Photoprotection of human dermal fibroblasts against ultraviolet light by antioxidant combinations present in tomato

In the current study, we evaluated and compared, for the first time in a cell model, the effect of lycopene alone or in association with various antioxidants present in tomato such as a-tocopherol or naringenin, on their capacity to protect against oxidative stress generated in human dermal fibroblasts (hdf) exposed to ultraviolet-A (UVA) light. UVA irradiation of hdf led to a reduced cell viability in a dose dependent manner. Similar effects were observed when cells were exposed to lycopene. This reduction was suppressed in the presence of naringenin but not with a-tocopherol. Reactive oxygen species production was strongly induced by UVA irradiation. Only co-incubation with naringenin (highest level) was able to inhibit this effect. The combination of lycopene : naringenin further increased the stability of the carotenoid. Heme-oxygenase 1 (HO-1) expression was induced by UVA irradiation but none of the antioxidants inhibited this effect at the concentrations used in the study. Indeed, lycopene (1 mu M) led to a further 2.5-fold rise in the UVA-induced HO-1 expression. However, this effect was suppressed by concomitant addition of naringenin. In our study, naringenin prevents oxidative degradation of lycopene. These results strengthen the hypothesis that combinations of dietary antioxidants present in tomato other than lycopene alone could play a role in the health effects of tomato as evidenced by epidemiological studies.