Antioxidant Beta-Carotene does not Quench Singlet Oxygen in Mammalian Cells.

GABRIELA N. BOSIO; THOMAS BREITENBACH; JULIETA PARISI; FRANCES BLAIKIE; MIGUEL REIGOSA; ELSA F. FREITAS DA SILVA; BRIAN PEDERSEN; DANIEL MARTIRE; PETER OGILBY

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 vol. 135 p. 272 - 279

0002-7863

Carotenoids, and β-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 β-carotene efficiently quenches singlet oxygen in solution-phase systems is invariably invoked when explaining the biological antioxidative properties of β-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 β-carotene. This observation requires a re-evaluation of β-carotene?s role as an antioxidant in mammalian systems and now underscores the importance of mechanisms by which β-carotene inhibits radical reactions.