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Evaluation of a new photosensitizer, meso‐tetra‐hydroxyphenyl‐chlorin, for use in photodynamic therapy: A comparison of its photobiological properties with those of two other photosensitizers
Author(s) -
Ma Liwei,
Moan Johan,
Berg Kristian
Publication year - 1994
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910570618
Subject(s) - photosensitizer , photodynamic therapy , chlorin , chemistry , lipophilicity , photochemistry , fluorescence , biophysics , porphyrin , irradiation , phthalocyanine , stereochemistry , organic chemistry , biology , optics , physics , nuclear physics
The properties of a new photosensitizer, meso‐tetra‐hydroxyphenyl‐chlorin (mTHPC), were studied using V79 cells (Chinese‐hamster lung fibroblasts). Comparisons were made with 2 other photosensitizers: photofrin II (PII) and meso‐tetra‐hydroxyphenyl‐porphyrin (mTHPP). A main advantage of mTHPC is that it has a strong absorption at 652 nm. Maximal cellular uptake of the dye was observed after 24 hr incubation of the cells with the drug. Using a confocal laser‐scanning fluorescence microscope, we observed a diffuse distribution of m THPC in the cytoplasm. Furthermore, the lipophilicity of mTHPC was compared with that of the components of PII by means of high‐pressure liquid chromatography (HPLC). Absorption and fluorescence spectroscopy indicated that aggregated as well as monomeric mTHPC was bound to the cells. The action spectrum for photo‐inactivation of the cells showed that aggregated mTHPC did not contribute significantly to its photosensitizing effects. In the present cellular system, the efficiency of photodynamic therapy (PDT) with mTHPC (cells were irradiated at a wavelength of 652 nm) was higher than with PII (irradiation at 630 nm) or with mTHPP (648 nm). The quantum yield for photo‐inactivation of cells was smaller for mTHPC than for mTHPP and PII. The addition of 1,3‐diphenylisobenzofuran (DPBF) reduced cell inactivation during PDT. Thus, PDT with mTHPC seems to act at least partly via a type‐II process. © 1994 Wiley‐Liss, Inc.