Prevention of UVB-induced Oxidative Stress and DNA damage in human keratinocytes by citrus and olive formulations

Solar ultraviolet (UV) radiation, especially UVB (290 nm-320 nm) component, causes DNA damage, pyrimidine dimmers, 8-hydroxy-2´-deoxyguanosine (8-OHdG), p53 induction, protein oxidation and generation of reactive oxygen species (ROS). Some polyphenols show the ability to protect the skin from the adverse effects of UVB radiation, including the risk of skin cancers. This study evaluated the protective effects of formulations containing citrus, rosemary and olive polyphenols (F1 and F2) against UVB-induced damage in human keratinocytes. F1 contained citrus, rosemary diterpenes and olive polyphenols and F2 citrus and olive flavones. The antioxidant capacity was determined using the ROS-sensitive dye 2’,7’-dichlorofluorescein diacetate (DCF-DA). Late apoptosis, mitochondrial membrane potential (MMP) and H2A.X histone phosphorylation were measured using Muse Cell Analyzer. The treatment with both formulations suppressed UVB-induced ROS production, and decreased late apoptosis, cell depolarization and DNA damage by H2A.X assay. In conclusion, these results suggest that the compounds present in both formulations might contribute to the observed protective effect. Formulations may be considered as candidates for oral or topical photoprotection and their mechanism of action may deserve further attention.