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THE EFFECTS OF PHOTOOXIDATION BY PROFLAVINE ON HeLa CELLS—1. THE MOLECULAR MECHANISMS *
Author(s) -
Roberts Joan E.
Publication year - 1981
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.1751-1097.1981.tb04296.x
Subject(s) - singlet oxygen , chemistry , hela , proflavine , photochemistry , dabco , radical , oxygen , biophysics , dna , biochemistry , cell , organic chemistry , biology , catalysis
— DNA and RNA syntheses were inhibited immediately after proflavine treated HeLa cells were irradiated with visible light (400–500 nm). The molecular mechanism for this photooxidation may be either a free radical‐mediated (Type I) or singlet oxygen‐mediated (Type II) reaction. Non‐toxic free radical and singlet oxygen quenchers were added to cells and sensitizer before irradiation to quench the appropriate excited state intermediate. Photooxidative damage (the inhibition of incorporation of [ 14 C]‐thymidine) in this system was greatly reduced in the presence of free radical quenchers (glutathione, penicillamine) and not significantly affected by the presence of singlet oxygen quenchers (α‐tocopherol, β‐carotene, DABCO). This suggests that at least part of the photodynamic damage in HeLa cells is via a Type I mechanism.