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, MáRTIRE DO, OGILBY PR.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 135 p. 272 - 279

0002-7863

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.