The induction of drug-metabolising enzymes is being increasingly recognised for its clinical importance in drug research and development. In the present study, we used a pregnane X receptor (PXR)-mediated reporter gene assay to evaluate the activating effects of various food, herb, and horticultural plant constituents on the PXR and a UGT1A1 reporter gene DNA construct. The results showed that of 102 naturally occurring constituents tested, 50 activated the PXR signaling pathway and induced expression of the UGT1A1 -reporter gene DNA construct. Eleven constituents strongly induced gene expression (a response of >70% compared to that associated with rifampicin), and were further evaluated in in vitro experiments to confirm the induction of UGT1A1 mRNA and protein expression. The results suggest that foods and herbs containing these constituents should be consumed with caution to avoid undesirable drug–drug interactions with co-administered drugs that are substrates for UGT1A1.
NTCP is specifically expressed on the basolateral membrane of hepatocytes, participating in the enterohepatic circulation of bile salts, especially conjugated bile salts, to maintain bile salts homeostasis. In addition, recent studies have found that NTCP is a functional receptor of HBV and HDV. Therefore, it is important to study the interaction between drugs and NTCP and identify the inhibitors/substrates of NTCP. In the present study, a LLC-PK1 cell model stably expressing human NTCP was established, which was simple and suitable for high throughput screening, and utilized to screen and verify the potential inhibitors of NTCP from 102 herbal medicinal ingredients. The results showed that ginkgolic acid (GA) (13 : 0), GA (15 : 1), GA (17 : 1), erythrosine B, silibinin, and emodin have inhibitory effects on NTCP uptake of TCNa in a concentration-dependent manner. Among them, GA (13 : 0) and GA (15 : 1) exhibited the stronger inhibitory effects, with IC 50 values being less than 8.3 and 13.5 μmol·L −1 , respectively, than the classical inhibitor, cyclosporin A (CsA) (IC 50 = 20.33 μmol·L −1 ). Further research demonstrated that GA (13 : 0), GA (15 : 1), GA (17 : 1), silibinin, and emodin were not substrates of NTCP. These findings might contribute to a better understanding of the disposition of the herbal ingredients in vivo , especially in biliary excretion.