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.

By application of a comparative aroma extract dilution analysis on the volatile fractions isolated by solvent extraction and solvent-assisted flavor evaporation (SAFE) from fresh raw Chinese ginger (Zingiber officinale Roscoe) and roasted ginger, 21 or 33 odorants, respectively, with flavor dilution (FD) factors in the range of 32–4096 were identified. In raw ginger, the highest FD factors were found for (E)-isoeugenol, 1,8-cineol, vanillin, geranial, and linalool. After roasting, in particular, the FD factors of 3-(methylthio)­propanal (cooked potato-like), 4-hydroxy-2,5-dimethyl-3­(2H)-furanone (caramel-like), 3-hydroxy-4,5-dimethyl-2­(5H)-furanone (seasoning-like), and geraniol were substantially increased. The application of static headspace/olfactometry (SHO) on ground raw ginger revealed a high FD factor for highly volatile acetaldehyde which clearly decreased after roasting. By contrast, the SHO application revealed high FD factors for malty smelling methylpropanal and 3-methylbutanal, which both were exclusively detected in roasted ginger. Thirteen odorants, namely, decanoic acid, (Z)-2-decenal, (Z)-4-decenal, (E)-4,5-epoxy-(E)-2-decenal, (E)-4,5-epoxy-(E)-2-undecenal, fenchol, (Z)-3-hexenal, 3-hydroxy-4,5-dimethyl-2­(5H)-furanone, 4-hydroxy-2,5-dimethyl-3­(2H)-furanone, 3-methyl-2-buten-1-thiol, 2-methylpropanal, (E)-2-nonenal, and 1-nonen-3-one, were identified in ginger for the first time. Chiral analysis showed a much higher percent by weight portion for the (R)-enantiomer in citronellal, citronellol, and linalool, which was not much changed during pan-frying.

Twenty key odorants recently identified in raw and roasted ginger were quantitated by means of stable isotope dilution assays, of which six assays were newly developed. Odor activity values (OAV; ratio of concentration to odor threshold) revealed 1,8-cineol (eucalyptus-like) with by far the highest value of 65 000 followed by myrcene (geranium-like), for which an OAV of 19 000 was calculated. In addition, (R)-citronellal, geranial, (R)-linalool, (E)-isoeugenol, and (E)-2-octenal contributed with high OAVs to the overall aroma profile of the fresh, raw ginger. An aroma recombinate prepared with 20 reference compounds in the same concentrations as determined in the ginger sample successfully matched the overall aroma profile. In the roasted ginger, 1,8-cineol and myrcene remained the most odor-active compounds, however, the increase in some odorants, for example, in geraniol and (Z)-2-decenal, in combination with the newly formed caramel-like smelling 4-hydroxy-2,5-dimethyl-3­(2H)-furanone (caramel-like) and 3-(methylthio)­propanal (potato-like) most likely caused the differences in the aroma profile initiated by the thermal treatment. A biomimetic aroma recombinate based on 21 aroma compounds was able to successfully simulate the aroma profile of the roasted ginger.