Excessive fat liver is an important manifestation of nonalcoholic fatty liver disease (NAFLD), associated with obesity, insulin resistance, and oxidative stress. In the present study, the effects of a high-fat, high-fructose diet (HFFD) on mRNA levels and activities of the antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), were determined in mouse livers and brains. The histomorphology of the livers was examined and the state of nonenzymatic reducing system was evaluated by measuring the glutathione system and the lipid peroxidation. Histopathology of the liver showed that fat accumulation and inflammation depended on the period of the HFFD-consumption. The levels of mRNA and enzymatic activities of SOD, CAT, and GPx were raised, followed by the increases in malondialdehyde levels in livers and brains of the HFFD mice. The oxidized GSSG content was increased while the total GSH and the reduced GSH were decreased, resulting in the increase in the GSH/GSSG ratio in both livers and brains of the HFFD mice. These observations suggested that liver damage and oxidative stress in the significant organs were generated by continuous HFFD-consumption. Imbalance of antioxidant condition induced by long-term HFFD-consumption might increase the risk and progression of NAFLD.

Oxidative stress is involved in the progression of several diseases such as diabetes, hypertension, and age-related diseases. Miroestrol (MR) is a potent phytoestrogen from the tuberous root of Pueraria mirifica, a plant used in traditional Thai medicine that is claimed to have rejuvenating effects. In this study, the effects of MR on the antioxidation system, including anti-lipid peroxidation; on the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase; and on glutathione content in the livers and uteri of β-naphthoflavone (BNF)-treated mice were determined. BNF-treated mice are a model of procarcinogen-exposed mice. The results showed that MR improved the antioxidant activities of SOD and CAT in the livers and uteri of both normal and BNF-treated mice, while estradiol (E2) increased SOD activity in the uteri of normal mice and CAT activity in the livers of both normal and BNF-treated mice. In the liver, MR increased the levels of several forms of glutathione, whereas in the uteri E2 and MR reduced the level of lipid peroxidation by decreasing the level of malondialdehyde. Therefore, the use of MR as an alternative hormone replacement therapy might be beneficial due to its ability to improve antioxidation systems.

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