Speedwell (Veronica officinalis) and Cough: evidence and sources

Ethnopharmacological relevance Extracts from Veronica officinalis L. are traditionally used for the treatment of lung diseases; however, the effective compounds and the mode of action are still unknown. Aim of the study Here we analyzed the effects of a standardized Veronica extract on genes expression and signalling protein production associated with the development of inflammatory lung diseases. Material and methods The degranulation capacity of primary mast cells, as well as gene expression and release of inflammatory mediators from human lung epithelial cells (A549 cells) were analyzed in relation to the synthetic drugs azelastine and dexamethasone. Gene and protein expression of cyclooxygenase-2 were investigated by semi-quantitative RT-PCR and western blotting, respectively. The involvement of phosphorylated mitogen-activated protein kinases and NF-κB signaling in regulation of these molecules were characterized by western blotting and electrophoretic mobility shift assays. Characteristic extract components were identified by LC-MS and verminoside was quantified by HPLC analysis. Results We demonstrated that Veronica officinalis has a small influence on the degranulation capacity of mast cells but rather inhibits gene and protein expression of the chemokine eotaxin in A549 lung epithelial cells, which is essential for recruitment of inflammatory-associated cells in lung diseases. Furthermore, release of the inflammatory mediator PGE(2) was diminished through inhibition of COX-2 expression via the NF-κB signaling pathway in TNF-α-activated A549 cells. Phytochemical analysis identified verproside and verminoside as the most abundant iridoid glycosides. Conclusion Our results are a contribution to explaining the observed anti-inflammatory effects of Veronica offcinalis extract on a molecular level. However, its clinical potency has at first to be proven in animals and subsequently in clinical trials.