• Title/Summary/Keyword: cytochrome P450 2E1

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Study on the Hepatoprotective Effect and Cytochrome P450 Regulation of Scutellaria Radix (황금의 간세포 보호활성 및 cytochrome P450 발현 조절에 관한 연구)

  • Ha, Ki-Tae;Jeong, Sang-Sin;Kim, Cheorl-Ho;Choi, Dall-Yeong;Kim, June-Ki
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.22 no.1
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    • pp.155-161
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    • 2008
  • Carbon tetrachloride $(CCl_4)-induced$ liver injury depends on a toxic agent that has to be metabolized by the liver NAPDH-cytochrome P450 enzyme system to a highly reactive intermediate. Although several isoforms of cytochrome P450 may metabolize $CC1_4$, attention has been focused largely on the cytochrome P450 2E1 (CYP2E1), which is ethanol-inducible. Alternations in the activity of CYP2E1 affect the susceptibility to hepatic injury from $CC1_4$. In this study, the liver protective effect of the hot water extracts of Scutellaria radix (SR) was investigated. The SR exhibited a hepatoprotective activity against $CCl_4-induced$ liver damage in Chang liver cells. The expression of CYP2E1, measured by RT-PCR and Western blot analysis, was significantly decreased by SR treatment in Chang cells. Based on these findings, it is suggested that hepatoprotective effect of SR possibly related to downregulation of CYP2E1 expression.

Induction of Phase II Enzymes and Inhibition of Cytochrome P450 Isozymes by Chitosanoligosaccharides

  • SHON, YUN-HEE;NAM, KYUNG-SOO
    • Journal of Microbiology and Biotechnology
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    • v.15 no.1
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    • pp.183-187
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    • 2005
  • Abstract The cancer chemopreventive potential of chitosanoligosaccharides was investigated by measuring the induction of quinone reductase and glutathione S-transferase activities and inhibition of cytochrome P450 1A1, 2B1, and 2E1 activities. Chitosanoligosaccharide I (1-${\kappa}$Da${\kappa}$Da) significantly induced glutathione S-transferase activity with a maximal 1.5-fold increase at 500 ${\mu}$g/ml, while chitosanoligosaccharide II (3-${\kappa}$Da${\kappa}$Da) (500 ${\mu}$g/ml) strongly induced quinone reductase (p<0.01) and glutathione S-transferase (p<0.005) activities. The in vitro incubation of rat liver microsomes with chitosanoligosaccharides I and II (2.5, 5, 50, and 500 ${\mu}$g/ml) showed a dose-dependent inhibiton of cytochrome P450 1A1, 2B1, and 2E1 activities. Chitosanoligosaccharide II was a more potent inhibitor of cytochrome P450 2B1 activity than chitosanoligosaccharide I. Accordingly, these findings suggest that chitosanoligosaccharides are potential chemopreventive agents.

Toxic action of N-dimethylphosphinothioyl carbofuran by oxidative activation process (산화적 활성화 과정을 통한 N-dimethoxyphosphinothioyl carbofuran의 독성발현)

  • Yang, Kyew-Wan;Lee, Seog-Jong;Kim, Song-Mun;Han, Dae-Sung;Hur, Jang-Hyun
    • The Korean Journal of Pesticide Science
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    • v.2 no.2
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    • pp.10-15
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    • 1998
  • The bimolecular inhibition rate constants of carbofuran and N-dimethylphosphinothioyl carbofuran(PSC) to acetylcholinesterase(AChE) were $7.7{\times}10^{5}\;M^{-1}{\cdot}min^{-1}$ and $1.2{\times}10^{3}\;M^{-1}{\cdot}min^{-1}$, respectively. These results showed that PSC required a bioactivation process for its toxic action because it didn't inhibit the target enzyme effectively. The potency of PSC as an inhibitor of AChE increased when PSC and AChE were incubated with microsomes fortified with NADPH compared with microsome alone. Piperonyl butoxide(PBO) addition to these coupled systems greatly reduced the inhibition of the target enzyme by blocking the bioactivation process. In vivo inhibition study of mouse brain AChE, $I_{50}$ value for AChE was 28 mg/kg for PSC and the value increased to 57 mg/kg when PBO was pretreated. This result showed that cytochrome $P_{450}$ would also play a role in the bioactivation process of PSC in vivo. And conversioin of carbofuran from PSC was 55 % in a chemical oxidation system using meta-chloroperoxybenzoic acid. The oxidative activation of PSC to carbofuran was shown to be essential for showing its toxicological action and cytochrome $P_{450}$ was identified as an important enzyme which participated in this process.

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A Study on the metabolism mechanism of Benzene, Toluene and Xylene by Cytochrome P-450 dependent radical-mediated (Cytochrome P-450 의존성 radical 전달에 의한 Benzene, Toluene, Xylene의 대사기전 연구)

  • 김기웅;장성근;김양호;문영한
    • 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

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METABOLISM AND DISPOSITION OF CHLORZOXAZONE IN RATS: EFFECTS OF ETHANOL AND DISULFIRAM

  • Kim, Dong-Hyun;Park, Misuk;Park, Jongsei
    • Toxicological Research
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    • v.9 no.1
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    • pp.35-44
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    • 1993
  • Role of rat cytochrome P-450 2E1(P-450 2E 1) in the metabolism of chlorzoxazone was examined by using several approaches' (1) selective inhibiton of catalytic activity in rat liver microsomes by diethyldithiocarbamate, (2) correlation of dimethylnitrosomine N-demethylation with chlorzoxazone 6-hydroxylation, and (3) immunoinhibition of catalytic activity with rabbit anti-rat P-450. The results indicated that P-450 2E1 is responsible for the metabolism of chlorzoxazone.

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Inhibitory Effects of Medicinal Herbs on Cytochrome P450 Drug Metabolizing Enzymes (생약추출물의 Cytochrome P450 약물대사 효소계 저해활성)

  • Jeong, Hye-Gwang;You, Ho-Jin;Chang, Young-Su;Park, Sung-Jun;Moon, Young-Hee;Woo, Eun-Rhan
    • Korean Journal of Pharmacognosy
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    • v.33 no.1 s.128
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    • pp.35-41
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    • 2002
  • The MeOH ext., $CH_2Cl_2$ Frac., EtOAc Frac., n-BuOH Frac., and $H_2O$ Frac. of 23 Korean medicinal herbs were prepared and were tested the inhibitory effects on Cytochrome P450 (Cyp) 1A1/2, 2B1/2, 2E1. Among the tested samples, the extracts of Selaginella tamariscina, Euonymus alatus, Salvia miltiorhiza, Angelica acutiloba, Rheum palmatum, Paeonia moutan, Scutellaria barbata, Tribulus terrestris, Hedyotis diffusa, Curcuma zedoaria, Rehmania glutinosa, Trogopterus xanthipes, Melandryum firmum, Achyranthes bidentata, Leonurus sibricus, Panax ginseng, Paeonia lactiflora, Poncirus trifoliata, Cnidium officinale, Cyperus rotundus, Corydalis ternata showed significant inhibitory effects on Cyp 1A1/2, 2B1/2, 2E1. The $IC_{50}$ values of those extracts were found to be below $50\;{\mu}g/ml$.

Inhibition of Acetylcholinesterase and Butyrylcholinesterase by Phosalone via Bioactivation (Phosalone의 활성화과정을 통한 acetylcholinesterase와 butyrylcholinesterase에 대한 활성 저해)

  • Lim, Geum-Choon;Han, Dae-Sung;Hur, Jang-Hyun
    • Applied Biological Chemistry
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    • v.38 no.2
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    • pp.174-178
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    • 1995
  • The purpose of this study was to investigate a role of cytochrome $P_{450}$, for the toxicity of the phosalone in in vitro and in vivo bioactivation systems. The bimolecular inhibition rate constants$(k_i)$ of the phosalone to acetylcholinesterase(AChE) and butyrylcholinesterase(BuChE) were approximately $10^2M^{-1}{\cdot}min^{-1}$, respectively, which meant a poor inhibitor. The potency of the phosalone as an inhibitor of AChE and BuChE was increased about 300 and 40 fold, respectively, when the inhibitor and the ChE were incubated with microsomes fortified with NADPH compared with microsome alone. Piperonyl butoxide(PB) addition to these coupled systems greatly reduced the inhibition of both target enzymes by blocking a bioactivation process. The $I_{50}$ value of the Phosalone alone for rat brain AChE was 170 mg/kg. When PB was pretreated, that value was altered to 42.5 mg/kg. PB pretreatment synergized the inhibition of brain AChE with four times. Rat blood erythrocyte AChE and plasma BuChE were similarly inhibited in vivo by the phosalone and PB pretreatment didn't affect significantly the pattern of the inhibition. The in vivo studies showed different results in the role of cytochrome $P_{450}$ from those of the in vitro studies.

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Responses in Hepatic Xenobiotic Metabolizing Enzymes and Sex Hormones of Yellowfin Goby Acanthogobius flavimanus in Nakdong Estuary (낙동강 하구에서 채집한 문절망둑 Acanthogobius flavimanus의 간장 약물대사효소계와 성호르몬 농도)

  • Lee, Ji-Seon;Jeong, Jee-Hyun;Han, Chang-Hee;Shim, Won-Joon;Jeon, Joong-Kyun
    • Korean Journal of Environmental Biology
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    • v.26 no.2
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    • pp.87-93
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    • 2008
  • To assess effects of contaminants on fish in Nakdong river, feral yellowfin goby Acanthogobius flavimanus were caugt in two different sites and its hepatic monooxygenase enzyme, including cytochrome P450 (CYP), NADPH-cytochrome P450 reductase (P450R), NADH-cytochrome b5 reductase (b5R), ethoxyresorufin deethylase (EROD), glutathione S-transferase (GST) were quantitatively determined. Gonadosomatic index (GSI), hepatosomatic index (HSI) and three sex steroid hormone (17$\beta$-estradiol, E2; testosterone, T; 11-ketotestosterone, 11-KT) levels of the fish were also investigated. HSI of fish from polluted site (site 1) were significantly higher than that of unpolluted site (site 2), but GSI levels were significantly lower in polluted site. No significant differences in plasma 11-KT and T levels were observed in two sites surveyed. E2 level was, however, significantly (p<0.05) higher in female fish from site 1 than site 2. In addition, hepatic EROD activity and CYP level of site 1 fish were lower than those of site 2 fish, whereas relatively high levels of P450R, b5R and GST activities were found in site 1. The results imply that yellowfin goby, especially female fish in Nakdong river estuary are affected from contaminants disrupting sex steroid hormone system.

Induction of Hepatic Microsomal Cytochrome P450 by N,N-dimethylformamide in Sprague-Dawley Rats (흰쥐에서 N,N-dimethylformamide에 의한 간장의 Microsomal Cytochrome P450의 유도)

  • Koh, Sang-Baek;Cha, Bong-Suk;Kang, Seung-Kyu;Joung, Hyo-Seok;Kim, Ki-Woong
    • Journal of Preventive Medicine and Public Health
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    • v.32 no.1
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    • pp.88-94
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    • 1999
  • Objectives. In order to gain a better understanding of the mechanism of DMF toxicity, recent studies have focused on hepatic drug metabolizing enzymes. In this study, we investigated the effects of DMF on the induction of P450 and the activities of other related enzymes in rat liver microsomes. Methods. DMF was administered to male Sprague Daweley rats by intraperitoneal injection at 0(control), 450(D1), 900(D2), 1,800(D3) mg DMF/kg body weight in olive oil once a day for three days. Hepatic P450 was measured by method of Omura and Sato. We evaluated selective assays for the three drug metabolizing cytochrome P450 isoenzymes 1A1, 2B1 and 2E1. Results. The content of microsomal protein, P450 and b5 were tended to be decreased in DMF treated group, but they were not statistically significant. The activity of NADPH-cytochrome P450 reductase was significantly increased dose dependently(p<0.01), but the activity of NADH-b5 reductase was decreased in the treated group(p<0.01). The activities of PROD and EROD were not significant between control and treated group. The activities of pNPH in the DMF treated groups were higher than that of the control group(p<0.01). When Western immunoblottings were carried out utilizing three monoclonal antibodies which were specific against P4501A1/1, P4502B1/2 and P4502E1, the strong density band corresponding to P4502E1 was observed with the microsomes obtained from the rats treated with DMF. But there were no significant increased in the P4501A1/2 and P4502B1/2 band densities in immunoblotting. Conclusions. These result suggested that P4502E1 was inducible by DMF and P4502E1 isozyme might be responsible for the hydroxylation of DMF to HMMF.

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Rubus coreanus Extract Attenuates Acetaminophen Induced Hepatotoxicity; Involvement of Cytochrome P450 3A4

  • Lee, Young-Ik;Whang, Kyung-Eun;Cho, Jin-Sook;Ahn, Byung-Min;Lee, Sang-Bum;Dong, Mi-Sook;Kim, Tae-Hyun
    • Biomolecules & Therapeutics
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    • v.17 no.4
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    • pp.455-460
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    • 2009
  • Foods of plant origin, especially fruits and vegetables, have attracted attention because of their potential benefits to human health. In this report, Rubi Fructus (RF), the dried unripe fruit of Rubus coreanus Miq (Rosaceae) and ellagic acid (EA) purified from RF were used to test their potential hepatoprotective effect against acetaminophen (AAP)-induced hepatotoxicity in rats. RF extract (RFext) and EA reduced the elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) in serum and the content of lipid peroxide in liver by AAP administration, while the increment of the cellular glutathione (GSH) content and the induction of glutathione S-transferase (GST) and glutathione peroxidase (GSH-PX) which were decreased by AAP administration. RFext and EA from RFext did not affect the two major form of cytochrome P450s, cytochrome P450 2E1 (CYP2E1) and cytochrome P450 1A2 (CYP1A2), but downregulated the cytochrome P450 3A4 (CYP3A4) related to the conversion of AAP to N-acetyl-P-benzoquinone imine (NAPQI). These results suggest that RFext and EA from RF exhibit a hepatoprotective effect not only by increasing antioxidant activities but also by down-regulating CYP3A4 in the AAP-intoxicated rat.