• BMB Reports
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• v.30 no.5
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• pp.370-377
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• 1997

A novel assay method is described for rapid quantitation of reaction rate of sterol ${\Delta}^7$-reductase (${\Delta}^7$-SR) which catalyzes reduction of the ${\Delta}^7$-double bond of sterols. Of six different organ tissues-liver, small intestine, brain, lung, kidney, and testis-. ${\Delta}^7$-SR activity was detected only in liver (2.30 nmol/min/mg protein) and testis (0.11 nmol/min/mg protein). Using a newly developed method which employs diet-induced enzyme proteins and ergosterol as substrate, we assessed both kinetics ($K_m=210\;{\mu}M$, $V_{max}=1.93\;nmol/min/mg$) and inhibition of the rat hepatic ${\Delta}^7$-SR against well-studied cholesterol lowering agents such as triparanol ($IC_{50}=16\;{\mu}M$). 3-$\beta$-[2-(diethylamino)ethoxy]androst-5-en-17-one (U18666A) ($IC_{50}=5.2\;{\mu}M$), and trans-1.4-bis(2-chlorobenzylaminomethyl)cyclohexane dihydrochloride (AY-9944) ($IC_{50}=0.25\;{\mu}M$). Of the three well-known AY-9944-sensitive cholesterogenic enzymes (i.e., ${\Delta}^7$-SR, sterol ${\Delta}^8$-isomerase, and sterol ${\Delta}^14$-reductase). ${\Delta}^7$-SR was found to be the most sensitive enzyme with a noncompetitive inhibition of this compound ($K_i=0.109\;{\mu}M$). Substrate specificity studies of the microsomal ${\Delta}^7$-SR indicate that the relative reaction rate for 7-dehydrocholesterol and ergosterol are 5.6-fold and 1.6-fold higher than that for lathosterol. ${\Delta}^7$-SR activity was also modulated by feeding rats a diet supplemented with 0.5% ergosterol (>2.6-fold) in addition to 5.0% cholestyramine plus 0.1% lovastatin ($\simeq$5.0-fold). Finally, microsomal ${\Delta}^7$-SR was solubilized by 1.5% 3-[3-(cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) and enriched on PEG (0~10%) precipitation, which should be suitable for further purification of the enzyme.

• Journal of Nutrition and Health
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• v.40 no.8
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• pp.701-707
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• 2007

This study was to investigate lipid peroxidation, antioxidant enzyme activity and DNA damage after exercise, and the protective effect of garlic against exercise-induced oxidative stress. Male Sprague-Dawley rats(4 weeks old) were randomly divided into three groups of 6 rats each; control group(Con) without garlic and exercise, Ex group with exercise alone, and Ex-G group with 2% garlic and exercise. For 4 weeks, rats were given diets containing 15% corn oil and 1% cholesterol with or without garlic. The swimming was selected as a model for exercise performance. Rats swam for 40 min a day, for 5 days a week. Group Ex and Ex-G showed significant lowering in body weight gain and fat accumulation compared to control. No significant changes were observed in levels of plasma cholesterol and triglyceride among three groups, demonstrating that exercise and garlic had no effects on changes of blood lipid. This finding of blood lipid seems to be due to higher plant sterol content in corn oil. The DNA tail moment of lymphocytes showed greater tendency in Ex and Ex-G than in control, but garlic supplements failed to suppress DNA damages. Compared to control, Ex had higher plasma TBARS which was lowered to the control's level in Ex-G with 2% garlic supplementation(p<0.05). Ex-G led to a higher hepatic superoxide dismutase(SOD) activity than control and Ex(p<0.05). Activity of hepatic catalase was also increased in Ex-G, while in Ex it was significantly low(p<0.05). It seemed that TBARS levels were related to the activities of SOD and catalase, and that garlic contributed to increasing the enzyme activities and led to decrease of TBARS. These results demonstrate that lipid peroxidation and DNA damage occur as a consequences of oxidative stress after exercise, and that antioxidant defense against oxidative stress could be enhanced by garlic supplementation through the induction of antioxidant enzymes. However, further investigations should be done on the garlic effect on DNA damage.

• YAKHAK HOEJI
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• v.40 no.4
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• pp.449-455
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• 1996

Betaine is one of the major water-soluble components in Lycii Fructus. In the present study the effect of repeated betaine treatment on the hepatotoxicity and the cytochrome P-4 50-dependent enzyme system was examined in adult female rats. Administrations of betaine (100 or 1,000mg/kg/day, ip) to rats repeatedly for 4 or 9 days did not evoke hepatotoxic response as determined by increases in glutamic pyruvic transaminase(GPT) and glutamic oxaloacetic transaminase(GOT) activities measured 24 hours following the final dose of betaine. The activities of aminopyrine N-demethylase, p-nitroanisole O-demethylase and p-nitrophenol hydroxylase as well as the contents of cytochrome P-450 were determined in hepatic microsomes of rats treated with betaine(1,000mg/kg/day, ip) for 4 or 9 days. Repeated treatment of rats with betaine for a period of 4 days induced a marginal decrease in the contents of cytochrome P-450, but did not influence the activities of p-nitrophenol hydroxylase, p-nitroanisole O-demethylase, or aminopyrine N-demethylase. Extension of the betaine treatment to 9 consecutive days failed to alter the parameters for hepatic drug metabolizing activity determined in the present study. Since repeated large doses of betaine were demonstrated to be tolerated by rats without showing any toxicity or changes in drug metabolizing enzyme activities in the liver, this compound appears to be relatively safe to animals upon long-term ingestion.

• Korean Journal of Pharmacognosy
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• v.31 no.2
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• pp.228-234
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• 2000

Effects of Houttuynia cordata on the level of lipid peroxide and the enzyme activities of the liver were investigated in bromobenzene-induced rats. Lipid peroxide content in liver was increased by bromobenzene. It was decreased when the methanol extract from the aerial parts of H. cordata was treated to the rat. The methanol extract reduced the activities of aminopyrine N-demethylase and aniline hydroxylase that increased by bromobenzene, however did not affect glutathione S-transferase activity. The methanol extract recovered the activity of epoxide hydrolase activity that decreased significantly by bromobenzene. We suggest that under our experimental conditions the extract might play an important play in the prevention of hepatotoxicity by reduction of aminopyrine N-demethylase and aniline hydroxylase activities as well as enhancement of epoxide hydrolase activity. Six phenolic compounds have been isolated from H. cordata and identified by means of spectral analysis as protocatechuic acid, quercetin, apigenin, afzelin, hyperoside and quercitrin.

• Biomolecules & Therapeutics
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• v.15 no.4
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• pp.261-265
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• 2007

Hydroxyproline (HYP) is a post-translational product of proline hydroxylation catalyzed by an enzyme prolyl 4-hydroxylase (P4H) which plays a crucial role in the synthesis of all collagens. Considering the role of collagen and its significance in many clinically important diseases such as liver fibrosis, a great deal of attention has been directed toward the development of an assay at cell-based system. The reason is that cell-based assay system is more efficient than enzyme-based in vitro system and takes much less time than in vivo system. Several assay procedures developed for P4H are laborious, time-consuming and not feasible for the massive-screening. Here, we report the cell-based assay method of prolyl 4-hydroxylase in immortalized rat hepatic stellate HSC-T6 cells. To optimize the cell culture condition to assay for HYP content, various concentrations of reagents were treated for different times in HSC-T6 cells. Our data showed that the treatment with ascorbate in a hypoxic condition for 24 h resulted in the maximal increase of HYP by 1.8 fold. Alternatively, cobalt chloride ($5\;{\mu}M$) and ascorbate ($50\;{\mu}M$) in normoxic states exhibited similar effect on the production of HYP as in a hypoxic condition. Therefore, cobalt chloride can be substituted for a hypoxic condition when an anaerobic chamber is not available. Rosiglitazone and HOE077, known as inhibitors of collagen, synthesis decreased P4H enzyme activity by 32.3% and 15%, respectively, which coincided with previous reports from liver tissues. The level of the smooth muscle ${\alpha}$-actin, a marker of activated stellate cells, was significantly increased under hypoxia, suggesting that our experimental condition could work for screening the anti-fibrotic compounds. The assay procedure took only 3 days after treatment with agents, while assays from the primary stellate cells or liver tissues have taken several weeks. Considering the time and expenses, this assay method could be useful to screen the compounds for the inhibitor of prolyl 4-hydroxylase.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.428-436
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• 2010

Sea-urchins (Anthocidaris crassispina) are widely distributed in the East Sea of Korea. The aim of this study was to evaluate the hepatoprotective effects of sea-urchin roe on bromobenzene (BB)-induced liver damage in rats. The antioxidative and detoxifying properties of sea-urchin roe in BB-poisoned rat liver was examined by chemical analysis of serum aminotransferase (AST, ALT), glutathione S-transferase (GST), $\gamma$-glutamylcystein synthetase, glutathione reductase, epoxide hydrolase, amino-N-demethylase (AD), aniline hydrolase (AH) enzyme activity, as well as lipid peroxide and glutathione contents. Sea-urchin roe inhibited the increase of serum AST, ALT enzyme activity. Increasing lipid peroxide contents and AD and AH activities were significantly decreased in ethanol extract of sea-urchin roe. GST, $\gamma$-glutamylcystein synthetase, glutathione reductase and epoxide hydrolase enzyme activities increased in sea-urchin roe-fed group, compared with the BB-treated group. These results suggest that sea-urchin roe facilitates recovery from liver damage by enhancing antioxidative defense mechanisms and hepatic detoxication metabolism.

• Journal of Life Science
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• v.13 no.2
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• pp.230-235
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• 2003

To investigate hepatoprotective activities of the root extract of Rosa davurica, the activities of hepatic enzymes, aminopyrine N-demethylase, aniline hydroxylase, glutathione S-transferase and epoxide hydrolase in rats intoxicated with bromobenzene were studied. Pretreatment with the methanol extract from the roots of Rosa davurica did not show any significant effects on the increases of the activities of aminopyrine N-demethylase and aniline hydroxylase, enzymes forming toxic epoxide by bromobenzene. There was no change in glutathione S-transferase activity by Rosa davurica. However, the activity of epoxide hydrolase, and epoxide-removing enzyme, was increased 33% by the administration of 500 mg/kg of the methanol extract. From the results, the protection of Rosa davurica against bromobenzene-induced hepatotoxicity is thought to be via enhancing the activity of epoxide hydrolase, an enzyme removing toxic epoxide rather than through epoxide-producing system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.5
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• pp.900-907
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• 2000

The antioxidant effects of dichloromethane, ethylacetate or water fraction of kimchi added to the 1% cholesterol diet were studied. Six New Zealand white rabbits in each group were fed either control diet (basal diet containing 1% cholesterol) or experimental diet containing dichloromethane (CH$_2$Cl$_2$), ethylacetate (EtOAc) or water ($H_2O$) fraction of kimchi in the control diet for 16 weeks. The amount of each solvent fraction of kimchi added to the experimental diet was equivalent to 5% of freeze-dried kimchi. Levels of hepatic lipid oxidation expressed as TBARS or peroxide value for the experimental groups were lower than that of control (p<0.05). Liver homogenated of the experimental group containing dichloromethane fraction of kimchi inhibited LDL oxidation in the presence of Cu++ by 46% (p<0.05). The activities of catalase, Glutathione peroxidase (GSH-Px), Cu, Zn-superoxide (Cu, Zn-SOD) and Mn-superoxide (Mn-SOD) of experimental groups were lower than those of control group. Low enzyme activities observed from the kimchi solvent fraction groups might be due to the level of lipid oxidation progressed less in these groups. The most significant antioxidant effects were observed from dichloromethane fraction of kimchi among the experimental groups. The major fatty acids of hepatic phospholipid of rabbit were C18:2 and C18:0. But the major fatty acid profile was changed into C16:0, C18:0, C18:1, and C18:2 when rabbit was fed 1% cholesterol diet for 16 weeks, and this profile was almost the same as in rabbit fed diet containing kimchi solvent fraction. The ratio for unsaturated fatty acid to saturated fatty acid decreased by cholesterol induced diet and it was not corrected by kimchi solvent fractions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.4
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• pp.475-482
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• 2015

This study was conducted to examine whether or not oligonol, a low molecular weight polyphenol derived from lychee fruit, has an ameliorative effect on diabetes-induced oxidative stress-related hepatic damage in streptozotocin (STZ)-induced diabetic rats. Oligonol (10 or 20 mg/kg body weight; O10 or O20, respectively) was orally administered every day for 10 days to STZ-induced diabetic rats, and its effects were compared to vehicle-treated diabetic (Veh) and non-diabetic rats. Administration of 20 mg/kg of oligonol significantly decreased liver weight compared with the Veh group (P<0.05). Elevated levels of hepatic glucose, reactive oxygen species, peroxynitrite, and lipid peroxidation were detected in diabetic vehicle rats, whereas oligonol treatment significantly attenuated these levels (P<0.05). In diabetic vehicle rats, hepatic antioxidant enzyme protein levels decreased, whereas oligonol treatment showed significant elevated results. For inflammation-related protein expression, oligonol-treated groups showed insignificant reduction. Oligonol improved expression of proapoptotic protein caspase-3 in the liver of diabetic rats (P<0.05). In conclusion, these results provide important evidence that oligonol exhibits an inhibitory effect on oxidative stress and apoptosis-related protein expression as well as a hepato-protective effect against the development of diabetic complications in STZ-induced type 1 diabetic rats.

• Biomolecules & Therapeutics
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• v.17 no.3
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• pp.318-324
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• 2009

1-Furan-2-yl-3-pyridin-2-yl-propenone (FPP-3) has recently been synthesized and characterized to have an anti-inflammatory activity through the inhibition of the production of nitric oxide. In the present study, adverse effects of FPP-3 on hepatic functions were determined in female BALB/c mice. When mice were administered with FPP-3 at 125, 250 or 500 mg/kg for 7 consecutive days orally, FPP-3 significantly increased absolute and relative weights of liver with a dose-dependent manner. In addition, FPP-3 administration dramatically increased the hepatotoxicity parameters in serum at 500 mg/kg, in association of hepatic necrosis. FPP-3 significantly induced several phase I enzyme activities. To elucidate the possible mechanism(s) involved in FPP-3 induced hepatotoxicity, we investigated the hepatic activities of free radical generating and scavenging enzymes and the level of hepatic lipid peroxidation. FPP-3 treatment significantly elevated the hepatic lipid peroxidation, measured as the thiobarbituric acid-reactive substance, and the activity of superoxide dismutase. Taken together, the present data indicated that reactive oxygen species might be involved in FPP-3-induced hepatotoxicity.