Licorice (Glycyrrhiza glabra)
Chemical basis of pregnane X receptor activators in the herbal supplement Gancao (licorice)
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Gancao, also known as licorice, has numerous beneficial pharmacological effects. Data regarding herb-drug interactions via hPXR and CYP3A4 with licorice is limited. Gancao extract seemed to activate hPXR, but has a weak effect on CYP3A4 in vivo. CYP3A4 and hPXR effects of bioactive components, glycyrrhizin and glycyrrhetinic acid, were also studied. Glycyrrhizin results showed no activation of hPXR in vivo or in vitro. Glycyrrhetinic acid showed no activation of hPXR in vitro, but it activated hPXR and induced CYP3A4 in vivo. Glabridin, another chemical compound found in licorice, showed mild PXR activation and moderate upregulation of CYP3A4.
1 . Metabolomic Profiling of Gancao Phytoconstituents (id=NPDI-OihIuQ)
Metabolomics Study
Results
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
PCA Plot
Instructions:
Select the number of dimensions to view in the PCA plot. Each dimension
corresponds with a principal component selected.
Data points represent the following samples (click to show/hide):
Click any dot in the plot to get more information about that particular data point in the
table below the plot.
In the 3-D plot, you can double click anywhere in the space to focus
the camera on that particular point and scroll to zoom in and out
Principal component analysis (PCA) scores plot
Squares represent samples linked to pharmacology and/or chemical characterization experiments.
Experimental Conditions
Ultra-performance liquid chromatography and quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS) (Waters Corporation, Milford, MA, USA) were used for the analysis of chemical components in Gancao extract. A 100 mm 2.1 mm UPLC BEH C-18 column (Acquity 1.7 mm) together with a gradient of aqueous acetonitrile with 0.1% of formic acid were used for chemical separation. QTOFMS was conducted in a negative mode with electrospray ionization. The data were collected by MassLynx 4.1 (Waters Corporation, Milford, MS, USA) and further analyzed by SIMCA-P (Umetrics, Kinnelon, NJ, USA).
Ultra-performance liquid chromatography and quadrupole time-of-flight mass spectrometry
Electrospray ionization
Negative
Gradient of aqueous acetonitrile with 0.1% of formic acid
100 mm 2.1 mm UPLC BEH C-18 column (Acquity 1.7 mm)
1 . Esculetin - hPXR Activation Experiment - 1 (id=NPDI-oJ9-pA)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
2 . Gancao 1:1000 - hPXR Activation Experiment - 1 (id=NPDI-fdQymA)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
A dose-dependent hPXR activation by Gancao extract (100- to 1000-fold dilution). The data in control groups were set as 1. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
3 . Gancao 1:100 - hPXR Activation Experiment - 5 (id=NPDI-tsyNWQ)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
A dose-dependent hPXR activation by Gancao extract (100- to 1000-fold dilution). The data in control groups were set as 1. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
4 . Gancao 1:200 - hPXR Activation Experiment - 4 (id=NPDI-6k7lVQ)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
A dose-dependent hPXR activation by Gancao extract (100- to 1000-fold dilution). The data in control groups were set as 1. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
5 . Gancao - hPXR Activation Experiment - 1 (id=NPDI-2aN3fA)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
Gancao extract was diluted 100-fold. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
6 . Gancao 1:800 - hPXR Activation Experiment - 2 (id=NPDI-uTdxOg)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
A dose-dependent hPXR activation by Gancao extract (100- to 1000-fold dilution). The data in control groups were set as 1. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
7 . Gancao 1:400 - hPXR Activation Experiment - 3 (id=NPDI-yaDA9A)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
A dose-dependent hPXR activation by Gancao extract (100- to 1000-fold dilution). The data in control groups were set as 1. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
8 . Glabridin - hPXR Activation Experiment - 1 (id=NPDI-JEa8WA)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
9 . Glabrol - hPXR Activation Experiment - 1 (id=NPDI-V1A9Uw)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
10 . Glycyrrhetinic acid - CAR Activation Experiment - 1 (id=NPDI-Ik84yA)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
Using cell-based reporter assays, neither CAR nor GR can be activated by GA.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Cell-based CAR reporter assays of GA (10 µmol/L). TCPOBOP (250 nmol/L) was used as a positive control for CAR activation.
Luciferase activity (Reporter gene assay)
11 . Glycyrrhetinic acid - GR Activation Experiment - 1 (id=NPDI-BSD3Hg)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
Using cell-based reporter assays, neither CAR nor GR can be activated by GA.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Cell-based GR reporter assays of GA (10 µmol/L). Dexamethasone (Dex, 10 nmol/L) was used as a positive control for GR activation.
Luciferase activity (Reporter gene assay)
12 . Glycyrrhetinic acid - hPXR Activation Experiment - 1 (id=NPDI-fCU6fg)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
13 . Glycyrrhizin - hPXR Activation Experiment - 1 (id=NPDI-kYQYbw)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
14 . Isoliquiritigenin - hPXR Activation Experiment - 1 (id=NPDI-VwDDFg)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
15 . Isoliquiritin - hPXR Activation Experiment - 1 (id=NPDI-bJS_nw)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
16 . Licochalcone B - hPXR Activation Experiment - 1 (id=NPDI-3xuV4Q)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
17 . Liquiritigenin - hPXR Activation Experiment - 1 (id=NPDI-BPK0rg)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
18 . Liquiritin - hPXR Activation Experiment - 1 (id=NPDI-xEliuw)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours
19 . Liquiritin apioside hPXR Activation Experiment - 1 (id=NPDI-fwE-hQ)
In Vitro Nuclear Receptor Induction Experiment
Induction was detected. Cutoff used —
Not available
- Pregnane X receptor (PXR)
Cell system PXR-transfected hepatic cells
Results
DPX2 cells were used for hPXR reporter assays. Effects of the identified compounds (10 µmol/L each) from Gancao extract on hPXR activation. Rifampicin (10 µmol/L) was used as the positive control.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
DPX2 cells (Puracyp, Inc; Carlsbad, CA, USA) were used for screening PXR activators, which were derived from HepG2 cells and stably transfected with hPXR and a luciferase-linked CYP3A4 promoter. The assays were conducted using a previously reported method with minor revisions. In brief, DPX2 cells were cultured in 96-well plates (5x10^5 cells/mL) for 24 h. Varying concentrations of Gancao extract or phytochemicals were prepared in a dosing medium and incubated with DPX2 cells for another 24 h. Rifampicin was used as a positive control for hPXR activation. All incubations were conducted in triplicate.
Luciferase activity (Reporter gene assay)
5x10^5 cells/mL in 96-well plates
48 hours