Identification of metabolites of liquiritin in rats by UHPLC-Q-TOF-MS/MS: metabolic profiling and pathway comparisonin vitroandin vivo

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.

Elucidating a Complicated Enantioselective Metabolic Profile: A Study From Rats to Humans Using Optically Pure Doxazosin

Doxazosin (DOX) is prescribed as a racemic drug for the clinical treatment of benign prostatic hyperplasia and hypertension. Recent studies found that the two enantiomers of DOX exhibit differences in blood concentration and pharmacological effects. However, the stereoselective metabolic characteristics and mechanisms for DOX are not yet clear. Herein, we identified 34 metabolites of DOX in rats based on our comprehensive and effective strategy. The relationship among the metabolites and the most discriminative metabolites between (−)-DOX and (+)-DOX administration was analyzed according to the kinetic parameters using state-of-the-art multivariate statistical methods. To elucidate the enantioselective metabolic profile in vivo and in vitro, we carefully investigated the metabolic characteristics of metabolites after optically pure isomers administration in rat plasma, rat liver microsomes (RLMs) or human liver microsomes (HLMs), and recombinant human cytochrome P450 (CYP) enzymes. As a result, the differences of these metabolites were found based on their exposure and elimination rate, and the metabolic profile of (±)-DOX was more similar to that of (+)-DOX. Though the metabolites identified in RLMs and HLMs were the same, the metabolic profiles of the metabolites from (−)-DOX and (+)-DOX were greatly different. Furthermore, four human CYP enzymes could catalyze DOX to produce metabolites, but their preferences seemed different. For example, CYP3A4 highly specifically and selectively catalyzed the formation of the specific metabolite (M22) from (−)-DOX. In conclusion, we established a comprehensive metabolic system using pure optical isomers from in vivo to in vitro, and the complicated enantioselectivity of the metabolites of DOX was clearly shown. More importantly, the comprehensive metabolic system is also suitable to investigate other chiral drugs.

The development and validation of a sensitive HPLC-MS/MS method for the quantitative and pharmacokinetic study of the seven components of Buddleja lindleyana Fort

Buddleja lindleyana Fort., a traditional Chinese medicine, has demonstrated anti-inflammatory, immunomodulatory, antidementia, neuroprotective, antibacterial, and antioxidant effects. Its flowers, leaves, and roots have been used as traditional Chinese medicines. A simple and rapid high-performance liquid chromatography method coupled with mass spectrometry (HPLC-MS/MS) was applied in the multicomponent determination of Buddleja lindleyana Fort., and the discrepancies in the contents from ten different habitats were analyzed. The present study simultaneously determined the concentrations of seven chemical compounds of Buddleja lindleyana Fort. extract in rat plasma via HPLC-MS/MS, which was applied in the pharmacokinetic (PK) study of Buddleja lindleyana Fort. A C18 column was used for chromatographic separation, and ion acquisition was achieved by multiple-reaction monitoring (MRM) in negative ionization mode. The optimized mass transition ion-pairs (m/z) for quantization were 591.5/282.8 for linarin, 609.4/300.2 for rutin, 284.9/133.0 for luteolin, 300.6/151.0 for quercetin, 268.8/116.9 for apigenin, 283.0/267.9 for acacetin, 623.3/160.7 for acteoside, and 252.2/155.8 for sulfamethoxazole (IS). A double peak appeared in the drug–time curve of apigenin, which was associated with entero-hepatic recirculation. There were discrepancies in the contents of seven chemical compounds from 10 batches of Buddleja lindleyana Fort., which were associated with the growth environments. Herein, the pharmacokinetic parameters of seven analytes in Buddleja lindleyana Fort. extract are summarized. The maximum plasma concentration (C_max) of linarin, rutin, luteolin, quercetin, apigenin, acacetin and acteoside were 894.12 ± 9.34 ng mL⁻¹, 130.76 ± 18.33 ng mL⁻¹, 77.37 ± 25.72 ng mL⁻¹, 20.15 ± 24.85 ng mL⁻¹, 146.42 ± 14.88 ng mL⁻¹, 31.92 ± 17.58 ng mL⁻¹, and 649.78 ± 16.42 ng mL⁻¹, respectively. The time to reach C_max for linarin, rutin, luteolin, quercetin, apigenin, acacetin, and acteoside were 10, 5, 5, 5, 180, 10 and 10 min, respectively. This is the first report on the simultaneous determination of seven active components for 10 different growing environments and the pharmacokinetic studies of seven active components in rat plasma after the oral administration of Buddleja lindleyana Fort. extract. This study lays the foundation for a better understanding of the absorption mechanism of Buddleja lindleyana Fort., and the evaluation of its clinical application.

Quality control and pharmacokinetics of Buddleja lindleyana Fort by HPLC-MS/MS.

A comprehensive profiling and identification of liquiritin metabolites in rats using ultra-high-performance liquid chromatography coupled with linear ion trap-orbitrap mass spectrometer

Liquiritin (LQ), a main component of liquorice, exerts various biological activities. However, insufficient attentions have been paid to the metabolism study on this natural compound until now. Our present study was conducted to investigate the LQ metabolites in rats urine, faeces and plasma using UHPLC-LTQ-Orbitrap mass spectrometer in both positive and negative ion modes. Meanwhile, post-acquisition data-mining methods including high-resolution extracted ion chromatogram (HREIC), multiple mass defect filters (MMDFs), neutral loss fragments (NLFs) and diagnostic product ions (DPIs) were utilised to screen and identify LQ metabolites from HR-ESI-MS to ESI-MSⁿ stage. As a result, a total of 49 metabolites were detected and characterised unambiguously or tentatively. These metabolites were presumed to generate through glucuronidation, sulfation, deglucosylation, dehydrogenation, methylation, hydrogenation, hydroxylation, ring cleavage and their composite reactions. Our results not only provided novel and useful data to better understand the biological activities of LQ, but also indicated that the proposed strategy was reliable for a rapid discovery and identification drug-related constituents in vivo.

Exploring stereoselective excretion and metabolism studies of novel 2-(2-hydroxypropanamido)-5-trifluoromethyl benzoic acid enantiomers

R-/S-2-(2-Hydroxypropanamido)-5-trifluoromethyl benzoic acid (R-/S-HFBA), as a novel COX inhibitor, was firstly reported to have remarkable anti-inflammatory and antiplatelet aggregation activities by our group. In our previous study, stereoselective differences in pharmacokinetics were found between HFBA enantiomers after oral and intravenous administration of each enantiomer to rats. The discrepancies might be associated with the excretion and metabolism of the two enantiomers. In this research, an UHPLC-MS/MS method was established and validated for quantification of R-/S-HFBA in rats urine, feces and bile samples in excretion study. Moreover, an ultra high performance liquid chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (UHPLC-FT-ICR-MS) method was employed to understand the metabolism of R-/S-HFBA in rats. Results showed that the total cumulative excretion of R-/S-HFBA in three routes were 65.8% and 58.5% of the dose, respectively. The urinary excretion of R-/S-HFBA was the main route, which accounted for 40.2% and 31.7% respectively; the cumulative biliary excretion of R-/S-HFBA were 11.3% and 7.4%; the cumulative amounts of R-/S-HFBA excreted directly via feces without absorption from the gastrointestinal tract were 14.3% and 19.4%, respectively. R-/S-HFBA existed stereoselective discrepancy in excretion. In addition, 8 metabolites of S-HFBA were detected and tentatively identified including glucuronidation, glycine and N-acetyl conjugation while R-HFBA existed 7 metabolites without glycine conjugation. Formation of metabolites of R-/S-HFBA also exhibited stereoselectivity. In summary, these new findings on excretion and metabolism of R-/S-HFBA provided valuable information for stereoselective pharmacokinetics and were greatly helpful for further investigation, such as safety and mechanism of action.

R-/S-2-(2-Hydroxypropanamido)-5-trifluoromethyl benzoic acid (R-/S-HFBA), as a novel COX inhibitor, was firstly reported to have remarkable anti-inflammatory and antiplatelet aggregation activities by our group.

A Complete Study of Farrerol Metabolites Produced in Vivo and in Vitro

Although farrerol, a characteristically bioactive constituent of Rhododendron dauricum L., exhibits extensive biological and pharmacological activities (e.g., anti-oxidant, anti-immunogenic, and anti-angiogenic) as well as a high drug development potential, its metabolism remains underexplored. Herein, we employed ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry coupled with multiple data post-processing techniques to rapidly identify farrerol metabolites produced in vivo (in rat blood, bile, urine and feces) and in vitro (in rat liver microsomes). As a result, 42 in vivo metabolites and 15 in vitro metabolites were detected, and farrerol shown to mainly undergo oxidation, reduction, (de)methylation, glucose conjugation, glucuronide conjugation, sulfate conjugation, N-acetylation and N-acetylcysteine conjugation. Thus, this work elaborates the metabolic pathways of farrerol and reveals the potential pharmacodynamics forms of farrerol.

Identification of Metabolites of Eupatorin in Vivo and in Vitro Based on UHPLC-Q-TOF-MS/MS

Eupatorin is the major bioactive component of Java tea (Orthosiphon stamineus), exhibiting strong anticancer and anti-inflammatory activities. However, no research on the metabolism of eupatorin has been reported to date. In the present study, ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) combined with an efficient online data acquisition and a multiple data processing method were developed for metabolite identification in vivo (rat plasma, bile, urine and feces) and in vitro (rat liver microsomes and intestinal flora). A total of 51 metabolites in vivo, 60 metabolites in vitro were structurally characterized. The loss of CH2, CH2O, O, CO, oxidation, methylation, glucuronidation, sulfate conjugation, N-acetylation, hydrogenation, ketone formation, glycine conjugation, glutamine conjugation and glucose conjugation were the main metabolic pathways of eupatorin. This was the first identification of metabolites of eupatorin in vivo and in vitro and it will provide reference and valuable evidence for further development of new pharmaceuticals and pharmacological mechanisms.

UHPLC-Q-TOF-MS/MS method based on four-step strategy for metabolites of hinokiflavone in vivo and in vitro

Hinokiflavone (HF), belonging to biflavonoids, possesses excellent pharmacological activities, including anti-inflammatory, antioxidant and antitumor activity. Nevertheless, its metabolism in vivo (rats) and in vitro (rat liver microsomes and intestinal flora) is presently not characterized. In this study, ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) based on four-step strategy was a rapid method for the detection of HF metabolites. A total of 41 metabolites in vivo, 49 metabolites in vitro were characterized. It also verified that intestinal tract exceeds the liver in the biotransformation of HF. More significant, the main metabolic pathways for HF were mainly bio-transformed to various mono-flavone resulting from the rupture of connective CO bonds, which exhibited a large distinction with other biflavones. Noteworthily, glutamine conjugation and glycine conjugation were considered as unique metabolic pathways of HF. The information obtained from this study contributes to better understanding of pharmacological mechanism of HF.

A comprehensive study of eriocitrin metabolism in vivo and in vitro based on an efficient UHPLC-Q-TOF-MS/MS strategy

Eriocitrin, a main flavonoid in lemons, possesses strong antioxidant, lipid-lowering and anticancer activities and has long been used in food, beverages and wine. However, its metabolism in vivo and in vitro is still unclear. In this study, an efficient strategy was developed to detect and identify metabolites of eriocitrin by using ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) based on online data acquisition and multiple data processing techniques. A total of 32 metabolites in vivo and 27 metabolites in vitro were obtained based on the above method. Furthermore, the main metabolic pathways of eriocitrin included reduction, hydrogenation, N-acetylation, ketone formation, oxidation, methylation, sulfate conjugation, glutamine conjugation, glycine conjugation, desaturation and demethylation to carboxylic acid. This study will lay a foundation for further studies on the metabolic mechanisms of eriocitrin.

41 metabolites of eriocitrin in vivo and in vitro was identified based on the efficient UHPLC-Q-TOF-MS/MS strategy.

A time-of-flight mass spectrometry based strategy to fast screen triterpenoids in Xanthoceras sorbifolia Bunge husks for bioactive substances against Alzheimer's disease

Xanthoceras sorbifolia Bunge is a folk medicine in China. Recently, the triterpenoids in its husks have attracted more and more attention for potential prevention against Alzheimer's disease. However, current studies on its bioactive substances were still insufficient. To reveal more bioactive substances, an efficient and practical strategy based on high resolution mass spectra coupled with multiple data mining techniques was developed to characterize the barrigenol type triterpenoids in the husks and dosed rat plasma. A total of 50 barrigenol type triterpenoids were identified in the husks, and 6 of these were detected in the rat plasma, which were regarded as bioactive candidates. To find the real bioactive substances, the neuroprotective effect of the candidates was further tested by calculating the PC12 cell viability against amyloid-β-induced cytotoxicity. As a result, three out of the six candidates exhibited obvious neuroprotction against amyloid-β-induced cytotoxicity on PC12 cells, indicating their potential to be bioactive substances against Alzheimer's disease. This study will be a valuable reference of the bioactive substances in Xanthoceras sorbifolia Bunge husks against Alzheimer's disease and the provided strategy can also be applied to the exploration of the effective constituents in other medicines.

An efficient strategy was developed to reveal the neuroprotective substances in X. sorbifolia husks.