• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.198-198
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• 2001

No report has been addressed to the CYP isoforms catalyzing chlorpropamide, a structural analogue of tolbutamide. To evaluate enzyme(s) mediating formation of 2-hydroxycWorpropamide, a major metabolite and identified by LC/Mass and NMR, incubation studies using human liver microsomes and cDNA expressed CYP were performed on the presence or absence of selective inhibitors of each CYP isoform. (omitted)

• Environmental Mutagens and Carcinogens
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• v.23 no.3
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• pp.99-102
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• 2003

IARC classified areca quid as a human carcinogen. Areca quid chewed in Taiwan includes Piper betle inflorescence, which contains high concentrations of safrole (15 mg/fresh weight). Safrole is a documented rodent hepatocarcinogen, and chewing areca quid may contribute to human exposure (420 $\mu$m in saliva). The carcinogenicity of safrole is mediated through 1'-hydroxysafrole formation, followed by sulfonation to an unstable sulfate that reacts to form DNA adducts. Using human liver microsomes and Escherichia coli membranes expressing bicistronic human P450s, CYP2E1 and CYP2C9 were identified as the main P450s involved in the activation of safrole. We have demonstrated the presence of stable safrole-dGMP adducts in human oral tissues following areca quid chewing using $^{32}$ P-postlabeling and HPLC mass spectrometry methods. By studying 88 subjects with a known AQ chewing history and 161 matched controls, we have demonstrated that the presence of safrole-DNA adducts in peripheral blood cells was correlated to AQ chewing, and CYP2E1 seemed to play an important role in the modulation of safrole-DNA adduct formation. We have also shown that safrole can form stable safrole-DNA adducts as well as oxidative damages in rodent liver. However, the stable safrole-DNA adducts may represent a more significant initial lesion as compared to the rapidly repaired safrole-induced 8-hydroxy-2'-deoxyguanosine. This oxidative DNA damage is mediated through the formation of hydoryxchavicol, the major safrole metabolite in human urine. Hydroxychavicol may have gone through two-electron oxidation to the o-quinone; then via one-electron reduction to semiquinone radicals to generate oxidative DNA damage. However, these reactive metabolites can be efficiently conjugated by GSH. These data suggest that safrole may contribute to the initiation of oral carcinogenesis through safrole-DNA adduct and not oxidative DNA damage. In addition, CYP2E1 may modulate this adduct formation.

• Toxicological Research
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• v.12 no.2
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• pp.155-161
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• 1996

The enzymatic properties for NADPH-P450 reductase domain of a fusion protein between human cytochrome P450 1A1 and rat NADPH-P450 reductase expressed in Escherichia coli were investigated. The fusion plasmid pCW/1A1OR-expressed E. coli membrane showed high NADPH-cytochrome c reductase activity ($830.1\pm 85.8 nmol\cdot min^{-1}\cdot mg protein^{-1}$), while pCW control vector and P 450 1A1 expression vector pCW/1A1 showed relatively quite low activity ($4.35\pm 0.49, 3.27\pm 0.50 nmol\cdot min^{-1}\cdot mg protein^{-1}$, respectively). The kinetic curves for NADPH-cytochrome c reductase followed typical Michaelis-Menten kinetics. The $K_{max}$ and $V_{max}$ for NADPH-dependent reductase activity were $8.24\pm 2.61\mu $and $817.9\pm 60.8 nmol\cdot min^{-1}\cdot mg protein^{-1}$, respectively, whereas those for cytochrome c-dependent reductase activity were $19.97\pm 2.86\mu M$ and $1303.5\pm 67.1 nmol\cdot min^{-1}\cdot mg protein^{-1}$. The reductase activities were also compared with those of rat, porcine and human liver microsomes. The activity of pCW/ 1A1OR-expressed E. coli membrane was 15.2-fold higher than that of rat liver microsome. Treatment with benzo(a)pyrene, 7-ethoxyresorufin and $\alpha$-naphthofiavone which are known as specific substrates or inhibitor for human P450 1A1 increased NADPH-cytochrome c reductase activity of fusion protein in E. coli membrane dose-dependently. These results demonstrate that the membrane topology of fused enzyme may be important for activity of its NADPH-P450 reductase domain.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1659-1664
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• 2012

TSAHC [4'-(p-toluenesulfonylamido)-4-hydroxychalcone] is a promising antitumorigenic chalcone compound, especially against TM4SF5 (four-transmembrane L6 family member 5)-mediated hepatocarcinoma. We evaluated the potential of TSAHC to inhibit the catalytic activities of nine cytochrome P450 isoforms and of P-glycoprotein (P-gp). The abilities of TSAHC to inhibit phenacetin O-deethylation (CYP1A2), coumarin 6-hydroxylation (CYP2A6), bupropion hydroxylation (CYP2B6), amodiaquine N-deethylation (CYP2C8), diclofenac 4-hydroxylation (CYP2C9), omeprazole 5-hydroxylation (CYP2C19), dextromethorphan O-demethylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1), and midazolam 1'-hydroxylation (CYP3A) were tested using human liver microsomes. The P-gp inhibitory effect of TSAHC was assessed by [$^3H$]digoxin accumulation in the LLCPK1-MDR1 cell system. TSAHC strongly inhibited CYP2C8, CYP2C9, and CYP2C19 isoform activities with $K_i$ values of 0.81, 0.076, and $3.45{\mu}M$, respectively. It also enhanced digoxin accumulation in a dose-dependent manner in the LLCPK1-MDR1 cells. These findings indicate that TSAHC has the potential to inhibit CYP2C isoforms and P-gp activities in vitro. TSAHC might be used as a nonspecific inhibitor of CYP2C isoforms based on its negligible inhibitory effect on other P450 isoforms such as CYP1A2, CYP2A6, CYP2B6, CYP2D6, CYP2E1, and CYP3A.

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.195-195
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• 2001

The inhibitory potentials of TCAs (imipramine, desipramine, amitriptyline, and nortriptyline) on phenytoin p-hydroxylation and probe metabolic pathways of each CYP isoforms were evaluated from incubation studies of human liver microsomes and cDNA-expressed cytochrome P450s in vitro in order to understand the mechanism of drug interaction between TCAs and phenytoin, a substrate of CYP2C9 and CYP2C19. (omitted)

• Mass Spectrometry Letters
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• v.14 no.1
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• pp.1-8
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• 2023

Eutylone, dibutylone, and dimethylone are potential psychotropic designer drugs. The purpose of this study was to investigate the in vitro metabolic pathways of synthetic cathinones with methylenedioxy groups. The three methylenedioxy derivatives were incubated with human liver microsomes. The metabolites were characterized based on liquid chromatography and quadrupole-time-of-flight mass spectrometry. Eutylone, dibutylone, and dimethylone were metabolized to yield three, six, and four metabolites, respectively. Reduction and demethylenation were the major metabolic pathways for all three drugs tested. However, dibutylone and dimethylone showed an additional metabolite generated via N-oxidation. These results provide evidence for the in vivo metabolism of methylenedioxy synthetic cathinones, and could be applied to the analysis of synthetic cathinones and their relevant metabolites in biological samples.

• Advances in Traditional Medicine
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• v.6 no.4
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• pp.274-285
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• 2006

Allium sativum (Family Amaryllidaceae or Liliaceae) is used worldwide for various clinical uses like hypertension, cholesterol lowering effect, antiplatelets and fibrinolytic activity etc. Due to these common house hold uses of Allium sativum, as a herbal supplements, and failure of patients to inform their physician of the over-the-counter supplements they consume leads to drugnutrient interactions with components in herbal supplements. Today these types of interactions between a herbal supplement and clinically prescribed drugs are an increasing concern. In vitro studies indicated that garlic constituents modulated various CYP (cytochrome P450) enzymes. CYP 3A4 is abundantly present in human liver and small intestine and contributes to the metabolism of more than 50% of commonly used drugs including nifedipine, cyclosporine, erythromycin, midazolam, alprazolam, and triazolam. Extracts from fresh and aged garlic inhibited CYP 3A4 in human liver microsomes. The in vivo effects of garlic constituents are found to be species depended and the dosing regimen of garlic constituents appeared to influence the modulation of various CYP isoforms. Studies have indicated that the inhibition of various CYPs by organosulfur compounds from garlic was related to their structure also. Studies using in vitro, in vivo, animal and human models have indicated that various garlic constituents can be the substrates, inhibitors and or inducers of various CYP enzymes. The modulation of CYP enzyme activity and expression are dependent on the type and chemical structure of garlic constituents, dose regime, animal species and tissue, and source of garlic thus this review throws light on the possible herb drug interaction with the use of garlic.

• Journal of Ginseng Research
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• v.43 no.4
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• pp.539-549
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• 2019

Background: 20(S)-Protopanaxadiol (PPD), the aglycone part of 20(S)-protopanaxadiol ginsenosides, possesses antidepressant activity among many other pharmacological activities. It is currently undergoing clinical trial in China as an antidepressant. Methods: In this study, an ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass tandem mass spectrometry method was established to identify the metabolites of PPD in human plasma and urine following oral administration in phase IIa clinical trial. Results: A total of 40 metabolites in human plasma and urine were identified using this method. Four metabolites identified were isolated from rat feces, and two of them were analyzed by NMR to elucidate the exact structures. The structures of isolated compounds were confirmed as (20S,24S)-epoxydammarane-12,23,25-triol-3-one and (20S,24S)-epoxydammarane-3,12,23,25-tetrol. Both compounds were found as metabolites in human for the first time. Upon comparing our findings with the findings of the in vitro study of PPD metabolism in human liver microsomes and human hepatocytes, metabolites with m/z 475.3783 and phase II metabolites were not found in our study whereas metabolites with m/z 505.3530, 523.3641, and 525.3788 were exclusively detected in our experiments. Conclusion: The metabolites identified using ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass spectrometry in our study were mostly hydroxylated metabolites. This indicated that PPD was metabolized in human body mainly through phase I hepatic metabolism. The main metabolites are in 20,24-oxide form with multiple hydroxylation sites. Finally, the metabolic pathways of PPD in vivo (human) were proposed based on structural analysis.

• Korean Journal of Medicinal Crop Science
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• v.10 no.4
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• pp.269-272
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• 2002

Ethanol and butanol fractionation of E. senticosus showed strong anti-oxidant activity, and methanol and water extracts also had high anti-oxidant activity. The anti-oxidant activities in ethanol and butanol fractionation were higher than or similar to those of ${\alpha}-tocopherol$. The cytotoxic effect of root extract of E. senticosus was evaluated on seven different human cancer cell lines, The extracts of leaf and stem of E. senticosus also had strong antioxidant activity, but the antioxidant activity in root extract was higher than those in leaf and stem extracts. Methanol, hexane, and aqueous fraction layer had much higher inhibitory activities on lipid peroxidation in rat liver microsomes compared with ${\alpha}-tocopherol$. The effect of root extract of E. senticosus was evaluated on six human cancer cell lines. The values of 50% growth inhibition $(GI_{50})$ for the extracts were mostly below $30{\mu}g/ml$, and the extracts are considered as active inhibitory compounds on cancer cells.

• Journal of Life Science
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• v.22 no.8
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• pp.991-998
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• 2012

Ginseng is one of the most commonly used herbal medicines and health foods. Korean red ginseng (KRG; Panax ginseng C.A. Meyer) extract is known to have potential therapeutic activities, such as anti-viral effects, the amelioration of food allergies, anti-oxidant effects, and obesity reduction. Nevertheless, no reports have been issued the modulatory effects of KRG extract on the activity of cytochrome P450 (CYP). In the present study, we investigated the modulatory effect of KRG extract in vitro and in vivo by using pooled human liver microsomes and male ICR mice. When human liver microsomes were incubated with KRG extract at 0.01-10 mg/ml, CYP1A2, 2B6, 2C19, 2D6, and 3A were not significantly inhibited by KRG extract, although CYP2B6 was slightly inhibited. Mice were orally administered KRG extract at 50, 250, or 500 mg/kg daily for 3, 7, or 14 days. However, the activities of CYPs in mouse livers were not significantly different from those of vehicle-treated controls. In conclusion, no significant ginseng-drug interaction was observed. KRG extract did not significantly modulate the activities of CYPs in vitro or in vivo.