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THE PHOTODYNAMIC EFFECTS OF PHOTOFRIN II, HEMATOPORPHYRIN DERIVATIVE, HEMATOPORPHYRIN, AND TETRASODIUM‐MESO‐TETRA(4‐SULFONATOPHENYL)PORPHINE in vitro :
Author(s) -
WEST CATHARINE M. L.,
MOORE JAMES V.
Publication year - 1989
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1989.tb04092.x
Subject(s) - hematoporphyrin , porphyrin , chemistry , photodynamic therapy , photosensitizer , drug , singlet oxygen , fluorescence , photochemistry , biophysics , nuclear chemistry , pharmacology , oxygen , organic chemistry , optics , medicine , physics , biology
Abstract The human colon adenocarcinoma cell line, WiDr, was exposed to Photofrin II, hemato‐porphyrin derivative (HPD), hematoporphyrin (HP) or tetrasodium‐meso‐tetra(4‐sulfonatophenyl)‐porphine (TPPS 4 ) followed by irradiation with light. Clonogenicity was determined and the resultant survival curves compared and shown to be qualitatively similar in shape. However, for equal amounts of drug in the medium, there were large differences in photosensitizing efficiency with Photofrin II approximately 5, 25 and 50 fold more effective than HPD. HP and TPPS 4 , respectively. For the same power used, all drugs were less efficient photosensitizers under red light (600–1100 nm) than under white light (300–1100 nm). For all drugs this could be explained in terms of changes in light absorption over the two wavelength ranges. Differences in clonogenic cell survival could not be explained in terms of differences in singlet oxygen production (from published values). A reduction in drug uptake into the cells was sufficient to explain the differences between Photofrin II, HPD and HP. while TPPS 4 was 5‐fold less effective compared to other drugs than would be expected from drug uptake measurements. Two methods for measuring drug uptake were compared and shown to give different results for Photofrin II. Measurement of drug fluorescence in 0.1 N NaOH yielded 5‐fold lower values than when measurements were in 1 N HCl following heat treatment to monomerise aggregated drug. Clearly the reliability of the method used in determining drug uptake must be carefully ascertained.