Toxicity of photoswitchable drugs

Even though the photopharmacological approach promises increased control over drug-selectivity, traditional studies on metabolic stability and the compounds’ long-term toxicity must not be neglected. As these properties change with structure, every compound needs to be assessed anew.

Azobenzenes have been used industrially for dyes and food-colorants for decades. There are approved drugs based on the azobenzene structure and some azobenzenes serve as pro-drugs. Thus, not only the drug-structure, but also the toxicity of the corresponding anilines/amines should be studied. The azobenzene-associated toxicity effects were studied extensively (Crit. Rev. Environ. Sci. Technol. 1993, 23, 249−324). Azobenzenes can be reduced to their corresponding aromatic amines or oxidized to diazonium salts. Metabolic oxidation of amines or aromatic amines to electrophilic species can lead to cell damage, as e.g. covalent DNA attachment.