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Cyanine Dyes as Protectors of K562 Cells from Photosensitized Cell Damage †
Author(s) -
Sima Paul D.,
Kanofsky Jeffrey R.
Publication year - 2000
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(2000)0710413cdapok2.0.co2
Subject(s) - cyanine , chemistry , photochemistry , singlet oxygen , quenching (fluorescence) , fluorescence , oxygen , organic chemistry , physics , quantum mechanics
Several cyanine dyes were found to protect K562 leukemia cells against toxicity mediated by cis ‐di(4‐sulfonatophenyl)diphenylporphine (TPPS 2 ) and light. Most cyanine dyes derived from dimethylindole were better photoprotectors than cyanine dyes with other structures. This correlated with the fact that cyanine dyes derived from dimethylindole were predominately monomeric at millimolar concentrations within K562 cells, while other cyanine dyes formed aggregates. For cyanine dyes that are derived from dimethylindole and have absorption band wavelengths greater than 700 nm, fluorescence‐energy transfer from TPPS 2 to the cyanine dye was the most important mechanism for photoprotection. There was no spectroscopic evidence for complex formation between the cyanine dyes and TPPS 2 . The dimethylindole derivative, 1,1′,3,3,3′,3′‐hexamethylindodicarbocyanine, was an excellent photoprotector, but a poor quencher of TPPS 2 fluorescence and a relatively poor singlet‐oxygen quencher. This cyanine dye may act by quenching excited triplet TPPS 2 . Singlet‐oxygen quenching may contribute to the photoprotection provided by cyanine dyes not derived from dimethylindole. Differences in the subcellular distribution of the various cyanine dyes studied may have contributed to the different apparent mechanisms of photoprotection.