Comparative studies on cytotoxicity of micropollutants in water: Principle of cytotoxicity matrix

Self-assembly and biological activities of ionic liquid crystals derived from aromatic amino acids

The self-assembly of amino acid-derived ionic liquid crystals (ILCs) into lamellar or micellar-like aggregates suggests that they might interact with biological membranes. To get some insight, guanidinium chlorides derived from the natural l-amino acids phenylalanine (Phe), tyrosine (Tyr) and 3,4-dihydroxyphenylalanine (DOPA) were synthesized and their mesomorphic properties were investigated via polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (SAXS, WAXS). Mesophase types depended on the number of alkoxy side chains. Phe- and Tyr-based ILCs with one and two side chains, respectively, self-assembled into smectic A bilayers (SmA2), while Dopa-derived ILCs with three side chains formed columnar (Colh) mesophases. The mesophase ranges for Phe ILCs increased steadily with side chain length, for Tyr- and Dopa-based ILCs, however, size matching effects were observed. To clarify whether the mesomorphic behaviour has an impact on biological properties, cytotoxic and antibacterial activities of the ILCs were studied. Phe and Tyr ILCs exhibited much higher cytotoxicities (against the L-929 mouse fibroblast cell line) and/or antibacterial activities (against Staphylococcus aureus) than Dopa ILCs, which were mostly inactive. Furthermore, within each series, the side chain length largely influenced the biological activity. Thus, the bulk mesophase behaviour appeared to correlate with the biological properties, in particular, the interactions with membranes, as shown by measuring the intracellular Ca2+ concentration in human monocytic U937 cells after treatment with the amino acid-based ILCs.

Evaluation on estrogenicity and oxidative hepatotoxicity of fossil fuel industrial wastewater before and after the powdered activated carbon treatment

There are 10 manufacturers who produce fossil fuel products in the Da-Hse Industrial District, Kaohsiung County, southwestern Taiwan. Before discharging the wastewater into the nearby aquatic environment, the pretreated wastewater from these manufacturers must be processed in a treatment plant which includes four major processing units: equalization, a primary clarifier, an aeration basin, and a final clarifier. In order to estimate the potential environmental risks of industrial wastewater from each manufacturer and the treatment efficiency of the powdered activated carbon treatment (PACT) system used in this wastewater treatment plant, in vitro bioassays for estrogenicity and oxidative hepatotoxicity were carried out using a stably transfected human breast cancer cell line, MVLN, and a human hepatocellular carcinoma cell line, HepG2, respectively. Estrogenic substances occurred in nine of 10 pretreated wastewaters from these manufacturers in which the relative luciferase activity ranged from 18.9% to 98.0% for 1-fold-condensed wastewaters corresponding to the concentration of the original wastewater. The estrogenicity was highest at the influent of the treatment plant and decreased through the treatment process. About 81% estrogenicity clearance was found through all processing units. On the other hand, oxidative hepatotoxic substances existed in seven of 10 pretreated wastewaters from these manufacturers in which relative TBARs activity ranged from 18.5% to 43.0% for 1-fold-condensed wastewater. The TBARs of influent samples apparently decreased through the processing units until the aeration basin, but abruptly rose in the final clarifier, which was a result of the addition of an active charcoal-retrieving agent with the molecular formula of (C(2)H(3))(n)CONHCH(2)N(CH(3))(3)Cl and which had high TBARs activity. No TBARs activity being found in effluent samples could be a consequence of allowing sufficient time for coagulation between the active charcoal and its retrieval agent which decreased the residual active charcoal-retrieving agent. We concluded that the industrial wastewater treatment plant using the PACT system in the Da-Hse Industrial District is suitable for removing estrogenic substances and oxidative hepatotoxic substances discharged from these industrial manufacturers.