Upregulation of UGT1A1 expression by ursolic acid and oleanolic acid via the inhibition of the PKC/NF-κB signaling pathway.

BACKGROUND: Isomeric ursolic acid (UA) and oleanolic acid (OA) compounds have recently garnered great attention due to their biological effects. Previously, it had been shown that UA and OA can exert important pharmacological action via the protein kinase C (PKC) and nuclear factor-κB (NF-κB) signaling, and that they can induce the expression of UDP-glucuronosyltransferase 1A1 (UGT1A1) in HepG2 cells. This study aims to investigate the role of PKC/NF-κB signaling in regulating the expression of UGT1A1 and examine how UA and OA induce UGT1A1 based on this signaling pathway. METHODS: HepG2 cells, hp65-overexpressed HepG2 cell and lentivirus-hp65-shRNA silenced HepG2 cells were stimulated with PKC/NF-κB specific agonists and inhibitors for 24 h in the presence or absence of UA and OA. The expression of UGT1A1, PKC, and NF-κB were determined by qRT-PCR, western blot, and dual-luciferase reporter gene assays. RESULTS: PKC/NF-κB activation downregulates UGT1A1 expression. This effect is countered by UA and OA treatment. Phorbol 12-myristate 13-acetate (PMA) and lipopolysaccharide (LPS), the agonists of PKC and NF-κB signaling, respectively, significantly inhibit hp65-mediated UGT1A1 luciferase activity. UA, OA, and the PKC/NF-κB inhibitors suppress this effect. PMA and LPS do not affect UGT1A1 activity in p65-silenced HepG2 cells; however, UA and OA mildly influence UGT1A1 expression in these cells. CONCLUSION: The activation of PKC/NF-κB signaling can significantly downregulate UGT1A1 expression. By inhibiting the PKC/NF-κB signaling pathway, UA and OA promote UGT1A1 expression in HepG2 cells.

Interactions of the major effective components in Shengmai formula with breast cancer resistance protein at the cellular and vesicular levels.

Shengmai Formula (SMF) is one of the traditional Chinese medicine representative formulas and is widely used for the treatment of cardio- and cerebrovascular disease. Previous studies demonstrated that the major effective ingredients in SMF can interact with each other based on some uptake transporters. However, the role of the efflux transporter breast cancer resistance protein (BCRP) in these interactions involving SMF remains unclear. The purpose of this study was to investigate the interactions of the major active components of SMF with BCRP and the compatibility mechanism of these complex components in SMF based on BCRP. We selected 4 main fractions, including ginseng total saponins (GTS), ophiopogon total saponins (OTS), ophiopogon total flavonoids (OTF), and fructus schisandrae total lignans (STL), and 12 bioactive components, including ginsenosides Re, Rd, Rb1, and Rg1, ophiopogonins D and D', methylophiopogonanones A and B, schizandrins A and B, and schizandrols A and B to explore the interactions of SMF with BCRP in LLC-PK1 and LLC-PK1/BCRP cells and BCRP membrane vesicles. The results showed that ginsenosides Re and Rg1, methylophiopogonanone B, and schizandrin A can be transported by BCRP into LLC-PK1/BCRP cells. Schisandrol B exhibited a markedly inhibitory effect on the transport function of BCRP and can significantly inhibit the uptake of methylophiopogonanone B and schizandrin A into LLC-PK1/BCRP cells. In "Inside-Out" BCRP membrane vesicles, BCRP mediated the transport of ginsenosides Re and Rg1, methylophiopogonanone B, and schizandrin A, with Km values of 111.9 ±â€¯31.26 µM, 82.01 ±â€¯16.72 µM, 57.06 ±â€¯8.789 µM, and 37.19 ±â€¯6.512 µM, respectively. GTS, STL, ginsenosides Rd and Rb1, and schisandrol B were potent inhibitors of BCRP and showed different degrees of inhibition on the transport of ginsenosides Re and Rg1, methylophiopogonanone B, and schizandrin A via BCRP. In conclusion, GTS, STL, ginsenosides Rd and Rb1, and schizandrol B are potential inhibitors of BCRP. Ginsenosides Re and Rg1, methylophiopogonanone B, and schizandrin A are potential substrates of BCRP, and their transport, which is mediated by BCRP, may be inhibited by potential inhibitors in SMF. There are potential interactions of these main effective components of SMF at the cellular and vesicular levels that are mediated by BCRP. The interplay of these bioactive components based on BCRP may be an important compatibility mechanism in SMF.

The major effective components in Shengmai Formula interact with sodium taurocholate co-transporting polypeptide.

BACKGROUND: Shengmai Formula (SMF) is widely used to treat cardiovascular disease such as chronic heart disease, coronary atherosclerotic heart disease, viral myocarditis, and others. Our previous studies have shown that OATP1B1/1B3 mediates the interactions between ophiopogon D and ginsenoside Rb1/Rd, which are the major active components in SMF. The herb-drug interactions that involve sodium taurocholate co-transporting polypeptide (NTCP) have been drawing increasing amounts of attention. PURPOSE: The aim of the present study was to investigate the interactions of the major effective components in SMF mediated by NTCP. METHODS: By using NTCP-overexpressing HEK293T cells and liquid chromatograph-mass spectrometer (LC-MS) analytical methods, we investigated the impact of the four main effective fractions and the 12 main effective components in SMF on NTCP-mediated sodium taurocholate (TCNa) uptake. The interactions of these effective components in SMF mediated by NTCP were further studied. RESULTS: The main effective fractions, ginseng total saponins (GTS), ophiopogon total saponins (OTS), ophiopogon total flavonoids (OTF), and fructus schisandrae total lignans (STL), all exhibited a certain inhibitory effect on the uptake of TCNa. Among the 12 main effective components, only ginsenoside Rg1, ophiopogon D', and schizandrin A showed inhibition of TCNa uptake, with IC50 values of 50.49 ± 4.24 µM, 6.71 ± 0.70 µM, and 45.80 ± 3.10 µM, respectively. Additionally, we found that ginsenoside Re and schizandrin B could be transported by NTCP-overexpressing HEK293T cells, and that the uptake of ginsenoside Re was significantly inhibited by OTS, OTF, STL, ginsenoside Rg1, ophiopogon D', and schizandrin A. The uptake of schizandrin B was significantly inhibited by GTS, OTS, OTF, and ophiopogon D'. CONCLUSION: Ginsenoside Rg1, ophiopogon D', and schizandrin A are potential inhibitors of NTCP and may interact with clinical drugs mediated by NTCP. Ginsenoside Re and schizandrin B are also potential substrates of NTCP, and their uptake mediated by NTCP was inhibited by the other components in SMF. The interaction of complex components based on NTCP may be one of the important compatibility mechanisms in SMF.