Human PXR-mediated transcriptional activation of CYP3A4 by "Fuzi" extracts.

OBJECTIVE: This study focused on determining whether the "Fuzi" (FZ) extracts from different extraction methods are related to pregnane X receptor (PXR) and cytochrome P450 3A4 (CYP3A4), and explore the mechanism.

METHODS: FZ was extracted under various conditions, and the components were identified by Ultra Performance Liquid Chromatography/Quad Time Of Flight Mass Spectrometry (UPLC/Q-TOF-MS). Annexin V-FITC and propidium iodide staining assays were used to measure the cell cytotoxicity of these extracts. Real-time PCR, western blot analysis and reporter gene assay were used to detect the expression changes of PXR and CYP3A4.

RESULTS: FZ extracts were found to contain high levels of monoester-diterpene alkaloids (MDAs) and diester-diterpene alkaloids (DDAs). FZ extracts were cytotoxic. Interestingly, we found that FZ extracts and DDAs can induce the expressions of PXR and CYP3A4. And the MDAs can inhibit the expressions of PXR and CYP3A4.

CONCLUSION: Different extracts of FZ can induce the expressions of PXR and CYP3A4 in different degrees. This may be related to the drug-drug interactions.