REAL-TIME DETECTION OF REACTIONS BETWEEN RADICALS OF LYCOPENE AND TOCOPHEROL HOMOLOGS

Laser flash photolysis of lycopene in homogeneous chloroform solution together with tocopherol homologues results in rapid formation of the lycopene radical cation and slower formation of tocopheroxyl radicals. Time-resolved detection by absorption spectroscopy of decay of the ly copene radical cation, of formation of the tocopheroxyl radicals, and of bleaching of lycopene has shown that alpha-tocopherol is able to re duce the lycopene radical cation and thereby partially regenerate lyco pene on a ms timescale. In contrast, lycopene is able to reduce the de lta-tocopheroxyl radical, whereas an equilibrium exists between the ly copene radical cation and beta- or gamma-tocopherol. The relative stab ility of these antioxidant radicals is hence: alpha-tocopheroxyl > lyc opene radical cation similar to beta-tocopheroxyl similar to gamma-toc opheroxyl > delta-tocopheroxyl.