Pharmacokinetics and metabolism study of veratramine in mice after oral administration using LC-MS/MS

Metabolite profiling of liquiritin in acute myocardial infarction model rat after intragastric administration using an information-dependent acquisition-mediated ultra-high-performance liquid chromatography-tandem mass spectrometry method

Liquiritin (LQ), a kind of flavonoid isolated from licorice, was proven to have great potential in treating heart failure. Pharmacokinetic evaluation is important for demonstrating clinical efficacy and mechanisms, and the prototype drug and its metabolite profiling are important for drug discovery and development. However, the metabolism of LQ in acute myocardial infarction (AMI) model rats still needs to be studied in depth. An information-dependent acquisition (IDA)-ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was applied to profile LQ metabolites in AMI model rat plasma. Protein precipitation and extraction were used for sample preparation. Chromatographic separation was achieved using an XSelect BEH C18 column (2.1 × 150 mm, 2.5 μm) using gradient elution method combining 0.1% formic acid and acetonitrile with a flow rate of 0.3 mL/min. Twelve metabolites were identified in IDA mode, sulfation, glucuronidation, methylation, methyl esterification, glutamine conjugation, and valine conjugation, and their composite reactions were presumed as the primary pathways of LQ metabolism. The variation in the peak areas showed that the time to reach the peak drug concentration of LQ and 12 metabolites was within 5 h. In summary, IDA-bridged UHPLC-MS/MS from characteristic fragment ions toward confidence-enhanced identification could effectively screen and profile metabolites.

Metabolic profiling of Qi-Yu-San-Long decoction in rat feces by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry combined with a post-targeted screening strategy

Research into traditional Chinese medicine metabolism in feces is one of the key avenues to understanding the fate of traditional Chinese medicines in vivo. In this study, we used ultraperformance liquid chromatography-quadrupole time-of-flight MS in combination with a post-targeted screening strategy to identify the prototype components and metabolites in rat feces after oral administration. Based on our group's previous research, the component database of Qi-Yu-San-Long decoction (QYSLD) was established. Prototype components were screened from the fecal samples based on summarized chromatographic and MS behaviors. According to the chemical structure characteristics of related compounds, the possible metabolic pathways were inferred, and the metabolites related to QYSLD were predicted. We extracted ion chromatograms by predicting the m/z values of metabolite excimer ions and identified related metabolites based on their retention time and fragmentation behavior. A total of 93 QYSLD-related xenobiotics were confirmed or tentatively identified in rat fecal samples, and the results indicated that the main metabolic pathways of QYSLD were hydrolysis, deglycosylation, oxidation, reduction, decarboxylation, methylation and acetylation. This study presents a rapid method for identifying the prototype components and metabolites, and offers valuable insights into the biotransformation profiling of QYSLD in rat feces.

Confirmative Structural Annotation for Metabolites of (R)-7,3'-Dihydroxy-4'-methoxy-8-methylflavane, A Natural Sweet Taste Modulator, by Liquid Chromatography-Three-Dimensional Mass Spectrometry

Flavonoids occupy the largest family of natural products and possess a broad spectrum of health benefits. Their metabolites are sometimes the truly effective molecules in vivo. It is still challenging, however, to unambiguously identify flavonoid metabolites using conventional LC-MS/MS. Herein, we aimed to pursue auxiliary structural clues to m/z values in both MS¹ and MS² spectra through LC coupled to three-dimensional MS (LC-3D MS). MS¹, as the first dimension, was in charge of suggesting theoretical molecular formulas, MS², the as second dimension, was responsible for offering substructures, and exactly, online energy-resolved MS (ER-MS), as the third dimension, provided optimal collision energies (OCEs) that reflected the linkage manners among the substructures. Metabolic characterization of a natural sweet taste modulator, namely, (R)-7,3'-dihydroxy-4'-methoxy-8-methylflavane (DHMMF), was conducted as a proof-of-concept. Extensive efforts, such as full MS¹ and MS² scans on IT-TOF-MS and predictive selected-reaction monitoring mode on Qtrap-MS, were made for in-depth metabolite mining. Seventeen metabolites (M1-M17) were captured from DHMMF-treated biological samples, including 17 (M1-M17), 10 (M4-M9, M11, M13, M14, and M16), and 2 (M5 and M10) metabolites from urine, plasma, and feces, respectively. Their structures were configured by integrating MS¹, MS², and OCE information. Except M10, all metabolites were new compounds. LC-MS/MS-guided chromatographic purification yielded three glucuronyl-conjugated metabolites (M5, M8, and M11), and NMR spectroscopic assays consolidated the structures transmitted from LC-3D MS. Demethylation, glucuronidation, and sulfation occurred as the primary metabolic pathways of DHMMF. Above all, LC-3D MS bridged LC-MS/MS from putatively structural annotation toward confidence-enhanced identification, beyond the metabolite characterization of flavonoids.

UPLC-MS/MS Method for the Simultaneous Quantification of Eight Compounds in Rat Plasma and Its Application to a Pharmacokinetic Study after Oral Administration of Veratrum (Veratrum nigrum L.) Extract

Veratrum nigrum L. is a well-known traditional Chinese medicine with a lot of pharmacological activities including antihypertensive, anticancer, and antifungal effects. In the current experiment, a rapid and sensitive UPLC-MS/MS method that takes only 7 min run time has been established and validated for simultaneous determination of eight bioactive compounds including cyclopamine, jervine, veratramine, polydatin, quercetin, apigenin, resveratrol, and veratrosine in rat plasma. The chromatographic separation of analytes and internal standard was performed on a Phenyl-Hexyl column (2.1 × 100 mm, 1.7 μm) with the mobile phase consisting of water (0.1% formic acid) and acetonitrile at a flow rate of 0.3 mL/min. An electrospray ionization (ESI) source was used to detect the samples in both positive and negative ion modes. The intra- and interday precisions of the compounds were less than 9.5% and the accuracy ranged from -10.8% to 10.4%. The extraction recoveries of the compounds were in the range of 85.1 ± 1.5% to 102.6 ± 8.0%, and the matrix effect ranged from 91.2 ± 4.5% to 113.8 ± 1.5%. According to the results of the stability test, the eight compounds have good stability under various conditions and the relative standard deviation (RSD) less than 13.2%. The pharmacokinetic parameters of the eight compounds in rat plasma after oral administration of Veratrum nigrum L. extract were successfully determined by the established UPLC-MS/MS method.

[Chemical-toxicological diagnosis of hellebore (veratrum) poisoning]

The problem of laboratory diagnosis of acute and fatal poisoning by hellebore, which is possible when used in traditional medicine, the erroneous use of hellebore preparations orally or use of various types of this plant for food, remains relevant. Currently, in the practice of chemical-toxicological laboratories and the bureau of forensic medical examination there is no single approach to the laboratory diagnosis of such poisoning. The diagnosis is most often based on anamnesis. In this regard, the development and validation of a legally significant methodology for the determination of hellebore alkaloids in various biological objects seems relevant. The physicochemical and toxic properties of alkaloids of various types of hellebore are characterized. It was shown that for the identification of hellebore alkaloids, it is advisable to use HPLC-MS/MS as the most sensitive and specific instrumental method corresponding to the characteristics of hellebore alkaloids (high molecular weight, high thermal lability, high polarity).

Quantification and confirmation of four aflatoxins using a LC-MS/MS QTRAP system in multiple reaction monitoring, enhanced product ion scan, and MS3 modes

A simple, rapid, and efficient liquid chromatography tandem mass spectrometry (LC-MS/MS) method, operated in electrospray ionization and quadrupole linear ion trap modes, has been developed for the identification and structural characterization of aflatoxins in peanuts and its derivative products or bean sauce. Samples (5 g) were extracted with acetonitrile/water/formic acid (79:20:1, v/v). After centrifugation and dilution, the extracts were separated on a C18 analytical column by gradient elution (acetonitrile/0.2% formic acid) and analyzed by UPLC-MS/MS. External calibration was used for qualification. The developed multiple reaction monitoring-information-dependent acquisition-enhanced product ion method enabled quantification and confirmation of the analytes in a single run. Enhanced product ion mode was used for qualitative analysis, while multiple reaction monitoring mode was used for quantitative analysis. An in-house library was constructed for identification. Calibration curves showed good linearity with correlation coefficients (r) higher than 0.994. Limits of detection were determined to be below 0.26 µg kg^-1 for most analytes. The recoveries for those substances were in the acceptable range of 80.2%-119.1%. A new LC-MS³ method was established for further confirmation. One pickled pepper peanut was found to contain aflatoxins B1, B2, and G1 with contents of 90.93, 26.64, and 1.92 µg kg^-1, respectively.

A Structure-Activity Relationship between the Veratrum Alkaloids on the Antihypertension and DNA Damage Activity in Mice

Veratrum plant contains a family of compounds called steroidal alkaloids which have been previously reported to cause DNA damage and blood pressure decrease in vivo. In this study, the antihypertensive effects and DNA damage in brain cells of 12 steroidal alkaloids separated from Veratrum plant were all evaluated to develop a relationship among chemical structure, antihypertensive activity and neurotoxicity by utilization of chemical principal component analysis (PCA) and hierarchical cluster analysis (HCA). Twelve steroidal alkaloids markedly reduced high blood pressure of hypertensive mice and also similarly induced varying degrees of DNA single-strand breaks in mouse cerebellum and cerebral cortex after oral administration. On the basis of the PCA and HCA results, it was suggested that the 3-carboxylic esters and benzene group play a core role in the DNA damage of brain cells, while more hydroxy groups in the A-ring and B-ring structure of jervine-type alkaloid led to stronger antihypertensive activity. The primary structure, activity and neurotoxicity relationship were discussed briefly.

Pharmacokinetics and enterohepatic circulation of jervine, an antitumor steroidal alkaloid from Veratrum nigrum in rats

Jervine, a novel steroidal alkaloid from Veratrum nigrum L., exhibits both antitumor effect and potential toxicity. The aim of study was to characterize the pharmacokinetic behaviors and enterohepatic circulation of jervine in rats. A rapid and simple ultra-high performance liquid chromatography-tandem mass spectrometric method was developed and validated for quantification of jervine and alpinetin (internal standard) in rat plasma. After extraction from rat plasma by a simple protein-precipitation method, the analyte was separated on a C₁₈ column (2.1 mm × 50 mm, 1.7 μm) using water with 0.1% formic acid and acetonitrile as the mobile phase delivered at a flow rate of 0.4 mL/min. Jervine and alpinetin were determined in the positive mode with multiple reaction monitoring (MRM) of the ion transitions at m/z 426.3 → 108.8 and m/z 271.0 → 166.9, respectively. Molecular docking method was used to investigate the binding of jervine to p-glycoprotein and dehydroepiandrosterone sulfotransferase. The method was well validated within acceptance limits including specificity, matrix effect, recovery, precision, accuracy, and stability, and was successfully applied to the pharmacokinetic study of jervine after oral and intravenous administration to rats. Jervine presented a small volume of distribution, fast absorption, high oral bioavailability, and enterohepatic circulation. The enterohepatic circulation was first observed in veratrum alkaloids, and was further investigated by molecular docking studies, which was related to the binding of jervine to p-glycoprotein and dehydroepiandrosterone sulfotransferase. The pharmacokinetic properties and enterohepatic circulation of jervine in rats provided a significant basis for the drug-drug interaction and toxicity study in the future.

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It is the first pharmacokinetic and bioavailability study of jervine in rats.

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A simple protein precipitation was used for pretreatment and the LLOQ was 0.25 ng/mL.

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The enterohepatic circulation was first observed in veratrum alkaloids.

Stilbenes from Veratrum maackii Regel Protect against Ethanol-Induced DNA Damage in Mouse Cerebellum and Cerebral Cortex

Ethanol is a principle ingredient of alcoholic beverages with potential neurotoxicity and genotoxicity, and the ethanol-associated oxidative DNA damage in the central nervous system is well documented. Natural source compounds may offer new options to protect the brain against ethanol-induced genotoxicity. Veratrum maackii Regel is a toxic rangeland plant linked to teratogenicity which is also used in traditional Chinese medicine as "Lilu" and is reported to contain a family of compounds called stilbenes that can have positive biological activity. In this study, nine stilbenes were isolated from the aerial parts of V. maackii Regel, and their structures were identified as cis-mulberroside A (1), resveratrol-4,3'- O-β-d-diglucopyranoside (2), mulberroside A (3), gentifolin K (4), resveratrol-3,5- O-β-d-diglucopyranoside (5), oxyresveratrol- 4'- O-β-d-glucopyranoside (6), oxyresveratrol-3- O-β-d-glucopyranoside (7), oxyresveratrol (8), and resveratrol (9) using ESI-MS and NMR techniques. The total concentration of extracted compounds 2-9 was 2.04 mg/g, suggesting that V. maackii Regel is a novel viable source of these compounds. In an in vivo comet assay, compounds 1-9 were observed to decrease DNA damage in mouse cerebellum and cerebral cortex caused by acute ethanol administration. Histological observation also revealed decreased brain injury in mice administered with compounds 1-9 after acute ethanol administration. The protective effects of compound 6 were associated with increasing T-SOD and GSH-PX activities and a decrease in NO and MDA concentrations. These findings suggest that these compounds are potent inhibitors of ethanol-induced brain injury possibly via the inhibition of oxidative stress and may be valuable leads for future therapeutic development.