UROCANIC ACID PHOTOBIOLOGY. PHOTOOXIDATION AND SUPEROXIDE FORMATION*

Abstract
Abstract— Photolysis of urocanic acid (UA) and nitro blue tetrazolium (NBT2+), under conditions wherein the NBT2+ absorbs the light, leads to oxidation of the UA by the NBT2+ excited state. When UA is itself photolyzed in the presence of oxygen and NBT2+, NBT2+ reduction again occurs, but in this event via the intermediate formation of superoxide.