2.3. Biochemical analysis
Vitamin E was extracted from the plasma and liver and analyzed following the instructions of a commercially available vitamin E assay kit (Institute of Biological Engineering of Nanjing Jiancheng, Nanjing, China). Briefly, in the presence of phenanthroline, Fe3+is reduced to Fe2+by vitamin E. Phenanthroline then forms a complex with Fe2+ forming a colored adduct. Vitamin E content can be calculated using the following equation: