Previous study showed that the cosmetic ingredient chemical
azulene and its derivative gauiazulene exhibited photomutagenicity four- to five-fold higher than spontaneous mutation in Salmonella typhimurium TA102. In this study,
phototoxicity including photogenotoxicity of
azulene in human Jurkat T-cells is reported. When the cell
suspensions are irradiated by light (UVA plus visible light) in the presence of
azulene, an
azulene dose-dependent cellular DNA damage is observed. At the highest
azulene concentration of 50 microM, the average DNA fragmentation
is 33 +/- 10%, determined by single cell gel electrophoresis (Comet assay). Cell viability assay using
fluorescein diacetate indicates that the cells could endure the damage and remain viable. Further study revealed that the combination of light and
azulene can cause single-strand cleavage on pure PhiX174 plasmid
DNA in
solution. Studies using scavengers reveal that
singlet oxygen and
free radicals are involved in causing DNA cleavage. This suggests that the photomutagenicity of
azulene in S. typhimurium TA102 could be due to DNA fragmentation caused by the concurrent exposure to
azulene and light.