Premium
The Microenvironment of DNA Switches the Activity of Singlet Oxygen Generation Photosensitized by Berberine and Palmatine
Author(s) -
Hirakawa Kazutaka,
Hirano Toru
Publication year - 2007
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.1751-1097.2007.00220.x
Subject(s) - photosensitizer , singlet oxygen , intersystem crossing , chemistry , photochemistry , palmatine , quenching (fluorescence) , photodynamic therapy , berberine , dna , electron transfer , intramolecular force , excited state , fluorescence , biophysics , singlet state , oxygen , stereochemistry , biochemistry , organic chemistry , physics , quantum mechanics , nuclear physics , biology
The effect of the interaction between DNA and the photosensitizer on photosensitized singlet oxygen ( 1 O 2 ) generation was investigated using DNA‐binding alkaloids, berberine and palmatine. These photosensitizers were bound to DNA by electrostatic force. Near‐infrared luminescence measurement demonstrated that the photoexcited alkaloids can generate 1 O 2 only when the photosensitizers are bound to DNA. A fluorescence decay study showed significant enhancement of the lifetime of their photoexcited state with the DNA binding. A calculation study suggested that the electrostatic interaction with DNA inhibits the quenching of the photoexcited state of these alkaloids via intramolecular electron transfer, leading to the prolongation of the lifetime of their excited state. This effect should enhance their intersystem crossing and the yield of energy transfer to molecular oxygen. The results show that the electrostatic interaction with DNA significantly affects the 1 O 2 generation activity of a photosensitizer. In addition, this interaction may be applied to the control and the design of photosensitizers for medical applications such as photodynamic therapy.