• Journal of Marine Bioscience and Biotechnology
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• v.1 no.2
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• pp.71-75
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• 2006

The effect of protein extract from Asterina pectinifera on proliferation of human breast cancer cells and activities of cytochrome P450 1A1 and ornithine decarboxylase was tested. Protein extract from Asterina pectinifera inhibited the growth of both estrogen-dependent MCF-7 and estrogen-independent MDA-MB-231 human breast cancer cells. Cytochrome P450 1A1 activity was significantly inhibited by the protein extract from Asterina pectinifera at concentrations of 80 (p<0.05), 120 (p<0.01) and $160{\mu}g/m{\ell}$ (p<0.01). The extract inhibited induction of ornithine decarboxylase by 12-O-tetradecanoylphorbol-13-acetate, a key enzyme of polyamine biosynthesis, which is enhanced in breast tumor promotion. Therefore, Asterina pectinifera is worth further investigation with respect to breast cancer chemoprevention or therapy.

• BMB Reports
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• v.38 no.3
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• pp.366-369
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• 2005

NADPH-cytochrome P450 reductase (CPR) transfers electrons from NADPH to cytochrome P450 and also catalyzes the one-electron reduction of many drugs and foreign compounds. Various spectrophotometric assays have been performed to examine electron-accepting properties of CPR and its ability to reduce cytochrome $b_5$, cytochrome c, and ferricyanide. In this report, reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) by CPR has been assessed as a method for monitoring CPR activity. The principle advantage of this substance is that the reduction of MTT can be assayed directly in the reaction medium by a continuous spectrophotometric method. The electrons released from NADPH by CPR were transferred to MTT. MTT reduction activity was then assessed spectrophotometrically by measuring the increase of $A_{610}$. MTT reduction followed classical Michaelis-Menten kinetics ($K_m\;=\;20\;{\mu}M$, $k_{cat}\;=\;1,910\;min^{-1}$). This method offers the advantages of a commercially available substrate and short analysis time by a simple measurement of enzymatic activity of CPR.

• BMB Reports
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• v.37 no.5
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• pp.629-633
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• 2004

NADPH-cytochrome P450 reductase (CPR) transfers electrons from NADPH to cytochrome P450, and catalyzes the one-electron reduction of many drugs and foreign compounds. Various forms of spectrophotometric titration have been performed to investigate the electron-accepting properties of CPR, particularly, to examine its ability to reduce cytochrome c and ferricyanide. In this study, the reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH) by CPR was assessed as a means of monitoring CPR activity. The principle advantage of DPPH is that its reduction can be assayed directly in the reaction medium by a continuous spectrophotometry. Thus, electrons released from NADPH by CPR were transferred to DPPH, and DPPH reduction was then followed spectrophotometrically by measuring $A_{520}$ reduction. Optimal assay concentrations of DPPH, CPR, potassium phosphate buffer, and NADPH were first established. DPPH reduction activity was found to depend upon the strength of the buffer used, which was optimal at 100 mM potassium phosphate and pH 7.6. The extinction coefficient of DPPH was $4.09\;mM^{-1}\;cm^{-1}$. DPPH reduction followed classical Michaelis-Menten kinetics ($K_m\;=\;28\;{\mu}M$, $K_{cat}\;=\;1690\;min^{-1}$). This method uses readily available materials, and has the additional advantages of being rapid and inexpensive.

• Korean Journal of Biological Psychiatry
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• v.7 no.1
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• pp.14-20
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• 2000

Recently atypical antipsychotics have been used as first line agent in the treatment of schizophrenia, and also played a significant role in the treatment of many kinds of psychiatric disorders. The pharmacokinetic and pharmacodynamic properties of these newer antipsychotics are well known through preclinical and early clinical trials. However, it is important to note the limitations of the results due to its relatively short experience. Clozapine is eliminated principally by the hepatic P450 1A2 and 3A4 cytochrome enzymes. 1A2 inducers such as carbamazepine and smoking can reduce its half-life, while 1A2 inhibitors such as SSRIs, especially fluvoxamine can increase its duration of action. Carbamazepine should be avoided in a patient on clozapine because of carbamazepine's potential effects on bone marrow. Benzodiazepines tend to increase the chances of sedation, delirium and respiratory depression. Risperidone is metabolized to 9-hydroxyriperidone by the hepatic P450 2D6 cytochrome enzymes. Fluoxetine and paroxetine, 2D6 inhibitors interfere with metabolism, but 9-hydroxyrisperidone has similar biological activity as parental drug, so it has little affect on the outcome. Olanzapine shows minimal capacity to inhibit cytochrome P450 isoenzymes and shows minimal chance of drug interaction. It is eliminated principally by the hepatic P450 1A2 and 2D6 cytochrome enzymes.

• Biomolecules & Therapeutics
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• v.3 no.4
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• pp.245-250
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• 1995

The carbon tetrachloride($CCl_4$) has been demonstrated to have a hepatotoxic effect in human or many other species. To investigate the enzyme induction of mixed function oxygenases in liver of male Sprague-Dawley rats a single 0.1, 0.5 mι/kg dose of carbon tetrachloride were given. At 24 hr after a single dose of 0.1 mι CC1$_4$/kg weight, methanol extract of Hedera rhombea leaves was administered with 100, 500 mg/kg weight. Assays of 7-ethoxyresorufin-Ο-deethylation(EROD),7-benzyloxyresorufin-Ο-deathylation(BROD),4-nitro-phenol-UDP-glucuronosyltransferase(UDPGT), Western blot and RNA slot blot were used as representatives of the activities of cytochrome P-450 enzymes. The change of the activity of CYP1A1 form measured by EROD assay and Western analysis using 1-7-1 monoclonal antibody was not observed. The activity CYP2B1 form by BROD assay and using 2-66-3 monoclonal antibody was remarkably increased. Elevated level of CYP2B1 mRNA was shown by slot hybridization with 2B1-specific probe. Administration of methanol extract of Hedera rhombea leaves reversed the enzyme activity and the level of mRNA, which suggest the chemoprotective effect of methanol extracts of Hedera rhombea leaves to carbon tetrachloride hepatotoxlcity.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.128-128
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• 1995

To investigate the mechanism of the regulation of cytochrome P450IA1 gene expression, ethoxyresorufin deethylase(EROD) and benzo(a)pyrene hydroxylase in B6 mouse liver, in isolated perfused rat liver system. and in B6 mouse hepatocyte Hepa-I cells were examined. In C57BL/6N mouse, 3-methylcholan- throne( 3MC ) treatment have resulted in the stimulation of EROD activity based on fluorometry by 2.79 fold comparirng with that of control. Measurement of mRNA of cytochrome P450 was carried out by either nothern blot or dot blot analysis. Findings are similar to that of studies with enzymes. Furhtermore, when RTPCR method was applied to detect mRNA in Hepa I cell and liver tissues the results were more clear. Cytochrome P450IA1 upstream DNA containing CAT construct was transfected into Hepa-1 cells. After transfection of CAT construct, 3MC and flavonoids, such as, chrysin, hesperetin, kaempferol, morin, myricetin and aminoyrine were treated. 48 Hours after treatments, cells were harvested and assayed for CAT mRNA by RTPCR. 3MC treatment to hepa I cells transfected with trout P450IA1-CAT construct increased CAT mRNA by 2.81 fold when it was compared with that of control. This increase CAT mRNA was decreased by concomitantly treated flavonoids and aminopyrine. The level of CAT protein was 29.2-58.0% of 3MC stimulated CAT protein. Results of this study suggested that RTPCR seems to be a very good method to study regulation of gene expression in liver tissue or Hepa cells.

• 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 $50\;{\mu}g/ml$.

• Toxicological Research
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• v.30 no.1
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• pp.33-38
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• 2014

The human cytochrome P450 2J2 catalyzes an epoxygenase reaction to oxidize various fatty acids including arachidonic acid. In this study, three recombinant enzyme constructs of P450 2J2 were heterologously expressed in Escherichia coli and their P450 proteins were successfully purified using a $Ni^{2+}$-NTA affinity column. Deletion of 34 amino acid residues in N-terminus of P450 2J2 enzyme (2J2-D) produced the soluble enzyme located in the cytosolic fraction. The enzymatic analysis of this truncated protein indicated the typical spectral characteristics and functional properties of P450 2J2 enzyme. P450 2J2-D enzymes from soluble fraction catalyzed the oxidation reaction of terfenadine to the hydroxylated product. However, P450 2J2-D enzymes from membrane fraction did not support the P450 oxidation reaction although it displayed the characteristic CO-binding spectrum of P450. Our finding of these features in the N-terminal modified P450 2J2 enzyme could help understand the biological functions and the metabolic roles of P450 2J2 enzyme and make the crystallographic analysis of the P450 2J2 structure feasible for future studies.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.109-109
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• 2001

The present study was done to investigate the relationship between Kupffer cells and alteration of cytochrome P-450 (CYP)-dependent drug metabolizing enzyme activities during polymicrobial sepsis. Male rats were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP) followed by fluid resuscitation. The gadolinium chloride (GdC1$_3$, 10 mg/kg), blocker of Kupffer cells, was pretreated intravenously at 48 h and 24 h prior to the induction of CLP. All assay parameters were determined at 24 h after CLP or sham operation. In CLP-treated rats, the mortality rate of animals increased to 50% and serum alanine (ALT) and aspartate aminotransferase (AST) levels also significantly elevated. However, this increase was not suppressed by GdC1$_3$ pretreatment. Microsomal lipid peroxidation markedly increased after CLP operation. This increase was significantly attenuated by pretreatment. Total cytochrome P-450 content and NADPH-cytochrome P-450 reductase activity were not changed after CLP operation, but GdC1$_3$pretreatment reduced total cytochrome P-450 content, The hepatic microsomal CYP 1A1, 1A2, 2Bl and 2El activities in CLP-induced rats were also not significantly different from sham-operated rats. However, GdC1$_3$pretreatment showed a moderate increase in CYP1A1 and 1A2 activities. Our findings suggest that Kupffer cells may be partly responsible for producing hepatocellular dysfunction during sepsis.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.195-200
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• 2006

The response of hepatic mixed function oxygenase (MFO) system was investigated in olive flounder exposed to formalin. Hepatic microsome of olive flounder incubated in vitro with formalin demonstrated the induction of cytochrome P450 (CYP), ethoxyresorufin deethylase (EROD), cytochrome P450 reductase (P450R) and cytochrome b5 reductase (b5R) activity. In addition, olive flounder was exposed to 100, 300 and 500 ppm of formalin for 1 h and then transferred to a flow-through type of 1000 L aquarium. Hepatic MFO enzyme activity was determined for 72 h. As the result, hepatic CYP, P450R and EROD activities increased following exposure of formalin, but b5R and GST showed no significant change. These results imply that CYP and P450R can be considered as main hepatic enzymes involving in detoxification of formalin.