Artificial Radical Generating and Scavenging Systems: Photo-Fenton Reagent and Caged Compounds

A photo-labile compound that is bioinactive but upon irradiation with light yields bioactive species, is called as “caged compound” (1 ) (see Scheme 1). Photolysis of caged compounds generating bioactive species, i.e., “uncaging,” has become a general method to produce a desired amount of bioactive species in a specific time interval at desired place or area of the target biological systems (1 ,2 ). This chapter deals with two caged free radicals: a caged hydroxyl radical, i.e., photo-Fenton reagent, and caged nitric oxides (NOs). Uncaging of these caged free radicals yield hydroxyl radical and NO, respectively, which are believed to be associated with free-radical tissue damage.