title: Antioxidant β-carotene does not quench singlet oxygen in mammalian cells.
abstract: 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.
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT-La Plata-CONICET, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900), La Plata, Argentina.
authors.forename: Gabriela N
authors.initials: GN
authors.lastname: Bosio
authors.forename: Thomas
authors.initials: T
authors.lastname: Breitenbach
authors.forename: Julieta
authors.initials: J
authors.lastname: Parisi
authors.forename: Miguel
authors.initials: M
authors.lastname: Reigosa
authors.forename: Frances H
authors.initials: FH
authors.lastname: Blaikie
authors.forename: Brian W
authors.initials: BW
authors.lastname: Pedersen
authors.forename: Elsa F F
authors.initials: EF
authors.lastname: Silva
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Mártire
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ogilby
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D026082:Singlet Oxygen / Q000737:chemistry*; D019207:beta Carotene / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D019207:beta Carotene; D026082:Singlet Oxygen