Production of coloured glass-ceramics from incinerator ash using thermal plasma technology.

Incineration is a major treatment process for municipal solid waste in Taiwan. It is estimated that over 1.5 Mt of incinerator ash are produced annually. This study proposes using thermal plasma technology to treat incinerator ash. Sintered glass-ceramics were produced using quenched vitrified slag with colouring agents added. The experimental results showed that the major crystalline phases developed in the sintered glass-ceramics were gehlenite and wollastonite, but many other secondary phases also appeared depending on the colouring agents added. The physical/mechanical properties, chemical resistance and toxicity characteristic leaching procedure of the coloured glass-ceramics were satisfactory. The glass-ceramic products obtained from incinerator ash treated with thermal plasma technology have great potential for building applications.

Impairment of hepatic cytochrome P-450-dependent monooxygenases by the malaria parasite Plasmodium berghei.

The effect of Plasmodium berghei infection on hepatic monooxygenase activities and cytochrome P-450 contents was investigated in mice. NIH/NMRI or A/J mice infected with active P. berghei showed 30-40% decreases in hepatic cytochrome P-450 contents and the ability to metabolize the test substrates, ethylmorphine and benzo(a)pyrene. These decreases were observed during the erythrocytic stage of the infection, but not during the initial exoerythrocytic stage, or after heat-inactivated sporozoites were injected. These results strongly suggest that malaria infections may significantly impair the capacity of the liver to metabolize drugs, carcinogens, and other foreign compounds.

Selective induction and inhibition of liver and lung cytochrome P-450-dependent monooxygenases by the PCBs mixture, Aroclor 1016.

The effects of the widely used industrial PCBs mixture, Aroclor 1016, as modifiers of monooxygenases were studied in rats and rabbits. From data presented, it is not possible to generalize the biological effects of PCBs observed with rats, namely, that they are potent, non-specific inducers of monooxygenase activities. In rat liver, Aroclor 1016 exhibited primarily the potent inducing effects of the barbiturate class of inducers. In contrast, in rabbits pretreated with Aroclor 1016, although cytochrome P-450 content of the liver was significantly increased, benzphetamine N-demethylase and benzo[a]pyrene hydroxylase activities were decreased 30-35%; and no changes in the O-deethylation of 7-ethoxycoumarin and 7-ethoxyresorufin were observed. These results strongly suggest differences in the regulation of cytochrome P-450 isozymes in the liver by the PCBs. A similar conclusion can be drawn from the pulmonary studies of Aroclor 1016-pretreated rabbits. In the lung, cytochrome P-450, form 2 and associated enzymic activities were markedly decreased, with little or no effect on the form 5 isozyme. Electrophoretic and chromatographic studies confirmed these findings. The induction and the repression of a form or forms of cytochrome P-450 by environmentally-derived chemicals may be important determinants of organ-targeted chemical toxicity.

Induction and inhibition of cytochrome P-450-dependent monooxygenases in hamster tissues by ethanol.

The effects of ethanol on hamster hepatic and extrahepatic monooxygenases were determined in the present study. Chronic ethanol administration increased cytochrome P-450 (P-450) content and monooxygenase activities towards aniline, N-nitrosodimethylamine, and 7-ethoxyresorufin. In contrast, benzphetamine and benzo(a)pyrene oxidation rates were decreased 21-24% by ethanol. In kidney, ethanol pretreatment increased P-450 content, aniline and N-nitrosodimethylamine oxidation activities. In lung, ethanol ingestion selectively increased aniline hydroxylation without affecting other monooxygenase activities. Intestinal monooxygenase activity was refractory to ethanol induction. Immunoblotting of the microsomal proteins showed that ethanol induced a protein cross-reactive with rabbit antibody raised against human P-450 2E1 in hamster liver, kidney, and lung. Immunoblotting analysis using mouse monoclonal antibody 1-12-3 raised against scup P-450 1A1 revealed that ethanol induced an immunorelated protein in hamster liver, kidney, and lung. Induction of P-450 2E1 and 1A was not observed with intestinal protein blots. Immunoblotting analysis using mouse monoclonal antibody 2-66-3 against rat P-450 2B1 showed inhibition of an immunorelated protein in ethanol-treated hamster liver. The inhibitory effect on P-450 2B was not observed with extrahepatic tissues. These results suggest that ethanol has the ability to induce P-450s 2E1 and 1A and to inhibit P-450 2B in hamster tissues.

Metabolism of benzo(a)pyrene by lung microsomes from rabbits pretreated with polychlorinated biphenyls and 2,3,4,7,8-pentachlorodibenzofuran.

The polychlorinated biphenyls (PCBs) mixture, Aroclor 1254, is a weak inducer of aryl hydrocarbon hydroxylase (AHH) activity in rabbit lung. In contrast, 2,3,4,7,8-pentachlorodibenzofuran (PCDF), like 3-methylcholanthrene (3-MC), caused a 3-fold increase in pulmonary AHH activity. An important finding of the present studies was that AHH activity, whether assayed by the flourometric or HPLC methods, was dependent on the buffer used in the incubation mixture. The metabolism of benzo(a)pyrene (BP) to its oxidative metabolites, as assayed by HPLC, revealed that PCBs, PCDF and 3-MC pretreatments caused greater than 15-fold and about 3- to 4-fold increase in the formation of the tumorigenic metabolites 9,10- and 7,8-dihydrodiols, respectively. In contrast to 3-MC and PCDF, PCBs caused a 75% decrease in the formation of the K-region metabolite, BP-4,5-dihydrodiol. These studies strongly suggest that the catalysis of BP metabolism is mediated by more than one isoform of cytochrome P450 (P450).

Polychlorinated biphenyls (PCBs) inducible monooxygenases in rabbits and mice: species and organ specificities.

The effects of the PCBs mixture, Aroclor 1254, as modifiers of monooxygenases were studied in rabbits and mice. From data presented, it is not possible to generalize the biological effects of PCBs observed with rats, namely, that they are potent, nonspecific inducers of monooxygenase activities. This environmental pollutant enhanced microsomal drug-metabolizing enzymes in livers of rabbits and C57Bl/6J and DBA/2J mice. In rabbit lung, it inhibited, and in rabbit kidney, it enhanced the metabolism of ethylmorphine. Further, at dosages used, PCBs were poor inducers of aryl (benzo(a)pyrene) hydroxylase activity in livers of C57BL/6J and DBA/2J mice; they enhanced aryl hydrocarbon hydroxylase activity in rabbit kidney but caused a significant depression of its activity in rabbit lung. These studies demonstrate that the biologic impact of the widely distributed environmental pollutant, PCBs, may differ in different species and emphasize the need to carry out toxicological studies in more than one species of animals. The differential effects observed on various organs may also be important determinants of organ-targeted chemical toxicity.

Induction of cytochrome P450 1A1 in human hepatoma HepG2 cells by 6-nitrochrysene.

The present study has determined the effects of 6-nitrochrysene (6-NC) on human cytochrome P450-dependent monooxygenases in human hepatoma HepG2 cells. Treatment of HepG2 cells with 6-NC increased the activities of microsomal benzo[a]pyrene hydroxylase, 7-ethoxycoumarin and 7-ethoxyresorufin O-deethylases, cytosolic glutathione S-transferase and N-acetyltransferase, and S9 metabolic activation of 6-NC in the Ames mutagenicity test. Immunoblot and RNA blot analyses revealed that 6-NC induced CYP1A1 protein and mRNA levels in the hepatoma cells. Nuclear transcription assay demonstrated that 6-NC increased the transcription rate of CYP1A1 gene in HepG2 cells. Treatment of human lung carcinoma NCI-H322 cells with 6-NC increased benzo[a]pyrene hydroxylase activity and CYP1A1 protein and mRNA levels. These results demonstrate that 6-NC is an inducer of human CYP1A1 and the induction occurs at a transcriptional level in HepG2 cells. The ability of 6-NC to induce liver and lung CYP1A1 may be an important factor to consider in assessing 6-NC metabolism and toxicity in humans.

Regioselective metabolism of benzo[a]pyrene and 7-chlorobenz[a]anthracene by fish liver microsomes.

Many polycyclic aromatic hydrocarbons (PAHs) and chlorinated PAHs in the environment are potent mutagens and carcinogens. Using benzo[a]pyrene (BaP) and 7-chlorobenz[a]anthracene (7-Cl-BA) as representatives of PAHs and chlorinated PAHs, respectively, we studied the metabolism of these compounds in liver microsomes of Tilapia (Oreochromis hybrid), one of the most common fish in south Asia. The regioselective metabolism of BaP and 7-Cl-BA by the fish liver microsomes resulted in the formation of hydroxylated and trans-dihydrodiol metabolites of both BaP and 7-Cl-BA. The metabolites were purified by HPLC and identified by both UV/VIS and mass spectroscopic methods. The fish liver microsomes metabolized BaP to form BaP-7,8-dihydrodiol (11%), 3-hydroxy-BaP (17%), and 9-hydroxy-BaP (22%) as the major products and metabolized 7-Cl-BA to form 7-Cl-BA trans-8,9-dihydrodiol as the major metabolite (40%). The Tilapia liver microsomal P-450 enzyme activities were inducible by pretreatment with 3-methylcholanthrene (3-MC), which increased microsomal aryl hydrocarbon hydroxylase and 7-ethoxyresorufin O-deethylase activities by 74- and 360-fold, respectively. The induction of these enzymes by 3-MC was greater in fish microsomes than in rat liver. This study is the first to demonstrate the regioselective metabolism of BaP and 7-Cl-BA by fish liver microsomes.

Suppression of microsomal cytochrome P450-dependent monooxygenases and mitochondrial oxidative phosphorylation by fullerenol, a polyhydroxylated fullerene C60.

The acute toxicity of fullerenol-1 was determined using mice pretreated intraperitoneally (i.p.) with polyhydroxylated C60 derivatives. The LD50 value of fullerenol-1 was estimated to be 1.2 g/kg. Pretreatments with 0.5 and 1.0 g/kg fullerenol-1 decreased cytochromes P450 and b5 contents, and NADPH-cytochrome P450 reductase, benzo[a]pyrene hydroxylase, 7-ethoxycoumarin O-deethylase, aniline hydroxylase, and erythromycin N-demethylase activities in liver microsomes. Pretreatments with 0.01 and 0.1 g/kg fullerenol-1 had no effect on these monooxygenases. Additions of fullerenol-1 to mouse liver microsomes suppressed monooxygenases activities toward benzo[a]pyrene, 7-ethoxycoumarin, aniline, and erythromycin with IC50 values of 42, 94, 102 and 349 microM, respectively. Fullerenol-1 exhibited noncompetitive and mixed-type of inhibition in benzo[a]pyrene hydroxylation and 7-ethoxycoumarin O-deethylation, respectively. Additions of fullerenol-1 to rat liver mitochondria resulted in a dose-dependent inhibition of ADP-induced uncoupling and markedly inhibited mitochondrial Mg2+ -ATPase activity with an IC50 value of 7.1 microM. These results demonstrate that fullerenol-1 can suppress the levels of the microsomal enzymes in vivo and decrease the activities of P450-dependent monooxygenase and mitochondrial oxidative phosphorylation in vitro.

Involvement of oxidative stress in motorcycle exhaust particle-induced DNA damage and inhibition of intercellular communication.

In this study, we investigated the involvement of reactive oxygen species (ROS) in the motorcycle exhaust particle (MEP)-induced genotoxic and non-genotoxic activity in mammalian cell systems. Initially, the capability of MEP to induce ROS was evaluated by using 2',7'-dichlorofluorescin diacetate (DCFH-DA) to detect hydrogen peroxide (H2O2). A five-fold increase in H2O2 was observed in Chinese hamster lung V79 and human lung carcinoma Calu-1 cells treated with 100 microg/ml MEP for 2 h. Under the same experimental conditions, only a two-fold elevation in H2O2 was detected in hepatic cell systems such as BNL.Cl.2, HepG2, and Hep3B. Treatment of the V79 cells with varying concentrations of MEP caused a dose-dependent increase in sister chromatid exchanges (SCEs), which are effectively inhibited by addition of antioxidants, N-acetyl-l-cysteine (NAC) and ascorbic acid. Furthermore, we determined the oxidized bases in the V79 cells after exposure to MEP. The result showed that 500 microg/ml MEP induced a 3.7-fold increase in thymine glycol (TG) and a seven-fold increase in 8-hydroxy-guanosine (8-OHGua) as compared to untreated cells. We subsequently examined whether MEP would affect gap junctional intercellular communication (GJIC), a tumor promotion process, in V79 cells. We found that MEP inhibited GJIC in a dose-response fashion. Maximal inhibition occurred at 500 microg/ml. The concentration that inhibited at 0.5 of the fraction of the control was 200 microg/ml. Interestingly, when cells were pretreated with NAC or ascorbic acid, they could abolish the MEP-mediated inhibition of GJIC. In addition, a moderate decrease of glutathione was observed in the V79 cells during exposure to MEP. Taken together, our findings suggest that MEP can induce oxidative stress in a broad range of cell lines, especially in lung cell systems. The MEP-induced oxidative stress was critically involved in both genotoxic and non-genotoxic activity.

Modulation of cytochrome P-450-dependent monooxygenases, glutathione and glutathione S-transferase in rat liver by geniposide from Gardenia jasminoides.

Geniposide is an iridoid glycoside extracted from the fruits of Gardenia jasminoides, which are used as a food colorant and as a traditional Chinese medicine for treatment of hepatic and inflammatory diseases. The effects of geniposide and G. jasminoides fruit crude extract on liver cytochrome P-450 (P-450)-dependent monooxygenases, glutathione and glutathione S-transferase were investigated using rats treated orally with the iridoid glycoside (0.1 g/kg body weight/day) or the fruit crude extract (2 g/kg/day) for 4 days. The treatments decreased serum urea nitrogen level but increased liver to body weight ratio, total hepatic glutathione content and hepatic cytosolic glutathione S-transferase activity. Treatments with geniposide and G. jasminoides decreased P-450 content, benzo[a]pyrene hydroxylation, 7-ethoxycoumarin O-deethylation, and erythromycin N-demethylation activities in liver microsomes without affecting aniline hydroxylation activity. The natural products had no effect on glutathione content and monooxygenase activities in kidney microsomes. Immunoblotting analyses of liver microsomal proteins using mouse monoclonal antibody 2-13-1 to rat P4503A1/2 revealed that geniposide and G. jasminoides crude extract decreased the intensity of a P4503A-immunorelated protein. Protein blots probed with mouse monoclonal antibody 1-12-3 to rat P4501A1 and rabbit polyclonal antibody against human P4502E1 showed that both treatments had little or no effect on P4501A and 2E proteins. The present findings demonstrate that geniposide from G. jasminoides has the ability to inhibit a P4503A monooxygenase and increase glutathione content in rat liver.

Induction of cytochromes P450 1A1 and 1B1 in human lung adenocarcinoma CL5 cells by frying-meat emission particulate.

The effect of airborne frying-meat emission particulate (FMEP) on cytochrome P450 (P450)-dependent monooxygenase was determined using human lung adenocarcinoma cell line CL5 treated with organic extract of FMEP prepared from beef, fish or pork. Treatment with fish FMEP extract caused greater increases of intracellular peroxide production and glutathione content than did beef and pork FMEP extracts. Treatment with 200 microg/ml beef, fish or pork FMEP extract for 6 h increased benzo[a]pyrene hydroxylase, 7-ethoxyresorufin and methoxyresorufin O-dealkylases activities in S9. Immunoblot analysis of S9 proteins from control cells and cells treated with FMEP extracts revealed that the airborne particulates increased proteins immunorelated to CYP1A1 and CYP1B1. Northern blot analysis of total cellular RNA from controls and cells treated with FMEP extracts showed that the cooking by-products increased the levels of CYP1A1 and CYP1B1 mRNA. Treatment with 1 microM dibenzo[a,h]anthracene for 6 h increased monooxygenase activities, CYP1A1 and CYP1B1 protein and mRNA levels in CL5 cells. Beef FMEP extract and dibenzo[a,h]anthracene also induced CYP1A1 and CYP1B1 in human lung carcinoma NCI-H322 cells. The present finding demonstrates that airborne particulates generated during the frying of beef, fish and pork can induce carcinogen-metabolizing CYP1A1 and CYP1B1 in the human lung-derived cell line CL5.

Induction of cytochrome P-450 1A1 in human hepatoma HepG2 and lung carcinoma NCI-H322 cells by motorcycle exhaust particulate.

The effects of motorcycle exhaust particulate (MEP) on human cytochrome P-450 (P-450)-dependent monooxygenases were determined using human hepatoma cell line HepG2 and lung carcinoma cell line NCI-H322 treated with organic extracts of MEP from a two-stroke engine. Gas chromatography and mass spectrometry analysis of MEP extract revealed the presence of carcinogens benzo[a]pyrene, benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[g,h,i]perylene, chrysene, and indeno[1,2,3-c,d]pyrene in the chemical mixture. Treatment with MEP extract produced concentration- and time-dependent increases of monooxygenase activity in HepG2 cells. Treatment of the cells with 100 microg/ ml MEP extract for 24 h markedly increased benzo[a]pyrene hydroxylation, 7-ethoxycoumarin, and 7-ethoxyresorufin O-deethylation activities in microsomes. Immunoblot analysis of microsomal proteins using mouse monoclonal antibody 1-12-3 against P-450 1A1 revealed that MEP extract induced a P-450-immunorelated protein in the hepatoma cells. RNA blot analysis of cellular total RNA using a human P-450 1A1 3'-end cDNA probe showed that MEP extract increased the level of a hybridizable P-450 mRNA. These P-450 1A1 inductive effects of MEP extract were similar to those from treatment with 10 microM benzo[a]pyrene or 3-methylcholanthrene (3-MC) in HepG2 cells. Treatment of lung carcinoma NCI-H322 cells with 100 microg/ml MEP extract, 10 microM benzo[a]pyrene, or 3-MC resulted in induction of monooxygenase activity, protein, and mRNA of P-450 1A1, similar to the induction observed with the hepatoma cells. The present study demonstrates that MEP extract has the ability to induce human hepatic and pulmonary P-450 1A1 in the liver- and lung-derived cell lines, and the induction involves a pretranslational mechanism. Induction of the human hepatic and pulmonary P-450 1A1 in vitro may provide important information in the assessment of MEP metabolism and toxicity in humans.

Effects of motorcycle exhaust on cytochrome P-450-dependent monooxygenases and glutathione S-transferase in rat tissues.

The effects of motorcycle exhaust (ME) on cytochrome P-450 (P-450)-dependent monooxygenases were determined using rats exposed to the exhaust by either inhalation, intratracheal, or intraperitoneal administration. A 4-wk ME inhalation significantly increased benzo[a]pyrene hydroxylation, 7-ethoxyresorufin O-deethylation, and NADPH-cytochrome c reductase activities in liver, kidney, and lung microsomes. Intratracheal instillation of organic extracts of ME particulate (MEP) caused a dose- and time-dependent significant increase of monooxygenase activity. Intratracheal treatment with 0.1 g MEP extract/kg markedly elevated benzo[a]pyrene hydroxylation and 7-ethoxyresorufin O-deethylation activities in the rat tissues 24 h following treatment. Intraperitoneal treatment with 0.5 g MEP extract/kg/d for 4 d resulted in significant increases of P-450 and cytochrome b5 contents and NADPH-cytochrome c reductase activity in liver microsomes. The intraperitoneal treatment also markedly increased monooxygenases activities toward methoxyresorufin, aniline, benzphetamine, and erythromycin in liver and benzo[a]pyrene and 7-ethoxyresorufin in liver, kidney, and lung. Immunoblotting analyses of microsomal proteins using a mouse monoclonal antibody (Mab) 1-12-3 against rat P-450 1A1 revealed that ME inhalation, MEP intratracheal, or MEP intraperitoneal treatment increased a P-450 1A protein in the hepatic and extrahepatic tissues. Protein blots analyzed using antibodies to P-450 enzymes showed that MEP intraperitoneal treatment caused increases of P-450 2B, 2E, and 3A subfamily proteins in the liver. The ME inhalation, MEP intratracheal, or MEP intraperitoneal treatment resulted in significant increases in glutathione S-transferase activity in liver cytosols. The present study shows that ME and MEP extract contain substances that can induce multiple forms of P-450 and glutathione S-transferase activity in the rat.

Induction of cytochrome P-450-dependent monooxygenases by isoniazid in hamster liver, kidney and lung.

The effects of isoniazid on liver, kidney, and lung monooxygenases were determined using hamsters administered 0.8% of the antituberculosis drug in drinking water. Binding of isoniazid to liver microsomal cytochrome P-450 induced a Type II difference spectrum and the spectral binding was enhanced in hamsters treated with isoniazid. The levels of cytochrome P-450, NADPH-cytochrome c reductase, and cytochrome b5 in the tissues microsomes from isoniazid-treated hamsters were similar to the respective levels in control animals. In the liver, treatment with isoniazid caused 5- and 3-fold induction of aniline hydroxylase and N-nitrosodimethylamine demethylase activities, respectively. The treatment was without effect on hepatic benzo(a)pyrene hydroxylase or 7-ethoxycoumarin O-deethylase activities. In the kidneys, isoniazid treatment caused 6-, 2-fold, and 42% increases in monooxygenase activities toward aniline, N-nitrosodimethylamine, and 7-ethoxycoumarin, respectively. However, the treatment caused a 15% decrease in renal benzo(a)pyrene hydroxylase activity. In the lungs, isoniazid caused a 69% increase in aniline hydroxylase and, in contrast, a 30% decrease in 7-ethoxycoumarin O-deethylase activities. The treatment had no significant effects on pulmonary catalytic activities toward N-nitrosodimethylamine and benzo(a)pyrene. Gel electrophoresis of liver and kidney microsomes from control and isoniazid-treated hamsters revealed that the treatment increased the intensity of a protein band in the P-450 molecular weight region. Immunoblotting of microsomal proteins showed that the protein band induced by isoniazid in the liver, kidney and lung was cross-reactive with antibody raised against ethanol-inducible human liver P-450.(ABSTRACT TRUNCATED AT 250 WORDS)

The hepatoprotective effects of Solanum alatum Moench. on acetaminophen-induced hepatotoxicity in mice.

Solanum alatum Moench. has been shown to have a protective effect against carbon tetrachloride (CCl4)-induced liver injury. Solanum alatum treatment (100 mg/kg, p.o.) decreased the elevation of serum alanine aminotransferase (ALT; GPT) and aspartate aminotransferase (AST; GOT) induced by acetaminophen (paracetamol) (600 mg/kg, i.p.) administration. It also decreased the extent of visible necrosis in liver tissue. In addition, Solanum alatum treatment restored hepatic glutathione (GSH) depletion induced by acetaminophen (600 mg/kg, i.p.) administration. Microsomal enzyme levels such as P-450, reductase, and aniline hydroxylation enzyme were also restored to normal levels after Solanum alatum administration. The hepatoprotective mechanism may function through direct binding with acetaminophen toxic metabolites, decreasing the attraction of acetaminophen metabolites for other cellular GSH or thiol protein. Additionally, Solanum alatum treatment increased the concentration of hepatic GSH and maintained a high level activity of GSTase, which led to acceleration of the excretion of toxic acetaminophen metabolites.

Hepatoprotective effects of Arctium lappa on carbon tetrachloride- and acetaminophen-induced liver damage.

The root of Arctium lappa Linne (A. lappa) (Compositae), a perennial herb, has been cultivated for a long time as a popular vegetable. In order to investigate the hepatoprotective effects of A. lappa, male ICR mice were injected with carbon tetrachloride (CCl4, 32 microl/kg, i.p.) or acetaminophen (600 mg/kg, i.p.). A. lappa suppressed the SGOT and SGPT elevations induced by CCl4 or acetaminophen in a dose-dependent manner and alleviated the severity of liver damage based on histopathological observations. In an attempt to elucidate the possible mechanism(s) of this hepatoprotective effect, glutathione (GSH), cytochrome P-450 (P-450) and malondialdehyde (MDA) contents were studied. A. lappa reversed the decrease in GSH and P-450 induced by CCl4 and acetaminophen. It was also found that A. lappa decreased the malondialdehyde (MDA) content in CCl4 or acetaminophen-intoxicated mice. From these results, it was suggested that A. lappa could protect the liver cells from CCl4 or acetaminophen-induced liver damages, perhaps by its antioxidative effect on hepatocytes, hence eliminating the deleterious effects of toxic metabolites from CCl4 or acetaminophen.

Modulation of microsomal cytochrome P450 by Scutellariae Radix and Gentianae scabrae Radix in rat liver.

The present study has determined the effects of Scutellariae Radix (Huangqin) and Gentianae scabrae Radix (Longdan) on liver microsomal cytochrome P450 (P450)-dependent mono-oxygenases using rats pretreated with crude extracts of medicinal herbs. Scutellariae Radix resulted in a 53% decrease of pentoxyresorufin O-dealkylase activity in liver microsomes. In contrast, Gentianae scabrae Radix caused a 50% increase of benzo(a)pyrene hydroxylase activity. Immunoblotting analysis of liver microsomes revealed that Scutellariae Radix induced and suppressed the levels of P450 1A and 2B proteins, respectively. Scutellariae and Gentianae scabrae Radixes had no effects on microsomal aniline hydroxylase activity and P450 2E1 protein.