Ex vivo/in vitro absorption of STW 5 (Iberogast) and its extract components.

To correlate the pharmacological effects of the fixed herbal combination STW 5 (Iberogast) containing nine extract components with its confirmed clinical efficacy, ex vivo/in vitro absorption tests were performed. For the investigation, the everted gut sac technique and, in a pilot study, the Caco-2-cell model were used. The absorption rate of the extracts was determined by measuring characteristic marker substances of each of the individual extracts using HPLC or GC techniques. The results allow us to conclude that the investigated substances from STW 5 possess a good bioavailability, which is in accordance with the rapid onset of the therapeutic efficacy and explains its known pharmacological effects and clinical efficacy in terms of multiple drug action and multi-target therapy, respectively.

Transport of alkamides from Echinacea species through Caco-2 monolayers.

To gain more insights into the human intestinal absorption of alkamides from Echinacea species, transport studies were performed with the human adenocarcinoma colonic cell line Caco-2 (ATCC) as a model to assess the epithelial transport of dodeca-2 E,4 E,8 Z,10 E/ Z-tetraenoic acid isobutylamides (1/ 2). 30 minutes after apical loading of 25 microg/ml 1/ 2, about 15 % of these alkamides were detectable on the basolateral side. Close monitoring of the transport during 6 hours revealed a nearly complete transport to the basolateral side after 4 hours and no significant metabolism was observable. Transport experiments performed at 4 degrees C showed only a slight decrease in transport, which is a strong hint that dodeca-2 E,4 E,8 Z,10 E/ Z-tetraenoic acid isobutylamides (1/ 2) cross biological membranes by passive diffusion. Nearly the same results were obtained after preincubation of the Caco-2 cells with lipopolysaccharides (LPS) or phorbol 12-myristate-13-acetate (PMA) to mimic an inflammatory status. These results support the assumption that the alkamides can be easily transported from the intestinum and hence may contribute to the in vivo effects of Echinacea preparations.