Panax ginseng Inhibits Metabolism of Diester Alkaloids by Downregulating CYP3A4 Enzyme Activity via the Pregnane X Receptor

Abstract

To investigate the effects of P. ginseng C.A. Mey (P. ginseng) on the metabolism of diester alkaloids and explore the potential mechanism. P. ginseng was administered orally to rats for 7 days, after which liver microsome samples were prepared and then incubated with diester alkaloids. Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry was used to determinate the concentration of diester alkaloids to calculate the clearance rate. The cocktail method was used to evaluate the effects of oral administration of P. ginseng extracts on the activities of cytochrome P450 (CYP) isoforms in rats through the changes in the pharmacokinetic parameters of the probe drugs. The protein and gene expression of CYP3A2 and pregnane X receptor (PXR) in rats were evaluated by western blotting and quantitative PCR. The specific enzyme inhibitor method and human recombinant enzyme method were used to identify the involvement of sub-CYPs in the metabolism of diester alkaloids in human liver microsomes (HLMs). The clearances of aconitine, mesaconitine, and hypaconitine in the P. ginseng groups were lower than those of the control group. The areas under the curve of midazolam were 2.37 ± 1.05, 4.96 ± 0.51, and 6.23 ± 1.30 mg·L−1·h for the low-, medium-, and high-dose P. ginseng groups, respectively, which were higher than that of the control (2.23 ± 0.64 mg·L−1·h). The clearances of midazolam for the medium- (1.87 ± 0.16 L·h−1·kg−1) and high-dose (1.60 ± 0.34 L·h−1·kg−1) P. ginseng groups were lower than that of the control group (4.66 ± 1.43 L·h−1·kg−1). After exposure to P. ginseng extracts, the gene and protein expression levels of CYP3A4 and PXR were decreased. The hepatic metabolism rates of aconitine, mesaconitine, and hypaconitine in HLMs were decreased to 60.37%, 21.67%, and 10.11%, respectively, when incubated with ketoconazole, a specific inhibitor for CYP3A. The kinetic plots indicated that the KM and Vmax values of CYP3A4 were 10.08 ± 3.26 μM and 0.12 ± 0.01nmol·mg protein−1·min−1 for aconitine, 131.3 ± 99.75 μM and 0.73 ± 0.44 nmol·mg protein−1·min−1 for mesaconitine, and 17.05 ± 9.70 μM and 0.16 ± 0.04 nmol·mg protein−1·min−1 for hypaconitine, respectively. The in vitro mean intrinsic clearance rates by CYP3A4 were 0.0119, 0.0056, and 0.0091 mL·nmol CYP−1·min−1 for aconitine, mesaconitine, and hypaconitine, respectively. Therefore we implied that P. ginseng inhibited the metabolism of diester alkaloids in vitro and decreased the CYP3A4 enzyme activity as well as the gene and protein expression of CYP3A4 and PXR in vivo. CYP3A4 had a larger effect on diester alkaloid metabolism than the other human CYP isoforms, CYP1A2, CYP2C9, and CYP2E1.

Effect of Single-Dose and Short-Term Administration of Si Jun Zi Tang on the Pharmacokinetics of Gefitinib in Rats

“…Some studies have shown that Chinese herbal ingredients in Si Jun Zi decoction influence CYP450 enzymes. A study [11] showed that ginseng reduced the CL of midazolam and caffeine, which were metabolized by CYP450 enzymes. CYP3A2 (an isozyme of CYP3A4) and gene expression levels in Sprague-Dawley rats exposed to P. ginseng extracts were evaluated by western blotting and quantitative PCR in the study [11] and compared with the control groups, P. ginseng downregulated the expression of CYP3A2 at both the protein and gene levels.…”

“…A study [11] showed that ginseng reduced the CL of midazolam and caffeine, which were metabolized by CYP450 enzymes. CYP3A2 (an isozyme of CYP3A4) and gene expression levels in Sprague-Dawley rats exposed to P. ginseng extracts were evaluated by western blotting and quantitative PCR in the study [11] and compared with the control groups, P. ginseng downregulated the expression of CYP3A2 at both the protein and gene levels. Another study [12] indicated that repeated administration of Sailuotong induced CYP1A2 and CYP2C11 but significantly inhibited CYP3A1/3A2 in rats, and these impacts were attributed to the ingredients of ginseng and gingko individually or cooperatively to a large extent.…”

“…Emerging evidence has shown that SJZ can play a significant role in suppressing tumours and has a protective effect against gastrointestinal mucosa damage induced by chemotherapy [9]. Some studies [11][12][13][14][15][16] have shown that Chinese herbal ingredients in Si Jun Zi decoction influence the CYP450 enzyme. e Liang Yang group [11] found that ginseng reduced the metabolic rate of midazolam and caffeine, which were metabolized by CYP450 enzymes.…”

“…Some studies [11][12][13][14][15][16] have shown that Chinese herbal ingredients in Si Jun Zi decoction influence the CYP450 enzyme. e Liang Yang group [11] found that ginseng reduced the metabolic rate of midazolam and caffeine, which were metabolized by CYP450 enzymes.…”

The toxicology and detoxification of Aconitum: traditional and modern views

“…Ginseng (Panax notoginseng) has the best combination effect with Aconitum , in terms of detoxification and enhancing drug action. In vitro experiment has shown that Ginseng could reduce the metabolism of DDAs through inhibition of CYP3A4 expression and activity [ 79 ]. In a rat model, Ginseng could slow down the metabolisms of DDAs from Fuzi when given orally [ 80 ].…”