Constituents from oak bark (Quercus robur L.) inhibit degranulation and allergic mediator release from basophils and mast cells in vitro.

ETHNOPHARMACOLOGICAL RELEVANCE: Oak bark has been used since ancient times in Europaen ethnomedicine because of its adstringent, antimicrobial and hemostatic features, e.g. as a remedy for the treatment of wounds and skin diseases. PURPOSE: Oak bark tannins are considered as bioactive natural products, interacting with surface proteins of mucous membranes and might be beneficial for the treatment of allergic diseases. This study investigated the effect of an oak bark decoction (OBD) and isolated tannin fractions on the degranulation capacity and cytokine/chemokine release from rat basophilic cells and human mast cells in vitro, which are essential for the initiation of early- and late-phase allergic reactions. METHODS AND METHODS: By chromatographic separation on Sephadex® LH-20 high- and low-molecular weight tannins were separated from OBD and the tannin composition analyzed by HPLC(DAD)-MSn. Then, the OBD and its fractions were tested in degranulation (ß-hexosaminidase activity) of allergen-specific-activated basophilic cells in a photometric assay. RESULTS: The OBD and the high-molecular tannin fraction showed a dose-dependent inhibition of cell degranulation. Furthermore, the OBD and particularly its high molecular weight tannin fraction exhibited an inhibitory activity on the IL-8-, IL-6- and TNF-α-secretion from stimulated human mast cells, detected and quantified by ELISA. CONCLUSION: The OBD and its high-molecular weight tannins revealed an impact on allergic mediator release of basophilic cells and human mast cells and thereby provide a rationale for the topical treatment with OBD preparations.

Anti-herpetic properties of hydroalcoholic extracts and pressed juice from Echinacea pallida.

Hydroalcoholic extracts and pressed juice from Echinacea pallida were phytochemically characterised by HPLC-MS analyses. Ferulic and caffeic acid derivatives were identified as major constituents. All tested extracts and pressed juice from Echinacea pallida exhibited a low cytotoxic activity on monkey kidney cells in vitro. The inhibitory activity of Echinacea against herpes simplex virus types 1 and 2 (HSV-1, HSV-2) was analysed with plaque reduction assays. All hydroalcoholic extracts exhibited high levels of antiviral activity against both types of herpesvirus in a dose-dependent manner. Plaque formation was significantly reduced by more than 99 % or completely absent. Pressed juice from E. pallida revealed the highest antiviral activity against HSV-1 and HSV-2 when compared to hydroalcoholic Echinacea extracts and even highly diluted Echinacea pressed juice still inhibited viral infectivity. Hydroalcoholic extracts were quite active against herpetic infection when HSV-1 or HSV-2 were pretreated with the extracts. In contrast, Echinacea pressed juice revealed antiviral activity during all phases of the viral replication cycle. Additionally, Echinacea pressed juice demonstrated protection of cells against viral infection. In conclusion, hydroalcoholic E. pallida extracts interfere with free herpesvirus but pressed juice is able to interact with herpesvirus inside and outside the cell as well as to protect cells against viral infection, probably by interfering with virus attachment. Hydroalcoholic extracts and pressed juice from E. pallida demonstrated high selectivity indices, a necessary prerequisite for a potential topical treatment of herpetic infections. Different types of Echinacea preparations, such as commercial tinctures, tablets, and teas, are expected to offer different antiviral profiles.