KEYNOTE: Photo-induced toxicity and photochemical transformation mechanism of polycyclic musks: Experimental and theoretical studies on tonalide

Polycyclic musks (PCMs), widely used as fragrance in cosmetics and household commodities, and they would be easily left over on the surface of skin and might be harmful to human beings through photo-induced reaction. Moreover,... [ view full abstract ]

Polycyclic musks (PCMs), widely used as fragrance in cosmetics and household commodities, and they would be easily left over on the surface of skin and might be harmful to human beings through photo-induced reaction. Moreover, the unabsorbed PCMs would be washed down the drain, eventually entering into aquatic environment. Once released into aquatic environment, PCMs may photo-chemically transform into other products, resulting in potential adverse impacts on aquatic ecosystems. Thus, photochemical processes of PCMs would impose risks to human beings and aquatic organisms.
This talk will focus on the two important photochemical processes of PCMs: (a): The photo-induced damage of amino acids using PCMs as photosensitizer during normal usage; (b): •OH-initiated indirect photochemical transformation of PCMs in both non-aqueous and aqueous solutions, due to hydrophobic properties of PCMs. Tonalide is selected as typical PCMs to elucidated transformation mechanisms, and the results show tonalide can initiate the photo-transformation of amino acids indeed, finally resulting in the damages to proteins and cells. The formed reactive species, O2•- and 1O2, could result in common and exceptional pathways of photosensitized transformation of amino acids. In aquatic ecosystems, tonalide also can be degraded by •OH via •OH-addition and H-abstraction pathways. The reaction rate constant in aqueous environment is 2 times faster than that in non-aqueous environment. Compared with original tonalide, all H-abstraction products was found to be declined bioaccumulation and aquatic toxicity, while •OH-addition products are more bioaccumulative and harmful to aquatic organisms. Therefore, particular attentions should be paid to PCMs and their transformation intermediates.