Comparative study of the effect of a herbal preparation (Imupret®) dissolved in different solvents on LPS-primed type II-like human lung epithelial A549 cells

Recently, there has been extensive effort to employ scientific methods to prove the efficacy of herbal extracts. The respiratory epithelium is a major portal of entry for pathogens and employes defense mechanisms to prevent colonization and infection. This study, therefore, was designed to evaluate the effect of a commercial herbal medical product (Imupret®, Bionorica AG) on the growth of A549 cells alone and in combination with non-toxic dose of LPS. For the stimulation of A549 cells LPS from Pseudomonas aeruginosa, an important respiratory pathogen, at concentration of 100µg/ml was used. Imupret® a herbal combination preparation from (Radix Althaeae, Flores Chamomillae, Herba Equiseti, Folia Juglandis, Herba Millefolii, Cortex Quercus and Herba Taraxaci) was dissolved in single solvents (bidest H₂O, cell culture medium, 70% (v/v) ethanol and DMSO). The cytotoxicity and antiproliferative effect of Imupret® was investigated with propidium iodide uptake and with WST-1 assay after 24h incubation. Solutions of Imupret® in different solvents showed dose-dependent growth inhibitory effect on A549 cells in the concentrations between 50–2000µg/ml. Comparative studies indicate quantitative differences with GI₅₀ values of 122–823µg/ml. The effect of water and DMSO extracts were about 6- and 4-fold more potent (p<0.05) than of medium and ethanol preparations (both exerted comparable effects). Viability of cells was not affected at any concentration. The growth inhibitory effect of water and DMSO extracts was significantly diminished in LPS-primed cells at concentrations above 100µg/ml, however in medium and ethanol preparations this effect was marginal. Results of this study showed differences between the herbal medical product dissolved in single solvents. These results suggested differences in the composition and/or concentration of compounds in single preparations and supported further pharmacological (chemical, analytical) analyses.