gms | German Medical Science

STW 5 (Iberogast^®) is a fixed combination of nine plant extracts with Iberis amara (STW 6) as one of its components. It is successfully used for treatment of functional dyspepsia and irritable bowel syndrome (IBS). Moreover, STW 5-II is a preparation without Angelica archangelica, Silybum marianum and Chelidonium majus. In this study we compared the effects of STW 5, STW 5-II and STW 6 on tone and acetylcholine (ACh)-induced contractions in intact and inflamed intestinal preparations. We used 1-1.5 cm long ileum and colon preparations of male Wistar rats to analyze region specific differences. The inflammation was induced by intraluminal instillation of 2,4,6-trinitrobenzene sulfonic acid (TNBS, 10 mM, 30 min). Incubation with STW 5 (512 µg/ml) reduced the tone and decreased ACh-induced contractions of untreated ileal and colonic preparations concentration dependently (64-512 µg/ml). The effects of STW 5-II in a concentration of 533.2 µg/ml were comparable to those of STW 5. STW 6 in equivalent concentrations (3-24.1 µg/ml) neither affected the tone nor the contractility. TNBS-induced inflammation was accompanied by a significant reduction of ACh-induced contractions. Co-incubation of TNBS with STW 5 (512 µg/ml), STW 5-II (533.3 µg/ml) or STW 6 (24.1 µg/ml) partially normalized the TNBS-induced attenuation of tone as well as of ACh-induced contractions in ileum preparations. In inflamed colon segments the co-incubation of TNBS with STW 6 in a high concentration (24.1 µg/ml) revealed protective effects whereas STW 5 as well as STW 5-II had no effects.

In conclusion, STW 5 and STW 5-II influenced ACh-induced contractions and tone in untreated ileal and colonic preparations, whereas STW 6 did not contribute to these effects. In TNBS-inflamed ileum preparations STW 5, STW 5-II as well as STW 6 normalized contractile disturbances, while in colon preparations only STW 6 was effective. Our study confirms region specific effects of these plant extracts.