Photosensitized Carcinogen Degradation and the Possible Role of Singlet Oxygen in Carcinogen Activation

Dye sensitized photo‐oxidation of various chemical carcinogens including 2‐acetylaminofluorene, benzo(a)pyrene, 9,10‐dimethyl‐1,2‐benzanthracene and 4‐nitroquinoline‐ N ‐oxide has been studied in the presence and absence of oxygen. Visible light from a filtered 150 W Xe arc was used for photolysis. and carcinogen destruction was monitored spectrophotometrically. The carcinogens were solubilized in aqueous solution within micelles of various lipid‐like surfactants. Photosensitized destruction of carcinogens by several triplet sensitizers has been observed. Enhanced damage in the presence of oxygen is also found. These results are consistent with photochemical oxidative damage to carcinogens being produced in aerated solutions via the sensitizer triplet state, possibly involving singlet oxygen. These manifold reactions are catalysed by micelles which concentrate polycyclic hydrocarbons in the non‐polar environment within the micelles where the exclusion of water probably increases reactive species lifetimes. This model photochemical system mimics the aerobic metabolic activation of chemical carcinogens, which in part is believed to be mediated by various forms of activated oxygen.