Molecular and Cellular Mechanisms in Photomedicine: Porphyrins in Cancer Treatment

摘要: The use of visible light in combination with a photosensitizing dye for the treatment various types tumors has been repeatedly attempted since early 1900s when topically applied eosin and sunlight were shown to induce regression skin tumors1. This approach appears be particularly attractive i) several photosensitizers polycyclic chemical structure, including xanthenes2, acridines3, psoralens4, display preferential affinity neoplastic as compared normal cells; ii) most cell constituents, particular proteins nucleic acids, are insensitive direct action light. In principle, these two properties should allow one restrict photodynamic effects causing inactivation necrosis dye-loaded tissue, no concomitant damage dye-free tissues, provided suitable set wavelengths is selected irradiation. Thus, therapy exhibits potential advantage respect other therapeutic modalities which based on ionizing radiations; latter cases, simultaneous irreversible tissues often limits extent efficacy treatment. Toward this aim, an ideal photosensitizer have following properties: lack systemic toxicity; selective uptake retention by malignant tissues; iii) absorption incident light; iv) efficient generation photoreactive species leading destruction tissues.