Beta-carotene enhances hydrogen peroxide-induced DNA damage in human hepatocellular HepG2 cells

In this study, the alkaline version of the comet assay has been used to determine the effect of beta-carotene supplementation (10 microM) on peroxide-initiated free radical-mediated DNA damage in human HepG2 hepatoma cells. In supplemented cells, beta-carotene failed to afford any protection against hydrogen peroxide-induced DNA strand breaks. Indeed, levels of strand breaks in supplemented cells were significantly higher than in cells exposed to hydrogen peroxide alone, especially after a long incubation period. In contrast, beta-carotene afforded significant levels of protection against DNA strand breaks when cells were treated with tert-butyl hydroperoxide. In this case, the level of protection increased as supplementation continued.