Phototoxicity of naphazoline. Evidence that hydrated electrons, nitrogen-centered radicals, and OH radicals trigger DNA damage: a combined photocleavage and laser flash photolysis study.

The potential phototoxic activity of naphazoline (NP), 2-(1-naphthylmethyl)imidazoline, was investigated by studying its photoreactivity toward DNA. Photocleavage studies combined with laser flash photolysis experiments provide clear evidence that the transient species produced under NP photolysis react with DNA, thereby promoting its breakage under both aerobic and anaerobic conditions. Hydrated electrons and nitrogen-centered radicals are involved in the photodamage under anaerobic conditions. Hydroxyl radicals generated by Haber-Weiss reaction seem to initiate the photocleavage observed under aerobic conditions. A photodynamic mechanism involving the participation of singlet oxygen does not seem to play a crucial role in the photoinduced DNA breakage. The interaction between the NP and the biopolymer is also investigated by using both steady state and time-resolved spectroscopy.