Response and deactivation of singlet oxigen by B-carotene in Hela cells.

BOSIO GN, BREITENBACH T, PARISI J, REIGOSA M, BLAIKIE FH, PEDERSEN BW, SILVA EF, MáRTIRE DO, OGILBY PR.

Congreso; congreso; 2012

J Am Chem Soc. 2013 Jan 9;135(1):272-9. doi: 10.1021/ja308930a. Epub 2012 Dec 28. Antioxidant ¦Â-carotene does not quench singlet oxygen in mammalian cells. Bosio GN, Breitenbach T, Parisi J, Reigosa M, Blaikie FH, Pedersen BW, Silva EF, M¨¢rtire DO, Ogilby PR. Source Instituto de Investigaciones Fisicoqu¨ªmicas Te¨®ricas y Aplicadas (INIFTA), CCT-La Plata-CONICET, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900), La Plata, Argentina. Abstract Carotenoids, and ¦Â-carotene in particular, are important natural antioxidants. Singlet oxygen, the lowest excited state of molecular oxygen, is an intermediate often involved in natural oxidation reactions. The fact that ¦Â-carotene efficiently quenches singlet oxygen in solution-phase systems is invariably invoked when explaining the biological antioxidative properties of ¦Â-carotene. We recently developed unique microscope-based time-resolved spectroscopic methods that allow us to directly examine singlet oxygen in mammalian cells. We now demonstrate that intracellular singlet oxygen, produced in a photosensitized process, is in fact not efficiently deactivated by ¦Â-carotene. This observation requires a re-evaluation of ¦Â-carotene´s role as an antioxidant in mammalian systems and now underscores the importance of mechanisms by which ¦Â-carotene inhibits radical reactions.