Characterization of metabolic profile of mosapride citrate in rat and identification of two new metabolites: Mosapride N-oxide and morpholine ring-opened mosapride by UPLC–ESI-MS/MS

New piperazine and morpholine derivatives: Mass spectrometry characterization and evaluation of their antimicrobial activity

Recently, pharmaceutical research has been focused on the design of new antibacterial drugs with higher selectivity towards several strains. Major issues concern the possibility to obtain compounds with fewer side effects, at the same time effectively overcoming the problem of antimicrobial resistance. Several solutions include the synthesis of new pharmacophores starting from piperazine or morpholine core units. Mass spectrometry-based techniques offer important support for the structural characterization of newly synthesized compounds to design safer and more effective drugs for various medical conditions. Here, two new piperazine derivatives and four new morpholine derivatives were synthesized and structurally characterized through a combined approach of Fourier transform-ion cyclotron resonance (FT-ICR) and Linear Trap Quadrupole (LTQ) mass spectrometry. The support of both high-resolution and low-resolution mass spectrometric data namely accurate mass measurements, isotopic distribution and MSn spectra, was crucial to confirm the success of the synthesis. These compounds were further evaluated for inhibitory activity against a total of twenty-nine Gram-positive and Gram-negative bacteria to determine the action spectrum and the antimicrobial effectiveness. Results demonstrated compounds' antimicrobial activity against many tested bacterial species, providing an inhibitory effect linked to different chemical structure and suggesting that the new-synthesized derivatives could be considered as promising antimicrobial agents.

Anti-fibrosis Attributes; UHPLC-MS/MS-Based pharmacokinetics profiling of a novel ATX inhibitor with excellent vivo efficacy in rat

3,4-Difluorobenzyl(1-ethyl-5-(4-((4-hydroxypiperidin-1-yl)-methyl)thiazol-2-yl)-1H-indol-3-yl)carbamate (NAI59), a small molecule with outstanding therapeutic effectiveness to anti-pulmonary fibrosis, is being developed as an autotaxin inhibitor candidate compound. To evaluate the pharmacokinetics and plasma protein binding of NAI59, a UPLC-MS/MS method was developed to quantity NAI59 in plasma and phosphate-buffered saline. The calibration curve linearity ranged from 9.95 ng·mL^-1 to 1990.00 ng·mL^-1 in plasma. The accuracy was -6.8%-5.9%, and the intra- and inter-day precision were within 15%. The matrix effect and recovery were within the criteria, as well as dilution integrity. The chromatographic and mass spectrometric conditions were also feasible to determine PBS samples, and it's proved that this method had good precision and accuracy in the range from 9.95 ng·mL^-1 to 497.50 ng·mL^-1 in PBS. It's the first time to determine the pharmacokinetics, absolute bioavailability, and plasma protein binding of NAI59 in rats by this established method. As a result, the pharmacokinetic profiles of NAI59 showed a dose-dependent relationship after oral administration, and the absolute bioavailability in rats was 6.3%. In addition, the results of protein binding showed that the combining capacity of NAI59 with plasma protein attained 90% and increased with the increase of drug concentration.

Esculetin: A review of its pharmacology and pharmacokinetics

Esculetin is a natural dihydroxy coumarin; it is mainly extracted from twig skin and the trunk bark of the Chinese herbal medicine Fraxinus rhynchophylla Hance. Emerging evidence suggests that esculetin has a wide range of pharmacological activities. Based on its fundamental properties, including antioxidant, antiinflammatory, antiapoptotic, anticancer, antidiabetic, neuroprotective, and cardiovascular protective activities, as well as antibacterial activity, among others, esculetin is expected to be a therapeutic drug for specific disease indications, such as cancer, diabetes, atherosclerosis, Alzheimer's disease (AD), Parkinson's disease (PD), nonalcoholic fatty liver disease (NAFLD), and other diseases. The oral bioavailability of esculetin was shown by studies to be low. The extensive glucuronidation was described to be the main metabolic pathway of esculetin and C-7 phenolic hydroxyl to be its major metabolic site. With the development of scientific research technology, the pharmacological effects of esculetin are identified and its potential for the treatment of diseases is demonstrated. The underlining mechanisms of action and biological activities as well as the pharmacokinetic data of the analyzed compound reported so far are highlighted in this review with the aim of becoming a proven, and applicable insight and reference for further studies on the utilization of esculetin.

Determination of Lekethromycin, a Novel Macrolide Lactone, in Rat Plasma by UPLC-MS/MS and Its Application to a Pharmacokinetic Study

Lekethromycin, a new macrolide lactone, exhibits significant antibacterial activity. In this study, a reliable analytical ultrahigh-performance liquid chromatography electrospray ionization quadrupole Orbitrap high-resolution mass spectrometry (UPLC-ESI-Orbitrap-MS) method was established and validated for the detection of lekethromycin in rat plasma. After a simple acetonitrile (ACN)-mediated plasma protein precipitation, chromatographic separation was performed on a Phenomenex Luna Omega PS C18 column (30 × 2.1 mm i.d. particle size = 3 μm) conducted in a gradient elution procedure using 0.5% formic acid (FA) in ACN and 0.5% FA in water as the mobile phase pumped at a flow rate of 0.3 mL/min. Detection was carried out under positive electrospray ionization (ESI+) conditions in parallel reaction monitoring (PRM) mode with observation of m/z 804.5580 > 577.4056 for lekethromycin and 777.5471 > 619.4522 for gamithromycin (internal standard, IS). The linear range was 5–1000 ng/mL (r² > 0.99), and the lower limit of quantification (LLOQ) was 5 ng/mL. The intra- and inter-day precision (expressed as relative standard deviation, RSD) values were ≤7.3% and ≤6.3%, respectively, and the accuracy was ≥90% ± 5.3%. The mean extraction recovery RSD valWeue was <5.1%. Matrix effects and dilution integrity RSD values were <5.6% and <3.2%, respectively. Lekethromycin was deemed stable under certain storage conditions. This fully validated method was effectively applied to study the pharmacokinetics of lekethromycin after a single intravenous administration of 5 mg/kg in rats. The main pharmacokinetic parameters were T_1/2λz, CL_obs and V_Z_obs were 32.33 ± 14.63 h, 0.58 ± 0.17 L/h/kg and 25.56 ± 7.93 L/kg, respectively.

Systematic metabolite profiling of N-acetyldopamine oligomers from Cicadae Periostracum in rats by ultra-high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry

Cicadae Periostracum (CP), the cast-off shell of Cryptotympana atrata, is specified in Chinese Pharmacopoeia for relieving fever and eliminating ulcer. N-acetyldopamine oligomers are the major characteristic bioactive components with antioxidant and anti-inflammatory activities that may be responsible for the efficacy of CP. However, the exposed components and metabolites of N-acetyldopamine oligomers of CP (NOCP) in vivo are still unknown. In present study, the metabolic profile of total NOCP and N-acetyldopamine dimer B in rats were systematically investigated by ultra-high liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). In biosamples of NOCP group, 34 prototypes and 15 metabolites were identified or tentatively characterized, including 5 metabolites in plasma, 3 prototype and 9 metabolites in urine, 2 metabolites in bile, 34 prototypes and 8 metabolites in feces, respectively. In dimer B group, the prototype and 8 metabolites were identified, including 2 metabolites in plasma, 4 metabolites in urine, 1 metabolite in bile and 5 metabolites in feces, respectively. Oxidation, and hydrogenation were supposed to be the major phase I reactions, while methylation, sulfation, and glucuronidation were the main phase II reactions of NOCP and dimer B. M10 and M13 might undergo enterohepatic circulation in rats. It is concluded that NOCP and dimer B were mainly absorbed in the form of metabolites, and metabolites are probably the major bioactive forms of NOCP and dimer B. The outcomes of this study provided helpful information for extensively elucidating biological and pharmacological mechanisms of NOCP.

Characterization of the metabolites of gigantol in rat, dog, monkey, and human hepatocytes using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry

RATIONALE

Gigantol (3',4-dihydroxy-3,5'-dimethoxybibenzyl) is a bibenzyl compound isolated from Dendrobii Caulis that has been widely used as a medicinal herb in China. To fully understand the mechanism of action of gigantol, it is necessary to determine its metabolic profile.

METHODS

Gigantol at a concentration of 20 μM was incubated with hepatocytes (rat, dog, monkey, and human) at 37°C. After 120 min incubation, the samples were analyzed using liquid chromatography coupled with electrospray ionization tandem mass spectrometry. The structures of the metabolites were characterized by their molecular masses, product ions, and retention times.

RESULTS

A total of 17 metabolites were detected and structurally identified. The metabolism involved the following pathways: (a) oxidation to form quinone-methide species and subsequently conjugation with glutathione (GSH); (b) demethylation to form demethylated gigantol, which was further conjugated with GSH; (c) hydroxylation to yield hydroxyl-gigantol followed by glucuronidation or GSH conjugation; and (d) glucuronidation to form glucuronide conjugates. Glucuronidation was the primary metabolic pathway in all tested species.

CONCLUSIONS

Hydroxylation, demethylation, glucuronidation, and GSH conjugation were the major metabolic pathways of gigantol. This study provides new information on the metabolic profiles of gigantol and helps us understand the disposition of the compound.

LC-MS/MS assay for the quantification of foretinib in rat plasma and its application to preclinical pharmacokinetic study

A simple and sensitive ultra-high-performance liquid chromatography tandem mass spectrometric method was developed and validated for the determination of foretinib in rat plasma. The analyte and internal standard were extracted from the bio-samples with acetonitrile and then separated on an Acquity UPLC BEH C₁₈ column (50 × 2.1 mm, 1.7 μm) using 0.1% formic acid aqueous and acetonitrile as mobile phase, at a flow rate of 0.4 ml/min. The mass detection was performed in positive selected reaction monitoring mode with precursor-to-product transitions at m/z 317.1 > 128.1 for foretinib and m/z 502.2 > 323.1 for internal standard. The assay was demonstrated to be linear in the concentration range of 0.5-1000 ng/ml, with correlation coefficient >0.999. The mean extraction recovery of foretinib from rat plasma was within the range of 84.55-88.09%, while the matrix effect was in the range of 88.56-99.21%. The intra- and inter-day precisions were <12.95% and the accuracy ranged from -7.55 to 8.57%. Foretinib was stable in rat plasma under the tested storage conditions. The validated assay was successfully applied to the pharmacokinetic study of foretinib in the rats. The results revealed that foretinib showed moderate elimination half-life, low clearance and dose-independent pharmacokinetic profiles inrats.

A novel LC-MS/MS method for the determination of ziritaxestat in rat plasma and its pharmacokinetic study

Ziritaxestat is a first-in-class autotoxin inhibitor. The purpose of this study was to develop a liquid chromatography/electrospray ionization tandem mass spectrometric (LC-MS/MS) method for the determination of ziritaxestat in rat plasma. The plasma sample was deproteinated using acetonitrile and then separated on an Acquity BEH C₁₈ column with water containing 0.1% formic acid and acetonitrile as mobile phase, which was delivered at 0.4 ml/min. Ziritaxestat and the internal standard (crizotinib) were quantitatively monitored with precursor-to-product transitions of m/z 589.3 > 262.2 and m/z 450.1 > 260.2, respectively. The total running time was 2.5 min. The method showed excellent linearity over the concentration range 0.5-2000 ng/ml, with correlation coefficient >0.9987. The extraction recovery was >82.09% and the matrix effect was not significant. Inter- and intra-day precisions (RSD) were <11.20% and accuracies were in the range of -8.50-7.45%. Ziritaxestat was demonstrated to be stable in rat plasma under the tested conditions. The validated LC-MS/MS method was successfully applied to study the pharmacokinetic profiles of ziritaxestat in rat plasma after intravenous and oral administration. Pharmacokinetic results demonstrated that ziritaxestat displayed a short half-life (~3 h) and low bioavailability (20.52%).

Morpholine as ubiquitous pharmacophore in medicinal chemistry: Deep insight into the structure-activity relationship (SAR)

Morpholine is a versatile moiety, a privileged pharmacophore and an outstanding heterocyclic motif with wide ranges of pharmacological activities due to different mechanisms of action. The ability of morpholine to enhance the potency of the molecule through molecular interactions with the target protein (kinases) or to modulate the pharmacokinetic properties propelled medicinal chemists and researchers to synthesize morpholine ring by the efficient ways and to incorporate this moiety to develop various lead compounds with diverse therapeutic activities. The present review primarily focused on discussing the most promising synthetic leads containing morpholine ring along with structure-activity relationship (SAR) to reveal the active pharmacophores accountable for anticancer, anti-inflammatory, antiviral, anticonvulsant, antihyperlipidemic, antioxidant, antimicrobial and antileishmanial activity. This review outlines some of the recent effective chemical synthesis for morpholine ring. The review also highlighted the metabolic liability of some clinical drugs containing this nucleus and various researches on modified morpholine to enhance the metabolic stability of drugs as well. Drugs bearing morpholine ring and those under clinical trials are also mentioned with the role of morpholine and their mechanism of action. This review will provide the necessary knowledge base to the medicinal chemists in making strategic structural changes in designing morpholine derivatives.

A simple liquid chromatography coupled with tandem mass spectrometry approach for the simultaneous quantification of thirteen compounds in rats following oral administration of raw and processed Fructus Xanthii: Application in a comparative pharmacokinetic study

A simple and sensitive analysis using ultra high performance liquid chromatography with a tandem mass spectrometric system operated in selected reaction monitoring mode was developed for the determination of 11 phenolic acids, atractyloside, and carboxyatractyloside in rat plasma. The two classes of analytes were then separated on a Waters ACQUITY™ UPLC HSS T3 column (50 mm × 2.1 mm, 1.8 µm) using gradient elution with a mobile phase of 0.2% formic acid in water containing 10 mM ammonium acetate and methanol. Detection was accomplished by selected reaction monitoring scanning via an electrospray source operating in negative ionization mode. The calibration curve was linear (R²  = 0.990) over a concentration range of 1.20-3500 ng/mL, while the validated lower limit of quantification was 1.20 ng/mL. The precision varied from 0.84 to 4.62%, and the accuracy varied within ±5%. The method proved robust with sample freezing and thawing and with short- and long-term sample storage. The established method was used for simultaneous quantification and was successfully used for the first time for the pharmacokinetic evaluation of 13 compounds after the intragastric administration of raw and processed Fructus Xanthii in rats. The results indicated that processing affects the absorption and metabolism of Fructus Xanthii extract. Importantly, the results also indicated the importance of processing for the clinical application of traditional Chinese medicine.

Pharmacokinetics and bioavailability study of ginsenoside Rk1 in rat by liquid chromatography/electrospray ionization tandem mass spectrometry

Ginsenoside Rk1 (Rk1) exhibited various potent biological activities. However, its pharmacokinetic profile in vivo remains unclear. In the present study, a simple and sensitive liquid chromatography tandem mass spectrometry method was developed and validated for determination of Rk1 in rat plasma and applied in a pharmacokinetic study. The sample was precipitated with acetonitrile and separated on a Zorbax Eclipse XDB C18 column (50 × 2.1 mm, 1.8 μm). The mobile phase was composed of 0.1% formic acid in water and acetonitrile at a flow rate of 0.4 mL/min. Rk1 and internal standard (ginsenoside Rg3) were quantitatively monitored with precursor-to-product ion transitions of m/z 765.4 → 441.5 and m/z 783.5 → 621.4, respectively. The assay was linear over the concentration range of 5-1000 ng/mL (r > 0.99) with the LLOQ of 5 ng/mL. Other parameters including intra- and inter-day precision and accuracy, extraction recovery and matrix effect were within the acceptable limits. The analyte was stable under the tested storage conditions. The validated method has been successfully applied to a pharmacokinetic study of Rk1 in rat plasma after intravenous (5 mg/kg) and oral (25 mg/kg, 50 mg/kg) administration. After oral administration, Rk1 could be detected in blood at 30 min and reached the highest concentration at 4.29~4.57 h. Our results demonstrated that Rk1 showed low clearance, moderate half-life (3.09-3.40 h) and low bioavailability (2.87-4.23%). The study will provide information for the further application of Rk1.

The tissue distribution and excretion study of mosapride and its active des-p-fluorobenzyl and 4'-N-oxide metabolites in rats by ultra-high performance liquid chromatography-tandem mass spectrometry method

1. Mosapride is a potent gastroprokinetic agent, and des-p-fluorobenzyl mosapride (M1) and mosapride-N-oxide (M2) are its two major active metabolites.2. The validated ultra-high performance liquid chromatography-tandem mass spectrometry method was successfully applied to the distribution and excretion of mosapride and its two active metabolites.3. Mosapride and its metabolites were distributed widely and rapidly in various tissues. The highest concentration of mosapride and M2 in both male and female rats was found in the duodenum, followed by cecum.4. The excretion study showed that a total of 71.8% (37.6, 22.4 and 11.8% for urine, feces and bile, respectively) and 66.3% (35.7, 22.8 and 7.8% for urine, feces and bile) of administered dose was recovered from male and female excreta. M1 was excreted in the largest dose percentage, followed by mosapride and M2, and the total cumulative excretion amounts were about 36.9, 28.1 and 11.6% in male rat, while 24.3, 25.9 and 16.2% in female rat. The results demonstrated for the first time that M2 is one of the important excretion forms of mosapride, which is much higher than that of mosapride in urine.5. This work could provide valuable information for further pharmacological and clinical studies of mosapride.

The synthesis and biological evaluation of a new bioactive metabolite of mosapride as a potential gastroprokinetic agent

Aim: To synthesize the new bioactive metabolites of mosapride (R)-N-[2-hydroxy-3-(4-fluorobenzyl)amino]-propyl-5-chlorine-4-amino-2-ethoxyben-zamide (R-isomer) and (S)-N-[2-hydroxy-3-(4-fluorobenzyl)amino]-propyl-5-chlorine-4-amino-2-ethoxybenzamide (S-isomer) and evaluate their in vitro and in vivo pharmacological and pharmacokinetic profiles. Results: S-isomer as a gastroprokinetic agent showed significant pharmacological activities in vivo. Furthermore, compared with the EC50 values for R-isomer and mosapride, S-isomer was proven to generate the same 5-HT4 receptor agonistic activity with a smaller amount. S-isomer exhibited significant differences in the pharmacokinetic properties, which indicate that higher absorption rate and extent compared with R-isomer. Conclusion: S-isomer might have great potential as a safe and effective prokinetic agent capable of lessening gastrointestinal symptoms and increasing quality of life.

Comparative pharmacokinetics of (S)-MP3950, a novel 5-HT4 receptor agonist, in normal and atropine-induced gastrointestinal motility disorders rats

1. (S)-MP3950 is the (S)-enantiomer of active metabolite of mosapride, which exhibits higher 5-HT₄ receptor agonistic effect than mosapride. It shows promise to become a novel drug candidate for the treatment of gastrointestinal motility disorders (GMDs). However, the pharmacokinetic behavior of (S)-MP3950 in the pathological state of GMDs remains unclear. Herein, we investigated the comparative pharmacokinetics of (S)-MP3950 in normal and GMDs rats. 2. The comparative pharmacokinetics of (S)-MP3950 in normal and atropine-induced GMD rats were studied by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The validated UPLC-MS/MS method was successfully applied to investigate the pharmacokinetic profiles of (S)-MP3950 in normal and atropine-induced GMDs rats. Results showed that comparing to normal rats, C_max reduced by 73.8%, AUC_0-t decreased by 57.6% and AUC_0-∞ declined by 56.8% in model rats. Additionally, the elimination half-life (t_1/2) and T_max were prolonged slightly. 3. The pharmacokinetic results demonstrated that the atropine-induced GMDs reduced the absorption of (S)-MP3950. The pharmacokinetics research in the pathological state might provide more useful information for further study of novel gastric motility candidates.

Assessment of N-Oxide Formation during Wastewater Ozonation

Worldwide, ozonation of secondary wastewater effluents is increasingly considered in order to decrease the load of organic contaminants before environmental discharge. However, despite the constantly growing knowledge of ozonation over the past few years, the characterization of transformation products (TPs) is still a major concern, particularly because such TPs might remain biologically active. It has been shown for selected tertiary amine pharmaceuticals that they react with ozone and form the corresponding N-oxides. This study therefore applies liquid chromatography-high resolution mass spectrometry (LC-HRMS) to assess the overall N-oxide formation during the pilot-scale ozonation of a secondary wastewater effluent from a major city in Germany. Sample analysis by LC-HRMS revealed the occurrence of 1,229 compounds, among which 853 were precursors attenuated by ozone and 165 were TPs. Further examination of precursors and TPs using Kendrick mass and Kendrick mass defect analysis revealed 34 pairs of precursors and products corresponding to a mono-oxygenation. Among these, 27 pairs (16% of all TPs) were consistent with N-oxides since the TP had a higher retention time than the precursor, a characteristic of these compounds. Using high resolution tandem mass spectrometry, 10 of these N-oxides could be identified and were shown to be stable during a subsequent filtration step.

Pharmacokinetic profile and metabolite identification of yuanhuapine, a bioactive component in Daphne genkwa by ultra-high performance liquid chromatography coupled with tandem mass spectrometry

Daphne genkwa Sieb. et Zucc. (Thymelaeaceae) is mainly used for the treatment of edema, asthma, and cancer in China and Korea for centuries. The major bioactive components in D. genkwa are daphnane-type diterpenoids, which showed pharmacological activities such as antileukemic, antifertility and skin irritants. In this study, the pharmacokinetics and metabolism profile of yuanhuapine, an effective and toxic diterpenoid, was investigated in rats. The plasma exposure of yuanhuapine was determined by ultra-performance liquid chromatography tandem triple-quadrupole mass spectrometry (UPLC-TQ-MS), and the pharmacokinetic parameters were calculated using the DAS 2.0 pharmacokinetic program. The metabolites were identified through ultra-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) and a Metabolynx™ (v4.1) program. After oral administration (5 mg/kg), yuanhuapine was slowly absorbed and reached a maximum concentration of 579.20 ± 212.85 ng/mL at 7.33 ± 1.03 h, it also eliminated slowly. As the cumulative excretion of yuanhuapine in urine and feces were only 0.7% and 3.3%, we supposed that biotransformation in vivo was of significant importance to this component. Not only the prototype but also twelve metabolites were found and tentatively identified in rat urine after oral administration of yuanhuapine. The metabolic pathway mainly involves hydroxylation, methylation, glucuronidation and cysteine conjugation during the phase I and phase II biotransformation pathway. All the information gained here was useful in understanding the pharmacological actions and toxic properties of yuanhuapine, and providing a meaningful basis for clinical application of such a bioactive compound of herbal medicines.

MS2Analyzer: A software for small molecule substructure annotations from accurate tandem mass spectra

Systematic analysis and interpretation of the large number of tandem mass spectra (MS/MS) obtained in metabolomics experiments is a bottleneck in discovery-driven research. MS/MS mass spectral libraries are small compared to all known small molecule structures and are often not freely available. MS2Analyzer was therefore developed to enable user-defined searches of thousands of spectra for mass spectral features such as neutral losses, m/z differences, and product and precursor ions from MS/MS spectra in MSP/MGF files. The software is freely available at http://fiehnlab.ucdavis.edu/projects/MS2Analyzer/ . As the reference query set, 147 literature-reported neutral losses and their corresponding substructures were collected. This set was tested for accuracy of linking neutral loss analysis to substructure annotations using 19 329 accurate mass tandem mass spectra of structurally known compounds from the NIST11 MS/MS library. Validation studies showed that 92.1 ± 6.4% of 13 typical neutral losses such as acetylations, cysteine conjugates, or glycosylations are correct annotating the associated substructures, while the absence of mass spectra features does not necessarily imply the absence of such substructures. Use of this tool has been successfully demonstrated for complex lipids in microalgae.

Selective hydrolysis of flavonoid glycosides by Curvularia lunata

Twelve flavonoid glycosides were involved in the biotransformation of the glycosyl moieties by Curvularia lunata 3.4381, and the products were analyzed by UPLC/PDA-Q-TOF-MS(E). Curvularia lunata displayed hydrolyzing activities on the terminal Rha or Glc units of some flavonoid glycosides. Terminal Rha with a 1 → 2 linkage of isorhamnetin-3-O-neohesperidoside and typhaneoside could be hydrolyzed by Curvularia lunata, but terminal Rha with a 1 → 6 linkage of rutin, typhaneoside, and quercetin-3-O-apiosyl-(1 → 2)-[rhamnosyl-(1 → 6)]-glucoside could not be hydrolyzed. Curvularia lunata could also hydrolyze the Glc of icariin, floramanoside B, and naringin. This is the first report of the hydrolysis of glycosyl units of flavonoid glycosides by Curvularia lunata. A new way to convert naringin to naringenin was found in this research.

Structure identification and elucidation of mosapride metabolites in human urine, feces and plasma by ultra performance liquid chromatography-tandem mass spectrometry method

1.  Mosapride citrate (mosapride) is a potent gastroprokinetic agent. The only previous study on mosapride metabolism in human reported one phase I oxidative metabolite, des-p-fluorobenzyl mosapride, in human plasma and urine using HPLC method. Our aim was to identify mosapride phase I and phase II metabolites in human urine, feces and plasma using UPLC-ESI-MS/MS. 2.  A total of 16 metabolites were detected. To the best of our knowledge, 15 metabolites have not been reported previously in human. 3.  Two new metabolites, morpholine ring-opened mosapride (M15) and mosapride N-oxide (M16), alone with one known major metabolite, des-p-fluorobenzyl mosapride (M3), were identified by comparison with the reference standards prepared by our group. The chemical structures of seven phase I and six phase II metabolites of mosapride were elucidated based on UPLC-MS/MS analyses. 4.  There were two major phase I reactions, dealkylation and morpholine ring cleavage. Phase II reactions included glucuronide, glucose and sulfate conjugation. The comprehensive metabolic pathway of mosapride in human was proposed for the first time. 5.  The metabolites in humans were compared with those in rats reported previously. In addition to M10, the other 15 metabolites in humans were also found in rats. This result suggested that there was little qualitative species difference in the metabolism of mosapride between rats and humans. 6.  In all, 16 mosapride metabolites including 15 new metabolites were reported. These results allow a better understanding of mosapride disposition in human.

HPLC method with fluorescence detection for the determination of ligustilide in rat plasma and its pharmacokinetics

CONTEXT

Few methods have been reported for the quantification of ligustilide (LIG) in biosamples: the pretreatment of the biological samples were laborious and time-consuming.

OBJECTIVE

A high-performance liquid chromatographic method with fluorescence detection (HPLC-FLD) for the determination of LIG in rat plasma was developed and validated. Pharmacokinetics and bioavailability of LIG were determined by systematic investigation in Sprague-Dawley rats.

MATERIALS AND METHODS

LIG was isolated from the volatile oil of Radix Angelica sinensis and further purified by silica gel column chromatography. Podophyllotoxin was used as an internal standard. The analytes were detected by using fluorescence detection at an excitation and emission wavelength of 290 and 395 nm during 0-4 min, and 336 and 453 nm during 4-14 min, respectively. LIG pharmacokinetics was studied in rats after oral and intravenous administration of 12.5, 25 and 50 mg/kg doses.

RESULTS

Two calibration curves (Y = 133.49 X - 14.27 (r = 0.9995), Y = 145.61 X + 13.76 (r = 0.9996)) were constructed in the range of 2.44-10,000 ng/mL for LIG with a lower limit of quantitation of 2.44 ng/mL. Both intra-day and inter-day precision were less than 6%. Accuracy ranged from 88.93 to 99.52%. The recovery ranged from 89.07 to 99.71%. The absolute bioavailability values were 71.36, 68.26 and 75.44% for oral doses of 12.5, 25 and 50 mg/kg, respectively.

CONCLUSION

The present HPLC-FLD method was rapid, sensitive and reliable. LIG was absorbed and eliminated rapidly in rat.

In vivo disposition and metabolism of madecassoside, a major bioactive constituent in Centella asiatica (L.) Urb

ETHNOPHARMACOLOGICAL RELEVANCE

Centella asiatica (L.) Urb. herb is frequently used in traditional Chinese medicine for many indications, such as traumatic injuries, keloid and scar. Madecassoside is the main active ingredient of this herb drug with higher content than other triterpenoid constituents. Understandings of pharmacokinetic profiles of madecassoside should be beneficial for its development as a therapeutic agent.

MATERIALS AND METHODS

Sprague-Dawley rats were intravenously and orally administered madecassoside (100 mg/kg), respectively. Plasma, heart, liver, spleen, lung, kidney, brain, bile, urine and feces were collected at the designed time points. Madecassoside concentrations in biological samples were determined by a sensitive and well-validated liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method. A liquid chromatography coupled with time-of-flight mass spectrometry (LC-TOF-MS) method was established to identify its major metabolites in feces. To further pursue the disposition characteristics of madecassoside in rats, the involvement of the hepatobiliary efflux transporters in biliary elimination were studied by combination with digoxin (P-glycoprotein inhibitor) or probenecid (multidrug resistance-associated protein inhibitor). A linked-rat model was also used to assess the role of enterohepatic circulation in the pharmacokinetics of madecassoside.

RESULTS

After a single oral dosing, madecassoside was widely distributed in heart, liver, spleen, lung and kidney of rats, and the levels of madecassoside in liver and kidney were relatively higher than other organs. The excretions of madecassoside in bile, urine and feces were 7.16% (0-12 h), 0.25% (0-72 h) and 24.68% (0-72 h), respectively. The findings suggested that madecassoside might excrete mainly by metabolites. The combination with either digoxin or probenecid significantly attenuated the excretion of madecassoside as parent from bile, indicating that P-glycoprotein and multidrug resistance-associated protein might contribute to the hepatobiliary elimination of madecassoside. The presence of enterohepatic circulation, as implied by double-humped profiles in plasma and tissue concentration-time curves, was confirmed by a linked-rat model. Furthermore, three metabolities of madecassoside were indentified in rat feces and the possible metabolic pathways were proposed.

CONCLUSIONS

These findings provide valuable information regarding in vivo process of madecassoside, and help us to recognize the efficacy and safety of madecassoside itself, the relevant herbs or herbal preparations.

Pharmacokinetics, tissue distribution and metabolism of senkyunolide I, a major bioactive component in Ligusticum chuanxiong Hort. (Umbelliferae)

ETHNOPHARMACOLOGICAL RELEVANCE

Ligusticum chuanxiong Hort. (Umbelliferae) is widely prescribed for treatment of cardiovascular diseases in China for centuries. One of the major bioactive components in L. chuanxiong is senkyunolide I (SEI), which shows pharmacological activities in anti-migraine and anti-oxidative damage.

MATERIALS AND METHODS

The aim of this study was to investigate in vivo pharmacokinetics, tissue distribution and metabolism of SEI in rats. The concentrations of SEI in plasma and tissues were determined by a high performance liquid chromatography (HPLC) method, and the pharmacokinetic parameters were calculated using and non-compartmental analysis. The metabolites were identified using high performance liquid chromatography tandem mass (HPLC-ESI-MS/MS) method.

RESULTS

After oral and intravenous administration, SEI was quickly eliminated from plasma and its oral bioavailability (BA) was about 37.25%, which was smaller than intraportal BA (81.17%), but similar to intraduodenal BA (36.91%), suggesting that gastric first-pass effect of SEI is negligible, and hepatic first-pass effect was approximately 18.83%. After oral administration, SEI could penetrate blood brain barrier and extensively distribute in tested tissues, with the descending order of AUC being kidney, liver, lung, muscle, brain, heart, thymus, and spleen in rat. The parent compound and nine metabolites were found and identified in rat bile after oral administration of SEI (36 mg/kg). The metabolic mechanism of SEI in rat mainly involves methylation, glucuronidation and glutathione conjugation during the phase II biotransformation pathway in rats.

CONCLUSIONS

The information gained here may provide a meaningful basis for clinical application of such a bioactive compound of herbal medicines.

Preparation and characterization of mosapride citrate inclusion complexes with natural and synthetic cyclodextrins

The aim of this work was to investigate the inclusion complexes between mosapride citrate and SBE7β-CD in comparison with the natural β-CD to enhance its bioavailability by improving the solubility and dissolution rate. The complexation efficiency value of SBE7β-CD was higher than that for β-CD. Solid binary systems of mosapride citrate with CDs were prepared by physical mixing, kneading and freeze-drying techniques at molar ratio of 1:1(drug:CD). Physicochemical characterization of the prepared systems was studied using X-ray diffractometry, differential scanning calorimetry, Fourier-transform infrared spectroscopy and scanning electron microscopy (SEM). Amorphous drug was detectable to large extent in inclusion complexes prepared using the freeze-drying technique. From the dissolution study of different inclusion complexes in simulated saliva solution (pH 6.8), we could concluded that irrespective of the preparation technique, the systems prepared using SBE7β-CD showed better performance than the corresponding ones prepared using β-CD. In addition, the freeze-drying technique showed superior dissolution enhancement than other methods especially when combined with the SBE7β-CD.

Identification of major metabolites in rat urine and plasma of N(6) -(4-hydroxybenzyl) adenine riboside by LC/MS/MS

N(6) -(4-hydroxybenzyl) adenine riboside, a novel neuroprotective compound found in Gastrodia elata at trace level, is regarded as a potential drug for the treatment of neural degenerative disease. To understand the metabolism of this compound, the metabolites in rat urine and plasma of N(6) -(4-hydroxybenzyl) adenine riboside were analyzed by HPLC-ESI-MS/MS after oral administration of this compound. Beside the parent compound, six phase I metabolites and four phase II metabolites in urine were detected by scanning all possible metabolites in extracted ion chromatograms mode. By comparing their product ion spectra and retention times with those of parent compound, these metabolites were identified and proved to be mainly formed via hydrolysis or hydroxylation in phase I, N-sulfation or N-glucuronidation in phase II or their combinations. Similarly, the parent compound, one phase I metabolite and two phase II metabolites were also identified in rat plasma. Therefore, the in vivo metabolic pathways of N(6) -(4-hydroxybenzyl) adenine riboside in rat were proposed.

Liquid chromatography-mass spectrometry for analysis of a novel beta(2)-adrenoceptor agonist trantinterol and its metabolites in beagle dog urine

A liquid chromatography-tandem mass spectrometry method was developed for the identification of metabolites of trantinterol, a novel beta(2)-adrenoceptor agonist, in beagle dog urine. The separation of metabolites was performed on a reversed-phase C(8) column using 0.1% formic acid in water and methanol (70 : 30, v/v) as the mobile phase. The structural information and elemental information of metabolites were acquired by an electrospray ionization tandem mass spectrometer and a quadrupole time-of-flight mass spectrometer, respectively. A total of 13 metabolites were detected and characterized on the basis of their tandem MS/MS fragmentation patterns. The accurate masses of nine metabolites were determined and two metabolites were further confirmed by comparing with reference standards. The metabolic pathways of trantinterol in beagle dog are proposed.