• Biomedical Science Letters
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• v.9 no.2
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• pp.75-84
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• 2003

To evaluate the influence of hepatic oxygen free radical systems on liver injury by topical p-phenylenediamine (PPD) application on rat skin, PPD (25 mg/16.5 $\textrm{cm}^2$) was topically applied to the abdominal region 5 times every other day and sacrificed. By PPD treatment, increasing rate of liver weight/body weight (%), serum activities of alanine aminotransferase and aspartate aminotransferase and decreasing rate of microsomal glucose-6-phosphatase activity were higher in the rats fed tungstate supplemented diet than those fed a standard diet. These findings indicate that group fed tungstate supplemented diet have more severe liver injury compared with group fed standard diet on topical PPD application. However, the activities of oxygen free radical generating enzymes such as xanthine oxidase (XO) and cytochrome P450 dependent aniline hydroxylase and those of oxygen free radical scavenging enzymes were not found to be different between these two animal groups. In the present study, a novel monitoring method to detect the generating of oxygen free radicals in liver extract was devised. Throughout this method, the oxidized PPD produced by oxygen free radicals was determined colorimetrically. The increasing rate of PPD oxidation by liver homogenate was higher in tungstate fed animals than in standard diet fed ones. Among the fractionations of liver extract, the mitochondrial and postmitochondrial fractions in the liver extract of tungstate fed animals led to a higher availability of PPD oxidation by PPD treatment compared with standard diet fed ones. In conclusion, these results suggest that an enhanced liver injury in tungstate fed animals treated with PPD may be due to oxygen free radicals produced in other systems except oxygen free radicals generating from cytosolic XO system. Especially, oxidative availability by PPD can be used for oxygen free radical detection in some tissue.

• Archives of Pharmacal Research
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• v.22 no.2
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• pp.99-107
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• 1999

A series of organosulfur compounds were synthesized with the aim of developing chemopreventive compounds active against hepatotoxicity and chemical carcinogesis. 2-(Allylthio) prazine (2-AP) was effective in inhibiting cytochrome P450 2E1-mediated catalytic activities and protein expression, and in inducing microsomal epoxide hydrolase and major glutathione S-transferases. 2-AP reduced the hepatotoxicity caused by toxicant sand elevated cellular GSH content. Development of skin tumors, pulmonary adenoma and aberrant crypt foci in colon by various chemical carcinogens was inhibited by 2-AP pretreatment. Anticarcinogenic effects of 2-AP at the stage of initiation of tumors were also observed in the aflatoxin B1 ($AFB_1$)-induced three-step medium-term hepatocarcinogenesis model. Reduction of $AFB_1$-DNA adduct by 2-AP appeared to result from the decreased formation of $AFB_1$-8,9-epoxide via suppression of cytochrome P450, while induction of GST 2-AP increases the excretion of glutathione-conjugated $AFB_1$ . 2-AP was a radioprotective agent effective against the lethal dose of total body irradiation and reduced radiation-induced injury in association with the elevation of detoxifying gene expression. 2-AP produces reactive oxygen species in vivo, which is not mediated with the thiol-dependent production of oxidants and that NF-KB activation is not involved in the induction of the detoxifying enzymes. the mechanism of chemoprotection by 2-AP may involve inhibition of the P450-mediated metabolic activation of chemical carcinogens and enhancement of electrophilic detoxification through induction of phase II detoxification enzymes which would facilitate the clearance of activated metabolites through conjugation reaction.

• Journal of Ginseng Research
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• v.27 no.1
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• pp.11-16
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• 2003

In this study, we investgated the effect of Red Ginseng (KRG) on liver damage induced by carbon tetrachloride (CTC) and galactosamine (GalN) in rats using indicator enzymes such as serum alanine/aspartate aminotransferases, sorbital dehydrogenase, lactate dehydrogenase, and ${\gamma}$-glutamyltransferase. Treatment of KRG restored these enzyme activities to near normal level compared to CTC or GalN treatment alone. Treatment of KRG also enhanced hepatic microsomal enzyme system, malondialdehyde formation, and depletion of reduced glutathione content, which were reduced by CTC or GalN. We also found that the decreased activities of glutathione S-transferase and glutathine reductase but not ${\gamma}$-glutamycysteine synthetase after KRG treatment restored to normal level. These results indicate that KRG has potent therapeutic activity against CTC- and GalN-induced hepatotoxicity in rat.

• Biomedical Science Letters
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• v.12 no.2
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• pp.91-97
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• 2006

The effects of intravenous administration of high concentration of taurocholic acid (TCA) on monoamine oxidase (MAO) A and B activities in rat liver mitochondria and microsomes were studied. These liver subcellular organelles and serum MAO activities were determined from the experimental rats with choledocho-caval shunt (CCS). The Michaelis-Menten constants in these hepatic enzymes were also measured. The activities of mitochondrial MAO A and B, and microsomal MAO B as well as their $V_{max}$ values were found to be decreased significantly in CCS plus TCA injected group then in the control group, such as CCS alone groups. However their $K_m$ values in the experimental groups did not vary. MAO of serum appeared in the CCS plus TCA injected groups only. The above results suggest that TCA represses biosynthesis of the MAO in the liver. The MAO of serum is believed to be caused by the increment of membrane permeability of hepatocytes upon TCA mediated liver cell necrosis.

• Journal of Nutrition and Health
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• v.34 no.8
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• pp.850-857
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• 2001

The study was designed to observe whether the conjugated linoleic acid supplemented to diet could reduce plasma levels of glucose and lipids which were increased in 27-weeks old Otsuka Long Evans Tokushima Fatty(OLETF) rats. Twenty male OLETF rats of 7 weeks old were fed an experimental diet containing 4.5%(w/w) total fat including 1% CLA and six of twenty rats were sacrified at 6 weeks feeding. The rest of OLETF rats was divided into 2 groups, one group was continuously fed for 14 weeks more the same experimental diet containing 1% CLA and the other group was fed control diet which eliminated CLA. CLA did not significantly reduce food intake and body weight gain in OLETF obese rats. Plasma triglyceride and total cholesterol level were significantly increased at older age of OLETF obese rats, but CLA could significantly reduce plasma cholesterol and triglyceride increased in obese rats. However, CLA was not strong enough to reduce the increased plasma glucose level and hepatic lipogenic enzyme acitivies. CLA was mostly deposited in epididymal fat pad and could be incorporated into hepatic microsomal membrane and did interfere the conversion of C18 : 0 into C18 : 1 in liver. In conclusion, CLA could have anti-atherogenic effect by reducing plasma cholesterol and triglyceride which was increased in genetically obese rats, but CLA(1%) was not good source of dietary fatty acid to reduce body fatness and plasma glucose which was increased by obese gene in older rats.

• Archives of Pharmacal Research
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• v.27 no.8
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• pp.867-872
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• 2004

Oxidative stress due to reactive oxygen species (ROS) can cause oxidative damage to cells. Cells have a number of defense mechanisms to protect themselves from the toxicity of ROS. Mitochondria are especially important in the oxidative stress as ROS have been found to be constantly generated as an endogen threat. Mitochondrial defense depends mainly on super-oxide dismutase (SOD) and glutathione peroxidase (GPx), whereas microsomal defense depends on catalase (CAT), which is an enzyme abundant in microsomes. SOD removes superoxide anions by converting them to $H_2O$$_2$, which can be rapidly converted to water by CAT and GPx. Also, GPx converts hydroperoxide (ROOH) into oxidized-glutathione (GSSG). Ovariectomized (OVX) rats are used as an oxidative stress model. An ovariectomy increased the levels of MDA, one of the end-products in the lipid peroxidative process, and decreased levels of the antioxidative enzymes； SOD, CAT and GPx. However, Chondroitin sulfate (CS) decreased the levels of MDA, but increased the levels of SOD, CAT and GPx in a dose-depen-dent manner. Moreover, inflammation and cirrhosis of liver tissue in CS- treated rats were sig-nificantly decreased. These results suggest that CS might be a potential candidate as an anti oxidative reagent.

• YAKHAK HOEJI
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• v.23 no.2
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• pp.111-118
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• 1979

It was previously reported that cytochrome P$_{450}$ content in liver was increased when Capsicum acetone extract was given chronically to rats. The present study is aimed to investigate the effect of capsaicin, a principal component of red pepper, on the drug metabolizing enzymes in rat liver. Capsaicin (5mg/kg) was given intraperitoneally once a day for seven days and zoxazolamine paralysis time and hexobarbital sleeping time were determined 24 hrs after the last dose of capsaicin. Plasma hexobarbital concentration was also determined five and 15 min after hexobarbital administration to rats. Zoxazolamine paralysis time and hexobarbital sleeping time were shortened by 31.6% and 37.1%, respectively, compared with control group. Plasma hexobarbital concentration was lowered by 26.2% after five min and by 35.2% after 15 min, respectively, compared with control group. However, administration of single dose of capsaicin did not affect the zoxazolamine paralysis time and hexobarbital sleeping time. Microsomal cytochrome P$_{450}$ content and NADPH-cytochrome C reductase activity were increased by 14.6% and 11.6%, respectively in the rats pretreated with capsaicin for seven days, while cytochrome b$_{5}$ content was not changed. These results suggest that treatment with capsaicin for seven days may induce the drug metabolizing enzyme in rat liver.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.11a
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• pp.135-140
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• 1994

Over past decades, numerous in vitro model has been developed to investigate drug metabolism. In the order of complexity we found the isolated perfused liver, hepatocytes in co-culture with epithelial cells, hepatocytes in suspension and in primary culture and subcellular hepatic microsomal fractions. Because they can be easily prepared from both animals (pharmacological and toxicological species) and humans (whole livers as well as biopsies obtained during surgery) hepatocytes in primary culture provide the most powerful model to better elucidate drug behavior at an early stage of preclinical development such as : 1. the characterization of main biotransformation reactions. 2. the identification of phase I and phase II isozymes involved in such reactions 3. the evaluation of interspecies differences allowing the selection of a second toxicological animal species more closely related to man on the basis of metabolic profiles 4. the detection of the inducing and/or inhibitory effects of a drug on metabolic enzymes, the prediction of drug interactions 5. the estimation of inter-individual variability in biotransformation reactions. The use of hepatocytes, and in particular those obstained from humans, at an early stage of drug development allows the obtention of more predictive preclinical data and a better knowledge of drug behavior in humans before the first administration of the drug in healthy volunteers.

• Toxicological Research
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• v.32 no.1
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• pp.21-33
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• 2016

Dichlorodiphenyltrichloroethane (DDT) is still used in certain areas of tropics and subtropics to control malaria and other insect-transmitted diseases. DDT and its metabolites have been extensively studied for their toxicity and carcinogenicity in animals and humans and shown to have an endocrine disrupting potential affecting reproductive system although the effects may vary among animal species in correlation with exposure levels. Epidemiologic studies revealed either positive or negative associations between exposure to DDT and tumor development, but there has been no clear evidence that DDT causes cancer in humans. In experimental animals, tumor induction by DDT has been shown in the liver, lung, and adrenals. The mechanisms of hepatic tumor development by DDT have been studied in rats and mice. DDT is known as a non-genotoxic hepatocarcinogen and has been shown to induce microsomal enzymes through activation of constitutive androstane receptor (CAR) and to inhibit gap junctional intercellular communication (GJIC) in the rodent liver. The results from our previously conducted 4-week and 2-year feeding studies of p,p'-DDT in F344 rats indicate that DDT may induce hepatocellular eosinophilic foci as a result of oxidative DNA damage and leads them to hepatic neoplasia in combination with its mitogenic activity and inhibitory effect on GJIC. Oxidative stress could be a key factor in hepatocarcinogenesis by DDT.

• Archives of Pharmacal Research
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• v.26 no.10
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• pp.800-804
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• 2003

The effects of KR-31378, a neuroprotective agent for ischemia-reperfusion damage, on liver microsomal cytochrome P450s (CYPs) were investigated in male Sprague Dawley rats. When rats were treated orally with KR-31378 for 7 consecutive days, CYP3A-selective erythromycin N-demethylase (ERDM) activity was significantly induced in a dose-dependent manner. In Western immunoblotting, CYP 3A proteins were clearly induced by treatment with KR-31378. Within 24 h after treatment with 80 mg/kg of KR-31378, ERDM activity was induced in liver microsomes in accompanied by induction of the level of CYP 3A proteins. The present results suggest that KR-31378 might modulate the expression of CYP 3A enzymes in humans.