• Nutrition Research and Practice
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• v.9 no.6
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• pp.592-598
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• 2015

BACKGROUND/OBJECTIVES: Increased mass of adipose tissue in obese persons is caused by excessive adipogenesis, which is elaborately controlled by an array of transcription factors. Inhibition of adipogenesis by diverse plant-derived substances has been explored. The aim of the current study was to examine the effects of the aqueous methanol extract of laver (Porphyra yezoensis) on adipogenesis and apoptosis in 3T3-L1 adipocytes and to investigate the mechanism underlying the effect of the laver extract. MATERIALS/METHODS: 3T3-L1 cells were treated with various concentrations of laver extract in differentiation medium. Lipid accumulation, expression of adipogenic proteins, including CCAAT enhancer-binding protein ${\alpha}$, peroxisome proliferator-activated receptor ${\gamma}$, fatty acid binding protein 4, and fatty acid synthase, cell viability, apoptosis, and the total content and the ratio of reduced to oxidized forms of glutathione (GSH/GSSG) were analyzed. RESULTS: Treatment with laver extract resulted in a significant decrease in lipid accumulation in 3T3-L1 adipocytes, which showed correlation with a reduction in expression of adipogenic proteins. Treatment with laver extract also resulted in a decrease in the viability of preadipocytes and an increase in the apoptosis of mature adipocytes. Treatment with laver extract led to exacerbated depletion of cellular glutathione and abolished the transient increase in GSH/GSSG ratio during adipogenesis in 3T3-L1 adipocytes. CONCLUSION: Results of our study demonstrated that treatment with the laver extract caused inhibition of adipogenesis, a decrease in proliferation of preadipocytes, and an increase in the apoptosis of mature adipocytes. It appears that these effects were caused by increasing oxidative stress, as demonstrated by the depletion and oxidation of the cellular glutathione pool in the extract-treated adipocytes. Our results suggest that a prooxidant role of laver extract is associated with its antiadipogenic and proapoptotic effects.

• Nutrition Research and Practice
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• v.10 no.1
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• pp.26-32
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• 2016

BACKGROUND/OBJECTIVES: It has been shown that vitamin A supplementation has different effects on skeletal health and the antioxidant system. Deficiency or excess of this vitamin can lead to health problems. Vitamin A can work as either an antioxidant or prooxidant depending on its concentration. The present study was conducted to investigate the effects of different doses of vitamin A supplementation on the antioxidant system in rats. MATERIALS/METHODS: Forty Spargue-Dawley male rats were divided into four groups according to the dose of vitamin A received: 0 (A0), 4,000 (A1), 8,000 (A2), and 20,000 (A3) IU retinyl palmitate/kg diet. After a feeding period of 4 wks, lipid peroxide levels, glutathione concentration, antioxidant enzyme activities, and vitamins A and E concentrations were measured. Histopathological changes were observed in rat liver tissue using an optical microscope and transmission electron microscope. RESULTS: Lipid peroxide levels in plasma were significantly decreased in the A1 and A2 groups compared to the A0 rats. Erythrocyte catalase and hepatic superoxide dismutase activities of the A2 group were significantly higher than those of the A0 group. Hepatic glutathione peroxidase activity was significantly lower in the A3 group compared to the other groups. Total glutathione concentrations were significantly higher in the A1 and A2 groups than in the A0 group. Histological examination of liver tissue showed that excessive supplementation of vitamin A might lead to lipid droplet accumulation and nuclear membrane deformation. CONCLUSIONS: These results indicate that appropriate supplementation of vitamin A might have a beneficial effect on the antioxidant system in rats.

• Korean journal of food and cookery science
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• v.12 no.3
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• pp.372-376
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• 1996

Antioxidative activities of the extracts from Schizandra Chinesis Baillon (Omija) with various solvent were compared with some commercial antioxidants. AS (antioxidative index; induction period of oil containing extract/induction period of control oil) of Omija extracts from five kinds of solvents (MeOH, EtOH, BtOH, EA, PE) and other antioxidants were shown as following orders: 0.02% BHT > 0.05% EA > 0.01% MeOH > 0.05% EtOH > 0.1% EA > 0.05% PE > 0.05％ BuOH >> 0.02% alpha-tocopherol. Antioxidative effects of 0.05% EA and 0.05% MeOH extracts during autoxidation (60${\pm}$ 2$^{\circ}C$) were higher than those (If the other extracts but were not greater than that of 0.02% BHT. However, Al of EA and MeOH, EtOH extracts during thermal oxidation (180${\pm}$2$^{\circ}C$) were greater than that of BHT. The antioxidant effect of alpha-tocopherol showed no apparent difference or a prooxidant effect as compared with result of control.

• Korean Journal of Food Science and Technology
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• v.3 no.3
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• pp.178-184
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• 1971

Samples of refined soybean oil were irradiated with lights from a 20-watt incandescent tungsten lamp, a 20-watt fluorescent daylight type lamp, a 20-watt low-pressure mercury vapor germicidal lamp, and direct sunlight for an experimental period of 147 days. Some samples were stored in a dark room throughout the period as a control. The peroxide values of all samples were measured every week. The induction period of the samples was arbitrarily taken as the time required for the samples to reach a peroxide value of 15. The induction period of the control was estimated at 198 days. Those of the samples irradiated with the incandescent light, the fluorescent light, the ultraviolet light, and the sunlight were estimated at 196, 119, 52 and 6 days, respectively. The sunlight showed by far the strongest prooxidant activity whereas the incandescent light showed the weakest but distinct prooxidant activity. The small temperature differences observed among the various samples throughout the experimental period did not seem to affect the oxidation rates of the irradiated samples in any significant way.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.4
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• pp.336-341
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• 1983

A study on the oxidation effect of some amino acids(glutamic acid, phenylalanine, alanine) addition to the linoleic acid emulsion was conducted. Amino acid solutions in concentrations of $10^{-2}$, $10^{-3}$ and $10^{-4}M$ were mixed with equal volume of linoleic acid emulsions. The prepared samples were incubated at $60{\pm}1^{\circ}C$ and the extent of diene conjugation and TBA values were measured by using the UV visible spectrophotometer. The results were as follows: 1) From the extent of diene conjugation, we found that the addition of phenylalanine and alanine prolonged the induction period and the addition of glutamic acid shortened. There was an optimum concentration for each amino acid to act as an antioxidant during the induction period. The optimum concentration of alanine was $10^{-3}M$ and that of phenylalanine was $10^{-2}M$. 2) The results of TBA values showed that three amino acids possesed antioxidant activity after the induction period. There was also an optimum concentration to act as antioxidant after the induction period. The optimum concentrations of glutamic acid, phenylalanine, and alanine were $10^{-2}$, $10^{-3}$, and $10^{-3}M$, respectively.

• Journal of Animal Science and Technology
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• v.44 no.4
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• pp.427-442
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• 2002

Conjugated linoleic acid(CLA) is a collective term for a group of positional (c8, c10; c9, c11; c10, c12, and c11, c13) and geometric(cis,cis; cis,trans; trans,cis; and trans,trans) isomers of octadecadienoic acid (linoleic acid) with conjugated double bond system. CLA has been shown to have a variety of biological effects. Major effects of CLA on health, such as anti-cancer, anti-oxidation, anti-atherosclerosis and improving immuno-responses, might be derived or partially derived from the alternated lipid metabolism after CLA feeding. Most of studies on the effect of CLA on fat metabolism are concentrated on rats, mice, pigs and other mammals. The CLA inhibited carcinogen-induced neoplasia in several animal models and inhibited the proliferation of human malignant melanoma, colorectal and breast cancer cells and CLA reduced the atherosclerosis. Several studies have determined the antioxidant property of CLA; however, the property still remains controversial. Some of the studies have shown that CLA acted as an antioxidant, whereas some other studies have demonstrated that CLA might be a prooxidant. Several studies suggested that CLA could reduce fat accumulation in mammals. CLA was suggested to promote muscle growth and reduce fat deposition in mouse, and improve feed efficiency in rats. CLA has been shown to inhibit the activity of stearoyl-CoA reductase. CLA also reduced the content of arachidonic acid. Since arachidonic acid, and eicosapentaenoic acid (EPA) and docosahexenoic acid (DHA) are synthesized by different pathways, reducing the synthesis of arachidonic acid may not mean reducing that of EPA and DHA. Many sutdies have been shown biological effects of CLA. Therefore, further research is needed to answer the following questions: 1) how to synthesize the new CLA by new methods, 2) why CLA has shown biological effects, 3) how to increase CLA effects in animal products.