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

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 as well as its 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 (-)-epigallocatechin-3-O-gallate (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.

HPLC-MS trace analysis of atropine in Lycium barbarum berries

The dried ripe fruits of Barbary wolfberry, Lycium barbarum L. are widely used in China for medicinal purposes and as a functional food. Previous investigations reported to have found atropine in Barbary wolfberries from India. These results have been questioned. Since then, however, there has been a discussion on whether the berries are suitable for human consumption. In order to determine the content of atropine, we have analysed eight samples of berries from China and Thailand for traces of atropine, using highly selective and sensitive HPLC-MS methods. Atropine was found in all examined samples in concentrations of maximally 19 ppb (w/w). Therefore, the content is far below toxic levels.

[Isolation and detection of phorbolesters in crotonoil with HPLC.]

A HPLC method using reversed-phase columns is described for the determination and isolation of phorbolesters in crotonoil. The identification of the compounds is based on an off-line combination of HPLC-MS, as well as on fatty acid analysis by GC. With this method several new phorbolesters of crotonoil could be detected. This method is also suitable for the determination of phorbol- or similar diterpenesters in other Euphorbiaceae.

[Chemical composition of the essential oil from melissa]

Different oil-samples of Melissa officinalis L. were analysed by capillary GC/MS, using fused silica columns and E.I.-Mass-spectrometry. Comparing the observed mass-spectra with those of a spectral collection, 70 compounds of the oil were identified. Geranial, neral, 6-methyl-5-hepten-2-one, citronellal, geranyl-acetate, beta-caryophyllene, and beta-caryophyllene-oxide comprise about 96%. The fingerprint of the capillary gas-chromatogramm permitted differentiation of the essential oil of Melissa officinalis, Cymbopogon winterianus and Nepeta cataria var. citriodora., as well as a standardisation of pharmaceutical preparations containing Melissa oil.

[Qualitative and Quantitative HPLC-Analysis of Cardiac Glycosides]

An analytical pathway for identification of cardenolides from Adonis, Convallaria, Strophanthus and Lophopetalum extracts by HPLC is described. Structure-retention-relationships between cardiac glycosides and HPLC-separations of Strophanthus gratus, Strophanthus kombé and Adonis vernalis drugs are discussed.

[DC- and HPLC-Analysis of Eleutherococcus.]

A rapid and reproducible TLC- and HPLC-analysis of root-extracts and preparations of ELEUTHEROCOCCUS SENTICOSUS on the basis of the characteristic lignans and other phenylpropan derivatives has been developed.

[Qualitative und quantitative Analyse von Herzglykosiddrogen durch HPLC-Verfahren]

The qualitative and quantitative estimation of cardiac glycosides from the leaves of Nerium species by an HPLC-method is described. The analysis is performed on a C 18 reversed phase column by gradient elution. For the quantitative estimation of the cardenolides Oleandrin is used as external standard. The cardenolide content in Nerium leaves of different origin showed marked differences in the quantitative distribution among the major glycosides.

[II1: TLC and HPLC-Analysis of Pyrrolizidine-N-oxid Alkaloids of Symphyti Radix]

A new TLC- and HPLC-method for the detection and estimation of the main alkaloids from Symphytum roots, Symphytine, Echimidine, Lycopsamine, and Acetyllycopsamine in their genuine N-oxide form is described. The method provides characteristic finger-prints for the constituents of the Symphytum drugs of different origin and varying harvest seasons.

[High-performance liquid chromatographic separation and quantitative determination of valepotriates in valeriana drugs and preparations (author's transl)]

It is possible directly to separate and analyse, quantitatively and qualitatively, the valepotriates from Valeriana crude extracts or from commercial Valeriana preparations by high-performance liquid chromatography. The separations are achieved on 4 or 8 mm I.D. columns packed with silica gel (particle size 10 micron) with n-hexane-ethyl acetate mixtures as eluent. A refractive index detection system is necessary for determining all of the valepotriates. If the concentration differences between didrovaltratum and valtratum are very great, an ultraviolet (UV) detector must be used and the determination must be conducted in two steps. For valtratum drugs UV detection alone will suffice. As internal standards p-dimethylaminobenzaldehyde should be used for extracts and preparations from valtratum races, and benzaldehyde in the presence of didrovaltratum races. This determination is superior to the combined thin-layer chromatographic-hydroxamic acid method used hitherto with respect to time consumption, precision, and sensitivity.