Lycopene and beta-carotene ameliorate catechol estrogen-mediated DNA damage

The consumption of fruits and vegetables is associated with a reduced risk of various ailments, including cancer and cardiovascular diseases. Carotenoids, such as lycopene and beta-carotene, are natural constituents of edible plants and may protect against disease. In this study, the influence of lycopene and beta-carotene on DNA damage caused by catechol-estrogens in vitro is examined. One possible mechanism by which catechol estrogens such as 4-hydroxyestradiol (4-OHE2) and 2-hydroxyestradiol, which cause DNA damage in naked plasmid DNA as well as in cells, contributing to the process of carcinogenesis, is through the generation of reactive oxygen species. It was found that both carotenoids at concentrations ranging from 0.25 to 10 microM significantly inhibit strand breakage induced by 4-OHE2/copper sulphate by up to approximately 90% in plasmid DNA with beta-carotene being slightly more effective. No prooxidant or cytotoxic effects were observed at the concentrations tested. These carotenoids had a similar, though reduced effect on DNA damage as measured by the comet assay, in Chinese hamster lung fibroblasts. The results obtained show that both lycopene and beta-carotene, most probably and mainly through their potent antioxidant properties, are able to inhibit catechol-estrogen-mediated DNA damage.