Metabolic profiles of 20(S)-protopanaxadiol in rats after oral administration using ultra-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry

A systematic strategy integrating solid-phase extraction, full scan range splitting, mass defect filter and precursor ion list for comprehensive metabolite profiling of Danqi Tongmai tablet in rats

In vivo metabolite profiling of herbal medicines remains a challenge due to the complex chemical composition and drastic interference from biological matrix. In this study, a systematic strategy was established for comprehensive metabolite profiling of Danqi Tongmai (DQTM) tablet, a combination of salvianolic acids and notoginsenosides, in rats after oral administration. This strategy was composed of six steps. Firstly, the rat plasma and tissue samples were collected at multiple time points to increase the representativeness of samples. Secondly, different sample preparation methods were systematically investigated including protein precipitation, liquid-liquid extraction and solid-phase extraction to obtain superior extraction efficiency for both salvianolic acids and notoginsenosides. Thirdly, the MS acquisition method was optimized by splitting the full scan range into two separate segments to improve the detection capability for minor components. Fourthly, an extended polygonal mass defect filter (EP-MDF) model was constructed to filter potential metabolites of salvianolic acids and notoginsenosides, and remove large amounts of interference ions. Fifthly, ion intensity-based time point-staggered precursor ion list (IITPS-PIL) was generated to trigger more targeted MS/MS acquisition for potential metabolites at the highest concentration. Finally, the absorbed prototypes and metabolites were comprehensively characterized by reference standards and MS/MS fragmentation. The proposed strategy significantly improved the detection ability for trace prototypes and metabolites in vivo. A total of 370 components, including 94 prototypes (38 confirmed with reference standards) and 276 metabolites, were tentatively characterized in rat plasma and tissue samples after oral administration of DQTM. Collectively, this paper provided an applicable reference for comprehensive metabolite profiling of herbal medicines in complex biological samples.

Characterization of the metabolites of GW1929 in rat by liquid chromatography coupled with electrospray ionization tandem mass spectrometry

RATIONALE

GW1929 is a potent PPAR-γ activator. To fully understand its mechanism of action, it is necessary to study the in vitro and in vivo metabolism.

METHODS

For in vitro metabolism, GW1929 was incubated with rat hepatocytes at 37°C for 2 h. For in vivo metabolism, rats were orally administered with GW1929 at a single dose of 10 mg/kg and plasma, urinary and fecal samples were collected at defined time points. All the samples were analyzed by the developed ultra-high-performance liquid chromatography combined with tandem mass spectrometry. The structures of metabolites were proposed according to their accurate masses and product ions.

RESULTS

A total of 17 metabolites, including seven glucuronide conjugates, were detected and structurally identified. M4 (hydroxylation), M13 (demethylation) and M14 (hydroxylation) were the most abundant metabolites. The metabolic pathways of GW1929 referred to hydroxylation, demethylation, deamination and glucuronidation.

CONCLUSIONS

The present study provided new information on the in vitro and in vivo metabolic profiles of GW1929 which will be helpful for a better understanding of the mechanism of the elimination of GW1929.

Tentative identification of 20(S)-protopanaxadiol metabolites in human plasma and urine using ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass spectrometry

BACKGROUND

20(S)-Protopanaxadiol (PPD), the aglycone part of 20(S)-protopanaxadiol ginsenosides, possesses antidepressant activity among many other pharmacological activities. It is currently undergoing clinical trial in China as an antidepressant.

METHODS

In this study, an ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass tandem mass spectrometry method was established to identify the metabolites of PPD in human plasma and urine following oral administration in phase IIa clinical trial.

RESULTS

A total of 40 metabolites in human plasma and urine were identified using this method. Four metabolites identified were isolated from rat feces, and two of them were analyzed by NMR to elucidate the exact structures. The structures of isolated compounds were confirmed as (20S,24S)-epoxydammarane-12,23,25-triol-3-one and (20S,24S)-epoxydammarane-3,12,23,25-tetrol. Both compounds were found as metabolites in human for the first time. Upon comparing our findings with the findings of the in vitro study of PPD metabolism in human liver microsomes and human hepatocytes, metabolites with m/z 475.3783 and phase II metabolites were not found in our study whereas metabolites with m/z 505.3530, 523.3641, and 525.3788 were exclusively detected in our experiments.

CONCLUSION

The metabolites identified using ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass spectrometry in our study were mostly hydroxylated metabolites. This indicated that PPD was metabolized in human body mainly through phase I hepatic metabolism. The main metabolites are in 20,24-oxide form with multiple hydroxylation sites. Finally, the metabolic pathways of PPD in vivo (human) were proposed based on structural analysis.

Dose-dependent exposure profile and metabolic characterization of notoginsenoside R1 in rat plasma by ultra-fast liquid chromatography-electrospray ionization-tandem mass spectrometry

Notoginsenoside R₁ (NGR₁ ), a diagnostic protopanaxatriol-type (ppt-type) saponin in Panax notoginseng, possesses potent biological activities including antithrombotic, anti-inflammatory, neuron protection and improvement of microcirculation, yet its pharmacokinetics and metabolic characterization as an individual compound remain unclear. The aim of this study was to investigate the exposure profile of NGR₁ in rats after oral and intravenous administration and to explore the metabolic characterization of NGR₁ . A simple and sensitive ultra-fast liquid chromatographic-tandem mass spectrometric method was developed and validated for the quantitative determination of NGR₁ and its major metabolites, and for characterization of its metabolic profile in rat plasma. The blood samples were precipitated with methanol, quantified in a negative multiple reaction monitoring mode and analyzed within 6.0 min. Validation parameters (linearity, precision and accuracy, recovery and matrix effect, stability) were within acceptable ranges. After oral administration, NGR₁ exhibited dose-independent exposure behaviors with t_1/2 over 8.0 h and oral bioavailability of 0.25-0.29%. A total of seven metabolites were characterized, including two pairs of epimers, 20(R)-notoginsenoside R₂ /20(S)-notoginsenoside R₂ and 20(R)-ginsenoside Rh₁ /20(S)-ginsenoside Rh₁ , with the 20(R) form of saponins identified for the first time in rat plasma. Five deglycometabolites were quantitatively determined, among which 20(S)-notoginsenoside R₂ , ginsenoside Rg₁ , ginsenoside F₁ and protopanaxatriol displayed relatively high exploration, which may partly explain the pharmacodynamic diversity of ginsenosides after oral dose.

Characterization of ginsenoside compound K metabolites in rat urine and feces by ultra-performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

Ginsenoside compound K (CK) is an active metabolite of ginsenoside and has been shown to have ameliorative property in various diseases. However, the detailed in vivo metabolism of this compound has rarely been reported. In the present study, a method using liquid chromatography quadrupole time-of-flight tandem mass spectrometry together with multiple data processing techniques, including extracted ion chromatogram, multiple mass defect filter and MS/MS scanning, was developed to detect and characterize the metabolites of CK in rat urine and feces. After oral administration of CK at a dose of 50 mg/kg, urine and feces were collected for a period of time and subjected to a series of pretreatment. A total of 12 metabolites were tentatively or conclusively identified, comprising 11 phase I metabolites and a phase II metabolite. Metabolic pathways of CK has been proposed, including oxidation, deglycosylation, deglycosylation with sequential oxidation and dehydrogenation and deglycosylation with sequential glucuronidation. Relative quantitative analyses suggested that deglycosylation was the main metabolic pathway. The result could offer insights for better understanding of the mechanism of its pharmacological activities.

In vitro and in vivo metabolic profiles of fasiglifam using ultrahigh-performance liquid chromatography combined with Q-Exactive Orbitrap tandem mass spectrometry

RATIONALE

Fasiglifam is an orally available and selective partial agonist of hGPR40 receptor, which was unexpectedly terminated at phase III clinical trials due to its severe hepatotoxicity. To fully understand the mechanism of action of fasiglifam, it is necessary to investigate its in vitro and in vivo metabolic profiles.

METHODS

For in vitro metabolism, fasiglifam was incubated with rat or human liver microsomes in the presence of β-nicotinamide adenine dinucleotide phosphate tetrasodium salt, glutathione (GSH) and uridine diphosphate glucuronic acid trisodium salt for 60 min. For in vivo metabolism, fasiglifam was orally administered to rats at a single dose of 20 mg/kg and the bile was collected. In vitro and in vivo samples were analyzed by the developed ultrahigh-performance liquid chromatography combined with Q-Exactive Orbitrap tandem mass spectrometry. The structures of metabolites were proposed according to their accurate masses and fragment ions.

RESULTS

A total of eight metabolites, including an acyl-GSH adduct, were detected and identified. M1 (acylglucuronide) and M5 (carboxylic acid derivative) were the major metabolites of fasiglifam. Metabolic pathways of fasiglifam involved oxygenation, oxidative dealkylation, dehydrogenation, glucuronidation and GSH conjugation. Fasiglifam may undergo metabolic bioactivation via acylglucuronide.

CONCLUSIONS

Oxidative dealkylation and glucuronidation were the predominant metabolic pathways of fasiglifam in vitro and in vivo. Metabolic bioactivation via acylglucuronide may be the perpetrator of its hepatotoxicity. Our findings would be helpful in understanding the disposition of fasiglifam as well as its hepatotoxicity.

Simultaneous determination of 20(S)-protopanaxadiol and its three metabolites in rat plasma by LC-MS/MS: application to their pharmacokinetic studies

The aim of this study was to develop an LC-MS/MS method for simultaneous determination of 20(S) protopanaxadiol (PPD) and its three metabolites, PPD-glucuronide (M1), (20S,24S)-epoxy-dammarane-3,12,25-triol (M2) and (20S,24R)-epoxydammarane-3,12,25-triol (M3), in rat plasma. Precipitation with acetonitrile was employed for sample preparation and chromatographic separations were achieved on a C₁₈ column. The sample was detected using triple quadrupole tandem mass spectrometer with selected reaction monitoring mode. The monitored precursor-to-product ion transitions were m/z 459.4 → 375.3 for PPD, m/z 635.4 → 113.0 for M1, m/z 477.4 → 441.4 for M2 and M3 and m/z 475.4 → 391.3 for IS. The developed assay was validated according to the guidelines of the US Food and Drug Administration. The calibration curves showed good linearity over the tested concentration ranges (r > 0.9993), with the LLOQ being 1 ng/mL for all analytes. The intra- and inter-day precisions (RSD) were < 9.51% while the accuracy (RE) ranged from -8.91 to 12.84%. The extraction recovery was >80% and no obvious matrix effect was detected. The analytes were stable in rat plasma with the RE ranging from -12.34 to 9.77%. The validated assay has been successfully applied to the pharmacokinetic study of PPD as well as its metabolites in rat plasma. According to the pharmacokinetic parameters, the in vivo exposures of M1, M2 and M3 were 11.91, 47.95 and 22.62% of that of PPD, respectively.

Identification of Human UDP-Glucuronosyltransferase 1A4 as the Major Isozyme Responsible for the Glucuronidation of 20(S)-Protopanaxadiol in Human Liver Microsomes

20(S)-protopanaxadiol (PPD), one of the representative aglycones of ginsenosides, has a broad spectrum of pharmacological activities. Although phase I metabolism has been investigated extensively, information regarding phase II metabolism of this compound remains to be elucidated. Here, a glucuronidated metabolite of PPD in human liver microsomes (HLMs) and rat liver microsomes (RLMs) was unambiguously identified as PPD-3-O-β-d-glucuronide by nuclear magnetic resonance spectroscopy and high resolution mass spectrometry. The chemical inhibition and recombinant human UDP-Glucuronosyltransferase (UGT) isoforms assay showed that the PPD glucuronidation was mainly catalyzed by UGT1A4 in HLM, whereas UGT1A3 showed weak catalytic activity. In conclusion, PPD-3-O-β-d-glucuronide was first identified as the principal glucuronidation metabolite of PPD in HLMs, which was catalyzed by UGT1A4.