Synergistic interactions of chamomile flower, myrrh and coffee charcoal in inhibiting pro-inflammatory chemokine release from activated human macrophages

Abstract

Abstract Background The herbal medicinal product Myrrhinil-Intest®, a combination of myrrh, chamomile flower extract and coffee charcoal is used for the maintenance therapy of inflammatory bowel disease. In vitro studies revealed that the herbal components influence chemokine signaling of human macrophages as part of an anti-inflammatory mechanism. However, the occurrence of synergistic effects remains unexplored. Aim The present study aims to investigate the synergistic effect of dual combinations of the plant extracts on the pro-inflammatory chemokine (CXCL13) release from activated human macrophages. Methods The single effect of myrrh, chamomile flower and coffee charcoal extract on CXCL13 release from lipopolysaccharide stimulated human macrophages was investigated using ELISA and IC50 values were determined. Budesonide served as positive control. To characterize the combined effect, IC50 values were used to prepare combinations of two plant extracts in different proportions to each other (3:5; 1:1; 5:3). Interpretation of the data was based on isobologram analysis and calculation of a combination index (CI). Results LPS-induced CXCL13 release from human macrophages was inhibited after treatment with myrrh (IC50 = 19 μg/ml), chamomile flower (IC50 = 82 μg/ml) and coffee charcoal (IC50 = 106 μg/ml) whereby the extent of inhibition was comparable to budesonide. All combinations of two plant extracts resulted in synergistic effects with varying magnitude (CI from 0.82 to 0.42). The combination of myrrh and coffee charcoal (ratio of 3:5) exhibited the strongest synergistic effect (CI = 0.42). Increasing amounts of coffee charcoal resulted in increased synergistic activity. Conclusion Synergistic effects between all plant components contribute to the anti-inflammatory activity of all dual combinations of the plant components and support the composition of the herbal combination.