Charge separation and photosensitized damage in DNA mediated by naphthalimide, naphthaldiimide, and anthraquinone.
Charge-separation and charge-recombination dynamics and oxidative DNA degradation were investigated for DNA modified with a photosensitizer (Sens) naphthalimide (NI), naphthaldiimide (ND), or anthraquinone (AQ). In all three Sens-modified DNA systems, the formation of long-lived charge-separated states was observed in which the lifetime increased with increasing numbers of A-T base pairs between Sens and the neighboring G-C base pair. The lifetime of the charge-separated state correlated well with the DNA damage yield, indicating that the charge-separated state provides time for the irreversible DNA oxidative damage to occur. The quantum yield of DNA damage was the lowest for ND-modified DNA due to the slow reaction of ND radical anion with molecular oxygen; the process needed to preclude charge recombination. The AQ-modified DNA resulted in the highest charge separation and subsequent DNA damage yield, which would be partly explained by the formation of the spin-forbidden triplet radical ion pairs during charge separation.
Kawai
Kiyohiko
K
The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan. kiyohiko@sanken.osaka-u.ac.jp
Osakada
Yasuko
Y
Matsutani
Eri
E
Majima
Tetsuro
T
D000042:Absorption; D000880:Anthraquinones / Q000494:pharmacology*; D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000235:genetics*; D004249:DNA Damage; D007700:Kinetics; D053644:Naphthalimides / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D017319:Photosensitizing Agents / Q000494:pharmacology*
D000880:Anthraquinones; D053644:Naphthalimides; D017319:Photosensitizing Agents; D004247:DNA