Radical scavenging and anti-inflammatory properties of STW 5 (Iberogast) and its components

A combination of ethanolic extracts from nine medicinal plants is successfully used in STW 5 (Iberogast((R))) for treatment of gastrointestinal disorders. To elucidate possible modes of action, the focus of this study is on antioxidant properties of the phytomedicine STW 5. In fact, functional gastrointestinal diseases, such as non-ulcer dyspepsia (NUD) and irritable bowel syndrome, are often initiated by or correlated to inflammatory processes, where oxidants such as reactive oxygen species (ROS) play a crucial role. Prominent in vivo sources of ROS generation are represented by the enzymes xanthine oxidase (XOD) or myeloperoxidase (MPO). Applying these enzymes in models in vitro, we show that STW 5 and its components possess strong antioxidant activities. Depending on the model investigated, even pro-oxidant activities of single components of STW 5 could be observed. Interestingly, these effects were absent in STW 5, indicating cooperation between the components. Moreover, if one of the component extracts of STW 5 is omitted, the antioxidant activity is reduced. Thus we conclude that all the single extracts combined in STW 5 are of importance for the therapeutic effect, working in concert. The component of STW 5 performing best in vitro differed with the model investigated, respectively, with ROS and ROS generators. In the XOD system, the extracts of lemon balm leaf and peppermint leaf showed the best antioxidant result, whereas concerning MPO driven chlorination reactions, bitter candy tuft extract was the most efficient antioxidant. Best protection against peroxynitrite induced oxidation of methionine like sulfur-compounds exhibited the STW 5 components lemon balm leaf, Matricaria flower and peppermint leaf.