Cytotoxicity of chrysene isomers to HepG2 cells

We evaluated the cytotoxicity of chrysene and its monomethylated isomers using HepG2 (human hepatoma) cells. The treatment groups were a control, solvent control (DMSO up to 0.1%), chrysene, and its 6 mono methyl isomers at 5 nM, 50 nM, 500 nM, and 5 uM (final concentrations). The assays were carried out in 24-well microplates with 3 technical replicates per treatment group. Cells were seeded at 10,000/well on day 0. Exposure time to treatments was 5 days. Sulforhodamine B fluorescence was measured on a Tecan microplate reader following the published SRB assay. All chrysenes were toxic at the 5 uM dose, and some toxicity (reduced cell density as indicated by sulforhodamine B dye binding) at the 500 nM dose as well. None were significantly toxic at 50 and 5 nM.