Transient photochemistry of naphazoline in a protein environment

The photoreactivity of naphazoline (NP), 2-(1-naphthylmethyl)imidazoline, i n the presence of bovine serum albumin (BSA) is investigated. The protein m icroenvironment affects markedly the efficiency of the photochemical deacti vation pathways of the NP transient intermediates photogenerated upon laser excitation. The triplet state of the drug associates with BSA and its life time increases by more than one order of magnitude. Hydrated electrons and nitrogen-centered radicals formed in the NP photolysis react efficiently wi th protein sites, behaving as sources of reductive and oxidative protein da mage, respectively. NP photoinduced protein structural modification is also observed.