• Environmental Mutagens and Carcinogens
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• v.24 no.4
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• pp.180-188
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• 2004

CYP1A1 is known to be inducible by xenobiotic compouds such as polyciclic aromatic hydrocarbons(PAHs) and 2,3,7,8-tetrachloro-dibenzo-p-dioxin(TCDD). These chemicals have been identified worldwide and can have a significant impact on the human health and well being of human and wildlife. Given these issues, the detection and quantification of these chemicals in biological, environmental and food samples is important. We investigated the effect of dietaty flavonoid, such as CYP1A1 promoter activity, 7-ethoxyresorufin-O-deethylase(EROD) activity and CYP1A1 mRNA expression induced by benzo(k)fluoranthene(B(k)F) in MCF-7 cells. Based on the three criteria of frequency of occurrence in the environment, toxicity and potential exposure to humans, B(k)F is one of the top-listed PAHs. We found that B(k)F significantly up-regulates the level of CYP1A1 promoter activity, EROD and CYP1A1 mRNA. when cells were treated with daidzein inhibited the B(k)-induced CYP1A1 prompter activity and mRNA level at high concentration. But daidzein exhibited stimulatory effects B(k)F-induced CYP1A1 promoter activity and mRNA level at low concentration. Overall, results from these studies demonstrate flavonoids might interfere the action of B(k) with AhR system to stimulate CYP1A1 gene expression.

• Journal of Microbiology and Biotechnology
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• v.25 no.9
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• pp.1417-1424
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• 2015

In this study, we tried to characterize Streptomyces peucetius CYP157C4 with homology modeling using three cytochrome P450 (CYP) structures (CYP157C1, CYP164A2, and CYP107L1), having discovered that CYP157C4 lacks the ExxR motif that was considered invariant in all CYPs. We used Discovery Studio 3.5 to build our model after first assessing the stereochemical quality and side-chain environment, and a 7-ethoxycoumarin substrate was docked into the final model. The model-substrate complex allowed us to identify functionally important residues and validate the active-site architecture. We found a distance of 4.56 Å between the 7-ethoxycoumarin and the active site of the heme, and cloning and an in vitro assay of the CYP157C4 showed the dealkylation of the substrate. Since the details regarding this group of CYP structures are still unknown, the findings of this study may provide elucidation to assist with future efforts to find a legitimate substrate.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.102-108
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• 2008

Many alternative biocidal additives were applied to antifouling paint to replace TBT, and Sea-Nine 211 is one of alternating organic booster compounds used in antifouling paint. In this study, extent of Sea-Nine 211 toxicity on marine benthic bivalve is evaluated. Sea-Nine 211 was injected to surf clam, Pseudocardium sachalinensis, that inhabitate northern part of Gangwon Province, Korea. Survival rate of the clam and xenobiotics metabolizing enzyme activities in digestive gland were measured during 4 day-exposure period. The results were compared with those of TBT exposed clam. There were no mortality of clam in the solvent (DMSO) control group and the three Sea-Nine 211 exposure groups (5, 25, 50 mg kg$^{-1}$ body weight), while the clam exposed to 1, 2 and 5 mg kg$^{-1}$ TBT chloride (TBTC) demonstrated 70, 30 and 0% survival rate, respectively. The Sea-Nine 211 exposure group showed a tendency of cytochrome P450 (CYP) induction according to the exposure duration, on the other hand, CYP content was decreased in the TBT exposure group. NADPH cytochrome P450 reductase activity slightly increase according to the exposure duration in the Sea-Nine 211 exposure group, while TBTC inhibit its activity as CYP content. Moreover, there was no significant change of NADH cytochrome b5 reductate activity in the clam epxosed to Sea-Nine 211. In the TBTC exposure group, its activity increased in early exposure period and then significantly decreased the rest of exposure period. All the results indicate that Sea-Nine 211 demonstrated a tendency to induce CYP level, while TBTC inhibits the CYP level, NADPH cytochrome P450 reductase and NADH cytochrome b5 reductase activities.

• Environmental Analysis Health and Toxicology
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• v.21 no.1 s.52
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• pp.13-19
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• 2006

화학적 예방효과가 있는 식물성 에스트로젠은 다양한 환성을 나타내며 여러 세포 수용체와 상호작용한다. Genistein은 isoflavone의 주요물질 중의 하나로 콩류에 존재하며 대표적인 식물성 에스트로젠이다. 본 논문에서는 유방암 세포주인 MCF-7에서 aryl hydrocarbon receptor(AhR)에 의해 매개되는 발암물질 활성화 경로에 대한 genistein의 영향을 살펴보았다. 세포에 genistein을 처리할 경우 cytochrome P450 1A1(CYP1A1) 약물대사효소의 특이적인 효소반응인 7-ethoxyresorufin O-deethylase (EROD) 활성도와 CYP1A1의 유전자 발현이 genistein의 농도 의존적으로 증가하였다. Genistein과 발암물질인 방향족탄화 수소 7, 12-dimethylbenz[a]anthracene(DMBA)를 동시 처리하였을 경우 DMBA에 의해 유도되어 증가된 EROD활성도와 CYP1A1의 유전자 발현이 genistein에 의해 감소하였다. 랫트의 간에서 분리한 세포질을 이용하여 genistein과 AhR의 대표적인 ligand인 2,3,7,8-tetrachlorodibenzo-p-dioxin과 경쟁적 결합에 대한 영향을 조사한 결과 genistein이 AhR에 경쟁적으로 결합함을 알 수 있었다. 이러한 결과들은 genistein이 천연 AhR ligand임을 암시한다. 따라서, 식물성 에스트로젠인 genistein은 AhR경로의 길항제/항진제로 작용할 수 있을 것으로 사료된다.

• Archives of Pharmacal Research
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• v.27 no.2
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• pp.239-245
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• 2004

KR-31543, (2S,3R,4S)-6-amino-4-[N-(4-chlorophenyl)-N-(2 -methyl-2H-tetrazol-5-ylmethyl) amino]-3,4-dihydro-2-dimethoxymethyl-3-hydroxy-2-methyl-2H-1-benzopyran, is a new neuroprotective agent for preventing ischemia-reperfusion damage. This study was performed to identify the metabolic pathway of KR-31543 in human liver microsomes and to characterize cytochrome P450 (CYP) enzymes that are involved in the metabolism of KR-31543. Human liver microsomal incubation of KR-31543 in the presence of NADPH resulted in the formation of two metabolites, M1 and M2. M1 was identified as N-(4-chlorophenyl)-N-(2-methyl-2H-tetrazol-5-ylmethyl)amine on the basis of LC/MS/MS analysis with a synthesized authentic standard, and M2 was suggested to be hydroxy-KR-31543. Correlation analysis between the known CYP enzyme activities and the rates of the formation of M 1 and M2 in the 12 human liver microsomes have showed significant correlations with testosterone 6$\beta$-hydroxylase activity (a marker of CYP3A4). Ketoconazole, a selective inhibitor of CYP3A4, and anti-CYP3A4 monoclonal antibodies potently inhibited both N-hydrolysis and hydroxylation of KR-31543 in human liver microsomes. These results provide evidence that CYP3A4 is the major isozyme responsible for the metabolism of KR-31543 to M1 and M2.

• Korean Journal of Clinical Pharmacy
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• v.26 no.4
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• pp.312-317
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• 2016

Objective: Midazolam is mainly metabolized by cytochrome P450 (CYP) 3A. Inhibition or induction of CYP3A can affect the pharmacological activity of midazolam. The aims of this study were to develop a population pharmacokinetic (PK) model and evaluate the effect of CYP3A-mediated interactions among ketoconazole, rifampicin, and midazolam. Methods: Three-treatment, three-period, crossover study was conducted in 24 healthy male subjects. Each subject received 1 mg midazolam (control), 1 mg midazolam after pretreatment with 400 mg ketoconazole once daily for 4 days (CYP3A inhibition phase), and 2.5 mg midazolam after pretreatment with 600 mg rifampicin once daily for 10 days (CYP3A induction phase). The population PK analysis was performed using a nonlinear mixed effect model ($NONMEM^{(R)}$ 7.2) based on plasma midazolam concentrations. The PK model was developed, and the first-order conditional estimation with interaction was applied for the model run. A three-compartment model with first-order elimination described the PK. The influence of ketoconazole and rifampicin, CYP3A5 genotype, and demographic characteristics on PK parameters was examined. Goodness-of-fit (GOF) diagnostics and visual predictive checks, as well as bootstrap were used to evaluate the adequacy of the model fit and predictions. Results: Twenty-four subjects contributed to 900 midazolam concentrations. The final parameter estimates (% relative standard error, RSE) were as follows; clearance (CL), 31.8 L/h (6.0%); inter-compartmental clearance (Q) 2, 36.4 L/h (9.7%); Q3, 7.37 L/h (12.0%), volume of distribution (V) 1, 70.7 L (3.6%), V2, 32.9 L (8.8%); and V3, 44.4 L (6.7%). The midazolam CL decreased and increased to 32.5 and 199.9% in the inhibition and induction phases, respectively, compared to that in control phase. Conclusion: A PK model for midazolam co-treatment with ketoconazole and rifampicin was developed using data of healthy volunteers, and the subject's CYP3A status influenced the midazolam PK parameters. Therefore, a population PK model with enzyme-mediated drug interactions may be useful for quantitatively predicting PK alterations.

• 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.

• Biomolecules & Therapeutics
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• v.19 no.2
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• pp.237-242
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• 2011

This study was designed to investigate the effects of glipizide on the pharmacokinetics of carvedilol after oral or intravenous administration of carvedilol in rats. Clinically carvedilol and glipizide can be prescribed for treatment of cardiovascular diseases as the complications of diabetes, and then, Carvedilol and glipizide are all substrates of CYP2C9 enzymes. Carvedilol was administered orally or intravenously without or with oral administration of glipizide to rats. The effects of glipizide on cytochrome P450(CYP) 2C9 activity and P-gp activity were also evaluated. Glipizide inhibited CYP2C9 activity in a concentration-dependent manner with 50% inhibition concentration ($IC_{50}$) of 18 ${\mu}M$. Compared with the control group, the area under the plasma concentration-time curve (AUC) was significantly increased by 33.0%, and the peak concentration ($C_{max}$) was significantly increased by 50.0% in the presence of glipizide after oral administration of carvedilol. Consequently, the relative bioavailability (R.B.) of carvedilol was increased by 1.13- to 1.33-fold and the absolute bioavailability (A.B.) of carvedilol in the presence of glipizide was increased by 36.8%. After intravenous administration, compared to the control, glipizide could not significantly change the pharmacokinetic parameters of carvedilol. Therefore, the enhanced oral bioavailability of carvedilol may mainly result from inhibition of CYP2C9-mediated metabolism rather than both P-gp-mediated effl ux in the intestinal or in the liver and renal elimination of carvedilol by glipizide.

• Environmental Mutagens and Carcinogens
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• v.24 no.4
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• pp.198-205
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• 2004

Cytochrome P4501B1(CYP1B1) is known to be inducible by xenobiotic compounds such as policyclic aromatic hydrocarbon(PAH) and dioxins such as 2,3,7,8-tetrachloro-dibenzo-p-dioxin(TCDD). And these induction of CYP1B1 is also regulated by many categories of chemicals. In order to investigate the effects of several chemicals on CYP1B1 gene expression in Hepa-I and MCF-7 cells, 5' flanking DNA of human CYP1B1 was cloned into pGL3 basic vector containing luciferase gene, and then transfected into these cells. After treatment of chemicals, the luciferase activity was measured. CYP1B1 enzyme metabolize PAHs and estradiol. CYP1B1 metabolize estradiol to 4-hydrozyestradiol that is considered as carcinogenic metabolite. Recent industrialized industrialized society, human has been widely been exposed to widespread environmental contaminants such as PAHs(polycyclic aromatic hydrocarbon) that are originated from the imcomplete combustion of hydrocarbons. PAHs are known to be ligands of the AhR(aryl hydrocarbon receptor). Induction of cytochrome P4501B1(CYP1B1) in cell culture is widely used as a biomarker for PAHs. Therefore we have studied the effect of PAHs in the human breast cancer cells MCF-7 to evaluate bioactivity of PAHs. We have used the United State of America EPA selected 13 different PAHs, PAHs mixtures and extracts from environmental samples to evaluate the bioassay system. We examined effects of PAHs on the CYP1B1-luciferase reporter gene and CYP1B1 mRNA level. Benzo(k)fluoranthene and dibenzo(a, h)anthracene showed strong response to CYP1B1 promoter activity stimulation, and also CYP1B1 mRNAs increase in MCF-7 cells in a concentration-dependent manner. RT-PCR analysis indicated that PAHs significantly up-regulate the level of CYP1B1 mRNA. Some flavonoids such as genistein, daidzein, chrysin, naringenin and morin were also investigeted. These flavonoids decreased B(k)F infuced luciferase activity at low concentration. But, these flavonoids exhibited stimulatory effect at high concentration.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.119.2-119.2
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• 2003

Exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes a variety of biological and toxicology effects, most of which are mediated by aryl hydrocarbon receptor (AhR). The ligand-bound AhR as a heterodimer with AhR nuclear translocator (ARNT) binds to its specific DNA recognition site, the dioxin-responsive element (DRE), and it results in increased transcription of CYP1A1 gene. Retinoic acid (RA) regulates the transcription of various genes for several essential functions through binding to two classes of nuclear receptors, the retinoic acid receptor (RAR) and retinoid X receptor (RXR). (omitted)