Porphyrins and related compounds as photodynamic sensitizers
It was shown early in this century that certain porphyrins are photosensitizers of the photodynamic type, i.e., they sensitize the photooxidative damage of biological systems on illumination in the presence of molecular oxygen. An extensive literature has accumulated on porphyrin-sensitized photodynamic effects on multicellular organisms (including humans), cells, biomacromolecules, and small organic molecules of biological importance. The mechanism of the porphyrin-sensitized injury to multicellular organisms is poorly understood; effects at the cellular level appear to be mediated by photodynamic damage to plasma and lysosomal membranes. Damage to proteins involves the photooxidation of certain types of amino acid residues. Efficiencies of porphyrins as photodynamic sensitizers depend critically on the metal chelated by the molecule; porphyrins containing paramagnetic metal atoms are typically nonsensitizers. The sensitizing efficiencies and substrate specificities of metal-free and diamagnetic metalloporphyrins are determined to some extent by the side chains on the molecule. In water solution, photosensitizing porphyrins give a good yield of long-lived triplet states on illumination which are quenched by molecular oxygen with high efficiency. Kinetic and product-formation studies with amino acids and proteins suggest that porphyrin-sensitized photooxidations occur by a singlet oxygen mechanism. The purpose of this paper is to review briefly the various kinds of studies that have been made with porphyrins as photosensitizers; the coverage of the literature is extensive rather than intensive in order to illustrate the great range of systems studied.
- Research Organization:
- Univ. of Utah, Salt Lake City
- OSTI ID:
- 7126202
- Journal Information:
- Ann. N.Y. Acad. Sci.; (United States), Vol. 24
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LYSOSOMES
BIOCHEMISTRY
MEMBRANES
PORPHYRINS
PHOTOCHEMISTRY
PHOTOSENSITIVITY
PROTEINS
OXIDATION
MOLECULES
OXYGEN
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
CHEMISTRY
CRYOGENIC FLUIDS
ELEMENTS
FLUIDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
SENSITIVITY
550200* - Biochemistry