Cytotoxicity of halogenated benzenes and its relationship with logP

The in vitro toxicity of a series of environmentally relevant halobenzenes was tested using a Chinese hamster lung fibroblast cell line and its relationship with the logarithm of octanol/water partition coefficient (logP) was investigated. Since we wanted to study the direct biological activity of the parent substances, we have used the V-79 cell line that does not express phase I metabolic activities. Moreover, because of the available knowledge on the substances, we decided to perform the colony-forming ability test (CFA) and to analyse the DNA damage by a cytofluorimetric assay. To identify the concentration range at which the toxic effect could be detected, a prescreen with the neutral red assay has been performed. All the substances tested were positive in the CFA, but, according to the concentration values inhibiting this activity by 50%, they can be divided into two groups of differing toxicity. The FACScan analysis shows for the majority of the halobenzenes a clear hypodiploid peak. A good correlation between values describing the concentration that inhibits CFA by 50% and logP was found, indicating that it depends on the hydrophobic properties of the compounds and that logP is a suitable descriptor.