UVA light-induced DNA cleavage by selected polycyclic aromatic hydrocarbons

After absorbing UV light energy, PAHs may transfer their energy to molecular oxygen to produce reactive oxygen species that cause a variety of damages to the cell. In this study, the light-induced DNA cleavage by some environmentally important 3-, 4-, and 5-ring PAHs and their derivatives was examined. The compounds studied included: anthracene, 9-nitroanthracene, 2-hydroxycarbazole, 6-aminochrysene, chrysene, 1,4-chryseneqinone, 3-aminofluoranthene, benzo(a)pyrene, DHBP, pyrene, 1-aminopyrene, 1-nitropyrene, and 1-bromopyrene. The experimental protocol is detailed. Results indicated that the UV-A light-induced cleavage by PAHs was both PAH concentration- and irradiation time-dependent. 1-Hydroxypyrene and 9-nitroanthracene were the two most potent compounds in terms of causing light-induced DNA cleavage. Substitution with a nitro, amino, or bromo group on pyrene lowered the C sub(25), which was the PAH concentration at which 25% of the original supercoiled Form 1 DNA was converted into relaxed open circular Form II DNA, by one order of magnitude.