ABSTRACT
Pregnane X receptor (PXR) is key transcription factors which mainly regulate the expression of CYP3A genes. At the molecular level, PXR has been revealed the protection mechanism of the body against xenochemicals and a major mode of the drug-drug interactions. Besides playing an important role in drug metabolism and interactions, PXR and its target genes also play an important role in maintaining normal physiological function and homeostasis. Therefore, it is necessary to study the regulation of PXR and its related pharmacological effects of TCM and natural products, and to provide new clues for the new pharmacological pathway.
Subject(s)
Animals , Humans , Drug Evaluation, Preclinical , Drugs, Chinese Herbal , Pharmacology , Gene Expression , Receptors, Steroid , Genetics , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To screen active components in Compound Danshen (CD) based on pregnane X receptor-cytochrome P450 3A4 (PXR-CYP3A4).</p><p><b>METHODS</b>By using PXR-CYP3A stable transfection human hepatoblastoma G2 (HepG2) cell lines engineering cell strain combined reporter genes technology, active components that induce or inhibit PXR-CYP3A4 paths in CD were screened, and confirmed at the level of enzymic activities. The experiment was divided into the positive control group (RIF 10 micro mol/L), the DMSO group (DMSO 0.1%), each dose of treatment groups (ginsenoside Rc, Rf, Rb2, Rg2, F2, F1, tanshinone I , isoborneol 5, 10, 25, 50, 100, and 200 micro mol/L; each with six duplicates). Cells medium was removed 36, 48, and 60 h after treatment. The activity of CYP3A4 was then determined in the supernant and the fold induction was calculated.</p><p><b>RESULTS</b>Compared with the DMSO group, the fold induction increased when ginsenoside Rc, Rf, Rb2, Rg2, F2, F1, tanshinone I , and isoborneol 50 and 100 micro mol/L was respectively intervened for 36, 48, and 60 h (P <0.05). When cells were treated with isoborneol 200 micro mol/L for 48 and 60 h,the fold induction of ginsenoside Rb2, Rg2, and F1 was significantly higher than that of the RIF group (P <0.05). Enzymic activity results showed that ginsenoside Rc, Rf, Rb2, F2, and F1 could increase the enzyme activity of CYP3A4 at 48 h (P <0.05).</p><p><b>CONCLUSION</b>Ginsenoside Rc, Rf, Rb2, F2, F1, tanshinone I, and isoborneol in DC could induce CYP3A4 enzymes.</p>
Subject(s)
Humans , Cytochrome P-450 CYP3A , Metabolism , Abietanes , Drugs, Chinese Herbal , Chemistry , Genes, Reporter , Ginsenosides , Metabolism , Hep G2 Cells , Receptors, Steroid , Metabolism , Salvia miltiorrhiza , TransfectionABSTRACT
In order to study effects of ginseng on the metabolism of drug belong to CYP3A4 substrate, screening of pregnane X receptor activation from ginsenosides was performed by reporter assay. Based on PXR-CYP3A stable translation cell lines, 13 ginsenosides were screened for pregnane X receptor activation by reporter assays, and RIF as the positive control. The effect of ginsenosides Rg1 onCYP3A4 mRNA expression was also investigated by RT-PCR. The PXR-CYP3A stable translation cell lines had good response to RIF, and the EC50 is 2.51 micro mol x L(-1). When the condition of final concentration was 10 micromol x L(-1), ginsenoside F2 and protopanaxatriol had moderate inductive effects on PXR. Panaxotriol, Rg2, pseudoginsenoside F11, Rg1, ginsenoside and Rb3 had inhibitory effects on PXR. Ginsenoside Rf1, Rg3, Rh2 and protopanaxdiol had no obvious effects on PXR. Rg1 down-regulated CYP3A4 mRNA expression in a concentration-dependent manner. Activation of pregnane X receptor by ginsenosides may influence the metabolism of drug belong to CYP3A4 substrate, and cause ginseng-drug interactions.