Oxidatively Generated Damage to DNA by UVA Radiation in Cells and Human Skin

Exposure of cells and human skin to UVA radiation oxidatively induces damage to DNA that consists mostly of 8-oxo-7,8-dihydroguanine (8-oxoGua), together with relatively minor amounts of oxidized pyrimidine bases and oligonucleotide strand breaks. Singlet oxygen generated by the type II photosensitization mechanism forms 8-oxoGua, with a small contribution by hydroxyl radicals. The mechanisms of UVA-mediated formation of DNA oxidation products indicate the absence of induction of double-strand breaks.