The hypothesis that iron and fat in the diet may affect green tea extract (GTE) bioactivity, in particular antioxidant capacity and gene expression, was proposed and tested in mice. Thirty mice were randomly assigned to have for 37 days free access to standard or high-fat diets with or without GTE and ferrous lactate. Mice were euthanized and specific organs were removed. Total antioxidant capacity (TAC) was measured using the ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity assays. Polymerase chain reaction was performed on liver and heart mRNA extracts. The FRAP assay showed that GTE from the standard diet did not affect plasma TAC but increased TAC of heart, aorta, and duodenum. GTE from diets enriched with iron resulted to lower TAC of liver and heart than diets with GTE alone. GTE from the fatty diet did not have any effect on TAC compared with fatty control diet, but increased TAC in heart and aorta compared with standard control diet. An effect on expression of the mapk-1 and NF-kB genes in heart was observed in the presence of GTE. These results suggest that GTE may exhibit bioactivity in some organs affected by dietary fat and iron. The findings of this study contribute to the elucidation of the role of dietary components on tea bioactivity.
Keywords: fat; genes; green tea; iron; mice; total antioxidant capacity.