Abstract:

Objective To analyze the quantitative constitutive relationship between the median-inhibitory concentration （IC₅₀） of halobenzoquinones （HBQs） to the human hepatocellular carcinoma HepG2 cells and structural parameters， and to explore the structural parameters that may affect the cytotoxicity of HBQs. Methods The HepG2 cells were cultured in vitro and cultured with different contentrations of HBQs solutions，at the same time， blank control group ［10% fetal bovine serum（FBS）+DMEM culture medium］ and negative control group ［（10% FBS+DMEM culture medium +1.33% methanol （MeOH）］ were set up. The action concentrations of HBQs were comfirmed with MTS and neural red uptake（NRU） methods，respectively.The survival rates of cells in various groups were detected by MTS and NRU methods， and the IC₅₀ of HBQs was calculated. The quantum chemical calculation module MOPAC was used to calculate the structural parameters of every kind of HBQs. Single-factor linear regression analysis was used to construct the quantitative structure-toxicity relationship （QSTR） models based on the IC₅₀ and structural parameters of the HBQs. Results The MTS method determination results showed that the action concentrations of 2，6-dichloro-1，4-benzoquinone（2，6-DCBQ） were 75， 100， 125， 150， 175， 200， 225， and 250 μmol·L^－1，the action concentrations of 2，6-dichloro-3-methyl-1，4-benzoquinone（DCMBQ） were 175， 200， 225， 250， 275， 300，and 325 μmol·L^－1， the action concentrations of 2，3，6-trichlorocyclohexa-1，4- benzoquinone（TCBQ） were 200， 225， 250， 275， 300， and 325 μmol·L^－1， the action concentrations of 2，5-dibromo-1，4-benzoquinone（2，5-DBBQ） were 75， 100， 125， 150， 175， and 200 μmol·L^－1，and the action concentrations of 2，6-dibromo-1，4-benzoquinone（2，6-DBBQ） were 200， 225， 250， 275， 300， 325 μmol·L^－1.The NRU method determination results showed that the action concentrations of 2，6-DCBQ were 25， 50， 75， 100， and 125 μmol·L^－1， the action concentrations of DCMBQ were 125， 150， 175， 200， 225，and 250 μmol·L^－1， the action concentrations of TCBQ were 175， 200， 225， 250， 275，and 300 μmol·L^－1，the action concentrations of 2，5-DBBQ were 75， 100， 125， 150，and 175 μmol·L^－1，the action concentrations of 2，6-DBBQ were 125， 150，175， 200， 225， and 250 μmol·L^－1.The survival rates of HepG2 cells in various groups were significantly decreased with the increase of HBQs concentration， showing a dose-response relationship. The cytotoxic effects of HBQs on the HepG2 cells detected by MTS method were 2，6-DCBQ>2，5-DBBQ>DCMBQ>TCBQ>2，6-DBBQ；and the cytotoxic effects of HBQs on HepG2 cells detected by NRU method were 2，6-DCBQ>2，5-DBBQ>DCMBQ>2，6-DBBQ>TCBQ.The single-factor multiple linear regression analysis results showed that the correlation analysis between IC₅₀ and structural parameters of the HBQs detected by MTS and NRU methods had no statistically significant differences（P>0.05）. Conclusion The substitution position， type and number of halogen atoms can affect the toxic effects of HBQs， and there is a trend that the more halogen substitution， the less toxic it is.

Key words: Halobenzoquinone, Cytotoxicity, Structural parameters, Quantitative structure-toxicity relationship