Quantitative structure activity relationship and toxicity mechanisms of chlorophenols on cells <Emphasis Type="Italic">in vitro</Emphasis>

dimethylthiazd-2-yl)-2,5-diphenylentra- zolium bromide (MTT) reduction assay was used to investi-gate the acute toxicity of 8 different chlorophenols (CPs) on rat connective tissue fibroblast L929 cells and human liver cancer HepG2 cells. Combined with the data from Quantita-tive Structure Activity Relationship (QSAR) approach of CPs by using the octanol-water partition coefficients (Kow), an effective model was deduced to evaluate the cytotoxicity of these chemicals. Furthermore, the relationship between the structures of CPs and their cytotoxicity was proposed. The results show that 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,6-dichlorophenol (2,6-DCP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and 2,3,4-tri- chlorophenol (2,3,4-TCP) induced apoptosis, whereas, 2,3,5,6- tetrachlorophenol (2,3,5,6-TeCP) and pentachlorophenl (PCP) demonstrated more characteristic of necrosis than apoptosis. These results establish a good experimental base both for developing the comparative evaluation of toxicity of CPs in vitro and for elucidating the toxicity mechanisms of them.