Molecular and cellular mechanisms of porphyrin photosensitization.

Mechanisms of porphyrin-sensitized photochemistry involving biomolecular substrates have been studied in a diverse array of in vitro and in vivo experimental protocols. Porphyrin-sensitized, singlet oxygen-mediated photooxidative damage has been implicated in peroxidation of cell membrane lipids; cross-linking of cell membrane and intracellular proteins; inhibition of cell membrane associated, cytosolic, mitochondrial and microsomal enzymes; disruption of intracellular organelles with release of inflammatory mediators and hydrolases; damage to DNA with retarded protein synthesis and delay in cell cycle; and activation of complement-generated inflammatory events leading to cell injury or death.