Abstract
Photoactive evaluation for cosmetic pigments in sunscreen agents, such as zinc oxide (ZnO), titanium dioxide (TiO2), aluminium oxide (Al2O3) and tungsten oxide (WO3), was carried out by examining DNA damage using agarose gel electrophoresis. Photoinduced DNA damage occurred in the presence of pigments under either aerated condition or oxygen gas atmosphere in the following order: WO3 ≈ Al2O3 ≈ rutile TiO2 < anatase TiO2 « TiO2 (P-25) « ZnO. The photoinduced oxidative activity of various pigments was assessed by the aromatic cleavage rate of phenol as a standard, which corresponds to the degree damaged to the supercoiled configuration of DNA (transformation to the linear form and/or relaxed form). L(+)-ascorbic acid (anti-oxidizing agent) can suppress the formation of photooxidative species such as ·OH radicals and/or ·OOH radicals. DNA damage under UV irradiation even in the presence of highly photocatalytic ZnO pigment was controlled by addition of the anti-oxidative enzyme catalase. DNA damage was depressed with increasing quantity of catalase.
