sGTE has strong neutralizing activity on SARS-CoV-2 resulting in an up to 6,3E+04-fold reduction of infectivity independent from the strain. The type of interaction of sGTE with surface proteins seems to be direct and non-specific concerning the viral surface protein structures and resembles the general non-specific activity of polyphenols. By HPLC-DAD analysis, eight catechins were identified in sGTE, with EGCG and (-)-epicatechin-3- O -gallate as the most abundant ones. The total content of catechin derivatives, calculated as catechin, was 76 g/100 g. LC-MS/MS and HPLC-DAD analyses of throat swabs after application of a sGTE spray have shown that the concentrations of green tea tannins in the pharyngeal mucosa are higher than the effective dose found in the in vitro studies with SARS-CoV-2, even 1 h after the last application. Conclusion The findings of this study suggest that sGTE has strong neutralizing activity on SARS-CoV-2 independent from the strain (Wuhan strain, beta- or delta-variants). sGTE might be relevant for reduction of corresponding viral infections when periodically applied to mouth and throat.

COVID-19 and per capitagreen tea consumption: update

“…Moreover, a recent work [21] reports that EGCG from green tea effectively blocks infection of SARS-CoV-2 and new variants . The latter is in line with the observation [22] that neutralizing activity of concentrated green tea extract is independent of the strain of SARS-CoV-2 (Wuhan strain, beta- or delta-variants).…”

“…Thus, it appears that previously reported differences in COVID-19 morbidity and mortality, reflecting epidemiological situation in January 2021 [32] and before [31], are consistent over a prolonged time. This consistency may be relevant to the reported efficacy of green tea catechins against several variants of SARS-CoV-2, which was observed in in vitro studies [21-22].…”

“…Interestingly, additional approach regarding green tea catechins and COVID-19 is also emerging [22]. This approach [22] focuses on the local application of green tea extract as a throat spray. It was demonstrated that the green tea extract formulation has strong neutralizing activity on SARS-CoV-2 independent of the strain (Wuhan strain, beta- or delta-variants) in VeroE6 cell culture model.…”

“…Currently, at least one placebo controlled study has been registered to access potential of EGCG-containing formulation (taken internally) in prevention of COVID-19 [44], but the results have not yet been reported. Interestingly, additional approach regarding green tea catechins and COVID-19 is also emerging [22]. This approach [22] focuses on the local application of green tea extract as a throat spray.…”

“…It was demonstrated that the green tea extract formulation has strong neutralizing activity on SARS-CoV-2 independent of the strain (Wuhan strain, beta- or delta-variants) in VeroE6 cell culture model. Additionally qualitative and quantitative tannin profile present on the oral mucosa after spray application has been investigated [22]. In relation to the ecological data discussed here, it seems to be of interest to study whether usual green tea consumption also substantially enhances the level of green tea constituents in oral mucosa.…”