• YAKHAK HOEJI
• /
• v.59 no.2
• /
• pp.49-54
• /
• 2015

In the present study we evaluated comparative herb-drug interaction potential of red ginseng total powder, ginsenoside Rg1, and Rb1 by inhibition of CYP isoforms including CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4 using pooled human liver microsomes (HLMs). As measured by liquid chromatography-electrospray ionization tandem mass spectrometry, red ginseng total powder inhibited significantly activities of CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and testosterone 6-beta hydroxylation by CYP3A4, but the $IC_{50}$ values were higher than $556{\mu}g/ml$. Activities of CYP2B6, CYP2C9, CYP2D6 and CYP3A4 were inhibited by ginsenoside Rb1. Also, activities of CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6 and testosterone 6-beta hydroxylation by CYP3A4 were inhibited by ginsenoside Rg1. The $IC_{50}$ values of ginsenoside Rb1 and Rg1 were higher than $200{\mu}g/ml$. Based on $IC_{50}$ values against CYP isoforms, ginsenosides-drug interactions by CYP inhibition may be very low in clinical situations.

• Archives of Pharmacal Research
• /
• v.26 no.8
• /
• pp.631-637
• /
• 2003

Chloroquine has been used for many decades in the prophylaxis and treatment of malaria. It is metabolized in humans through the N-dealkylation pathway, to desethylchloroquine (DCQ) and bisdesethylchloroquine (BDCQ), by cytochrome P450 (CYP). However, until recently, no data are available on the metabolic pathway of chloroquine. Therefore, the metabolic pathway of chloroquine was evaluated using human liver microsomes and cDNA-expressed CYPs. Chloroquine is mainly metabolized to DCQ, and its Eadie-Hofstee plots were biphasic, indicating the involvement of multiple enzymes, with apparent $K_m and V_{max}$ values of 0.21 mM and 1.02 nmol/min/mg protein 3.43 mM and 10.47 nmol/min/mg protein for high and low affinity components, respectively. Of the cDNA-expressing CYPs examined, CYP1A2, 2C8, 2C19, 2D6 and 3A4/5 exhibited significant DCQ formation. A study using chemical inhibitors showed only quercetin (a CYP2C8 inhibitor) and ketoconazole (a CYP3A4/5 inhibitor) inhibited the DCQ formation. In addition, the DCQ formation significantly correlated with the CYP3A4/5-catalyzed midazolam 1-hydroxylation (r=0.868) and CYP2C8-catalyzed paclitaxel 6$\alpha$-hydroxylation (r = 0.900). In conclusion, the results of the present study demonstrated that CYP2C8 and CYP3A4/5 are the major enzymes responsible for the chloroquine N-deethylation to DCQ in human liver microsomes.

• Toxicological Research
• /
• v.15 no.1
• /
• pp.95-101
• /
• 1999

Cytochrome P450 (CYP) 3A4 metabolizes aflatoxin B1 (AFB1) to AFB1-exo-8,9-epoxide (8,9-epoxidation) and aflatoxin Q1 (AFQ1; 3$\alpha$-hydroxylation) simultaneously. We investigated whether each metabolite was formed via its own binding site of CAP3A4 active site. Kinetics of the formation of the two metabolites were sigmoidal and consistent with the kinetics of substrate activation. The HIll model predicted that two substrate binding wites are involved in the oxidationof AFB1 by CYP3A4. Dehydronifedipine, a metabolite of nifedipine generated by CYP3A4, inhibited the formation of AFQ1 without any inhibition in the formation of AFB1-exo-8,9-epoxidation. Dehydronifedipine was found to act as a reversible competitive inhibitor against 3$\alpha$-hydroxylation of AFB1. Vmax and S0.5 of the 8,9-epoxidation were not changed in the presence of 0, 50, or 100 $\mu\textrm{M}$ dehydronifedipine. S0.5 of 3$\alpha$-hydroxylation was increased from 58$\pm$4 $\mu\textrm{M}$ to 111$\pm$8 $\mu\textrm{M}$ in the presence of 100 $\mu\textrm{M}$ nifedipine whereas Vmax was not changed. These results suggest that there exist two independent binding sites in the active site of CAP3A4 . One binding site is responsible for AFB1-exo-8,9-epoxidation and the other is involved in 3$\alpha$-hydroxylation of AFB1. Dehydronifedipine might selectively bind to the site which is responsible for the formation of AFQ1 in the active site of CYP3A4.

• Archives of Pharmacal Research
• /
• v.27 no.3
• /
• pp.319-323
• /
• 2004

Cytochrome P450 (CYP) 3A4 is of great interest because of its important roles in the oxidation of numerous drugs and xenobiotics. HDJ-1, a molecular chaperone in human, is known to assist the correct folding of unfolded proteins. To achieve a high yield of recombinant human CYP3A4 in Escherichia coli, the CYP3A4 encoding gene was co-expressed with the chaperone HDJ-1, under the control of an inducible tac promoter in a bicistronic format. The levels of expression of the CYP3A4 in the bicistronic construct reached up to 715 nmol $(liter culture)^{-1}$ within 16 h at $37^{\circ}C$, which was about a 3.3-fold increase compared to that of the CYP3A4 alone without the HDJ-1. By co-expression with HDJ-1, the catalytic activity of CYP3A4 was also increased by -15-fold. The amount of activity increase was similar to that of the CYP production at the whole cell level. The present over-expression system may be useful for the rapid production of large amounts of active CYP3A4 in E. coli.

• Mass Spectrometry Letters
• /
• v.14 no.3
• /
• pp.116-119
• /
• 2023

Gynostemma pentaphyllum (Thunb.) Makino extract, a natural product with a history of traditional use, has gained attention for its potential health benefits. This study aimed to investigate its effects on key cytochrome P450 (CYP) enzymes using LC-MS/MS. Human liver microsomes and cDNA-expressed CYP2C8, CYP2C9, CYP2C19, and CYP3A4 supersomes were employed. Enzyme activity was assessed based on the formation of CYP-specific marker metabolites. The resulting data showed that the extract exhibited inhibitory effects on CYP2C8, CYP2C9, CYP2C19, and CYP3A4. Thus, G. pentaphyllum extract may influence the pharmacokinetics of drugs metabolized by CYP2C8, CYP2C9, CYP2C19, and CYP3A4. These findings emphasize the importance of considering potential herb-drug interactions when incorporating this extract into therapeutic regimens or dietary supplements.

• Korean Journal of Microbiology
• /
• v.40 no.3
• /
• pp.221-225
• /
• 2004

Novel cytochrome P450 hydroxylase (CYP) genes were isolated and characterized from P. autotrophica cosmid DNA library using an actinomycete CYP-specific PCR product as a screening probe. The cosmids containing four unique CYP genes (pESK601, 602, 603, 604, 605) were identified, and the four CYP genes were completely sequenced to be homologous to other known Actinomycetes CYP genes involved in various secondary metabolic pathways. Among all novel actinomycete CYP genes found in P. autotrophica, the CYP genes present in pESK601 were revealed to be highly homologous to the CYP genes involved in polyene-type amphotericin and nystatin antibiotic biosynthesis. The nucleotide sequences of the CYP flanking region in pESK601 also revealed the polyene-type biosynthetic genes, implying the presence of a cryptic polyene-type antifungal biosynthetic gene cluster in P. autotrophica.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2003.11a
• /
• pp.88-88
• /
• 2003

Cytochrome P-450 3A4 (CYP3A4) is major enzyme in human liver, the role of this is detoxification and metabolizing more than 50% clinical drugs in use. Expression of CYP3A4 is transciptionally regulated by the Pregnenolone X receptor (PXR), of which human form is Steroid and Xenobiotics receptor (SXR). SXR is activated by wide range of endogenous and exogenous compounds, and then induces CYP3A4 gene expression. In the previous study, it has been known that proximal promoter (-864 to +64) does not response to chemical inducers such as pregnenolone 16a-carbonitrile (PCN), Rifampicin, Estrogen in terms of transcription of CYP 3A4 in cultured cells. Here, we developed luciferase reporter gene assay system to detect SXR-based CYP 3A4 transcriptional activity. We have used CYP3A4-Luc plasmid that contains proximal promoter of human CYP3A4 gene upstream of the luciferase gene. We did transient transfection of 3A4-luciferase gene and SXR. In the HepG2 cells transfected with CYP3A4-Luc, when rifampicin treatment was combined with histone deacetylase inhibitor (HDAC Inhibitor), such as Trichostatin A, Hc-toxin and IN 2001 of the luciferase activity was induced 10-20 fold over control.

• Proceedings of the Korea Society of Environmental Toocicology Conference
• /
• 2003.10a
• /
• pp.178-178
• /
• 2003

Cytochrome P-450 3A4 (CYP3A4) is major enzyme in human liver, the role of this Is detoxification and metabolizing more than 50% clinical drugs in use. Expression of CYP3A4 is transciptionally regulated by the Pregnenolone X receptor (PXR), of which human form is Steroid and Xenobiotics receptor (SXR). SXR is activated by wide range of endogenous and exogenous compounds, and then induces CYP3A4 gene expression. In the previous study, it has been known that proximal promoter (-864 to ＋64) does not response to chemical inducers such as pregnenolone 16a-carbonitrile (PCN), Rifampicin, Estrogen in terms of transcription of CYP 3A4 in cultured cells. Here, we developed luciferase reporter gene assay system to detect SXR-based CYP 3A4 transcriptional activity. We have used CYP3A4-Luc plasmid that contains proximal promoter of human CYP3A4 gene upstream of the luciferase gene. We did transient transfection of 3A4-luciferase gene and SXR. In the HepG2 cells transfected with CYP3A4-Luc, when rifampicin treatment was combined with histone deacetylase inhibitor (HDAC Inhibitor), such as Trichostatin A, Hc-toxin and IN 2001 of the luciferase activity was induced 10-20 fold over control.

• The Journal of Internal Korean Medicine
• /
• v.29 no.4
• /
• pp.846-855
• /
• 2008

Objects : The aim of this study was to investigate the influence of five herbal medicines on cytochrome P450 3A4 drug-metabolizing enzymes in human liver microsomes. Methods : To use human liver microsomes, an extract of five herbal medicines, which are Artemisia princeps Pampan, Sophora jeponica Linne, Panax notoginseng F. H. Chen, Lithospermum Erythrorhizon Sieb., and Cirsium maackii Maxim, which together are called Jihyulyak(止血藥, drugs for arresting bleeding, hemostatics), was co-incubated and measured for relative enzyme activity in incubation condition compared to ketoconazole, a representative inhibitor of CYP 3A4. Results : We showed that all five of the traditional herbal medicines had no inhibition effect of CYP 3A4 at 10, 20, 30, 40, and $50{\mu}g/ml$ doses in human liver microsomes, although Sophora japonica Linne(SJL) showed a little inhibition at about 81% inhibition rate of control. However, this result is not enough to prove that SJL has a CYP 3A4 inhibition effect. Moreover, we can't make sure that those rates had significant induction effect on CYP 3A4. Conclusions : The result of this study could support that those herbal medicines are safer than chemical drugs, even if this is the basic step to prove that result.

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.120.2-120.2
• /
• 2003

Cytochrome P-450 3A4 (CYP3A4) is major enzyme in human liver, the role of this is detoxification and metabolizing more than 50% clinical drugs in use. Expression of CYP3A4 is transciptionally regulated by the Pregnenolone X receptor (PXR), of which human form is Steroid and Xenobiotics receptor (SXR). SXR is activated by wide range of endogenous and exogenous compounds, and then induces CYP3A4 gene expression. In the previous study, it has been known that proximal promoter (-864 to +64) does not response to chemical inducers such as pregnenolone 16a-carbonitrile (PCN), Rifampicin, Estrogen in terms of transcription of CYP 3A4 in cultured cells. (omitted)