Evaluation of the cytoprotective effects of individual and combined constituents of the combination drug STW 5

We investigated the effects of individual herbal extracts of STW 5 (Iberogast®) for cytoprotective action in CaCo-2 cells. Possible synergistic effects were determined by isobologram analysis of LPS (10ng/ml, 2h)-induced cell toxicity using a commercially available LDH kit. STW 5 significantly inhibited LPS-induced LDH-release. Comparable effects were found with lemon balm, whereas in equivalent concentrations to STW 5 the effects of Iberis amara, peppermint, chamomile, angelica and milk thistle were less potent. Caraway and celandine had stimulatory effects. Isobolgram analysis indicated that a 2-h exposure to peppermint and Iberis amara (ratio 0.5/0.5) had a synergistic effect. Less pronounced synergy was observed using the component ratio 0.75/0.25. An additive effect was present in the ratio 0.25/0.75. Application of peppermint together with milk thistle (ratio 0.5/0.5) showed ratio-independent synergistic effects whereas the combined application of chamomile and Iberis amara had ratio-independent additive effects. The combination of chamomile and angelica (ratio 0.5/0.5) exerted an additive effect, the ratio 0.75/0.25 showed an antagonistic effect which increased using the ratio 0.25/0.75.The observations confirm that the components of STW 5 contribute differently to the cytoprotective effect in CaCo-2 cells and clearly indicate that synergistic, additive and antagonistic effects exist between the extracts which are ratio dependent.