Characterization of photodynamic effects of meso-tetrakis-(4-methoxyphenyl) porphyrin: biological consequences in a human carcinoma cell line

MARIÁNGELES LA PENNA; M. GABRIELA ALVAREZ; E. INES YSLAS; VIVIANA RIVAROLA ; EDGARDO N. DURANTINI

DYES AND PIGMENTS

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2001 vol. 49 p. 75 - 82

0143-7208

The photodynamic behavior of 5,10,15,20-tetrakis(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 cells 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 population) and TMP intracellular concentration was found, indicating that TMP localizes at unsaturated sites within the cells. TMP photosensitized singlet molecular oxygen (12) with a quantum yield of 0.65. When the amino acid l-tryptophan was used to assess 12- mediated photooxidation in a homogeneous medium, singlet molecular oxygen (1g) mediation appeared to be mainly responsible for the cell inactivation. These in vitro results enhance our understanding of the phototoxicity of porphyrins in cellular media and the sensitivity of Hep-2 cells to photodamage.