Free radicals of tocopherol model compound, 6-hydroxy-2,2,5,7,8-pentamethylchroman which are produced from the reaction with superoxide ion, O2: studies by high-performance liquid chromatography.

Reaction of superoxide ion, O2-, with alpha-tocopherol model compound, 6-hydroxy-2,2,5,7,8-pentamethylchroman (lb), was investigated by high-performance liquid chromatography (HPLC). Chromatogram of the reaction mixture showed three peaks with retention times of 2.5, 1.8 and 1.5 min, and each peak height was dependent on the concentration of O2. Chemical species having the retention time of 1.5 min was ascribed to chromanoxyl radical (3), and the other chemical species having the retention times of 2.5 and 1.8 min were identified with the model compound (lb) and 2-hydroxy-2-methyl-4-(3, 5, 6-tri-methylbenzoquinone-2-yl) butane (2), respectively. This is a first evidence that the free radicals from tocopherol model compounds was separated by HPLC.