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Photobleaching of Hypericin Bound to Human Serum Albumin, Cultured Adenocarcinoma Cells and Nude Mice Skin ¶
Author(s) -
Uzdensky Anatoly B.,
Iani V.,
Ma L.W.,
Moan J.
Publication year - 2002
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 - 10.1562/0031-8655(2002)0760320pohbth2.0.co2
Subject(s) - hypericin , photobleaching , singlet oxygen , photodynamic therapy , photochemistry , photosensitizer , chemistry , in vivo , fluorescence , human serum albumin , human skin , biophysics , oxygen , biochemistry , biology , organic chemistry , optics , pharmacology , microbiology and biotechnology , physics , genetics
Hypericin is a promising photosensitizer for photodynamic therapy (PDT) characterized by a high yield of singlet oxygen. Photobleaching of hypericin has been studied by means of absorption and fluorescence spectroscopy in different biological systems: in human serum albumin solution, in cultured human adenocarcinoma WiDr cells and in the skin of nude mice. Prolonged exposure to light (up to 95 min, 100 mW/cm 2 ) of wavelength around 596 nm induced fluence‐dependent photobleaching of hypericin in all studied systems. The photobleaching was not oxygen dependent, and singlet oxygen probably played no significant role. Emission bands in the spectral regions 420–560 nm and above 600 nm characterize the photoproducts formed. An emission band at 615–635 nm was observed after irradiation of cells incubated with hypericin or of mouse skin in vivo but not in albumin solution. The excitation spectrum of these products resembled that of hypericin. Hypericin appears to be more photostable than most sensitizers used in PDT, including mTHPC and Photofrin.