• 대한의생명과학회지
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• 제20권2호
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• pp.56-61
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• 2014

This study attempted to confirm the antioxidative potential of luteolin against tert-butyl hydroperoxide (t-BHP) induced oxidative damage and to investigate its molecular mechanism related to glutathione (GSH)-dependent enzymes in HepG2 cells. Treatment with luteolin resulted in attenuation of t-BHP induced generation of reactive oxygen species (ROS) and oxidative stress-mediated cell death. In addition, accelerated expression of GSH-dependent antioxidative enzymes, glutathione peroxidase (GPx) and glutathione reductase (GR), and heme oxygenase (HO)-1, as well as strengthened GSH content was induced by treatment with luteolin, which was in accordance with increased nuclear translocation of nuclear factor-erythroid 2 p45-related factor 2 (Nrf2), a transcription factor for phase 2 enzymes, in a dose-dependent manner. These results suggest that the cytoprotective potential of luteolin against oxidative damage can be attributed to fortified GSH-mediated antioxidative pathway and HO-1 expression through regulation of Nrf2 in HepG2 cells.

• Nutritional Sciences
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• 제7권3호
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• pp.133-137
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• 2004

The present study was designed to investigate the effects of genistein, daidzein, and quercetin on the antioxidative systems of normal rats. Male Sprague-Dawley rats were divided randomly into seven groups and treated with flavonoids at either 2 or 20 mg/day or through vehicle for four weeks. Lipid peroxidation in the liver was inhibited significantly following administration of quercetin. Genistein and daidzein did not have significant effects except in rats treated with 20mg daidzein/day. Genistein and daidzein treatment did not affect the content of $\alpha$-tocopherol in the serum and liver, while quercetin caused a slight increase. In hepatic glutathione and its related enzymes, genistein and daidzein treatment tended to cause a decrease in $\alpha$-tocopherol content, although no significant difference was found. However, quercetin treatment significantly decreased the content of glutathione together with the activity of glutathione reductase in all doses in the liver but there was no significant difference in the brain. Interestingly, daidzein treatment in the brain at 2mg/day significantly increased glutathione (27.1% p＜0.05) compared with the control group, while at 20mg/day glutathione decreased significantly (26.6%, p＜0.05). In conclusion, genistein has not antioxidant effects. Daidzein quercetin may have the capacity to produce not only antioxidants but also have adverse effects including the production of pro-oxidants. Therefore, people should consider consumption at a high dosage.

• BMB Reports
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• 제31권6호
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• pp.554-559
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• 1998

Activities of glutathione- and thioredoxin-related enzymes and phenylpropanoid-synthesizing enzymes were measured and compared in the developing leaves of Arabidopsis thaliana. Phenylalanine ammonia-lyase activity is maximal in the leaves of 2-wk-grown Arabidopsis. Tyrosine ammonia-lyase activity is maximal in the leaves of 3-wk-grown and 4-wk-grown Arabidopsis. Activity of thioitransferase, an enzyme involved in the reduction of various disulfide compounds, is higher in younger leaves than in older ones. A similar pattern was obtained in the activity of thioredoxin, a small protein known as a cofactor of ribonucleotide reductase and a regulator of photosynthesis. Activity of glutathione reductase is also higher in the younger leaves. Malate debydrogenase activity remains relatively constant during the development of Arabidopsis leaves. The results offer preliminary information for further approach to elucidate the mechanism of growth-dependent variations of these enzymes.

• Nutrition Research and Practice
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• 제11권3호
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• pp.206-213
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• 2017

BACKGROUN/OBJECTIVES: Although studies have revealed that black garlic is a potent antioxidant, its antioxidant mechanism remains unclear. The objective of this study was to determine black garlic's antioxidant activities and possible antioxidant mechanisms related to nuclear factor erythroid 2-like factor 2 (Nrf2)-Keap1 complex. METHODS/MATERIALS: After four weeks of feeding rats with a normal fat diet (NF), a high-fat diet (HF), a high-fat diet with 0.5% black garlic extract (HF+BGE 0.5), a high-fat diet with 1.0% black garlic extract (HF+BGE 1.0), or a high-fat diet with 1.5% black garlic extract (HF+BGE 1.5), plasma concentrations of glucose, insulin,homeostatic model assessment of insulin resistance (HOMA-IR) were determined. As oxidative stress indices, plasma concentrations of thiobarbituric acid reactive substances (TBARS) and 8-isoprostaglandin $F2{\alpha}$ (8-iso-PGF) were determined. To measure antioxidant capacities, plasma total antioxidant capacity (TAC) and activities of antioxidant enzymes in plasma and liver were determined. The mRNA expression levels of antioxidant related proteins such as Nrf2, NAD(P)H: quinone-oxidoreductase-1 (NQO1), heme oxygenase-1 (HO-1), glutathione reductase (GR), and glutathione S-transferase alpha 2 (GSTA2) were examined. RESULTS: Plasma glucose level, plasma insulin level, and HOMA-IR in black garlic supplemented groups were significantly (P < 0.05) lower than those in the HF group without dose-dependent effect. Plasma TBARS concentration and TAC in the HF+BGE 1.5 group were significantly decreased compared to those of the HF group. The activities of catalase and glutathione peroxidase were significantly (P < 0.05) increased in the HF+BGE 1.0 and HF+BGE 1.5 groups compared to those of the HF group. The mRNA expression levels of hepatic Nrf2, NQO1, HO-1, and GSTA2 were significantly (P < 0.05) increased in the HF with BGE groups compared to those in the HF group. CONCLUSIONS: The improvements of blood glucose homeostasis and antioxidant systems in rats fed with black garlic extract were related to mRNA expression levels of Nrf2 related genes.

• 생약학회지
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• 제36권2호통권141호
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• pp.81-87
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• 2005

The effects of the DWP-04 [DDB:selenium yeast:glutathione (31.1 : 6.8 : 62.1 (w/w%)] on acetaminophen detoxification enzyme system were studied in rats. Treatment with DWP-04 was prevented againt acetaminophen-induiced hepatotoxicity in rat as evidenced by the decreased formation of lipid peroxide. Effect of DWP-04 on the activities of free radical-generating enzymes, free radical scavenging enzymes and glutathione-related enzymes as well as detoxification mechanism of DWP-04 against acetaminophen-treated was investigated in rat. Activities of cytochrome p450, cytochrome b5, aminopyrine demethylase and aniline hydroxylase as free radical-generating enzymes activities were decreased by the treatment with DWP-04 against acetaminophen treated. Although acetaminophen-induced hepatotoxicity results in the significantly decrease in the level of hepatic glutathione and activities of glutathine S-transferase, quinone reductase, glutathione reductase and ${\gamma}-glutamyl-$cysteine synthetase, these decreasing effects were markedly lowered in the DWP-04-treated rat. Therefore, it was concluded that the mechanism for the observed preventive effect of DWP-04 against the acetaminophen-induced hepatotoxicity was associated with the decreased activities in the free radical-generating enzyme system.

• Tuberculosis and Respiratory Diseases
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• 제41권3호
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• pp.222-230
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• 1994

연구배경 : Paraquat는 광범위 제초제로서 널리 사용하고 있으나, 중독시 치명적인 중독 증상을 일으킨다. 특히 폐에서는 진행성 불가역성 폐섬유종을 일으키는데, 이의 기전으로 산소유리기와 관계가 있으나 아직은 생화학적 기전이 명확하지 않다. paraquat에 의한 산소유리기가 생기면 glutathione의 변화와 G6PDH, SOD, catalase 및 glutathione peroxidase등의 효소 활성의 변화가 생길 것으로 생각되며, 특히 catalase가 많이 관여할 것으로 생각되어진다. 방법 : Catalase 억제제인 aminotriazole을 사용하여 paraquat만 쓰는 것과 paraquat와 aminotriazole을 같이 투여할때 생쥐의 생존율을 알아보고, 실험군을 정상대조군, Group A(aminotriazole투여군), Group B(paraquat 투여군), Group C(paraquat와 amino-triazole 병합투여군) 4군으로 나누어 폐조직에서 glutathione량, G6PDH, SOD, catalase 및 glutathione peroxidase활성도를 측정하여 비교했다. 결과 : Paraquat와 aminotriazole 병합 투여군의 생존율이 paraquat투여군보다 현저히 감소하였고, paraquat 투여로 인하여 폐 glutathione량은 정상대조군에 비해 20%정도 감소 되었으나, aminotriazole의 투여로 인한 폐 glutathione량의 변화는 없었다. Paraquat투여로 폐 SOD, catalase 및 glutathione peroxidase활성이 모두 유의한 감소를 나타냈는데, 특히 catalase가 가장 큰 효소활성 감소를 나타냈으며, paraquat와 aminotriazole병합투여군에서는 catalase와 glutathione peroxidase활성이 paraquat단독투여군에 비하여 유의한 효소활성감소를 나타냈고, SOD는 효소활성의 변화가 감지되지 않았다. 결론 : Paraquat투여시 catalase활성이 유의하게 감소되는 점으로 보아 paraquat독성이 catalase활성과 밀접하게 연관되는 것으로 사료되며, 또한 paraquat의 독성이 aminotriazole의 병합 투여로 더욱 증가되어 나타나는데, 이러한 결과는 aminotriazole투여로 catalase활성의 감소가 크게 나타나나 glutathione량의 변화는 없는 점으로 보아 aminotriazole투여에 의한 paraquat독성의 증가는 총 폐 glutathione량의 변화에 의한 영향보다는 catalase활성감소에 의한 결과로 생각된다. Paraquat와 aminotriazole를 병합 투여하여 catalase활성이 억제되면 증가된 과산화수소로 hydroxyl radicals이 생성되고, 이에 의한 폐 세포손상이 유발되어 나타나는 것으로 사료된다.

• Toxicological Research
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• 제29권3호
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• pp.165-172
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• 2013

Acetaminophen (APAP) known as paracetamol is the main ingredient in Tylenol, which has analgesic and anti-pyretic properties. Inappropriate use of APAP causes major morbidity and mortality secondary to hepatic failure. Overdose of APAP depletes the hepatic glutathione (GSH) rapidly, and the metabolic intermediate leads to hepatocellular death. This article reviews the mechanisms of hepatotoxicity and provides an overview of current research studies. Pharmacokinetics including metabolism (activation and detoxification), subsequent transport (efflux)-facilitating excretion, and some other aspects related to toxicity are discussed. Nuclear factor erythroid 2-related factor 2 (Nrf2)-regulated gene battery plays a critical role in the multiple steps associated with the mitigation of APAP toxicity. The role of Nrf2 as a protective target is described, and potential natural products inhibiting APAP toxicity are outlined. This review provides an update on the mechanism of APAP toxicity and highlights the beneficial role of Nrf2 and specific natural products in hepatoprotection.

• Toxicological Research
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• 제11권2호
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• pp.267-271
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• 1995

A single large dose of ethanol as well as chronic ethanol consumption produces alcoholic fatty liver in human and experimental animals. We examined the effects of YH439, a potential hepatoprotective agent, on alcoholic fatty liver generation in adult female rats. In rats treated with YH439 (250 mg/kg, po) 4 hr prior to a single dose of ethanol (6 g/kg, po), a significant decrease in hepatic triglyceride accumulation was observed. YH439 also has an inhibitory effect on hepatic triglyceride and cholesterol accumulation induced by repeated ethanol treatments for one week. Because it has been known that induction of alcoholic fatty liver is associated with lipid peroxidation and/or hepatic glutathione depression, the effect of YH439 on these parameters was determined in the livers of rats treated with ethanol. Coadministration with YH439 inhibited MDA formation and gIutathione depression induced by acute or repeated ethanol administration. In order to determine the effect of YH439 on ethanol metabolism in vivo, disappearance of ethanol from blood was measured. In rats treated with a single dose of ethanol (6 g/kg, po), the ethanol concentration in blood reached a peak approximately 120 min following the treatment which declined linearly for 18 hrs. YH439 had no effect on the decline of blood ethanol concentration regardless of the dose of ethanol given to rats. These results in this study suggest that YH439 has an inhibitory effect on fatty liver generation induced by acute or repeated ethanol consumption through a mechanism not directly related to the rate of ethanol metabolism in vivo.

• Advances in Traditional Medicine
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• 제9권3호
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• pp.225-231
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• 2009

The present study deals with the amelioration by Lagerstroemia speciosa Linn. leaf extract against hepatotoxicity induced by carbon tetrachloride ($CCl_4$), which was evaluated in terms of serum marker enzymes like serum glutamate pyruvate transaminase, serum glutamate oxaloacetate transaminase, alkaline phosphatase, serum total bilirubin, total protein levels along with concomitant hepatic and antioxidants like superoxide dismutase, catalase, glutathione, glutathione peroxidase and lipid peroxidation enzymes were monitored. These biochemical parameters altered by the single dose level of $CCl_4$ (0.75 ml/kg body weight, i.p). Pre treatment with L. speciosa prior to the administration of $CCl_4$, at the doses of 50 and 250 mg/kg. body weight/day, p.o. for 7 days, significantly restored all the serum and liver tissue parameters near to the normal levels, respectively. Silymarin was used as a reference standard, prior to the administration of $CCl_4$ to rats. These findings indicate the protective potential of L. speciosa against hepato toxicity which possibly involve mechanism related to its ability of selective inhibitors of (reactive oxygen species like antioxidants brought about significant inhibition of TBARS suggesting possible involvement of $O_2{\cdot}-$, $HO_2{\cdot}$, and ${\cdot}OH$. In conclusion, the amelioration may be attributed to the synergistic effects of its constituents rather than to any single factor as the leaves are rich in tannins, sterols, flavonoids, saponins etc.

• The Korean Journal of Physiology and Pharmacology
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• 제27권1호
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• pp.9-20
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• 2023

The mechanism is unclear for the reported protective effect of hyperbaric oxygen preconditioning against oxidative stress in tissues, and the distinct effects of hyperbaric oxygen applied after stress. The trained mice were divided into three groups: the control, hyperbaric oxygenation preconditioning, and hyperbaric oxygenation applied after mild (fasting) or hard (prolonged exercise) stress. After preconditioning, we observed a decrease in basal levels of nitric oxide, tetrahydrobiopterin, and catalase despite the drastic increase in inducible and endothelial nitric oxide synthases. Moreover, the basal levels of glutathione, related enzymes, and nitrosative stress only increased in the preconditioning group. The control and preconditioning groups showed a similar mild stress response of the endothelial and neuronal nitric oxide synthases. At the same time, the activity of all nitric oxide synthase, glutathione (GSH) in muscle, declined in the experimental groups but increased in control during hard stress. The results suggested that hyperbaric oxygen preconditioning provoked uncoupling of nitric oxide synthases and the elevated levels of GSH in muscle during this study, while hyperbaric oxygen applied after stress showed a lower level of GSH but higher recovery post-exercise levels in the majority of antioxidant enzymes. We discuss the possible mechanisms of the redox response and the role of the nitric oxide in this process.