Spectrum-effect relationship of hemostatic effects of Notoginseng Radix et Rhizoma with different commodity specifications / 中国中药杂志

This article aims to establish the fingerprints, determine the hemostatic pharmacodynamic indicators, and explore the spectrum-effect relationship of Notoginseng Radix et Rhizoma in 12 different specifications. Firstly, HPLC and liquid chromatography-mass spectrometry(LC-MS) were employed to establish the fingerprints of Notoginseng Radix et Rhizoma. The rat plasma recalcification experiment and the rat gastric bleeding experiment were conducted to determine the pharmacodynamic indicators, including plasma recalcification time(PRT), thrombin time(TT), prothrombin time(PT), and activated partial thromboplastin time(APTT). Afterwards, the partial least squares method was employed to explore the spectrum-effect relationship of Notoginseng Radix et Rhizoma in different specifications. Twenty-six common peaks were detected in the HPLC fingerprints of different specifications of Notoginseng Radix et Rhizoma, and 11 out of the 26 common peaks represented saponins. The content of dencichine was determined by LC-MS. The rat experiments showed that the pharmacodynamic indicators were significantly different among different specifications of Notoginseng Radix et Rhizoma. The spectrum-effect relationship was explored between 27 common components and pharmacodynamic indicators. Among them, 16 components had positive effects on the pharmacodynamic indicators of Notoginseng Radix et Rhizoma, and 11 exerted negative effects. This study provides a basis for the precision medication and quality control of Notoginseng Radix et Rhizoma.

Efficient validated method of UPLC-MS/MS to determine curcumin in rat plasma and ovarium

Curcumin, a lipophilic polyphenol derived from the roots of Curcuma longa. Recently, it has been widely investigatedas a therapeutic agent for cancer. Thus, there is a growing interest in measuring curcumin concentrations in theplasma and other target tissues in relevant animal models. We developed and validated a simple, fast, and reliablemethod for quantifying curcumin in biological matrices by Ultra Performance Liquid Chromatography (UPLC)-MassSpectrometry (MS)/MS. The liquid chromatography system is using rapid separation on Acquity UPLC®BEH C18with gradient mobile phase contained formic acid and acetonitrile. Prior to detection, curcumin and internal standard(IS) were ionized using electrospray ionization positive source and the ions were monitored at m/z 369 → 177 and 260→ 183 for curcumin and IS, respectively. The calibration curve was linear (r ≥ 0.99) over the concentration range of1–50 ng/ml and 1–30 ng/ml for rat plasma and for ovary homogenate, respectively. The lower limit of quantificationwas 1 ng/ml. The mean accuracy ranged from 98.9% to 103.2% and 98% to 108.9%, while the coefficient of variation(CV) values of precision in rat plasma were below 11.92% and 10.47% for within and between run, respectively. Inrat ovary homogenate, the mean concentration and CV of within run accuracy and precision were 95.53%–109.78%and 3.34%–9.14%, respectively. The developed method was used to quantify curcumin in rat plasma and ovary afteran oral gavage. In conclusion, the developed and validated method should be useful for quantification of curcuminaccurately and precisely in plasma and target organs from relevant animal models of human diseases.

LC-MS/MS determination of deoxyelephantopin, a novel anti-tumor candidate in rat plasma and its application to a pharmacokinetic study in rats

Abstract A specific, sensitive and robust LC-MS/MS method was developed and validated for the quantification of deoxyelephantopin in rat plasma using simvastatin as an internal standard as per regulatory guidelines of Bioanalytical Method Validation. Plasma sample was prepared through liquid-liquid extraction. Chromatographic separation was performed on an Agela-C18 analytical column (1.8 µm, 2.1 mm × 50 mm) with an isocratic mobile phase consisting of 0.05% formic acid (dissolved in acetonitrile) and water (55:45, v/v) at a flow rate of 0.5 ml/min. The column oven was maintained at 40 ºC and the injection volume was 4 µl. Elution of deoxyelephantopin and the internal standard occurred at 5.1 and 6.3 min, respectively. The total chromatographic run time was 7.5 min. A linear response function was constructed in the concentration range of 13.2-2640 ng/ml. The intra- and inter-day precision and accuracy were in the range of 1.4-14.8% and -11.7 to 14.1%, respectively. The validated LC-MS/MS was successfully applied to the pharmacokinetic study of deoxyelephantopin after intravenous injection of 1, 2 and 4 mg/kg and oral administration of 7.5, 15 and 30 mg/kg deoxyelephantopin in rats. After oral and intravenous administration, the C max and AUC values of deoxyelephantopin increased dose-dependently.

Simultaneous determination of six bioactive components of total flavonoids of Scorzonera austriaca in rat tissues by LC-MS/MS: application to a tissue distribution study

ABSTRACT A liquid chromatography-tandem mass spectrometry method was developed and validated for simultaneous determination of six bioactive constituents including vitexin, orientin, isoorientin, 2"-O-β-D-xylopyranosyl isoorientin, 2"-O-β-D-xylopyranosyl isovitexin, and 6-C-L-α-arabipyranosyl vitexin in rats' various tissues using isoquercitrin as the internal standard. Biological samples were pretreated by protein precipitation with acetonitrile. Chromatographic separation was carried out on a C18 column with a gradient mobile phase consisting of acetonitrile and 0.1% aqueous formic acid. All analytes and internal standard were quantitated through electrospray ionization in negative ion selected reaction monitoring mode. The mass transitions were as follows: m/z 431 → 311 for vitexin, m/z 447 → 327 for orientin or isoorientin, m/z 579 → 459 for 2"-O-β-D-xylopyranosyl isoorientin, m/z 563 → 293 for 2"-O-β-D-xylopyranosyl isovitexin, m/z 563 → 353 for 6-C-L-α-arabipyranosyl vitexin, and m/z 463 → 300 for the internal standard, respectively. The lower limits of quantification for the six analytes in different tissue homogenates were 0.8-2.2 ng/ml. The validated assay was successfully applied to a tissue distribution study of the six components in rats after intravenous administration of total flavonoids of Scorzonera austriaca Willd; Asteraceae. The results of the tissue distribution study showed that the high concentrations of six components were mainly in the kidney.

Pharmacokinetics of oleracimine in rats by ultra-high-performance liquid chromatography

The novel alkaloid, oleracimine, presented remarkable anti-inflammatory bioactivity, and therefore, its pharmacokinetics was investigated in rat plasma after intravenous and oral administration by using a rapid ultra-high-performance liquid chromatography (UHPLC) method with UV detection at 270 nm. The analysis was performed on a shim-pack ODS column (75 mm×2 mm, 1.6 µm particle size, Shimadzu, Japan) column using isocratic elution with a mobile phase consisting of methanol-water (62:38, v/v) within 3 min. The results indicated that oleracimine was rapidly distributed with Tmax for 11.7 min after oral administration, which presented the double-peak phenomenon in the pharmacokinetic profile with a higher oral absolute bioavailability of 55.1% ± 7.83%.

Development and validation of a high throughput LC–MS/MS method for simultaneous quantitation of pioglitazone and telmisartan in rat plasma and its application to a pharmacokinetic study / 药物分析学报

Management of cardiovascular risk factors in diabetes demands special attention due to their co-existence. Pioglitazone (PIO) and telmisartan (TLM) combination can be beneficial in effective control of cardiovascular complication in diabetes.In this research,we developed and validated a high throughput LC–MS/MS method for simultaneous quantitation of PIO and TLM in rat plasma. This developed method is more sensitive and can quantitate the analytes in relatively shorter period of time compared to the previously reported methods for their individual quantification. Moreover, till date, there is no bioanalytical method available to simultaneously quantitate PIO and TLM in a single run. The method was validated according to the USFDA guidelines for bioanalytical method validation.A linear response of the analytes was observed over the range of 0.005–10μg/mL with satisfactory precision and accuracy. Accuracy at four quality control levels was within 94.27%–106.10%. The intra-and inter-day precision ranged from 2.32% to 10.14% and 5.02% to 8.12%,respectively.The method was reproducible and sensitive enough to quantitate PIO and TLM in rat plasma samples of a preclinical pharmacokinetic study.Due to the potential of PIO-TLM combination to be therapeutically explored,this method is expected to have significant usefulness in future.

Development of a UPLC–MS/MS method for determination of pimavanserin tartrate in rat plasma:Application to a pharmacokinetic study / 药物分析学报

A simple, rapid and sensitive method based on an ultra-performance liquid chromatography–tandem mass spectrometry(UPLC–MS/MS)has been developed and validated for the determination of pimavanserin in rat plasma.The analyte was extracted by protein precipitation with methanol and separated on an ACQUITY BEH C18column(100 mm×2.1 mm,1.7μm;Waters,USA),with an isocratic elution of acetonitrile-water containing 10 mM ammonium acetate (70:30, v/v), at a flow rate of 0.2 mL/min for 2.5 min. The analyte and clarithromycin (the internal standard) were detected and quantified in positive ion mode using multiple reaction monitoring transitions at m/z 428.2 → 223.0 for pimavanserin and m/z 748.5 → 589.5 for clarithromycin. Relative coefficient (r) for the calibration curve was more than 0.9980. The intra-day and inter-day precisions(relative standard deviation,RSD%)were less than 13.3% and 10.5%,respectively,and the accuracy(relative error,RE%)was within ± 11.5%.The analytical method was successfully applied to a routine pharmacokinetic study of pimavanserin in rats after oral administration at the dose of 10 mg/kg.

Simultaneous determination of seven bioactive compounds and pharmacokinetics in rat plasma after oral administration of Yindan Xinnaotong Ruanjiaonang by UPLC-MS/MS / 中国中药杂志

To estabish ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for simultaneous determination of quercetin(QCT), isorhamnetin(ISR), kaempferol(KMF), ginkgolide A(GA), ginkgolide B(GB), ginkgolide C(GC) and bilobalide(BB) in rat plasma and investigate the pharmacokinetic process of seven compounds after oral administration of Yindan Xinnaotong Ruanjiaonang, The results indicated that all calibrations curves showed good linearity (r≥0.997 1). RSD of intra-day and inter-day precisions were all within 11%. The matrix effects and extraction recovery were in the range of 93.28%-103.6% and 72.43%-95.77% respectively. The peak concentration (Cmax) of QCT, ISR, KMF, GA, GB, GC and BB were (45.02±11.28), (49.90±13.82), (27.85±8.38), (76.31±18.19), (76.54±15.43), (35.35±10.28), (48.70±12.34) μg•L⁻¹, respectively. The peak time (tmax) of seven constituents were (0.33±0.11), (0.50±0.23), (0.33±0.14), (0.75±0.29), (1.0±0.35), (1.5±0.23), (0.75±0.50) h, respectively. UPLC-MS/MS method established in this research was proved to be so rapid and sensitive that it can be applied to the pharmacokinetic study of seven bioactive constituents in Yindan Xinnaotong Ruanjiaonang.

Simultaneous Determination of Six Bioactive Components of Jiawei Baiteng Extracts in Plasma by HPLC-TQ-MS/MS and Their Pharmacokinetics in Rats / 中国药学杂志

OBJECTIVE: To establish an HPLC-TQ-MS/MS assay for simultaneous determination of berberine, plantamajoside, saikosaponin a, tetrahydropalmatine, paeoniflorin and amygdalin in rat plasma and investigate the pharmacokinetics of Jiawei Baiteng extracts in rats. METHODS: The separation was achieved on an Agilent Poroshell 120 EC-C18 column(3.0 mm × 100 mm, 2.7 μm) at 35℃. The mobile phase was consisted of 0.05% formic acid aqueous solution and acetonitrile containing 0.05% formic acid, eluting with a gradient procedure. Mass spectrometry was performed in the multiple reaction monitoring (MRM) mode, with programmed ionization modes witching and time segment scanning. The ion reactions for quantification were as follows: m/z 335.9→m/z 319.9 (berberine, ESI+), m/z 639.1 → m/z 160.9 (plantamajoside, ESI-), m/z 779.3 → m/z 617.4 (saikosaponin a, ESI-), m/z 356.0→m/z 192.0(tetrahydropalmatine, ESI+), m/z 449.1→m/z 121.1(paeoniflorin, ESI-), m/z 456.1→m/z 323.1(amygdalin, ESI-), m/z 323.9→m/z 126.9(gliclazide, internal standard, ESI+) and m/z 321.9→m/z 170.1 (gliclazide, internal stand- ard, ESI-). Blood samples were collected in heparinized tubes via the retinal venous plexus from each rat after a single oral dose of Jiawei Baiteng extracts(3.1 g·kg-1). The plasma samples were pretreated by methanol precipitation to remove protein components, and then analyzed by HPLC-TQ-MS/MS. The pharmacokinetic parameters of the bioactive components of Jiawei Baitengex tracts in rats were calculated by DAS (Drug and Statistics for Windows) software(Version 2.0). RESULTS: The methodological test showed that the linear concentration ranges of berberine, plantamajoside, saikosaponin a, tetrahydropalmatine, paeoniflorin and amygdalin were 0.59-292.50, 0.68-168.75, 6.05-1 512.50, 0.68-337.50, 6.70-1675.00 and 5.60-1400.00ng·mL-1, respectively. The limits of quantification (LOQs) of the six analytes were 0.59, 0.68, 6.05, 0.68, 6.70 and 5.60 ng·mL-1, respectively. The HPLC-TQ-MS/MS method was also validated with good precision, recovery and stability, which conformed to the analytical standards of biological samples. CONCLUSION: The established method is proved to be sensitive, simple and reliable, which is suitable for the pharmacokinetic study of Jiawei Baiteng extracts.

An UHPLC-MS/MS method for simultaneous determination of quercetin 3-O-rutinoside, kaempferol 3-O-rutinoside, isorhamnetin 3-O-rutinoside, bilobalide and ligustrazine in rat plasma, and its application to pharmacokinetic study of Xingxiong injection / 中国天然药物

The present study was designed to develop and validate a rapid, sensitive, and reliable ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous determination of five major active constituents in the traditional Chinese medicinal preparation Xingxiong injection (XXI) in rat plasma, including quercetin 3-O-rutinoside (QCR), kaempferol 3-O-rutinoside (KFR), isorhamnetin 3-O-rutinoside (ISR), bilobalide (BB), and ligustrazine (LGT). The plasma samples were pretreated by protein precipitation with acetonitrile. The chromatographic separation was achieved on a Waters Symmetry C analytical column (2.1 mm × 100 mm, 3.5 μm) with a mobile phase of 0.1% aqueous formic acid (A)-acetonitrile (B). Quantitation of the five bioactive constituents was achieved. Naringin was used as the internal standard (IS). All the calibration curves showed good linearity (r > 0.996) over the concentration range, with the lowest limit of quantification (LLOQ) between 2-18 ng·mL. The intra- and inter-day accuracy and precision of the analytes were both within acceptable limits. Moreover, satisfactory extraction recoveries (90.92%-104.03%) were obtained by protein precipitation. The validated method was successfully applied to a pharmacokinetic study of XXI in rats after intravenous administration at three doses. The pharmacokinetic parameters of the five compounds varied in a dose-dependent manner within the tested dosage range. The present study was the first report of pharmacokinetic study for XXI.

Quantification of (-)doxazosin at very low concentration in rat plasma samples by SPE-LC-MS/MS / 药学学报

Previous publications showed that the value of LLOQ (lowest limit of quantification) for doxazosin and its enantiomers in biological samples were above 0.1 ng·mL-1. The present study was designed to establish a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification at very low concentration of (-)doxazosin in rat plasma after intravenous administration of (-)doxazosin (3.0 mg·kg-1). The plasma samples containing prazosin as an internal standard were extracted by solid-phase extraction (SPE) and separated on Acquity BEH C18(50 mm×2.1 mm, 1.7 μm) column under alkaline conditions of the mobile phase. (-)Doxazosin was monitored under positive ionization condition by multiple reaction monitoring (MRM) with an ESI source. The good linear range of (-)doxazosin varied from 10.4 pg·mL-1 to 13 ng·mL-1(r=0.9922), and the lowest limit of quantification was 10.4 pg·mL-1. An assessment of the matrix effect using post-extraction spiking method and post-column infusion method demonstrated that co-eluting matrix components did not significantly influenced the ionization of (-)doxazosin and prazosin (IS). Using the new method, we accurately measured (-)doxazosin concentration at 48 h after intravenous administration in the rats, and the concentration was 0.0344±0.0102 ng·mL-1. The method is specific, sensitive, and suitable for determining (-)doxazosin at very low concentration in rat plasma samples.

Concentration Determination and Pharmacokinetics of Vinblastine in Rat Plasma by HPLC-MS/MS / 中国药师

Objective:To establish an HPLC-MS/MS method for the determination of vinblastine in rat plasma. Methods:Aceto-nitrile was used to precipitate protein in the samples after the addition of internal standard, and then the concentration was analyzed by HPLC/MS/MS. All the separations were carried out on an Ultimate C18 column (150 mm × 2. 1 mm, 5. 0 μm). The mobile phase was composed of acetonitrile and 10 mmol·L-1 ammoniumacetate (containing 0. 1% formic acid) (49 ∶51) and was pumped at a flow rate of 0. 3 ml·min-1 under 40 °C. The detection was performed with multiple reactions monitoring (MRM) using electrospray ioniza-tion (ESI). The precursor/product ion transitions were monitored at m/z 811. 4→m/z 224. 2 (positive ion mode) for vinblastine and m/z 825. 4→m/z 807. 4(positive ion mode) for internal standard vincristine. Results:Good linearity of vinblastine was obtained with-in the range of 0. 457-950 ng·ml-1(r=0. 997 1). The lower limit of quantification was 0. 457 ng·ml-1. The extraction recoveries were within the range of 89. 15%-95. 28%. The precision of intra-and inter-day was not more than 7. 95%. T1/2 of vinblastine in rats was (5. 86 ± 2. 37) h, and AUC(0-t) and AUC(0-∞) was (68. 45 ± 14. 51) and (95. 03 ± 33. 09)μg·L-1 ·h, respectively. Conclu-sion:The method is fast, sensitive and accurate, which provides research basis for the development of vinblastine and transporters re-search in medicine. The concentration of vinblastine in rats is low, and the half-life is long.

Development of an LC-MS/MS method for the quantitation of deoxyglycychloxazol in rat plasma and its application in pharmacokinetic study$ / 药物分析学报

Deoxyglycychloxazol (TY501) is a glycyrrhetinic acid derivative which exhibits high anti-inflammatory activity and reduced pseudoaldosteronism compared to glycyrrhetinic acid. In this study, a sensitive and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was established for the quantitation of TY501 in rat plasma. Plasma samples were treated by precipitating protein with methanol and supernatants were separated by a Symmetry C8 column with the mobile phase consisting of me-thanol and 10 mM ammonium formate (containing 0.1%of formic acid) (90:10, v/v). The selected reaction monitoring (SRM) transitions were performed at m/z 647.4-191.2 for TY501 and m/z 473.3-143.3 for astragaloside aglycone (IS) in the positive ion mode with atmospheric pressure chemical ionization (APCI) source. Calibration curve was linear over the concentration range of 5–5000 ng/mL. The lower limit of quantification was 5 ng/mL. The mean recovery was over 88%. The intra-and inter-day precisions were lower than 6.0% and 12.8%, respectively, and the accuracy was within 71.3%. TY501 was stable under usual storage conditions and handling procedure. The validated method has been successfully applied to a pharmacokinetic study after oral administration of TY501 to rats at a dosage of 10 mg/kg.

Pharmacokinetic comparison of roxithromycin under normoxic and hypoxic conditions in rats by UPLC/MS/MS / 中国药理学通报

Aim To study and compare the pharmaco-kinetic parameters of roxithromycin under normoxic and hypoxic rats. Methods A highly effective and rapid ultra-performance liquid chromatography with tandem mass spectrometry ( UPLC-MS/MS) method with posi-tive electrospray ionization source was successfully de-veloped and validated for quantification of roxithromy-cin in rat plasma. Sprague-Dawley rats were randomly divided into the hypoxia and normoxic groups. Each rat obtained a single dose of roxithromycin with 10 mg · kg-1 via intragastric administration. The pharmacoki-netic parameter comparison between normoxic and hy-poxic groups was calculated by SPSS software using in-dependent sample t test method. Results The main pharmacokinetic parameters of roxithromycin between the normoxic and hypoxic rats were:the AUC(0-t) 7 576 and 3 761 μg·h·L-1 , MRT(0-t) 5. 6 and 7. 7 h, T1/2 3. 4 h and 3. 9 h, CL 1. 5 and 3. 0 L · h-1 · kg-2 , tmax3. 1 and 3. 4 h, Cmax 1 116 and 372 μg·L-1 , re-spectively. The levels of Cmax and AUC of roxithromy-cin in hypoxic rats were statistically lower than those in normoxic rats. Conclusion The exposure level of rox-ithromycin in hypoxic rats markedly decreased. Our re-sults may provide an important experimental basis to adjust the dosage for roxithromycin in hypoxic clinical practice.

Metabonomics on toxicity reduction of Glycyrrhizae Radix et Rhizoma for Aconiti Lateralis Radix Preparata in Sini Tang / 中国中药杂志

To analyze the endogenous metabolite changes in rat plasma after intervention by Sini Tang and Sini Tang without Glycyrrhizae Radix et Rhizoma based on GC-MS metabonomics technology, and study the toxicity reduction effect of Glycyrrhizae Radix et Rhizoma in Sini Tang on Aconiti Lateralis Radix Preparata. Eighteen SD rats were randomly divided into normal group, Sini Tang group and Sini Tang without Glycyrrhizae Radix et Rhizoma group on average. The rats in Sini Tang group and Sini Tang without Glycyrrhizae Radix et Rhizoma group were treated respectively with physic liquor by intragastric administration at the dose of 0.02 mL•g ⁻¹ (equivalent to 0.8 g•mL ⁻¹ crude drugs) once a day for 7 days. The rats in normal group were given with equal volume of saline solution. The plasma samples were collected from each rat 0.5 h after the last administration for GC-MS detection. The data was used for multivariate statistical analysis to obtain 14 potential metabolic markers(13 of them were identified). Then their relative content and metabolic pathways were analyzed. Compared with Sini Tang without Glycyrrhizae Radix et Rhizoma group, seven metabolic markers of were reduced in Sini Tang group. Analysis on physiological functions of these potential metabolic markers showed that the Glycyrrhizae Radix et Rhizoma in Sini Tang could reduce the toxicity of Aconiti Lateralis Radix Preparata by adjusting the glycolysis, lipid metabolism, citrate cycle and some amino acids metabolism.

Development and validation of an HPLC-MS/MS analytical method for quantitative analysis of TCBA-TPQ, a novel anticancer makaluvamine analog, and application in a pharmacokinetic study in rats / 中国天然药物

We have recently designed and synthesized several novel iminoquinone anticancer agents that have entered preclinical development for the treatment of human cancers. Herein we developed and validated a quantitative HPLC-MS/MS analytical method for one of the lead novel anticancer makaluvamine analog, TCBA-TPQ, and conducted a pharmacokinetic study in laboratory rats. Our results indicated that the HPLC-MS/MS method was precise, accurate, and specific. Using this method, we carried out in vitro and in vivo evaluations of the pharmacological properties of TCBA-TPQ and plasma pharmacokinetics in rats. Our results provide a basis for future preclinical and clinical development of this promising anticancer marine analog.

Determination of atractylon in rat plasma by a GC-MS method and its application to a pharmacokinetic study / 药物分析学报

A sensitive and selective method based on gas chromatography hyphenated to mass spectrometry (GC-MS) was developed and validated for the determination of atractylon in rat plasma. Plasma samples were processed by liquid-liquid extraction with ethyl acetate-n-hexane (1:1, v/v) using acetophenone as an internal standard (IS). Analytes were determined in selective ion monitoring (SIM) mode using target ions at m/z 108.1 for atractylon and m/z 105.1 for acetophenone. The calibration curve was linear over the concentration range of 10-1000 ng/mL with lower limit of quantification of 10 ng/mL. The intra- and inter-day precision variations were not more than 10.4% and 9.6%, respectively, whilst accuracy values ranged from -6.5% to 4.9%. Extraction recovery of the assay was satisfactory. This method was suc-cessfully applied to quantification and pharmacokinetic study of atractylon in rat plasma after in-tragastric administration of Atractylodis extract.

Direct injection HILIC-MS/MS analysis of darunavir in rat plasma applying supported liquid extraction / 药物分析学报

A novel bioanalytical method was developed and validated for the quantitative determination of darunavir (DRV) in rat plasma by employing hydrophilic interaction chromatography and tandem mass spectrometry (HILIC–MS/MS) with supported liquid extraction (SLE). Irbesartan (IRB) was used as an internal standard (IS). The analyte in rat plasma (200 mL) was isolated through SLE using ethyl acetate as the eluting solvent. The chromatographic separation was achieved on Luna-HILIC (250 mm*4.6 mm, 5 μm) column with a mobile phase of 0.1% of formic acid in water:acetonitrile (5: 95, v/v), at a constant flow rate of 1.0 mL/min. The MS/MS ion transitions for DRV (548.1-392.0) and IS (429.2-207.1) were monitored on an ion trap mass spectrometer, operating in the multiple reaction monitoring (MRM) mode. The lower limit of quantitation (LLOQ) was 0.2 ng/mL and quantitation range was 0.2–5000 ng/mL. The method was validated for its selectivity, sensitivity, carryover, linearity, precision, accuracy, recovery, matrix effect and stability. The method was successfully applied to pharmacokinetic study in rats.

Comparison of conventional and supported liquid extraction methods for the determination of sitagliptin and simvastatin in rat plasma by LC-ESI-MS/MS / 药物分析学报

Three extraction methods were compared for their efficiency to analyze sitagliptin and simvastatin in rat plasma by LC–MS/MS, including (1) liquid–liquid extraction (LLE), (2) solid phase extraction (SPE) and (3) supported liquid extraction (SLE). Comparison of recoveries of analytes with different extraction methods revealed that SLE was the best extraction method. The detection was facilitated with ion trap-mass spectrometer by multiple reactions monitoring (MRM) in a positive ion mode with ESI. The transitions monitored were m/z 441.1→325.2 for simvastatin, 408.2→235.1 for sitagliptin and 278.1→260.1 for the IS. The lower limit of quantification (LLOQ) was 0.2 ng/mL for sitagliptin and 0.1 ng/mL for simvastatin. The effective SLE offers enhanced chromatographic selectivity, thus facilitating the potential utility of the method for routine analysis of biological samples along with pharmacokinetic studies.

Quantification of neomangiferin in rat plasma by liquid chromatography-tandem mass spectrometry and its application to bioavailability study$ / 药物分析学报

Neomangiferin, a natural C-glucosyl xanthone, has recently received a great deal of attention due to its multiple biological activities. In this study, a rapid and sensitive ultra-high performance liquid chroma-tography tandem mass spectrometry (UHPLC–MS/MS) method for the quantification of neomangiferin in rat plasma was developed. Using chloramphenicol as an internal standard (IS), plasma samples were subjected to a direct protein precipitation process using methanol (containing 0.05% formic acid). Quan-tification was performed by multiple reactions monitoring (MRM) method, with the transitions of the parent ions to the product ions of m/z 583.1-330.9 for NG and m/z 321.1-151.9 for IS. The assay was shown to be linear over the range of 0.2–400 ng/mL, with a lower limit of quantification of 0.2 ng/mL. Mean recovery of neomangiferin in plasma was in the range of 97.76%–101.94%. Relative standard deviations (RSDs) of intra-day and inter-day precision were both o 10%. The accuracy of the method ranged from 94.20%to 108.72%. This method was successfully applied to pharmacokinetic study of neomangiferin after intravenous (2 mg/kg) and intragastric (10 mg/kg) administration for the first time. The oral absolute bioavailability of neomangiferin was estimated to be 0.53%7 0.08%with an elimination half-life (t1/2) value of 2.74 7 0.92 h, indicating its poor absorption and/or strong metabolism in vivo.