• Preventive Nutrition and Food Science
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• v.3 no.1
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• pp.62-66
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• 1998

The effect of dietary capsaicin (8-methyl-N-vanillyl-6-nonenamide, CAP) on drug-metabolizing enzyme activities was investigated in mice. Male ICR mice were divided into 4 groups and fed diets containing 0, 5, 20, 100 ppm CAP for 4 seeks. Hepatic drug-metabolizing enzyme activities and serum alanine aminotransferase and aspartate transaminease activities were measured. There was no difference in hepatic alanine aminotransferse and aspartate transaminase activities among the groups. Hepatic microsomal cytochrome P450 in CAP fed groups, but p-nitrophenol hydroxylase and the cytosolic acitivity of glutathione S-transferase activities were decreased in the dietary CAP supplemetned groups compared to the control. These results suggest that the dietary CAP at a low dose differentially modulates drug-metabolizing enzyme acitvities without causing hepatic toxicity.

• BMB Reports
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• v.32 no.3
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• pp.226-231
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• 1999

In vitro effects of acetone on cytochrome P450 (P450)-dependent benzo(a)pyrene (B(a)P) hydroxylation supported by cumene hydroperoxide (CuOOH) or NADPH/$O_2 $ systems were studied using 3-methylcholanthrene-pretreated rat liver microsomes. The maximal rate of B(a)P hydroxylation at constant concentration ($80\;{\mu}M)$ of the substrate was observed in the presence of $30\;{\mu}M$ CuOOH. However, at concentrations higher than $30\;{\mu}M$ CuOOH the hydroxylation rates were rapidly decreased. In contrast to CuOOH, at a concentration of $200\;{\mu}M$ NADPH, B(a)P hydroxylation rate reached a plateau. At concentrations higher than $200\;{\mu}M$ NADPH, the rates of substrate hydroxylation were maintained at the maximal rate with no inhibition. Acetone at 1% (v/v) enhanced both CuOOH- and NADPH/$O_2$-supported B(a)P hydroxylation at the optimal concentrations of the cofactors. At concentrations higher than 1% (v/v) acetone, substrate hydroxylation was sterero specific under the support of these two cofactors; it was strongly enhanced with $30\;{\mu}M$ CuOOH, but rather inhibited in the $200\;{\mu}M$> NADPH/$0_2 $ system. The lipid peroxidation rate induced during CuOOH-supported P450-dependent B(a)P hydroxylation was increased as CuOOH concentrations were increased. Acetone in the concentration range of 2.5~7.5%(v/v) inhibited lipid peroxidation during CuOOH supported B(a)P hydroxylation. The finding that CuOOH-supported B(a)P hydroxylation is greatly enhanced by acetone suggests that acetone may contribute more to the activation of oxygen (for the insertion of oxygen into the substrate) in the presence of CuOOH than with NADPH/$O_2$. Acetone may also contribute to the partial inhibition of destruction of microsomal membranes by lipid peroxidation.

• Biomolecules & Therapeutics
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• v.2 no.2
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• pp.141-148
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• 1994

This study was done to determine whether specific alterations exist in hepatic microsomal function after varying periods of ischemia (IS) and reperfusion (RP) during microsomal lipid peroxidation occurs. Rats were pretreated with $\alpha$-tocopherol to inhibit lipid peroxidation or with vehicle (soybean oil). Control animals were time-matched sham-ischemic animals. Four groups of animals were studied: Group 1 (sham), group 2 (30 mins IS), group 3 (60 mins IS) and group 4 (90 mins IS). After 1, 5 or 24 hr of reperfusion, liver microsomes were isolated and cytochrome P-450s were studied. In all vehicle-treated ischemic rats, serum ALT levels peaked at 5 hr and were significantly reduced by $\alpha$-tocopherol pretreatment. Similarly, microsomal lipid peroxidation was elevated in all vehicle-treated ischemic animal groups, but this elevation was prevented by $\alpha$-tocopherol pretreatment. Cytochrome P-450 content was significantly decreased in both group 3 and group 4. In all vehicle-treated ischemic animal groups, aminopyrine N-demethylase activity was significantly decreased for the entire reperfusion period. $\alpha$-Tocopherol inhibited reductions of cytochrome P-450 content and aminopyrine N-demethylase activity at both 1 hr and 5hr of reperfusion but did not affect the reduced levels of cytochrome P-450 content and aminopyrine N-demethylase activity at 24 hr of reperfusion. Aniline p-hydroxylase activity was significantly decreased in group 4, whereas it was increased in group 3. These decreases and increases were prevented by $\alpha$-tocopherol pretreatment. Our finding suggests that abnormalities in microsomal drug metabolizing function occur during hepatic ischemia and reperfusion in vivo and this is attributed to microsomal lipid peroxidation.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.99-107
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• 1998

Numerous studies have demonstrated a negative association between cigarette smoking and Parkinson's disease. The present study was undertaken to investigate whether chronic exposure of mice to cigarette smoke a(footed the metabolism of 1-methyl-1113,6-tetrahydro-pyridine (MPTP) by cytochrome P4SO (P-450) or flavin-containing monooxygenase (FMO) in the hepatic microsomes of C57BL6/J mice. Adult male C57BL6/J mice were exposed to mainstream smoke generated from 15 cigarettes for 10 min a day and 5 day per week for 6 weeks. MPTP (10 mg/kg body weight) was administered to mice by subcutaneous injection for 6 consecutive days. Microsolnal P-450 content was increased by MPTP, smoke exposure, or both, but NADPH cytochrome P-450 reductase activity was rather decreased by the same treatments. The activities of benzo(a)pyrene hydroxylase, 7-ethoxycoumarin O-deethylase and ethoxyresorufin O-deethylase were significantly increased by the exposure of cigarette smoke, but were not or little affected by MPTP treatment. Benzphetamine N-demethylase activity was not affected either by MPTP treatment or by cigarette smoke exposure, but it was significantly increased by the combined MPTP treatment with cigarette smoke exposure, showing their synergic effect for the induction of the enzyme activity. Interestingly, in vitro studies of hepatic FMO and P-450 system both O-oxygenation and N-demethylation of MPTP were increased in the smoke-exposed or in the MPTP-treated mice. These results suggest that the enhancement in the N-demethylation as well as O-deethylation of P-450 system and in the N-oxygenation of FMO activity by cigarette smoke exposure in mouse liver may contribute to attenuating the neurotoxic effects of MPTP on the nigrostriatal dopaminergic neurons.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.6
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• pp.965-972
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• 2004

In the present study, it is observed that Monascus diet may have a hepatoprotective effect on the liver damage induced by bromobenzene in rats. By treatment with bromobenzene (400 mg/kg, i.p.) once a day for 3 consecutive days, the liver damage was reduced in rats fed 2% Monascus diet, based on the liver functional and histopathological findings. Furthermore, retreatment of bromobenzene to the animals with damaged liver showed higher decreasing rate of hepatic glutathione content and increasing rate of cytochrome P450 dependent aniline hydroxylase activity at 4 h in rats fed 2% Monascus diet than those fed STD diet, and V$_{max}$ in glutathione S-transferase was higher in liver of rats fed 2% Monascus diet than those fed STD diet. On the other hand, activities of antioxidant enzymes such as hepatic glutathione S-transferase, catalase and superoxide dismutase were generally higher both in bromobenzene and 2% Monascus diet treated group than those fed STD diet. In conclusion, the rats fed 2% Monascus diet showed lower liver damage than those fed STD diet, which may be due to the acceleration of bromobenzene metabolism and detoxication of oxygen free radicals.s.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.185.2-185.2
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• 2003

Effects of diallyl sulfide (DAS), a component of garlic, on thioacetamide-induced hepatotoxicity were investigated in male ICR mice. When mice treated subcutaneously with 100, 200 and 400 mg/kg of DAS in corn oil for three consecutive days, the activity of cytochrome P450 (P450) 2E1-selective p-nitrophenol hydroxylase was dose-dependently suppressed. In addition, the activities of P450 2B-selective benzyloxyresorufin O-debenzylase and pentoxyresorufin O-depentylase were dose-dependently induced by the treatment with DAS. (omitted)

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.04a
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• pp.107-107
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• 1997

Cytochrome P450 enzymes have been intensively investigated in hepatic tissues and several mammalian cell lines. Compared to most studies about cytochrome P450 isozymes in liver in vivo and hepatic, cell lines in vitro, the study of cytochrome P450IA1 in human breast cancer cells could be very important to understand the mechanism of the regulation of CYPIA1 gene expression and cell growth. MCF-7 human breast cancer cells are well characterized to study estrogen and antiestrogen action due to the fact that they contain high level of estrogen receptor and have biological markers characterized. And also MCF-7 cells express high level of arylhydrocarbon hydroxylase activity and human cytochrome P450IA1 cDNA was cloned from MCF-7 cells. Ah receptor was characterized in many breast cancer cell lines and polycyclic aromatic hydrocarbon such as 3-MC induced the expression of CYPIA1 gene and cytochrome P450- dependent monooxygenase activity. We undertook a study to examine the effect of estrogens and other chemicals on the regulation of human CYPIA1 gene expression in MCF-7 cells via RTPCR analysis, that might help us to understand the mechanism of the regulation of CYPIA1 gene expression and MCF-7 cell growth. Expression vector containing the functional 5'-regulatory region of human CYPIA1 fused to the CAT reporter gene was transfected into estrogen receptor positive MCF-T cells or estrogen receptor negative MDA-MB-231 cells. After these cells were treated with various chemicals, RTPCR was carried out to measure both CYPIA1 mRNA and CAT mRNA levels. 1nM 3-MC increased in both P450 and CAT mRNA levels over those of control by two folds in MCF-7 cells but does not in MDA-MB-231 cells. Estrogen or tamoxifen or retinoic acid or chrysin decreased in both P450 and CAT mRNA levels that were induced by 3-MC in MCF-7 when each chemical was administered with 3-MC concomitantly. These results suggested that the level of CYPIA1 gene expression is modulated with estrogen-related molecules and make it possible to speculate that ER is related to CYPIA1 gene expression and cell growth in breast cancer cells. [Supported by grants from the Korean Ministry of Education ]

• BMB Reports
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• v.32 no.3
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• pp.232-238
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• 1999

Sex differences in the induction of microsomal cytochrome P-450 (CYP) and the activities of several related enzymes of Sprague-Dawley rats treated with 1-bromopropane (1-BrP) were investigated. Male and female rats were exposed to 50, 300, and 1800 ppm of 1-BrP per kg body weight (6 h a day,S days a week, 8 weeks) by inhalation. The mean body weight of 1-BrP treated groups increased according to the day elapsed, but four and five weeks respectively after the start of the exposure, the mean body weight of male and female rats had significantly reduced in the group treated with 1800 ppm 1-BrP compared with the control group (p<0.01). While the relative weights of liver increased in both sexes, statistical significance in both sexes was found only in the group receiving 1800 ppm/kg of 1-BrP (p<0.01). The total contents of CYP, $b_5$, NADPH-P-450 reductase, NADH $b_5$ reductase, ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-dealkylase (PROD), and p-nitrophenol hydroxylase (pNPH) activities were examined for the possible effects of 1-BrP. No significant changes in the CYP and $b_5$ contents, NADPH-P-450 reuctase, NADH $b_5$ reductase, ethoxyresorufin-O-deethylase (EROD), and pentoxyresorufin- O-dealkylase (PROD) were observed between the control and treated groups. The activity of pNPH increased steadily with the increase in the concentration of 1-BrP in both sexes, but was significantly increased only in the 1800 ppm-treated group of male rats (p<0.05). When Western blottings were carried out with three monoclonal antibodies (MAb 1-7-1, MAb 2-66-3, and MAb 1-98-1) which were specific against CYP1A1/2, CYP2B1/2, and CYP2E1, respectively, a strong signal corresponding to CYP2E1 was observed in microsomes obtained from rats treated with 1-BrP. Glutathione S-transferase (GST) activity and the content of lipid peroxide significantly increased in the treated groups compared with the control group (p<0.05). These results suggest that 1-BrP can primarily induce CYP2E1 as the major form and that GST phase II enzymes play important roles in 1-BrP metabolism, showing sex-dependence in the metabolic mechanism of 1-BrP in the rat liver.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.6
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• pp.702-708
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• 1993

The study was attempted to elucidate the mechanism of GE-132(100mg/kg, p.o. for 6 weeks) on the metabolism of bromobenzene (460mg/kg, i.p. bid, for 2 days), which has potent carcinogenicity, mutagenicity and hepatotoxicity. It showed that activities of cytochrome p-450, aminopyrine demethylase and aniline hydroxylase, which have epoxide generating property, were not changed by GE-132 treatment. On the other hand, epoxide hydrolase was not changed but that glutathione S-transferase was significantly increased by GE-132 treatment. And also ${\gamma}-glutamylcysteine$ synthetase was not changed following the GE-132 treatment, but the activity of glutathione reductase was significantly increased. The level of hepatic glutathione which was decreased by bromobenzene recovered markedly by GE-132 pretreatment. It is concluded that the mechanism for the observed effect of GE-132 on bromobenzene metabolism is due to the induction of glutathione S-transferase.

• Toxicological Research
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• v.3 no.1
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• pp.1-8
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• 1987

In vitro induction of cytochrome 450 associated monooxygenase activities by phenobarbital (PB) and 3-methylcholanthrene (MC) was investigated in primary cultures of adult rat hepatocytes. PB and MC were added to the culture 24 hr after the initial plating of hepatocytes. A signiftcant increase of the activities of 7-ethoxycoumarin 0-deethylase and aryl hydrocarbon hydroxylase were observed in MC and PB treated culture. MC caused about 500% induction of the initial oxidation rates of both enzymes in 48 hr. However the PB maintained both enzyme activities close to the level of freshly isolated hepatocytes. Biphenyl 4-hydroxylase and aminopyrine N-demethylase activities were also induced by MC and PB. But the level of induction was less than that occuring with 7-ethoxycoumarin 0-deethylase and aryl hydrocarbon hydroxylase. When aflatoxin $B_1$ was added to the hepatocyte cultures which have been treated with MC or PB, it caused a significant increase of the unscheduled DNA synthesis at higher dose of aflatoxin $B_1$ as compared to those of untreated control hepatocyte cultures. The results suggest that microsomal enzyme activities can be selectively controlled preferably in hepatocyte cultures by the in vitro induction method. This principle may be useful for studying the metabolism and other toxicological studies.