• 생물정신의학
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• 제7권1호
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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.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1995년도 춘계학술대회
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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.

• 동의생리병리학회지
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• 제21권6호
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• pp.1534-1542
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• 2007

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 Sprague-Dawley (SD) rats and Chang cell. And the SR also showed significant decrease of malodialdehyde (MDA) and increase of glutathion (GSH), catalase activity in rat liver homogenate. The expression of cytochrome P450 2E1 (CYP2E1), measured by RT-PCR and western blot, was significantly decreased in the SR treated SD rats and Chang cell. But $CCl_4$ and SR has no significant effect on 1A1 and 3A1 isoform of cytochrome P450. Based on these findings, it is suggested that hepatoprotective effects of SR possibly related to antioxidative effects and downregulation of CYP2E1 expression.

• Preventive Nutrition and Food Science
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• 제8권2호
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• pp.158-161
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• 2003

This study investigated the effects of a ${\gamma}$-irradiated pork (0-30 kGy) diet on lipid peroxidation, cytochrome P-450 content, microsomal glucose 6-phosphatase (G-6-Pase) activity and antioxidative defense systems in diethylnitrosamine (DEN)-induced rat hepatocarcinogenesis. The body weight of rats fed irradiated diets did not change significantly. Liver weight was significantly increased by the administration of DEN, but not by irradiated diets at any dose level. There were no significant effects of gamma irradiation on the content of microsomal malondialdehyde (MDA), cytochrome P-450, or on the activity of G-6-Pase. However, with DEN treatment, cytochrome P-450 content was significantly increased while microsomal G-6-Pase activity was significantly decreased. The ${\gamma}$-irradiated diet supplement did not affect serum retinol or $\alpha$-tocopherol concentrations. However, it did cause a significant decrease in hepatic retinol at 30 kGy. With DEN treatment, hepatic retinol content was even more significantly (p<0.05) decreased compared to the non-irradiated control. The enzyme activities related to antioxidative defense systems, including glutathione peroxidase (GSH-Px), glutathione reductase (GSH-Rx) and glutathione S-transferase (GST) were not affected by gamma irradiation. Those results suggest that an irradiated pork diet up to 30 kGy may not cause a health hazard in experimental animals.

• BMB Reports
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• 제37권5호
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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.

• Biomolecules & Therapeutics
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• 제27권6호
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• pp.577-583
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• 2019

Human cytochrome P450 2C9 is a highly polymorphic enzyme that is required for drug and xenobiotic metabolism. Here, we studied eleven P450 2C9 genetic variants-including three novel variants F69S, L310V, and Q324X-that were clinically identified in Korean patients. P450 2C9 variant enzymes were expressed in Escherichia coli and their bicistronic membrane fractions were prepared The CO-binding spectra were obtained for nine enzyme variants, indicating P450 holoenzymes, but not for the M02 (L90P) variant. The M11 (Q324X) variant could not be expressed due to an early nonsense mutation. LC-MS/MS analysis was performed to measure the catalytic activities of the P450 2C9 variants, using diclofenac as a substrate. Steady-state kinetic analysis revealed that the catalytic efficiency of all nine P450 2C9 variants was lower than that of the wild type P450 2C9 enzyme. The M05 (R150L) and M06 (P279T) variants showed high $k_{cat}$ values; however, their $K_m$ values were also high. As the M01 (F69S), M03 (R124Q), M04 (R125H), M08 (I359L), M09 (I359T), and M10 (A477T) variants exhibited higher $K_m$ and lower $k_{cat}$ values than that of the wild type enzyme, their catalytic efficiency decreased by approximately 50-fold compared to the wild type enzyme. Furthermore, the novel variant M07 (L310V) showed lower $k_{cat}$ and $K_m$ values than the wild type enzyme, which resulted in its decreased (80%) catalytic efficiency. The X-ray crystal structure of P450 2C9 revealed the presence of mutations in the residues surrounding the substrate-binding cavity. Functional characterization of these genetic variants can help understand the pharmacogenetic outcomes.

• 사상체질의학회지
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• 제24권4호
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• pp.84-91
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• 2012

Objectives : The purpose of this study is to investigate the inhibitory or inductive potentials of Yuldahanso-tang (YDT) and Chungsimyonja-tang (CST), herbal formulas for Taeeumin, on cytochrome P450 (CYP450) drug metabolizing enzyme. The mechanisms for the herbal formula-drug interaction has not been well reported in spite of the chance for co-administration with conventional drugs. Methods : To evaluate the interaction potential of YDT-drug or CST-drug, the fluorescence-based enzyme assays on CYP450 isozymes including CYP3A4, CYP2C19, CYP2D6 and CYP2E1 were established in vitro. The inhibitory effects of herbal formulas were characterized with $IC_{50}$ values. Results : YDT showed inhibitory effects on CYP2D6 and CYP2E1-mediated metabolism, while it exhibited week inhibition on CYP3A4 and CYP2C19 relatively. CST exerted relatively weak inhibitory effects on the four CYP450 isozymes compared to that of YDT. Conclusions : These results suggest that the herbal formula-drug interaction could be occur when YDT are co-administered with drugs mediated by CYP2D6 or CYP2E1.

• 한국약용작물학회지
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• 제24권1호
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• pp.7-13
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• 2016

Background : Ginger has been extensively used in foods and traditional medicines in Asian countries. Despite its frequent consumption in daily life, the mechanism of potential interactions between ginger components-drug has not been examined. To elucidate the mechanism of governing the effects of 6-shogaol, a primary constituent of dried ginger, on human cytochrome P450 (CYP) isoenzymes an incubation studies were carried out using pooled human liver microsome (HLM). Methods and Results : CYP isoenzyme specific substrate was incubated with multiple concentrations of inhibitor, HLM and cofactors. 6-shogaol showed a potent inhibitory effect on CYP2C9, CYP1A2 and CYP2C19 with half maximal inhibitory concentration ($IC_{50}$) values of 29.20, 20.68 and $18.78{\mu}M$ respectively. To estimate the value of the inhibition constant ($K_i$) and the mode of inhibition, an incubation study with varying concentrations of each CYP isoenzyme-specific probe was performed. 6-shogaol inhibited CYP2C9 and CYP2C19 noncompetitively ($K_i=29.02$ and $19.26{\mu}M$ respectively), in contrast, the inhibition of CYP1A2 was best explained by competitive inhibition ($K_i=6.33{\mu}M$). Conclusions : These findings suggest that 6-shogaol may possess inhibitory effects on metabolic activities mediated by CYP1A2, CYP2C9 and CYP2C19 in humans.

• Journal of Microbiology and Biotechnology
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• 제27권5호
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• pp.983-989
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• 2017

NADPH-P450 reductase (NPR) transfers electrons from NADPH to cytochrome P450 and heme oxygenase enzymes to support their catalytic activities. This protein is localized within the endoplasmic reticulum membrane and utilizes FMN, FAD, and NADPH as cofactors. Although NPR is essential toward enabling the biochemical and pharmacological analyses of P450 enzymes, its production as a recombinant purified protein requires a series of tedious efforts and a high cost due to the use of $NADP^+$ in the affinity chromatography process. In the present study, the rat NPR clone containing a $6{\times}$ Histidine-tag (NPR-His) was constructed and heterologously expressed. The NPR-His protein was purified using $Ni^{2+}$-affinity chromatography, and its functional features were characterized. A single band at 78 kDa was observed from SDS-PAGE and the purified protein displayed a maximum absorbance at 455 nm, indicating the presence of an oxidized flavin cofactor. Cytochrome c and nitroblue tetrazolium were reduced by purified NPR-His in an NADPH-dependent manner. The purified NPR-His successfully supported the catalytic activities of human P450 1A2 and 2A6 and fungal CYP52A21, yielding results similar to those obtained using conventional purified rat reductase. This study will facilitate the use of recombinant NPR-His protein in the various fields of P450 research.

• 동의생리병리학회지
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• 제16권6호
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• pp.1201-1206
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• 2002

In oriental medicine, human being is classified into four groups according to their body constitution status (;tae-yang, tae-eum, so-yang, and so-eum persons) considering the differences in function of internal organs and characteristics. Four body constitution, called 'sa-sang' has been recognized as an important factor for diagnosing the patients before madical teratment. Yet, the criteria to divide body constitutions or its scientific principle are not clearly defined. As an initial effort to elucidate biological priciples underlying four body constitution groups, we studied genetic variations among three constitution groups (tae-eum, so-yang, and so-eum persons). Noting distinct responses to ingested food and administered drugs among three groups, SNPs and haplotype experiments were performed in 2D6, 2C9, and 1A2 DNA regions of the cytochrome P450 gene. Significant variability in SNPs types was found in 2D6 region. Moreover, haplotyping in 2D6 region showed relatively high occurrences of haplotype 3 and 5 in so-eum person, haplotype 6 in tae-eum person, and hyplotype 1 in so-yang person. These results indicate that individuals with different body constitutions respond differently to ingested food and drugs, which might reflect constitution-specific genetic background. The genetic approach would therefore be useful to reveal intrinsic differences among four constitution body groups in the responsiveness to various drugs and external stimulations to human body.