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Effects of STW 5 (Iberogast®) and STW 6 (Iberis amara) on gastrointestinal inflammation in vitro
Herbal drugs like STW 5 (Iberogast®) have proved their efficacy in clinical trials offering a therapeutic alternative against functional dyspepsia. STW 5 is a fixed mixture of nine plant extracts whereas Iberis amara (STW 6) forms the main component. It is well established that STW 5 influences gastrointestinal motility and has antiinflammatory effects on blood cells with unclear mechanisms. The study was aimed to compare the effects of STW 5 and STW 6 on inflammatory processes in the isolated rat ileum. Pharmacological (ACh-induced isometric contraction) and molecular biological (q-RT-PCR to detect mRNA of TNF-α) investigations were done. The inflammation was induced by instillation of 2,4,6-trinitrobenzolsulfonic acid (TNBS, 0.01 M, 30min). Artificial physiological solution was used as control. TNBS induced a significant decrease of the ACh-evoked (1mM) contraction. This effect correlated with morphological changes of the mucosa and the muscular layers that were represented by the van Gieson staining. Co-instillation of TNBS with STW 5 (64–512µg/ml) or STW 6 (3–24.1µg/ml), respectively, prevented the TNBS-induced damage. The protective effect of STW 5 and STW 6 was antagonized by the selective adenosine A2A antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine (CSC, 0.2µM). The q-RT-PCR data support the protective effect of the herbal extracts.
Our study indicates that the herbal preparations STW 5 and STW 6 have protective effects on gastrointestinal inflammation and suggest the involvement of adenosine A2A receptors, which could be add up to the total effect in the treatment of functional dyspepsia.