Validated liquid chromatography–tandem mass spectrometry method for determination of totally nine probe metabolites of cytochrome P450 enzymes and UDP-glucuronosyltransferases

Influence of Zhuanggu Guanjie Pill on Seven Cytochrome P450 Enzymes Based on Probe Cocktail and Pharmacokinetics Approaches

BACKGROUND

The use of herbal medicines has tremendously increased over the past few decades. Case reports and controlled clinical investigations of herbal-drug interactions have been reported. Since Cytochrome P450 (CYP) enzymes play an important role in drug interactions. The evaluation of the influence of herbal medicines on the activities of CYPs is beneficial to promote scientific and rational clinical use of herbal medicines.

OBJECTIVE

Herein, we aimed to develop and validate a method to simultaneously quantify seven CYP cocktail probe drugs consisting of phenacetin (PNC), bupropion (BPP), losartan potassium (LK), omeprazole (OMP), dextromethorphan (DM), chlorzoxazone (CZZ) and midazolam (MDZ) and their respective metabolites in a single acquisition run and use this method to evaluate the influence of Zhuanggu Guanjie Pill (ZGGJP) on seven CYPs.

METHODS

A cost-effective and simple UHPLC-(±)ESI-MS/MS method for simultaneous determination of seven probe drugs and metabolites in rat plasma was developed and validated. Male and female rats were randomly divided into three groups and treated with 1.2 g/kg/d ZGGJP, 5 g/kg/d ZGGJP and 0.5% CMC-Na for 14 consecutive days. After 24 h of the last administration, all rats were administrated orally with probe drugs. The influence of ZGGJP on the CYPs was carried out by comparing the metabolic ratio (Cmax, AUC0-t) of metabolites/probe drugs in rats.

RESULTS

The calibration curves were linear, with correlation coefficient > 0.99 for seven probe drugs and their corresponding metabolites. Intra- and inter-day precisions were not greater than 15% RSD and the accuracies were within ± 15% of nominal concentrations. The ZGGJP showed significant inductive effect on CYP1A2, CYP2B6, CYP2C9 and CYP3A in male and female rats.

CONCLUSION

ZGGJP had inductive effects on CYP1A2, CYP2B6, CYP2C9 and CYP3A in male and female rats.

Study on the effects of Zhuanggu Guanjie Pill, a modern Chinese medicine formula, on the activities and mRNA expression of seven CYP isozymes in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Zhuanggu Guanjie Pill (ZGGJP), a modern Chinese medicine formula, is composed of 12 herbs and has been used to treat osteoporosis in China for almost 30 years. However, no in vivo study of the influences of ZGGJP on the cytochrome P450 (CYP) activities have been reported.

AIM OF THE STUDY

The aim of this study was to evaluate the effects of ZGGJP on the activities and the mRNA expression of CYP enzymes (CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A) and their corresponding nuclear receptor levels in rats.

MATERIALS AND METHODS

After 7 days oral treatment of ZGGJP at low- and high-dose, cocktail solution was given to rats. Blood samples were collected at series of time points. The plasma concentrations of probe drugs and their corresponding metabolites were determined by UPLC-MS/MS. The influence of ZGGJP on the activities of seven CYPs were evaluated the metabolic ratios (Cmax and AUC0-t) for metabolites/probe drugs. In addition, the effects of ZGGJP on the mRNA expression of CYPs and their corresponding nuclear receptors in rat liver were evaluated by real-time PCR.

RESULTS

ZGGJP showed significant inductive effects on CYP1A2 and CYP2B6 of both male and female rats. The influence of ZGGJP on CYP2C9 and CYP3A showed gender difference. ZGGJP could induce the activities of CYP2C9 and CYP3A in female rats, but have no influence on the activities in male rats. ZGGJP had no effects on CYP2D6, CYP2C19 and CYP2E1. The mRNA expression results of CYPs were in accordance with the pharmacokinetic results. The mRNA expression levels of constitutive androstane receptor (CAR) and vitamin D receptor (VDR) were increased significantly in female rats at high dosage, but no significant changes were observed in male rats.

CONCLUSION

ZGGJP had inductive effects on CYP1A2 and CYP2B6 in both male and female rats. The results showed that ZGGJP could induce the activities of CYP2C9 and CYP3A in female rats, but had no effect in male rats. This may suggest that the influence of ZGGJP on CYP2C9 and CYP3A exhibit gender difference. The inductive effects of ZGGJP on the activities of CYPs, exhibiting gender difference, may be regulated by CAR and VDR. Therefore, co-administration of ZGGJP with other drugs, especially using CYP2C9 and CYP3A substrates in females, may need dose adjustment to avoid herb-drug interaction.

Transcriptome sequencing reveals high-salt diet-induced abnormal liver metabolic pathways in mice

BACKGROUND

Although salt plays an important role in maintaining the normal physiological metabolism of the human body, many abnormalities in the liver caused by a high-salt diet, especially with normal pathological results, are not well characterized.

METHODS

Eight-week-old female C57BL/6 mice were randomly divided into a normal group and a high salt group. These groups were then fed with normal or sodium-rich chow (containing 6% NaCl) for 6 weeks. Liver injury was evaluated, and the influences of a high-salt diet on the liver were analyzed by transcriptome sequencing at the end of week 6.

RESULTS

We found that although no liver parenchymal injury could be found after high-salt feeding, many metabolic abnormalities had formed based on transcriptome sequencing results. GO and KEGG enrichment analyses of differentially expressed genes revealed that at least 15 enzymatic activities and the metabolism of multiple substances were affected by a high-salt diet. Moreover, a variety of signaling and metabolic pathways, as well as numerous biological functions, were involved in liver dysfunction due to a high-salt diet. This included some known pathways and many novel ones, such as retinol metabolism, linoleic acid metabolism, steroid hormone biosynthesis, and signaling pathways.

CONCLUSIONS

A high-salt diet can induce serious abnormal liver metabolic activities in mice at the transcriptional level, although substantial physical damage may not yet be visible. This study, to our knowledge, was the first to reveal the impact of a high-salt diet on the liver at the omics level, and provides theoretical support for potential clinical risk evaluation, pathogenic mechanisms, and drug design for combating liver dysfunction. This study also provides a serious candidate direction for further research on the physiological impacts of high-salt diets.

Evaluation of the effect of Bovis Calculus Artifactus on eight rat liver cytochrome P450 isozymes using LC-MS/MS and cocktail approach

Bovis Calculus Artifactus (BCA) is the main substitute for natural Calculus bovis, a traditional drug in China used to treat high fever, convulsion, and sore throat. The effect of BCA on cytochrome P450 (CYP) activities is unknown. This study was to investigate the effect of BCA on eight rat hepatic microsomal CYPisozymes to evaluate the potential drug interactions using the cocktail approach.Metabolites of the eight isoform probe substrates of CYP isozymes were quantified by LC-MS/MS. The method was validated by incubating known CYP inhibitors α-naphthoflavone (CYP1A2), thiotepa (CYP2B1), quercetin (CYP2C7), sulfaphenazole (CYP2C6), ticlopidine (CYP2C11), quinidine (CYP2D1), ketoconazole (CYP3A1),4-methylpyrazole (CYP2E1) with individual probe substrate and rat liver microsomes. The formation rates of the corresponding metabolites of the eight probe substrates were determined to evaluate the activity of each isozyme.The results showed that BCA has different degrees of inhibitory effect on four CYP450 isoforms (CYP2C6, CYP2C11, CYP2D1, CYP3A1) (p < 0.05), but no significant influence on CYP1A2, 2B1, 2C7 or 2E1 (p > 0.05). Attention should be paid to the BCA-drug interactions by careful monitoring and appropriate dosage adjustments in the concurrent use of the drugs which are metabolized by CYP1A2, CYP2C19, and CYP3A4. Abbreviations: BCA, bovis calculus artifactus; CYP, cytochrome P450; DDIs, drug-drug interactions; ESI, electrospray ionization; MRM, multiple reaction monitoring; NBC, Natural Bovis Calculus; QC, quality control; T CM, traditional Chinese medicine.

Characterization of a Novel CYP1A2 Knockout Rat Model Constructed by CRISPR/Cas9

CYP1A2, as one of the most important cytochrome P450 isoforms, is involved in the biotransformation of many important endogenous and exogenous substances. CYP1A2 also plays an important role in the development of many diseases because it is involved in the biotransformation of precancerous substances and poisons. Although the generation of Cyp1a2 knockout (KO) mouse model has been reported, there are still no relevant rat models for the study of CYP1A2-mediated pharmacokinetics and diseases. In this report, CYP1A2 KO rat model was established successfully by CRISPR/Cas9 without any detectable off-target effect. Compared with wild-type rats, this model showed a loss of CYP1A2 protein expression in the liver. The results of pharmacokinetics in vivo and incubation in vitro of specific substrates of CYP1A2 confirmed the lack of function of CYP1A2 in KO rats. In further studies of potential compensatory effects, we found that CYP1A1 was significantly upregulated, and CYP2E1, CYP3A2, and liver X receptor β were downregulated in KO rats. In addition, CYP1A2 KO rats exhibited a significant increase in serum cholesterol and free testosterone accompanied by mild liver damage and lipid deposition, suggesting that CYP1A2 deficiency affects lipid metabolism and liver function to a certain extent. In summary, we successfully constructed the CYP1A2 KO rat model, which provides a useful tool for studying the metabolic function and physiologic function of CYP1A2. SIGNIFICANCE STATEMENT: Human CYP1A2 not only metabolizes clinical drugs and pollutants but also mediates the biotransformation of endogenous substances and plays an important role in the development of many diseases. However, there are no relevant CYP1A2 rat models for the research of pharmacokinetics and diseases. This study successfully established CYP1A2 knockout rat model by using CRISPR/Cas9. This rat model provides a powerful tool to study the function of CYP1A2 in drug metabolism and diseases.

UPLC-MS/MS analysis of CYP1A-mediated ethoxyresorufin-O-deethylation activity in the rat kidney microsomes

Ethoxyresorufin (ER)-O-deethylation (EROD) activity has been widely used to assess cytochrome P450 1A (CYP1A) activity. The kinetics of CYP1A activity have been well characterized in the liver microsomes. However, studies in kidney microsomes are limited due to the much lower EROD activity in this organ. Here, we developed and validated a sensitive UPLC-MS/MS assay for the characterization of the EROD activity in the rat kidney microsomes. In a 50 µL reaction mixture, rat kidney microsomes (0.25 mg/mL) were incubated with ER (0.1-5 µM) and NADPH (1 mM) for 10 min. Acidic solvents, such as trichloroacetic acid or formic acid, used for quenching of the metabolic reactions and precipitation of the proteins, unexpectedly caused a spontaneous formation of resorufin (RES) from ER. Therefore, the metabolic reactions were terminated by adding acetonitrile, containing a deuterated internal standard (IS). Chromatographic separation was achieved on a C₁₈ UPLC column, and the MS/MS ion transitions were 213.9/185.9 for RES and 220.0/192.0 for IS. The assay was validated in the linear range of 0.5 nM to 75 nM of RES and had a lower limit of quantitation of 0.5 nM. The overall recoveries of RES (90%-99%) and IS (85%-103%) were relatively high, with minimal matrix effect. The assay was successfully applied to the estimation of the Michaelis-Menten (MM) kinetics of EROD activity in the rat kidney microsomes (n = 3), which showed a maximum velocity of 2.68 ± 0.17 pmol/min/mg and a MM constant of 1.72 ± 0.24 µM (mean ± SD). It is concluded that our sensitive and specific analytical method, coupled with the optimized microsomal incubation conditions, provides a robust platform for further investigations of the effects of xenobiotics, environmental factors, or pathophysiologic conditions on the kinetics of EROD activity in the kidney microsomes.

Changes in cytochrome P450 gene expression and enzyme activity induced by xenobiotics in rabbits in vivo and in vitro

As considerable inter-species differences exist in xenobiotic metabolism, developing new pharmaceutical therapies for use in different species is fraught with difficulties. For this reason, very few medicines have been registered for use in rabbits, despite their importance in inter alia meat and fur production. We have developed a rapid and sensitive screening system for drug safety in rabbits based on cytochrome P450 enzyme assays, specifically CYP1A1, CYP1A2 and CYP3A6, employing an adaptation of the luciferin-based clinical assay currently used in human drug screening. Short-term (4-h) cultured rabbit primary hepatocytes were treated with a cytochrome inducer (phenobarbital) and 2 inhibitors (alpha-naphthoflavone and ketoconazole). In parallel, and to provide verification, New Zealand white rabbits were dosed with 80 mg/kg phenobarbital or 40 mg/kg ketoconazole for 3 d. Ketoconazole significantly increased CYP3A6 gene expression and decreased CYP3A6 activity both in vitro and in vivo. CYP1A1 activity was decreased by ketoconazole in vitro and increased in vivo. This is the first report of the inducer effect of ketoconazole on rabbit cytochrome isoenzymes in vivo. Our data support the use of a luciferin-based assay in short-term primary hepatocytes as an appropriate tool for xenobiotic metabolism assays and short-term toxicity testing in rabbits.<p> </p>

Diet-induced non-alcoholic fatty liver disease affects expression of major cytochrome P450 genes in a mouse model

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is associated with impaired liver function, and resveratrol could suppress NAFLD progression. This study examined the effects of NAFLD on the expression of major cytochrome P450 (CYP) subtypes in the liver and whether the expression could be attenuated by resveratrol.

METHODS

C57BL/6 mice (male, 10 weeks of age) were fed a high-fat and high-sucrose (HFHS) diet to induce NAFLD. Major Cyp subtype mRNA expression in the liver was measured by real-time RT-PCR.

KEY FINDINGS

Body and liver weights at 4 and 12 weeks were significantly higher in mice fed the HFHS diet compared with control. The HFHS diet significantly increased the accumulation of cholesterol and triglycerides at 12 weeks. Under this condition, the HFHS diet increased the expression of Cyp1a2 and decreased that of Cyp3a11 at 1 week and thereafter. On the other hand, Cyp1a1, 2b10 and 2c29 mRNA expression levels in the liver were significantly increased at 12 weeks only. Resveratrol (0.05% (w/w) in diet) slightly suppressed lipid accumulation in the liver, but failed to recover impaired Cyp gene expression levels in NAFLD.

CONCLUSIONS

Drug metabolism may be impaired in NAFLD, and each Cyp subtype is regulated in a different manner.

Simultaneous determination of bupropion, metroprolol, midazolam, phenacetin, omeprazole and tolbutamide in rat plasma by UPLC-MS/MS and its application to cytochrome P450 activity study in rats

A specific ultra-performance liquid chromatography tandem mass spectrometry method is described for the simultaneous determination of bupropion, metroprolol, midazolam, phenacetin, omeprazole and tolbutamide in rat plasma with diazepam as internal standard, which are the six probe drugs of the six cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19 and CYP2C9. Plasma samples were protein precipitated with acetonitrile. The chromatographic separation was achieved using a UPLC® BEH C18 column (2.1 × 100 mm, 1.7 µm). The mobile phase consisted of acetonitrile and water (containing 0.1% formic acid) with gradient elution. The triple quadrupole mass spectrometric detection was operated by multiple reaction monitoring in positive electrospray ionization. The precisions were <13%, and the accuracy ranged from 93.3 to 110.4%. The extraction efficiency was >90.5%, and the matrix effects ranged from 84.3 to 114.2%. The calibration curves in plasma were linear in the range of 2-2000 ng/mL, with correlation coefficient (r(2) ) >0.995. The method was successfully applied to pharmacokinetic studies of the six probe drugs of the six CYP450 isoforms and used to evaluate the effects of erlotinib on the activities of CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19 and CYP2C9 in rats. Erlotinib may inhibit the activity of CYP2B6 and CYP3A4, and may induce CYP2C9 of rats.

Effects of Alismatis rhizome on rat cytochrome P450 enzymes

CONTEXT

Alismatis rhizome (RA) (Water Plantain Family, also called "Zexie" in Chinese), one of the commonly used components of traditional Chinese medicines, is derived from the dried rhizomes of Alisma orientalis (Sam.) Juzep. (Alismataceae).

OBJECTIVE

This study explores the RA influences on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) by using cocktail probe drugs in vivo.

MATERIALS AND METHODS

A cocktail solution at a dose of 5 mL/kg, which contained phenacetin (20 mg/kg), tolbutamide (5 mg/kg), chlorzoxazone (20 mg/kg) and midazolam (10 mg/kg), was orally administration to rats treated twice daily with RA (10, 20 and 40 g/kg) for consecutive 14 days. Blood samples (0.2 mL) were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0 (Wenzhou Medical College, Zhejiang, China).

RESULTS

In the experiment, there was a statistically significant difference in the t1/2, Cmax, AUC(0-∞) and CL for phenacetin and midazolam, while there was no statistical pharmacokinetics difference for tolbutamide and chlorzoxazone. Our study showed that treatment with multiple doses of RA had an inductive effect on rat CYP1A2 and an inhibitory effect on rat CYP3A4 enzyme activity. However, RA has no inductive or inhibitory effect on the activities of CYP2C9 and CYP2E1.

CONCLUSIONS

Caution is needed when RA is co-administration with some CYP1A2 or CYP3A4 substrates in clinic, because it may result in treatment failure and herb-drug interactions.