• 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.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.

• BMB Reports
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• v.30 no.1
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• pp.73-79
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• 1997

This study was designed to investigate the effects of dietary garlic powder on cytochrome P450 enzymes and membrane stability in murine hepatocarcinogenesis initiated by diethylnitrosamine (DEN). Male Sprague-Dawley rats received a single intraperitoneal injection of DEN (200 mg/kg body wt) dissolved in saline. After 2 weeks on a basal diet, animals were fed diets containing 0. 0.5. 2.0. or 5.0% garlic powder for 6 weeks, and were subjected to two-thirds partial hepatectomy. The areas of placental glutathione S-transferase (GST-P) positive foci were inhibited in rats fed with garlic diets. GST-P is the most effective marker for DEN-initiated lesions. Hepatic microsomal lipid peroxidation was significantly decreased in rats fed with 2.0 and 5.0% garlic powder diets compared with that observed in the control animals and hepatic microsomal glucose 6-phosphatase (G6Pase) activity was found to increase significantly in rats fed 0.5 and 2.0% garlic powder diets. Thus as little as 0.5% garlic powder has a positive effect on the stability of hepatic microsomal membranes. p-Nitrophenol hydroxylase (PNPH) activity and the level of cytochrome P450 2E1 protein in the hepatic microsomes from rats fed diets containing 2.0 and 5.0% garlic powder were much lower than those of control microsomes. Rats fed 5.0% garlic powder diets exhibited the lowest P450 2E1 activity and protein levels among groups. Pentoxyresorufin O-dealkylase activity and immunoblot (cytochrome P450 2B1) analyses were not different between groups. However, the levels of cytochrome P450 1A1/2 protein in rats fed 0.5 and 2.0% garlic powder were significantly induced compared to controls. These results suggest that 2.0% garlic powder is effective in inhibiting the areas of GST-P positive foci, modulating certain isoforms of cytochrome P450 enzymes and stabilizing the hepatic microsomal membrane. Thus, the selective modification of cytochrome P450 enzymes and membrane stability by dietary garlic powder may influence areas of GST-P positive foci and chemoprevention of post-initiation of rat hepatocarcinogenesis.

• Biomedical Science Letters
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• v.7 no.2
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• pp.65-70
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• 2001

We have carried out PCR reactions to investigate if cytochrome P450 (P450) enzymes (1A1, 1A2, 2C8, 2E1 and 3A4), which are well hewn to be the key enzymes in detoxification process and/or synthesis of steroids in the liver, are expressed in the human brain, too. P450 1A1, 2C8 and 2E1 were expressed clearly. However, P450 1A2 and 3A4 were not detectable. Their expression levels in the human brain could be extremely low or they were not expressed at all. One base substitution at nucleotide 290 (A->G) was identified in P450 1A1. It is suspected to be an individual polymorphism. Our results should contribute to the better understanding of the role of cytochrome P450 enzymes in the human brain.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.148.2-149
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• 2003

Recently we have reported that various hydroxystilbenes show strong inhibition of human cytochrome P450 1 enzyme activities. A series of syntheic trans-stilbene derivatives were prepared and their inhibitory potentials were evaluated with the bacterial membrane of recombinant human cytochrome P450 1A1, 1A2 and 1B1 coexpressed with hyman NADPH-P450 reductase to find a new inhibitor of cytochrome P450 enzymes. Of the compounds tested, SY-081 exhibited a potent inhibition of human cytochrome P450 1B1 with an $IC_50$ value of 2.6 nM. (omitted)

• The Korean Journal of Pesticide Science
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• v.7 no.1
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• pp.45-50
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• 2003

This study was conducted to understand the role of oxidative enzyme cytochrome $P_{450}$ in the bioactivation of benfuracarb and to know metabolites of benfuracarb by cytochrome $P_{450}$. The bimolecular imhibition rate constant $(k_i)$ of benfuracarb on acetylcholinesterase (AChE) was as low as $1.1{\times}10^3\;M^{-1}\;min^{-1}$, suggesting that benfuracarb should be activated for its toxic action. The potency of benfuracarb on AChE in the oxidase system (cytochrome $P_{450}$ + NADPH) in vitro was 10-fold higher than that of control (cytochrome $P_{450}$). Such a similar result was also found in the oxidase + PBO system. In vivo the $I_{50}$ of benfuracarb was 22.7mg $kg^{-1}$, but pie-treatment of piperonyl butoxide (PBO) reduced the $I_{50}$ by >100mg $kg^{-1}$. This result suggests that cytochrome $P_{450}$ was involved in the activation of benfuracarb. Using microsomal oxidase system, metabolites of benfuracarb were elucidated. Fifty-eight percent of benfuracarb was converted to carbofuran, a major toxic metabolite, in the oxidase system, while only less than two percent of benfuracarb was converted to carbofuran in the oxidase + PBO system. These results also suggest that cytochrome $P_{450}$ was involved in the activation of benfuracarb. Overall results indicate that cytochrome $P_{450}$ could be involved in the bioactivation of benfuracarb to carbofuran.

• 대한예방의학회:학술대회논문집
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• 1998.10b
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• pp.291-292
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• 1998

• Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.28-31
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• 2002

Effects of cimetidine, a cytochrome P450 inhibitor, on the benzo[a]pyrene (BaP)-mediated cytochrome P450 induction and lipid peroxidation of liver in olive flounder, Paralichthys olivaceus, were investigated. Fish were fed either a cimetidine-supplemented diet or a cimetidine-free control diet once daily to satiation for 3 days. After 6 hrs of last feeding, the fish received intraperitoneal (i.p.) injection of BaP (20 mg/kg of body weight) dissolved in sterile corn oil $(100 \mu L)$ or received only a corn oil i.p. injection. At 1, 2, 3, and 7 days after the injection, hepatic cytochrome P450 and thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation, were analyzed. BaP injection resulted in an increase of hepatic cytochrome P450, and the fish fed the cimetidine-supplemented diet before injection of BaP showed delayed increase of hepatic cytochrome P450 compared to the fish fed a cimetidine-free diet and BaP injected. Injection of BaP clearly induced hepatic lipid peroxidation, and consistently higher TBAR values were shown in the fish fed a cimetidine­supplemented diet before injection of BaP than the fish injected with BaP alone.

• Archives of Pharmacal Research
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• v.21 no.3
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• pp.305-309
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• 1998

Human cytochrome P450 1A2 is one of the major cytochrome P450s in human liver. It is known to be capable of activating a number of carcinogens such as arylamines and heterocyclic amines. In order to develop the new bacterial mutagenicity test system with human P450, a full length of human P450 1A2 cDNA inserted into pCW bacterial expression vector was introduced to Escherichia coli WP2 uvrA strain which is a well-known E. coli strain for bacterial reverse mutagenicity assay. Expressed human P450 1A2 showed typical P450 hemoprotein spectra. Maximum expression was achieved at 48 hrs after incubating at $30^{\circ}C$ in terrific broth containing ampicillin, IPTG and other supplements. High level expression of P450 1A2 in E. coli WP2 uvrA membranes was determined in SDS-PAGE. The well-known mutagens 2-aminoanthracene and MElQ increased the revertant colonies of E. coli WP2 uvrA expressing human P450 1A2 without an exogenous rat hepatic post-mitochondrial supernatant (S9 fraction) in a dose-dependent manner. The results show that the functional expression of human P450 in bacterial mutagenicity tester strain will provide a useful tool for studying the mechanism of the mutagenesis and carcinogenesis of new drugs and environmental chemicals.

• Toxicological Research
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• v.13 no.4
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• pp.385-391
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• 1997

Inductive effects of cytochrome P450 2B1 by $\alpha$- and $\beta$-ionone were characterized in individual liver lobes of male Sprague Dawley rats. When rats were administered ionones orally at 100, 300, and 600 mg/kg for 24 hr, cytochrome P450 2B1 was induced dose-dependently in liver S-9 fractions as measured by P450 2B-specific monooxygenases and Western immunoblotting. The activity of P450 1A- and P450 2B-specific monooxygenases was differentially expressed in each lobe of normal liver. In addition, the monooxygenase activity was induced by $\alpha$- and $\beta$-ionone with different potency in each lobe of the liver. Our present results indicate that the different induction of P450s by $\alpha$- and $\beta$-ionone in each lobe may explain different susceptibilities of rat liver lobes to certain hepatotoxicants which require metabolic activation for their toxicity and that $\alpha$- and $\beta$-ionone may be useful model inducers of P450 2B1 in studying the toxic mechanism of certain toxicants which may require the metabolic activation by P450.