title: Light-Activated Pharmaceuticals: Mechanisms and Detection.
abstract: Photodynamic therapy relies on the interaction between light, oxygen and a photosensitizing agent. Its medical significance relates to the ability of certain agents, usually based on porphyrin or phthalocyanine structures, to localize somewhat selectively in neoplastic cells and their vasculature. Subsequent irradiation, preferably at a sufficiently high wavelength to have a significant pathway through tissues, results in a photophysical reaction whereby the excited state of the photosensitizing agent transfers energy to molecular oxygen and results in the formation of reactive oxygen species. Analogous reactive nitrogen species are also formed. These contain both nitrogen and oxygen atoms. The net result is both direct tumor cell death and a shutdown of the tumor vasculature. Other processes may also occur that promote the anti-tumor response but these are outside the scope of this review.
authors.affiliation: Department of Pharmacology Wayne State University School of Medicine Detroit, MI 48201 (USA) phone: +0013135771787 dhkessel@med.wayne.edu.
authors.forename: David
authors.initials: D
authors.lastname: Kessel
authors.forename: John
authors.initials: J
authors.lastname: Reiners
keywords: apoptosis; autophagy; photodynamic therapy; reactive nitrogen species; reactive oxygen species