• Korean Journal of Acupuncture
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• v.19 no.2
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• pp.57-61
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• 2002

The activities of phase I enzymes in the liver of mice were examined following the intragastric application of Cnidium officinale Makino aqua-acupunture solution (COMAS). Treatment of mice with COMAS resulted in decreases of cytochrome P450 1A1-dependent ethoxyresorufin-O-deethylation and cytochrome P450 2E1-dependent p-nitrophenol and aniline hydroxylation activities. These findings suggest that COMAS has chemopreventive potential by inhibiting cytochrome P450 1A1 and cytochrome P450 2E1 activities in mice.

• Toxicological Research
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• v.11 no.2
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• pp.205-213
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• 1995

This study was undertaken to investigate the effects of organic solvents on xenobiotic metabollzing enzyme system in vivo by meaas of experimental conditions i.e. (1) single group which was treated by benzene (B), toluene (T) and xylene (X), respectively, (2) combination group which was treated by mixture of benzene+toluene (BT), benzene+xylene (BX), and toluene+xylene (TX), respectively, (3) mixture group which was treated by benzene+ toluene+xylene mixture (M), and to interpreat the interaction between the organic solvents metabolizing enzymes. 1. The contents of cytochrome P-450 in liver microsomes were increased (p < 0.01) in organic solvents treated groups, and the contents of cytochrome P-450 were increased by following order of B < T < M < BT=BX < X < TX. 2. The activity of cytochrome P-450 dependent AHHase was significantly higher in organic solvents treated groups than in control group (p < 0.01), and the activity of AHHase was increased by following order of B < T < BT=BX=TX=xylene < M. 3. The activity of NADPH P-450 reductase was significantly higher in organic solvents treated groups than in control group (p < 0.01), and the order of M < combinated group < X < T

• Toxicological Research
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• v.9 no.2
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• pp.177-186
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• 1993

Previous results from several laboratories have demonstrated that tumor necrosis factor-alpha (TNFalpha) depressed cytochrome P-450 (P-450)-dependent drug metabolism in vivo. However, there is some debate whether the action of TNFalpha is mediated by its direct effects on hepatocytes, or is indirectly mediated through the release of other mediators like IL-1 from macrophages. In the present studies, we investigated the effects of TNFalpha on P-450-dependent drug metabolizing enzyme as measured by 7-ethoxyresorufin O-deethylase (EROD) activity.

• 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.

• Journal of Environmental Health Sciences
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• v.19 no.3
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• pp.58-63
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• 1993

In order to elucidate the alteration of drug-metabolizing enzymes and mechanism in the animal with hepatic injury and ketosis, the regulation of P450IIE was studied in the rats with heaptic injury caused by CCl$_4$ and with ketosis caused by streptozotocin and high-fat diet. P450IIE expression in liver was examined by the combination of enzyme activities, Western immunoblot, and mRNA Northern blot analyses using specific polyclonal antibody and cDNA probe for P450IIE. Enzyme activity and amounts of immunoreactive P450IIE were rapidly decreased in a time-dependent manner after a single dose of CCl$_4$ . However, the decreases in P450IIE enzyme activity and immunoreactive protein by CCl$_4$ were not accompanied by a decline in its mRNA level. The data thus suggested a post-translational reduction of P450IIE by CCl$_4$. The enzyme activities (aniline hydroxylase) in hepatic microsomes were elevated about 2-3-fold by streptozotocin and feeding with a high fat diet. This increases in enzyme activities were also accompanied by 3-fold increases in immunoreactive P450IIE protein and its mRNA. Our data thus indicated that P450IIE induction during the ketosis appears to be due to pretranslational activation.

• Toxicological Research
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• v.12 no.2
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• pp.155-161
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• 1996

The enzymatic properties for NADPH-P450 reductase domain of a fusion protein between human cytochrome P450 1A1 and rat NADPH-P450 reductase expressed in Escherichia coli were investigated. The fusion plasmid pCW/1A1OR-expressed E. coli membrane showed high NADPH-cytochrome c reductase activity ($830.1\pm 85.8 nmol\cdot min^{-1}\cdot mg protein^{-1}$), while pCW control vector and P 450 1A1 expression vector pCW/1A1 showed relatively quite low activity ($4.35\pm 0.49, 3.27\pm 0.50 nmol\cdot min^{-1}\cdot mg protein^{-1}$, respectively). The kinetic curves for NADPH-cytochrome c reductase followed typical Michaelis-Menten kinetics. The $K_{max}$ and $V_{max}$ for NADPH-dependent reductase activity were $8.24\pm 2.61\mu $and $817.9\pm 60.8 nmol\cdot min^{-1}\cdot mg protein^{-1}$, respectively, whereas those for cytochrome c-dependent reductase activity were $19.97\pm 2.86\mu M$ and $1303.5\pm 67.1 nmol\cdot min^{-1}\cdot mg protein^{-1}$. The reductase activities were also compared with those of rat, porcine and human liver microsomes. The activity of pCW/ 1A1OR-expressed E. coli membrane was 15.2-fold higher than that of rat liver microsome. Treatment with benzo(a)pyrene, 7-ethoxyresorufin and $\alpha$-naphthofiavone which are known as specific substrates or inhibitor for human P450 1A1 increased NADPH-cytochrome c reductase activity of fusion protein in E. coli membrane dose-dependently. These results demonstrate that the membrane topology of fused enzyme may be important for activity of its NADPH-P450 reductase domain.

• Archives of Pharmacal Research
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• v.27 no.2
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• pp.199-205
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• 2004

Cytochrome P450 (P450) 1 enzymes such as P450 1A1, 1A2, and 181 are known to be involved in the oxidative metabolism of various procarcinogens and are regarded as important target enzymes for cancer chemoprevention. Previously, several hydroxystilbene compounds were reported to inhibit P450 1 enzymes and were rated as candidate chemopreventive agents. In this study, we investigated the inhibitory effect of 2-[2-(3,5-dimethoxyphenyl)vinyl]-thiophene (DMPVT), produced from the chemical modification of oxyresveratrol, on the activities of P450 1 enzymes. The inhibitory potential by DMPVT on the P450 1 enzyme activity was evaluated with the Escherichia coli membranes of the recombinant human cytochrome P450 1A1, 1A2, or 1B1 coexpressed with human NADPH-P450 reductase. DMPVT significantly inhibited ethoxyresorufin O-deethylation (EROD) activities with $IC_{50}$ values of 61, 11, and 2 nM for 1A1, 1A2, and 1B1, respectively. The EROO activity in OMBA-treated rat lung microsomes was also significantly inhibited by OMPVT in a dose-dependent manner. The modes of inhibition by DMPVT were non-competitive for all three P450 enzymes. The inhibition of P450 1B1-mediated EROD activity by OMPVT did not show the irreversible mechanism-based effect. The loss of EROD activity in P450 1B1 with OMPVT incubation was not blocked by treatment with the trapping agents such as glutathione, N-acetylcysteine, or dithiothreitol. Taken together, the results suggested DMPVT to be a strong noncompetitive inhibitor of human P450 1 enzymes that should be considered as a good candidate for a cancer chemopreventive agent in humans.

• Korean Journal of Veterinary Research
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• v.44 no.2
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• pp.185-193
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• 2004

The effects of membrane lipid peroxidation and retinyl palmitate on rat liver microsomal functions were investigated in vitro. Rat liver homogenates exposed to oxygen tension for 0, 3, 6, 9 or12 hours and lipid peroxidation levels were evaluated by the measurements of fluorescence intensity, malondialdehyde (MDA) and retinyl palmitate. The fluorescence intensity of homogenates and microsomes were elevated and retinyl palmitate concentrations were decreased. But the concentration of MDA was not affected to exposure time. Therefore, fluorescence intensity and retinyl palmitate concentration were used to analyze the correlation between lipid peroxidation and microsomal functions. To investigate the liver microsomal functions, the microsome was isolated from rat liver homogenates exposed to oxygen. The concentration of cytochrome P450 and the activity of NADPH-cytochrome P450 reductase in liver microsomes were gradually decreased with increasing the exposure time. The correlation between fluorescence intensity of microsomes showed a very high inverse correlation of -0.97 and -0.93, respectively. The decrease of cytochrome P450 concentration was due to the regeneration of cytochrome P450 to cytochrome P420. Also, the activities of cytochrome P450-dependent aminopyrine demethylase and benzpyrene hydroxylase of liver microsomes were gradually decreased with increasing the exposure time. The correlation with fluorescence intensity of microsome showed a high inverse correlation of -0.97 and -0.91, respectively. The retinyl palmitate concentrations of rat liver homogenates were decreased with increasing the exposure time. The decrease of retinyl palmitate concentration was followed by a low concentration of cytochrome P450 and activity of NADPH-cytochrome P450 reductase. The correlation indicated high direct correlation of 0.92 and 0.93, respectively. The decrease of retinyl palmitate concentration was also accompanied by the reduction of aminopyrine demethylase and benzpyrene hydroxylase activities. The correlation was analyzed a high direct correlation of 0.90 and 0.85, respectively. In conclusion, these studies have shown that the membrane lipid peroxidation of rat liver microsome proportionally decreased microsomal enzyme activities in vitro experiments.

• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.579-585
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• 2003

The studies were carried out on the correlation between microsomal lipid peroxidation level and drug metabolizing enzyme activities in rat liver microsomal suspensions on various ages (2-week-old, 2, 4, 8, and 12-month-old). The lipid peroxidation levels of liver homogenates tended to be elevated in a 4-month-old rat livers, but it was a little decreased in 8 and 12-month-old rat livers. The lipid peroxidation levels of microsomal suspension was not shown any significant differences by ages. Lipid peroxidation levels and microsomal cytochrome P450 and NADPH-cytochrome c reductase activity showed a direct correlation (r=0.72 and r=0.64), respectively. The activities of cytochrome P450-dependent aminopyrine-N-demethylase and benzpyrene hydroxylase in rat liver microsomes were increased by ages up to 8-month-old rats and maintained in 12-month-old rats. The correlation between lipid peroxidation levels and these cytochrome-dependent enzyme activities showed a high direct correlation (r=0.97 and r=0.81), respectively.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.23-28
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• 2003

To evaluate the effect of cyclohexane(CH) treatment on the liver cytochrome P-450 dependent aniline hydroxylase(CYPdAH) activity in alcohol-pretreated animals, CH(1.56 g/kg body weight) was intraperitoneally administered to Sprague-Dawley male rats, which had been drunk 15％ alcohol in distilled water for 1,3 and 6 weeks. CH was injected to rats 4 times every other day and the animals were sacrificed at 24 hours after injection of CH. In the alcohol-pretreated rats, liver injuries were not demonstrated on the basis of the liver weight per body weight, the levels of serum alanine aminotransferase and hepatic microsomal glucose-6-phosphatase activities. By the CH treatment, alcohol-pretreated animals showed the significantly increased activity of hepatic microsomal CYPdAH. Concomitantly $V_{max}$ value in CYPdAH was more increased, whereas $K_{M}$ value more decreased in alcohol-pretreated animals by the treatment of CH. In conclusion, the increasing cause of microsomal CYPdAH in CH-treated rats pretreated with alcohol may be due to induction of enzyme protein in rat liver.r.r.