• BMB Reports
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• 제33권4호
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• pp.321-325
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• 2000

Quinone reductase was purified to homogeneity from bovine liver by using ammonium sulfate fractionation, ionexchange chromatography, and gel filtration chromatography. The enzyme utilized either NADH or NADPH as the electron donor. The enzyme catalyzed the reduction of several quinones and other artificial electron acceptors. Furthermore, the enzyme catalyzed NAD(P)H-dependent reduction of azobenzene. The apparent Km for 1,4-benzoquinone and azobenzene was 1.64 mM and 0.524 mM, respectively. The reduction of azobenzene by quinone reductase was almost entirely inhibited by dicumarol or Cibacron blue 3GA, potent inhibitors of the mammalian quinone reductase. In the presence of 1.0${\mu}M$ Cibacron blue 3GA, azoreductase activity was lowered by 45%, and almost complete inhibition was seen above 2.0 ${\mu}M$ Cibacron blue 3GA.

• Archives of Pharmacal Research
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• 제13권2호
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• pp.132-135
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• 1990

Polyhydroxystilbenes including resveratrol were reported to competitively inhibit monoamine oxidase-A-without structural relation with substrates and cynthetic inhibitors for the enzyme. We attempt to explore a plausible mechanism for their inhibitory activity on MAO-A. All the polyhydroxystilbenes tested showed the antioxidant activity on liver homogenate. Furthermore, the antioxidant activity turned out to closely correlate with the MAO-A inhibitory activity.

• Toxicological Research
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• 제28권3호
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• pp.165-172
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• 2012

Raphanus sativus (Cruciferaceae), commonly known as radish is widely available throughout the world. From antiquity it has been used in folk medicine as a natural drug against many toxicants. The present study was designed to evaluate the hepatoprotective activity of radish (Raphanus sativus) enzyme extract (REE) in vitro and in vivo test. The $IC_{50}$ values of REE in human liver derived HepG2 cells was over 5,000 ${\mu}g/ml$ in tested maximum concentration. The effect of REE to protect tacrine-induced cytotoxicity in HepG2 cells was evaluated by MTT assay. REE showed their hepatoprotective activities on tacrine-induced cytotoxicity and the $EC_{50}$ value was 1,250 ${\mu}g/ml$. Silymarin, an antihepatotoxic agent used as a positive control exhibited 59.7% hepatoprotective activity at 100 ${\mu}g/ml$. Moreover, we tested the effect of REE on carbon tetrachloride ($CCl_4$)-induced liver toxicity in rats. REE at dose of 50 and 100 mg/kg and silymarin at dose of 50 mg/kg were orally administered to $CCl_4$-treated rats. The results showed that REE and silymarin significantly reduced the elevated levels of serum enzyme markers induced by $CCl_4$. The biochemical data were supported by evaluation with liver histopathology. These findings suggest that REE, can significantly diminish hepatic damage by toxic agent such as tacrine or $CCl_4$.

• 대한한방내과학회지
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• 제24권1호
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• pp.84-93
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• 2003

Objectives : The aim of this study was to investigate effects of the Sungjuchunggan-tang(Xingjiuqinggan-tang), which has been used for alcoholic diseases in Oriental medicine, on alcoholic metabolism and alcoholic liver damage. Methods : We evaluated the activities of alcohol dehydrogenase(ADH)and aldehyde dehydrogenase(ALDH), and measured the levels of AST, ALT, glucose, triglyceride, HDL-cholesterol, LDL-cholesterol and phospholipid in serum of guinea pigs. Results and Conclusions : In this experiment, Sungjuchunggan-tang, Pharbitidis Semen and Puerariae Radix significantly suppressed the activity of ADH which is a precursor enzyme of acetaldehyde. Sungjuchunggan-tang and Pharbitidis Semen significantly suppressed the activity of ALDH, which is a catabolic enzyme, and increased its level. Due to alcohol consumption, level of ALT and AST were significantly reduced. These experimental results suggest that Sungjuchunggan-tang and Pharbitidis Semen inhibit the formation of acetaldehyde in the metabolism of alcohol, and affect the recovery of weakened liver functions caused by alcohol.

• 생약학회지
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• 제15권2호
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• pp.91-97
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• 1984

The investigation was aimed to study the effect of ginseng ethanol extract on the hepatic ethanol-metabolizing enzyme activity in vivo. The extract (100mg/kg/day) was administered orally to Sprague-Dawley rats for $7{\sim}10$ days and their microsomal ethanol oxidizing system(MEOS) and catalase activities were measured. The MEOS activity in the rat treated with the extract was not significantly different from that of the normal group. Microsomal fraction containing MEOS was separated and the MEOS activity was measured after preincubation for 5, 60 and 180 min, respectively. There were no significant differences in MEOS activities between the normal and treated groups preincubated for 5, 60 and 180 min. The activity in the rat treated with single i.p. injection of 95% $CCl_4$ (0.5ml/kg) was decreased by 48%, compared to the normal group and in the rat treated with the extract (100mg/kg) for $7{\sim}10$ days, the decrease of the MEOS activity was potentiated. Catalase activity in the rat treated with the extract (100mg/kg) was similar to that obtained from the normal group.

• BMB Reports
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• 제30권3호
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• pp.222-228
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• 1997

Protein phosphatase 2C (PP2C) is one of the four major serine/threonine phosphatases which is dependent on $Mg^{2+}$ for its activity. PP2C was purified from rat liver cytosol and its characteristics were investigated. The substrate employed for routine assay was $[^{32}P]casein$ phosphorylated by PKA. The purification process involved DEAE chromatography, ammonium sulfate fractionation, phenyl sepharose chromatography, sephacryl 5-200 gel filtration, and histone agarose chromatography. The SDS-PAGE of PP2C showed one major single protein band at a position corresponding to a molecular mass of 43 kd and the purification fold was 637. The enzyme showed a pH optimum of 8 and $K_M$ value was $1.9\;{\mu}M$. However, when the substrate was changed to $[^{32}P]histone$, the pH optimum was shifted to 7 and $K_M$ value was $2.3\;{\mu}M.\;Mg^{2+}$ was essential to the enzyme activity and okadaic acid did not exert any inhibitory effect on the enzyme. To examine residue in the active site of PP2C effects of some protein-modifying reagents were tested.

• 대한한의학회지
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• 제17권1호
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• pp.21-36
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• 1996

This study was undertaken to examine the effect of Jwagyuyeum and Woogyuycum, being known to reinforce Kidney-yin and yang, on the activities of endogenous antioxidant enzymes and the production of oxygen free radicals in the liver and kidney tissues, Alterations in enzyme activities were observed after in vivo treatment in rats, Jwagyuyeum and Woogyuyeum caused a significant increase in the activities of superoxide dismutase(SOD) and catajase Jwagyuyeum significantly increased the activity of glutathione peroxidase in both liver and kidney, but the enzyme activity was not significantly altered by Woogyuyeum. Treatment in vitro of Jwagyuyeum and Woogyuyeum decreased the production of oxygen free radicals in a dose-dependent fashion. These results suggest that Jwagyuyeum and Woogyuyeum stimulate the activities of antioxidant enzymes and inhibit directly the production of oxygen free radicals. These effects of both herbs may contribute to prevent the oxygen free radical-induced impairment of cell function.

• 한국식품영양과학회지
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• 제27권1호
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• pp.149-156
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• 1998

The purpose of this study was to investigate the effects of vitamin E supplementation on the activities of antioxidative enzymes in liver of KK mice of various ages and various duration of diabetes. Diabetes was induced by feeding high fat diet containing 20% corn oil(wt/wt). Weaned KK mice were fed high fat diet containing 51 IU or 2080 IU vitamin E per kg diet. Animals were sacrificed at 4, 6, and 9 months of age. In nondiabetic group, we found the decrease of antionxidative enzyme activities with aging. In diabetic group, antioxidative enzyme activities were decreased, and the change of hepatic vitamin E was related to glutathione peroxidase activity (r=0.71, p<0.001). Treatment with vitamin E did not modify the level of fasting blood glucose. However, it was observered that glutathione reductase and glutathione peroxidase activities as well as hepatic glutathione levels were increased by vitamie E supplementation, whereas catalase activity did not changed. The present result suggest that high vitamin E supplementation protects against lipid peroxidative damage in diabetic KK mice.

• 약학회지
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• 제25권4호
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• pp.145-151
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• 1981

The effect of ginseng methanol extract on hepatic drug metabolizing enzyme in rat was investigated. The ginseng methanol extract (100mg/kg) was administered orally to Sprague Dawley rats for 7days and the contents of cytochrome $P_{450}$ and NADPH cytochrome c reductase in liver were measured by the method of Stanton et al. and Mazel respectively. The content of liver cytochrome $P_{450}$ and NADPH cytochrome c reductase in the rats treated with ginseng methanol extract (100mg/kg) were increased by 21.9% and l6.6% respectively and their increases were statistically significant. Single i.p. injection of phenobarbital (100mg/kg) to the rats produced approximately 25% increase in cytochrome $P_{450}$ content in this investigation and further stimulation was produced in the rats pretreated with ginseng methanol extract (100mg/kg). On the other hand, single i.p. injection of 95% $CCl_{4}$ (0.5ml/kg) showed 29% decrease in cytochrome $P_{450}$ content and 10.5% decrease in NADPH cytochrome c reductase activity. The degree of inhibition of cytochrome $P_{450}$ content in the rats pretreated with ginseng methanol extract (100mg/kg) was similar to that observed in the $CCl_{4}$ alone treated group, but NADPH cytochrome c reductase activity was increased by 65% in the rats pretreated with ginseng methanol extract (100mg/kg). These results suggest that ginseng is the hepatic drug metabolizing enzyme inducing agent in the rat and the effect is similar to phenobarbital.

• Biomolecules & Therapeutics
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• 제31권3호
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• pp.330-339
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• 2023

Liver kinase B1 (LKB1) is a crucial tumor suppressor involved in various cellular processes, including embryonic development, tumor initiation and progression, cell adhesion, apoptosis, and metabolism. However, the precise mechanisms underlying its functions remain elusive. In this study, we demonstrate that LKB1 interacts directly with malic enzyme 3 (ME3) through the N-terminus of the enzyme and identified the binding regions necessary for this interaction. The binding activity was confirmed to promote the expression of ME3 in an LKB1-dependent manner and was also shown to induce apoptosis activity. Furthermore, LKB1 and ME3 overexpression upregulated the expression of tumour suppressor proteins (p53 and p21) and downregulated the expression of antiapoptotic proteins (nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and B-cell lymphoma 2 (Bcl-2)). Additionally, LKB1 and ME3 enhanced the transcription of p21 and p53 and inhibited the transcription of NF-κB. Moreover, LKB1 and ME3 suppressed the phosphorylation of various components of the phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B signaling pathway. Overall, these results suggest that LKB1 promotes pro-apoptotic activities by inducing ME3 expression.