Tocopherols, lipid-soluble antioxidants play a crucial role in the antioxidant defense system in higher plants. The antioxidant function of α-tocopherol has been widely studied; however, experimental data on the formation of its oxidation products is missing. In this study, we attempt to provide spectroscopic evidence on the detection of oxidation products of α-tocopherol formed by its interaction with singlet oxygen and lipid peroxyl radical. Singlet oxygen was formed using photosensitizer rose bengal and thylakoid membranes isolated from Arabidopsis thaliana. Singlet oxygen reacts with polyunsaturated fatty acid forming lipid hydroperoxide which is oxidized by ferric iron to lipid peroxyl radical. The addition of singlet oxygen to double bond carbon on the chromanol head of α-tocopherol forms α-tocopherol hydroperoxide detected using fluorescent probe swallow-tailed perylene derivative. The decomposition of α-tocopherol hydroperoxide forms α-tocopherol quinone. The hydrogen abstraction from α-tocopherol by lipid peroxyl radical forms α-tocopheroxyl radical detected by electron paramagnetic resonance. Quantification of lipid and protein hydroperoxide from the wild type and tocopherol deficient (vte1) mutant Arabidopsis leaves using a colorimetric ferrous oxidation-xylenol orange assay reveals that α-tocopherol prevents formation of both lipid and protein hydroperoxides at high light. Identification of oxidation products of α-tocopherol might contribute to a better understanding of the protective role of α-tocopherol in the prevention of oxidative damage in higher plants at high light.

• MeSH
• alpha-Tocopherol chemistry   metabolism   MeSH
• Antioxidants chemistry   metabolism   MeSH
• Arabidopsis genetics   growth & development   metabolism   radiation effects   MeSH
• Lipid Peroxides chemistry   metabolism   MeSH
• Oxidation-Reduction MeSH
• Oxidative Stress * MeSH
• Hydrogen Peroxide chemistry   metabolism   MeSH
• Singlet Oxygen chemistry   metabolism   MeSH
• Light adverse effects   MeSH
• Vitamin E chemistry   metabolism   MeSH
• Free Radicals chemistry   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• alpha-Tocopherol MeSH
• Antioxidants MeSH
• Lipid Peroxides MeSH
• Hydrogen Peroxide MeSH
• Singlet Oxygen MeSH
• tocopheroxy radical MeSH Browser
• Vitamin E MeSH
• Free Radicals MeSH