Characterization of Photodynamic Effects of Meso-tetrakis (4-methoxyphenyl) Porphyrin : Biological Consequences in a Human Carcinoma Cell Line.

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Summary *

The photodynamic behavior of 5,10,15,20 -terakis(4-methoxyphenyl)porphyrin (TMP) has been investigated in solutions containing photo-oxidizable substrates and in the presence of Hep-2 human larynx-carcinoma cell line. It has been found that Hep-2 cells rapidly incorporate TMP until an intracellular concentration of ~0.018 mmol of TMP/106 cells is reached. The survival of the irradiated cell treated with TMP was dependent upon both light exposure level and intracellular sensitizer concentration. In addition, a linear dependence of the photoinactivation rate (1/D50, where D50 represents the light exposure level required to inactivate 50 % of the cell poulation9 and TMP intracellular concentration was found, indicating that TMP localizes at unsaturated sites within the cells. TMp photosensitized singlet molecular oxigen (1L2) with a quantum yield of 0.65. when the amino acid L-tryptophan was used to assess (1L)g -mediated photooxidation in a homogeneous medium, singlet molecular oxygen (1 9 mediation appeared to be mainly responsible for the cell inactivation. These in vitro results enhance our understanding of the ohototoxicity of porphyrins in cellular media and the sensitivity of Hep-2 cells to photodamage. Information provided by the agent in SIGEVA