Such a mode of action is also supported by the PubChem Bioassay Database (http://​pubchem.​ncbi.​nlm.​nih.​gov), which quotes a preliminary EC50 value of 8.9 μM TCC for the inhibition of luciferase. The focus of the present study was to get more information about the biocide in cell-based assays as well as about interactions of TCC and MWCNT. Our results on the activity of TCC in the ER-responsive cells provide an explanation for the mechanism how chemicals enhance the endocrine-disrupting

activity of chemicals [54]. Chemicals acting as endocrine-disrupting compounds (EDC) affect the ER receptor and lead to activation/inhibition of hormone-dependent gene expression [54]. However, EDC may also alter hormone A-1210477 ic50 receptor function simply by changing phosphorylation of the receptor (activating him) without the responsible chemical or natural ligand ever binding to the receptor [135]. Clearly, further examinations are required MCC950 concentration especially the confirmation of our findings in vivo. Triclocarban at concentrations up to 1.6 μM showed no generation of ROS in three cell lines. Two similar studies suggested the production of reactive oxygen species in rat thymocytes after an incubation time of 1 h to 300 nM or higher concentrations of TCC [126, 129]. On the contrary, Fukunaga and coworkers [128] supposed that the same cells recovered the HDAC cancer initial loss of cellular glutathione as a biomarker of oxidative stress in the continued

presence of 300 nM TCC. Thus, the PD184352 (CI-1040) ability of TCC to generate ROS in human cell lines is still under discussion and further research is required. Interaction of MWCNT and TCC Most reported studies have illustrated that the CNT surface area is an adsorbent for organic chemicals, such as polycyclic aromatic hydrocarbons, phenolic compounds, and endocrine disrupting chemicals [29, 136, 137]. In the present study, we determined for the first time lower cell toxicity in MWCNT- and TCC-treated H295R cells compared to the cytotoxic potential of TCC alone. Even the antiestrogenic potential of TCC in the ER Calux assay with T47Dluc cells was reduced in the presence of MWCNT compared

to the absence of the nanotubes in the whole experimental design. To our knowledge, the influence of MWCNT on the availability of TCC was not examined before. The antimicrobial agent TCC seems to interact with MWCNT resulting in a lower available concentration of TCC in the test medium. This could be proven in the ER Calux assay (Figure  4). Treatment of the cells with higher levels of CNT combined with a lower TCC concentration (0.5% of the nanotubes) did not result in a decrease of luciferase activity compared to same concentrations of the antimicrobial biocide and the mixture of MWCNT and TCC (concentration 1% of that of CNT). Only few studies have been conducted to understand the adsorption of organic contaminants by CNT [25–27, 29, 138–140]. A common observation from these studies was that CNT are very strong adsorbents for hydrophobic organic compounds.