Genotoxicity of Colloidal Fullerene C60

Previous genotoxicity tests of aqueous fullerene C60 suspension (aqu-C60) yielded both positive and negative results. In the present study, aqu-C60 elicited positive responses in two bacterial genotoxicity tests, the Bacillus subtilis Rec-assay and the umu test at concentrations as low as 0.048 mg/L and 0.43 mg/L, respectively. In mammalian cell experiments, aqu-C60 showed a significant growth inhibitory effect on human hepatocarcinoma HepG2 cells at 0.46 mg/L. The level of the oxidative DNA lesion 8-oxo-7,8-dihydro-2′-deoxyguanosine, measured by liquid chromatography tandem mass spectrometry, was slightly but not significantly increased in HepG2 cells treated with 0.46 mg/L for 24 h, whereas the level of the lipid peroxidation-related DNA lesion α-methyl-γ-hydroxy-1,N2-propano-2′-deoxyguanosine was not changed. Under the same conditions, we did not detect any bulky DNA adducts, as measured by 32P-postlabeling/polyacrylamide gel electrophoresis analysis. Our data suggest that aqu-C60 has DNA-damaging pote...