Porphyrins as photosensitizers.
The porphyrins have two important roles in photobiology: in photosynthesis, which has evolved and is highly organized morphologically; and in the photodynamic effect, which is adventitious. The damage to tissue that results from photodynamic action is regarded as arising from a number of pathways, but singlet oxygen generation is a major route. Even for the latter mechanism, a number of target molecules are possible. Compared with photosynthesis, it is a very disorganized process. Since the mid 1970s there have been increasing efforts to turn the photodynamic effect to good use as the basis of a phototherapy for cancer. The field has been dominated by the photosensitizer haematoporphyrin derivative. This is a complex mixture of molecules, and although we are learning more about it, it seems unlikely that it will be possible to separate out a useful single substance. A second generation of porphyrin sensitizers is emerging, which, unlike haematoporphyrin derivative, is designed for the job in hand. Some of these photosensitizers, especially the hydroporphyrins, look quite promising.
Bonnett
R
R
Department of Chemistry, Queen Mary College, London, UK.
Berenbaum
M
M
D010778:Photochemotherapy; D011166:Porphyrins / Q000494:pharmacology*; D011838:Radiation-Sensitizing Agents
D011166:Porphyrins; D011838:Radiation-Sensitizing Agents