• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.6
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• pp.859-866
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• 1995

This study was done to investigate the effects of chronic ethanol feeding on hepatic microsomal cytochrome system, lipid peroxidation and peroxide metabolizing enzyme activities in 2-acetylaminofluorene(2-AAF) treated rats. Male Sprague-Dawley rats, weighing 120~125g, were pair-fed liquid diets containing 35% of total calories either as ethanol or isocaloric carbohydrates for 6 weeks. After 4 weeks of experimental diet feeding, 2-AAF(100mg/kg body weight) was injected twice a week intraperitoneally. Both weight and percent liver weight per body weight were significantly changed by ethanol feeding. Hepatic microsomal lipid peroxide value and the activities of glutathione(GSH) peroxidase and GSH reductase were not changed by either ethanol or 2-AAF treatment. However the analysis of cytochrome systems showed that both ethanol and 2-AAF increased cytochrome P-450 and bs contents although cytochrome P-450 content was moe affected by 2-AAF while cytochrome b5 content by ethanol. Cytosolic GSH S-transferase activity, which is often elevated during chemical carcinogenesis, also significantly increased by either ethanol feeding or 2-AAF treatment. Overall values for the cytochrome contents and GSH S-transferase activities were highest in 2-AAF treated rats fed ethanol. These results might support the hypothesis that the increase in liver cancer risk associated with chronic ethanol consumption might be due to, at least in part, enhancement of carcinogen bioactivation by ethanol.

• Journal of Nutrition and Health
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• v.35 no.6
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• pp.643-649
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• 2002

This study was done to investigate effects of ${\gamma}$-irradiated pork feeding on the formation of glutathione S-transferase placental form positive (GST-P$^{+}$) foci, lipid peroxidation, cytochrome P450 system and microsomal glucose 6-phosphatase activity in diethylnitrosamine (DEN)-initiated rat hepatocarcinogenesis. Weaning Sprague-Dawley male rats were fed the diet containing ${\gamma}$-irradiated ground pork at the dose of 0, 3, 10, 30 kGy as a 20％ of protein source for 8 weeks. One week after feeding, rats were intraperitoneally injected twice with a dose of DEN (50 mg/kg BW). As a promote.,0.05％phenobarbital was fed in drinking water from one week after DEN treatment until the end of experiment. At the end of 8th week, rats were sacrificed and hepatic GST-P$^{+}$ foci, microsomal malondialdehyde (MDA) and conjugated diene contents were determined. In addition, cytochrome P450 content and the activities of NADPH cytochrome P450 reductase and glucose 6-phosphatase were also measured. There was no significant effect by gamma irradiation on microsomal MDA content, conjugated diene, cytochrome P450 content and activities of NADPH cytochrome P450 reductase and glucose 6-phosphatase. However with DEN treatment, microsomal MDA content showed a increasing tendency. Cytochrome P450 content was also significantly increased while microsomal glucose 6-phophatase activity was significantly decreased with DEN treatment. However the activity of NADPH cytochrome P450 reductase was not affected. An interesting finding in this study was that the number and area of hepatic GST-P$^{+}$ foci of rats fed gamma irradiated pork were tended to be decreased by high dose of irradiation, but were not significantly different. These results might imply that the consumption of low dose of gamma irradiated pork does not affect the formation of hepatic GST-P$^{+}$ foci and lipid peroxide and membrane stability.ability.

• 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.

• 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.

• 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

• Journal of Nutrition and Health
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• v.27 no.5
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• pp.442-450
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• 1994

The purpose of this study was to determine the effects of 2-AAF injection time on hepatic lipid peroxide metabolism and cytochrome P450 content in Sprague-Dawley rats fed diets containing high amounts of vegetable oils or animal fats(15%, w/w). Fifty mg of 2-AAF/kg of body weight/day was injected in PEG 300 intraperitonially for 3 consecutive days after 4 or 8 weeks to rats fed corn oil(CO) or lard(LA) diet. The contents of lipid peroxide and cytochrome P450, and the activities of superoxide dismutase(SOD), glutathione peroxidase(GSH-peroxidase) and glutathione S-transferase(GSH-S-transferase) were determined in hepatic microsomal or cytosolic fraction. Microsomal thiobarbituric acid reactive substances(TBARS) and cytochrome P450 contents increased in Co group injected 2-AAF after 4weeks. Cytosolic SOD activity increased in CO group injected 2-AAF after 4 weeks and in LA group injected 2-AAF after 4 or 8 weeks. Cytosolic GSH-S-transferase activity increased in LA group compared to CO group without 2-AAF injection. GSH-S-transferase activity increased in CO group injected 2-AAF after 4 or 8 weeks and in LA group injected 2-AAF after 4 weeks. Therefore, it may be suggested that 2-AAF injection increase the contents of lipid peroxide or cytochrome P450, and detoxifying enzyme activities in rats fed CO diet for short period and in rats fed LA diet for longer period.

• 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.

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.53-53
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• 2002

Inhibitory effects of Cu$\^$2＋/ on the cytochrome P450 (P450)-catalyzed reactions of liver microsomes and reconstituted systems containing purified P450 and NADPH-P450 reductase (NPR) were seen. However, Zn$\^$2＋/, Mg$\^$2＋/, Mn$\^$2＋/, Ca$\^$2＋/, and Co$\^$2＋/ had no apparent effects on the activities of microsomal P450s. Cu$\^$2＋/ inhibited the reactions catalyzed by purified P450s lA2 and 3A4 with IC$\sub$50/ values of 5.7 and 8.4 ${\mu}$M, respectively.(omitted)

• Toxicological Research
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• v.18 no.3
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• pp.249-257
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• 2002

Cytochrome P450 3As such as 3A4 and 3A5 metabolize a wide range of pharmaceutical compounds. The vectors for the expression of fusion protein containing an N-terminal human P450 3A4 or P450 3A5 sequences and a C-terminal rat NADPH-cytochrome P450 reductase moiety were constructed. These plasmids were used to express the fusion protein in Escherichia coli DH5$\alpha$ cells. High levels of expression were achieved (100~200 nmol/liter) and the expressed fusion protein in E. coli membranes were catalytically active for nifedipine oxidation, a typical enzymatic activity of P450 3A4. The NADPH-P450 reductase activities of these fusion protein were also determined by measuring reduction of cytochrome c. To fine a specific Inhibitor of P450 3A4 from naturally occurring chemicals, a series of isothiocyanate compounds were evaluated for the inhibitory activity of P450 using the fusion proteins in E. coli membranes. Of the five isothiocyanates (phenethyl isothiocyanate, phenyl isothiocyanate, benzol isothiocyanate, benzoyl isothiocyanate and cyclohexyl isothiocyanate) tested, benzoyl isothiocyanate showed a strong inhibition of P450 3A4 with an $IC_{50}$value of 2.8 $\mu\textrm{M}$. Our results indicate that the self-sufficient fusion protein will be very useful tool to study the drug metabolism and benzyl isothiocyanate may be valuable for characterizing the enzymatic properties of P450 3A4.

• Journal of Society of Preventive Korean Medicine
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• v.15 no.1
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• pp.1-16
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• 2011

Objectives : The mechanisms for korean traditional medicine-drug interaction has not been well reviewed in spite that the chance for co-administration with western drugs or diet supplements has been increased. Especially, it is well known that various cytochrome P450s play a major role in drug-drug interaction. Of course, Korean traditional medicines is not excluded in a view of metabolism or biotransformation by cytochrome P450. This article was focused on reviewing the possible roles of cytochrome P450 in Korean traditional medicine-drug interaction, Also, the directions for further studies were suggested in terms of Korean traditional medicine-drug interaction. Methods : New studies for korean traditional medicine-drug interaction were reviewed and summarized in terms of cytochrome P450 activities by various Korean traditional medicines and western drugs. Results and Conclusions : Even if a few studies related to Korean traditional medicine-drug interactions was carried out, almost no studies for Korean traditional medicine-drug interactions has been found in a view of cytochrome P450. It was suggested that Korean traditional medicines and their decoction should be analyzed that how they effects on cytochrome P450, expecially CYP 1, 2, 3 families and how they interact with western drugs.