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The aim of the present investigation was to better understand the pharmacokinetic profile of bilberry (Vaccinium Myrtillus) anthocyanins and the role of glucose transporters (sGLT1 and GLUT2) on their absorption. In particular, the absorption of 15 different anthocyanins contained in a standardized bilberry extract (Mirtoselect ® ) was measured in rats by a validated LC-ESI–MS/MS approach. The plasma concentration peak (C max ) of 11.1 ng/mL was reached after 30 min and fasting condition significantly increased the bioavailability of anthocyanins by more than 7 fold in respect to fed rats. Glucose co-administration did not interfere with the overall anthocyanin uptake. Bioavailability of each anthocyanin was then estimated by comparing the relative content in plasma vs extract. The 15 anthocyanins behaved differently in term of bioavailability and both the aglycone and the sugar moiety were found to affect the absorption. For instance, arabinoside moiety was detrimental while cyanidin enhanced bioavailability. Computational studies permitted to rationalize such results, highlighting the role of glucose transporters (sGLT1 and GLUT2) in anthocyanins absorption. In particular a significant correlation was found for the 15 anthocyanins between sGLT1 and GLUT2 recognition and absorption. [ABSTRACT FROM AUTHOR]

CKD-712 is a potential treatment for sepsis, as it exhibits protective effects against lipopolysaccharide-mediated platelet aggregation, inducible nitric oxide synthase expression, and cecum-ligation puncture-induced septic mortality in mice. In this study, we develop a rapid and sensitive LC–MS/MS method for determining CKD-712 in rat plasma. CKD-712 and papaverine hydrochloride (an internal standard) were analyzed using an LC–MS/MS system consisting of an Agilent HPLC system (HP-1100) equipped with an Atlantis HILIC Silica (2.1 × 50 mm, 3 μm) column and a API 4000 (Applied Biosystems/MDS Sciex, USA) in a positive ESI mode. We utilized multiple reaction monitoring (MRM) at m / z transitions of 306.2–164.0 to analyze CKD-712, and 340.3–202.1 m / z for IS, with a mobile phase of acetonitrile (0.025% trifluoroacetic acid):20 mM ammonium acetate (94:6, v/v) at a flow rate of 0.25 mL/min. The lower limit of quantification (LLOQ) was 5 ng/mL, with a linearity ranging from 5 to 1000 ng/mL ( r > 0.999). Validation parameters including specificity, precision, accuracy, matrix effect, recovery, dilution effect and stability results were well within acceptance criteria, and applied successfully on a pharmacokinetic study in rats. [ABSTRACT FROM AUTHOR]

Table olives are especially rich in pentacyclic triterpenic compounds, which exert several biological activities. A crucial step in order to know if these compounds could contribute to the beneficial and healthy properties of this food is their measurement in blood. Therefore, the present study describes a simple and accurate liquid-liquid extraction followed by LC-QqQ-MS analysis for the simultaneous determination of the main pentacyclic triterpenes from Olea europaea L. in rat plasma. The method was validated by the analysis of blank plasma samples spiked with pure compounds, obtaining a linear correlation, adequate sensitivity with a limit of quantification ranging from 1 nM for maslinic acid to 10 nM for uvaol. Precision and accuracy were lower than 10% in all cases and recoveries were between 95 and 104%. The oral administration of olives to rats and its determination in plasma verified that the established methodology is appropriate for bioavailability studies. [ABSTRACT FROM AUTHOR]

Myostatin, also known as growth differentiation factor 8 (GDF-8), is a protein acting as a negative regulator in skeletal muscle growth. Inhibition of myostatin by therapeutic agents provides opportunities for current unmet medical needs. In order to better understand drug engagement to aid the drug development, we have developed a hybrid LC-MS/MS method which can differentially measure myostatin and another protein from the same GDF family, GDF-11. Although the two proteins share high homology, the LC-MS/MS assay provided the specificity based on monitoring of unique surrogate peptide generated from enzymatic digestion. An automated sample preparation platform, Agilent AssayMap Bravo, was used for automated immunocapture. Capture antibody that is non-competing with our investigational drug and has similar binding affinity to both myostatin and GDF-11 was used. Therefore, total myostatin and GDF-11 including both free form and drug-bound form were captured and measured. The enriched sample was digested after reduction and alkylation. Two surrogate peptides (IPAMVVDR for myostatin and IPGMVVDR for GDF-11) were monitored and the lower limit of quantitation (LLOQ) was established at 1.0 ng/mL for myostatin and 0.1 ng/mL for GDF-11. The accuracy was demonstrated with recovery for IPAMVVDR between 99.2% and 103.1% and for IPGMVVDR between 90.3% and 114.5%. The developed hybrid assay exhibits sufficient sensitivity, accuracy and specificity to differentiate between the highly structurally similar myostatin and GDF-11. This analytical approach was successfully applied to a rat toxicology study, and was demonstrated to be a powerful tool for biomarker measurement in the present of a therapeutic agent. [ABSTRACT FROM AUTHOR]

A rapid, simple and sensitive ultra-high performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method was developed and validated for the determination of hederasaponin B, an active triterpenoid saponin widely existed in Hedera helix L. Plasma samples were processed by protein precipitation with acetonitrile and separated on a Thermo Hypersil GOLD C18 (2.1 mm × 50 mm,1.9 μm) at flow rate of 0.3 ml/min, with a gradient elution consisting of acetonitrile and water containing 0.1% (v/v) formic acid at 30 °C and detected by electrospray ionization mass spectrometry in the positive multiple reaction monitoring (MRM) mode. The linearity was found to be within the concentration range of 0.5-5000 ng/ml with a lower limit of quantification of 0.5 ng/ml. The absolute oral bioavailability of hederasaponin B was 0.24 ± 0.49%. This indicated that the concentration-time course of the hederasaponin B existed a double-peak phenomenon. This method was further applied to the determination of hederasaponin B in rat plasma and showed good practicability, for the first time, after intragastric (25 mg/kg) and intravenous (2 mg/kg) administration in rats. [ABSTRACT FROM AUTHOR]

In this study, various neurosteroids in brain and plasma were simultaneously determined using liquid chromatography-tandem mass spectrometry and their profile changes in a stress-induced rats were investigated. The investigated neurosteroids are as follows: progesterone (P4), 5α-dihydroprogesterone (5α-DHP), 5β-dihydroprogesterone, estrone, androstenedione (AE), cortisol, cortisone, corticosterone (CORT), dehydroepiandrosterone (DHEA), pregnanolone (3α,5β-THP), allopregnanolone (ALLO), 11-deoxycorticosterone (DOC), 11-deoxycortisol, pregnenolone (PREG), and 5α/5β-tetrahydrodeoxycorticosterone (5α/5β-THDOC). Brain and plasma samples were processed using solid-phase extraction with methanol and acetic acid (99:1), and derivatized with a hydroxylamine reagent. Separation was achieved within 13 min at a flow rate of 0.4 mL/min with a C18 column (3.0 × 50 mm, 2.7 μm). The triple quadrupole mass spectrometer was operated in the positive electrospray ionization mode. Using this method, the neurosteroid level variation was quantitated and investigated in the brain and plasma upon immobilization stress in rats. As a result, AE, CORT, DOC, P4, 5α-DHP, 5α/5β-THDOC, DHEA, 3α,5β-THP, ALLO, and PREG levels were significantly altered in both the brain and plasma samples when stress was induced. These findings demonstrated that stress leads to the alteration of the GABAergic neurosteroid profile. The present results will be helpful for furthering an understanding of the role of neurosteroids in stressed conditions. [ABSTRACT FROM AUTHOR]

Benzoylpaeoniflorin (BP) is a potential therapeutic agent against oxidative stress related Alzheimer’s disease. In this study, a more rapid, selective, and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed to determine BP in rat plasma distinguishing with a monoterpene isomer, benzoylalbiflorin (BA). The method showed a linear response from 1 to 1000 ng/mL (r>0.9950). The precision of the interday and intraday ranged from 2.03 to 12.48% and the accuracy values ranged from −8.00 to 10.33%. Each running of the method could be finished in 4 minutes. The LC-MS/MS method was validated for specificity, linearity, precision, accuracy, recovery, and stability and was found to be acceptable for bioanalytical application. Finally, this fully validated method was successfully applied to a pharmacokinetic study in rats following oral administration. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA), a chronic systemic inflammatory disorder affects many adults. Sinomenine, a natural product, has been clinically available for the treatment of RA in China. SND-117, a sinomenine derivative with much more potent activity, might serve as a candidate for anti-arthritis. The aim of the present study was to develop a sensitive and rapid high performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) method for quantification of SND-117 in rat plasma and to understand its absolute bioavailability. The HPLC–MS/MS method was developed and fully validated for determination of SND-117 in rat plasma, and the pharmacokinetic differences were investigated after different administration routes. The pharmacokinetics parameters were calculated by non-compartment model with DAS 3.0 software. After the oral or intravenous administration of different doses of SND-117, the time to peak is 1.5 h, half-life time is 8–10 h. The absolute oral bioavailability of SND-117 in rats was 9.60%. The results showed that SND-117 in rats was quickly absorbed, slowly eliminate, and the kinetics were linear. This method was suitable for pharmacokinetic studies of SNA-117 in rats. [ABSTRACT FROM AUTHOR]

Introduction Liquid Chromatography Tandem Mass Spectrometry (LC–MS/MS) allows for the direct analysis of multiple hormones in a single probe with minimal sample volume. Rodent-based animal studies strongly rely on microsampling, such as the dry blood spot (DBS) method. However, DBS suffers the drawback of hematocrit-dependence (non-volumetric). Hence, novel volumetric microsampling techniques were introduced recently, allowing sampling of fixed accurate volumes. We compared these methods for steroid analysis in the rat to improve inter-system comparability. Experimental We analyzed steroid levels in blood using the absorptive microsampling devices Whatman® 903 Protein Saver Cards, Noviplex™ Plasma Prep Cards and the Mitra™ Microsampling device and compared the obtained results to the respective EDTA plasma levels. Quantitative steroid analysis was performed via LC–MS/MS. For the determination of the plasma volume factor for each steroid, their levels in pooled blood samples from each human adults and rats (18 weeks) were compared and the transferability of these factors was evaluated in a new set of juvenile (21 days) and adult (18 weeks) rats. Hematocrit was determined concomitantly. Results Using these approaches, we were unable to apply one single volume factor for each steroid. Instead, plasma volume factors had to be adjusted for the recovery rate of each steroid and device individually. The tested microsampling systems did not allow the use of one single volume factor for adult and juvenile rats based on an unexpectedly strong hematocrit-dependency and other steroid specific (pre-analytic) factors. Discussion Our study provides correction factors for LC–MS/MS steroid analysis of volumetric and non-volumetric microsampling systems in comparison to plasma. It argues for thorough analysis of chromatographic effects before the use of novel volumetric systems for steroid analysis. [ABSTRACT FROM AUTHOR]

A sensitive and robust LC–MS/MS method has been developed and validated to determine the concentrations of tacrolimus and its major metabolite 13-O-desmethyl tacrolimus (13-ODMT) in kidney tissue from rats who received tacrolimus intra-peritoneally at doses of 0.5 mg/kg and 2 mg/kg. The samples were prepared by a liquid-liquid extraction procedure using ethyl ether as the extraction solvent and ascomycin as the internal standard. Chromatographic separation was achieved using Phenomenex Kinetex column (2.6 μm C18 100 Å, 100 × 2.1 mm, Phenomenex, Torrance CA) and a gradient mobile phase of water and methanol-acetonitrile (50:50, v/v) both containing 0.1% formic acid. The limit of quantification was 0.25 ng/ml and the calibration curves covered a concentration range from 0.25 to 50 ng/ml. Intra-and inter-assay precision and accuracy for both tacrolimus and 13-ODMT were all within FDA guidelines for bioanalysis. Extraction efficiency for tacrolimus ranged from 67.00 to 74.90% and from 66.70 to 78.40% for 13-ODMT. Several challenges interfering with the performance of the method such as phospholipid build-up have also been addressed. Kidney tissue samples from six rats receiving either 0.5 or 2 mg/kg dose were analyzed and resulted in a median concentration of 11.54 and 0.72 ng/ml for tacrolimus and 13-ODMT, respectively, for the lower dose level, and a median concentration of 8.89 ng/ml and 1.50 ng/ml for tacrolimus and 13-ODMT, respectively, at the higher dose level. [ABSTRACT FROM AUTHOR]

Clematidis Radix et Rhizoma is a traditional Chinese medicine widely used for treating arthritic disease. Clematis triterpenoid saponins (TS) and clematichinenoside AR (C-AR) have been considered to be responsible for its antiarthritic effects. However, the underling mechanism is still unclear because of their low bioavailability. To address of this issue, metabolomics tools were performed to determine metabolic variations associated with rheumatoid arthritis (RA) and responses to Clematis TS, C-AR and positive drug (Triptolide, TP) treatments. This metabolomics investigation of RA was conducted in collagen-induced arthritis (CIA) rats. Liquid chromatography/mass spectrometry and multivariate statistical tools were used to identify the alteration of serum and urine metabolites associated with RA and responses to drug treatment. As a result, 45 potential metabolites associated with RA were identified. After treatment, a total of 24 biomarkers were regulated to normal like levels. Among these, PC(18:0/20:4), 9,11-octadecadienoic acid, arachidonic acid, 1-methyladenosine, valine, hippuric acid and pantothenic acid etc, were reversed in Clematis TS and C-AR groups. Tetrahydrocortisol was regulated to normal levels in Clematis TS and TP groups, while 3,7,12-trihydroxycholan-24-oic acid was regulated in C-AR and TP groups. Biomarkers like citric acid, p -cresol glucuronide, creatinine, cortolone were reversed in TP group. [ABSTRACT FROM AUTHOR]

Purpose: To explore the therapeutic effect and mechanism of action of Si-jun-zi decoction (SJZD) in rat spleen deficiency syndrome. Methods: Spleen deficiency syndrome was induced in a rat model with reserpine. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) and partial least squaresdiscriminate models (PLS-DA) were used to analyze the difference in global metabolite profile within all groups. Variable importance projection (VIP > 1) and Student's t-test (p < 0.05) were used for biomarker selection. Results: Enzymatic results showed that the level of amylase (AMY), pepsin (LPS) and pepsase were significantly lower in the untreated rats than in normal control rats and SJZD group rats (P < 0.05). Histopathological analysis showed there were significant pathological changes in the untreated rats compared with the normal control group and SJZD group rats. PLS-DA score plots of the untreated group rats clustered separately from control rats, whereas SJZD group rats clustered closely to normal control rats. Twenty potential biomarkers, including phospholipid and fatty acids, were screened. The relative content of 20 metabolites showed significant differences in the untreated group compared with control and SJZD groups (p < 0.05). Six potentially perturbed metabolic pathways were found, which might be potential targets pathways for SJZD intervention in spleen deficiency syndrome. Conclusion: Metabolomics approach is an effective tool for understanding the therapeutic mechanisms of SJZD. [ABSTRACT FROM AUTHOR]

Till date, no analytical method published to detect Cisplatin has been validated according to the U.S. Food and Drug Administration (FDA) guidance using liquid chromatography mass spectrometry (LC–MS/MS). We report, a validated LC–MS/MS method for quantitative determination of cisplatin in rat plasma and urine according to FDA guidlines. Cisplatin is a platinum containing compound used for the treatment of different types of cancers. Quantitative determination of cisplatin has been carried out using atomic absorption spectroscopy, high pressure liquid chromatography with phosphorescence, ultra-violet detection, or with inductively coupled plasma mass spectrometry. Few LC–MS/MS methods have been reported for the analysis of cisplatin either for direct quantification or indirect by derivatizing with organic compounds but none of the reported methods have validated the method. The developed and validated assay presented here is a highly sensitive LC–MS/MS method developed and validated for the quantitative determination of cisplatin following derivatization with diethyldithiocarbamate (DDTC) in order to detect platinum (Pt) of cisplatin, suitable for pharmacokinetic studies in rats and to further use it to study human toxicology. Chromatographic separation was achieved using a Poroshell 120 EC-C 18 column (3 × 50 mm, 2.7 μm) with a binary gradient mobile phase. Quantification was performed on a triple quadruple with electrospray ionization and detection was performed using multiple reaction monitoring. The method has a limit of detection of 1 ng/mL, and the quantifiable range was 3–3000 ng/mL in rat plasma and urine. The method was accurate and precise with an accuracy and precision for intra-day and inter-day of ±20% for lower limit of quantitation and of ±15% for low, mid and high quality control samples. This method was successfully applied to study the pharmacokinetic profile of cisplatin in rat plasma and urine given a range of doses from 0.5 to 3.5 mg/kg. [ABSTRACT FROM AUTHOR]

Glimepiride (GLI) is prescribed for the management of type-2 diabetes where as pitavastatin (PIT) for the treatment of diabetes associated dyslipidemia. Both the drugs are metabolized by CYP2C9 and have the potential of altering the enzyme through either inhibition or induction. In this respect, we present a simple, fast and validated bioanalytical LC–MS/MS method for the simultaneous estimation of GLI and PIT from rat plasma. Waters XTerra RP HPLC column (4.6 × 100 mm, 5 μm) with mobile phase consisting of acetonitrile and 10 mM ammonium acetate (pH-6.0) in the ratio 85:15 ( v/v ) at a flow rate of 1 mL/min was used for the chromatographic separation. The negative ionization mode with MRM transitions: m / z 420.17 → 288.13 for PIT, m / z 489.59 → 350.12 for GLI and m / z 380.08 → 316.31for celecoxib as internal standard (IS). A total run time of 3 min and LLOQ was found to be 5 ng/mL for both PIT and GLI. The method was applied to study the drug interaction between GLI and PIT in rat liver microsomes. In vivo rat pharmacokinetics study showed there was a 1.29-fold increase in AUC 0-∞ and 1.2-fold decrease in the clearance of PIT in presence of GLI. No notable difference in the pharmacokinetic profile of GLI was observed upon the intravenous co-administration of PIT. [ABSTRACT FROM AUTHOR]

Crocin and crocetin in rat plasma were simultaneously analysed using ultra-performance liquid chromatography tandem mass spectroscopy (UPLC–MS/MS), and method was fully validated. For the first time, levels of both crocin and crocetin in plasma were profiled after oral administration of crocin, and this UPLC–MS/MS approach was applied to evaluate pharmacokinetics and relative bioavailability of crocin and crocetin in rats. It was shown that crocin transformed into crocetin quickly in the gastrointestinal tract, and crocetin was 56–81 fold higher exposed in rat plasma than crocin after oral administration of crocin. A comparison study revealed that an oral administration of equal molar crocin achieved higher exposure of crocetin in rat plasma than that of crocetin. It was suggested that oral administration of crocin has the advantages over crocetin, and crocetin may be the active component potentially responsible for the pharmacological effect of crocin. [ABSTRACT FROM AUTHOR]

A liquid chromatography coupled with electrospray ionization mass spectrometry method was developed and validated for simultaneous determination of seven bioactive constituents including astragaloside IV, calycosin, glycyrrhizic acid, enoxolone, saikosaponin D, ferulic acid and hesperiden in rats’ various tissues using diclofenac as the internal standard (IS). Biological samples were pretreated by protein precipitation with acetonitrile. The chromatographic separation was carried out on a C18 column with a gradient mobile phase consisting of acetonitrile and water (containing 0.1% formic acid and 4 mM ammonium acetate). All analytes and IS were quantitated through electrospray ionization in negative ion multiple reaction monitoring mode. The mass transitions were as follows: m / z 829.7 → 783.3 for astragaloside IV, m / z 283.3 → 267.7 for calycosin, m / z 821.6 → 350.0 for glycyrrhizic acid, m / z 469.9 → 425.2 for enoxolone, m / z 825.7 → 779.6 for saikosaponin D, m / z 192.5 → 133.9 for ferulic acid, m / z 609.1 → 301.0 for hesperiden and m / z 293.6 → 249.9 for the IS, respectively. The lower limits of quantification for the seven analytes in different rat tissues were 0.2–20 ng/mL. Bu-zhong-yi-qi-tang (Hochuekkito in Japan, Bojungikki-tang in Korea) is one of the most frequently prescribed traditional herbal formulas used in Korea, Japan, and China to treat gastrointestinal diseases, cancer and chronic fatigue syndrome. The validated method was successfully applied to a tissue distribution study of the seven components in rat tissue after oral administration of Bu-zhong-yi-qi-tang concentrated granule. The results of the tissue distribution study showed that the high concentration of seven components were mainly in the gastrointestinal tract. [ABSTRACT FROM AUTHOR]

A sensitive and rapid ultra-performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC–ESI–MS/MS) method was developed for the simultaneous analysis of anemoside B4, phellodendrine, berberine, palmatine, obakunone, esculin, esculetin, toosendanin (IS 1 of anemoside B4), tetrahydropalmatine (IS 2 of phellodendrine, berberine, palmatine and obakunone) and scopoletin (IS 3 of esculin and esculetin) and to compare the pharmacokinetics of these active ingredients in normal and ulcerative colitis rats. After methanol deproteinization, solvents were evaporated at 40 °C under a gentle stream of nitrogen. Chromatography was performed using a C18 column with a gradient elution of 0.1% aqueous formic acid and acetonitrile at 0.4 ml/min. Detection and measurement were performed on a 4000 QTRAP UPLC–MS/MS system from AB Sciex in the multiple reaction monitoring (MRM) mode. Phellodendrine, berberine, palmatine, obakunone, esculin, esculetin, tetrahydropalmatine (IS 2 ) and scopoletin (IS 3 ) were monitored under positive ionization conditions. Anemoside B4, and toosendanin (IS 1 ) were monitored under negative ionization conditions. The optimized mass transition ion-pairs ( m / z ) were 1221.1/750.7 for anemoside B4, 343.2/193.2 for phellodendrine, 337.1/321.0 for berberine, 353.0/336.9 for palmatine, 455.1/161.1 for obakunone, 341.2/179.2 for esculin, 179.1/123.0 for esculetin, 573.4/531.4 for toosendanin (IS 1 ), 356.2/192.2 for tetrahydropalmatine (IS 2 ) and 193.0/133.1 for scopoletin (IS 3 ). [ABSTRACT FROM AUTHOR]

A simple, sensitive and selective ultra-fast liquid chromatography-tandem mass spectrometry (UFLC–MS/MS) method was established for simultaneous determination and pharmacokinetic study of rosmarinic acid (RA), salvianolic acid D (Sal D), lithospermic acid (LA) and salvianolic acid B (Sal B) in rat plasma after intravenous administration of salvianolic acid for injection (SAFI). Three doses of administration, containing 14, 28 and 56 mg/kg, were investigated in this study. Plasma samples were pretreated using protein precipitation (PP) with pre-cooled acetonitrile. Chromatographic separation was achieved on a CORTECS™ UPLC C18 column (1.6 μm, 2.1 × 100 mm) with a mobile phase composed of 0.1% formic acid aqueous (V/V) and 0.1% formic acid acetonitrile (V/V). Analytes were detected using electrospray ionization (ESI) source in negative ionization mode and quantified in multiple reaction monitoring (MRM) mode. The validated method is stable and reliable. No significant difference of half lives ( t 1/2 ) of four analytes at three doses was observed. Area under the curve (AUC 0-∞ ) and peak concentration (C max ) of the four analytes demonstrated a linear increase in across the doses with the linear correlation r of each analyte at three doses were greater than 0.95. It indicated that the pharmacokinetic behavior of SAFI is positively related to dose at the range of 14–56 mg/kg. [ABSTRACT FROM AUTHOR]

A sensitive, selective and precise liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of propofol (PRO) in rat serum and hair has been developed. 3-Bromomethyl-propyphenazone was used as derivatization reagent forming propofol-methyl-propyphenazone compound. The derivatization reaction was optimized and validated for maximum MS sensitivity. The MS instrumental sensitivity reached to 10 attogram. The serum samples were extracted by using Chromabond C 8 columns, while hair samples extracted with methanol. The tendency of volatility of PRO was minimized by adding triethylamine to the extract before the use of nitrogen gas for evaporation of solvent. The limit of quantitation (LLOQ) was 0.01 pg/mL and the assay was linear to 10000 pg/mL. The intra-and inter-day precision (RSD%) ranged from 0.33 to 3.44% while the accuracy (E r %, relative error) were −6.4 to 1.1%. The ionization suppression, due to reagent, was minimized by reacting the excess reagent with methanol, and eluting to waste before MS ionization source (2–4.5 min). The method was successfully applied for detection and determination of PRO in rat serum and hair after 7–28 days from administration of only one dose of propofol (10 mg/kg). [ABSTRACT FROM AUTHOR]

Genipin-1- o -glucuronic acid and genipin-monosulfate are two major metabolites from geniposide and genipin. Based on diabetic rat model, we developed a simultaneous quantification method to investigate their comparative pharmacokinetics by online mircrodialysis-ultra performance liquid chromatography–mass spectrometry (MD-UPLC–MS/MS) without their standard compounds. Online microdialysis sampling could avoid unexpected contamination or degradation of the analytes during the storage and transfer steps. Combined with good sensitivity, selectivity and selectivity of UPLC–MS/MS, online MD-UPLC–MS/MS method could real-timely monitor metabolites in rat blood for quantitative analysis. Our research found that AUC 0→t of genipin-1- o -glucuronic acid and genipin-monosulfate in blood of diabetic group were 17.68 and 7.58 times than those in normal group, respectively, and AUC 0→t of genipin-1- o -glucuronic acid was 2.28 times than that of genipin-monosulfate in blood of diabetic group, which revealed the effect of diabetes on the pharmacokinetic properties of the two metabolites. This study not only provides an approach for pharmacokinetic studies for various metabolites from herb medicines, but also can predict druggability of their bioactive metabolites. The insight obtained should facilitate drug development and toxicity research. [ABSTRACT FROM AUTHOR]

Therapeutic monoclonal antibodies (mAbs) have heterogeneities in their structures. Multiple studies have reported that the variety of post-translational modifications could affect the pharmacokinetic profiles or pharmacological potencies of therapeutic mAbs. Taking into the account that the structural modification of mAbs would affect the efficacy, it is worth investigating the structural alteration of therapeutic mAbs in the blood and the relationship between their structures and pharmacological effects. Herein, we have developed the method to isolate rituximab from plasma in which endogenous IgGs interfere the detection of rituximab, and successfully developed the analytical method with a liquid chromatograph time-of-flight mass spectrometer to detect the structure of rituximab in plasma with errors less than 30 parts per millions. Eight types of carbohydrate chains in rituximab were detected by this method. Interestingly, time-dependent changes in carbohydrate chains such as AAF (G2F) and GnGn (G0) were observed in rats, although the amino acids were stable. Additionally, these structural changes were observed via incubation in plasma as in the rat experiment, suggesting that a certain type of enzyme in plasma caused the alterations of the carbohydrate chains. The present analytical methods could clarify the actual pharmacokinetics of therapeutic mAbs, and help to evaluate the interindividual variations in pharmacokinetics and efficacy. [ABSTRACT FROM AUTHOR]

Triple-negative breast cancer (TNBC) is a heterogeneous and clinically aggressive disease with no approved targeted therapy. Curcumin has shown therapeutic potential against TNBC, but it shows low bioavailability and low efficacy when administered as a free drug. Here we describe a novel vehicle forin vivodelivery of curcumin based on the phosphorylated calixarene POCA4C6. Curcumin-loaded POCA4C6 micelles (CPM) were prepared using the thin-film method and they showed a unilamellar structure with an average particle size of 3.86 nm. The micelles showed high curcumin encapsulation efficiency and loading was based on liquid chromatography-tandem mass spectrometry. Studies with cell cultures suggest that CPM can sustainably release curcumin in a pH-dependent manner. The micelles efficiently inhibited proliferation, invasion, migration and tumor spheroid formation by BT-549 human breast cancer cells. These effects involved increased apoptosis and reduced levels of nuclear β-catenin and androgen receptor. After injection into tumor xenografts, CPM persisted in the tumor tissue and efficiently inhibited tumor growth without causing obvious systemic toxicity. CPM also significantly reduced levels of CD44+/CD133+breast cancer stem cells. Our results highlight the potential of CPM as an effective therapy against TNBC. [ABSTRACT FROM AUTHOR]

Identification of metabolic profile of traditional Chinese medicine in vivo is always a challenge task. Usually, screening out and identifying the exogenous compounds manually from total ion chromatograms (TICs) of biologic samples is time-consuming and strenuous. In this study, a systematic identification strategy based on LC–MS was adopted to clarify the metabolic profiling of Zhi-Zi-Hou-Po decoction ( ZZHPD ) in rat. Bile, urine and feces samples of rat were obtained after oral administration and then analyzed by LC–MS after proper preparation. The xenobiotics were screened out from TICs globally and rapidly by untargeted metabolomics-driven strategy (UMDS) based on the combined of XCMS online (a web-based platform to process LC–MS data), MetAlign (a software to process LC–MS data) and SIMCA-P (a software for data analysis). Most of the xenobiotics were identified by means of series product ions filtering (sPIF), which was based on the database-hit of ZZHPD (including prototype and metabolites). Then the unmatched constituents were identified tentatively and their source and metabolic pathway were clarified by using diagnostic fragment ions strategy (DFIS). As a result, a total of 83 compounds including 44 prototype compounds and 39 metabolites were rapidly identified or tentatively characterized from the biologic samples, and among them, four of which were found for the first time. Further research on the correlations of these prototype compounds and metabolites revealed that glucuronidation is the main metabolic pathways of ZZHPD in rat bile and urine, while prototype compounds were the abundant ingredients detected in rat feces. [ABSTRACT FROM AUTHOR]

A sensitive and reliable high-performance liquid chromatography with tandem mass spectrometry was developed and validated for the quantification of swertisin in rat plasma. The samples were prepared with methanol by protein precipitation. Swertisin was separated by using an Agilent Poroshell 120 EC-C18 column (4.6mm × 50 mm, 2.7 µm) with the mobile phase consisted of acetonitrile and water containing 0.1% formic acid running at a flow rate of 0.3 mL/min for 5 min. The analytes were detected with the multiple reaction monitoring in the negative electrospray ionization source for quantitative response of swertisin [M-H]- (445.1→281.7) and puerarin (internal standard) [M-H]- (415.1×295.0). Precision (relative standard deviation, RSD%) of the inter-day and the intra-day was <9.89% and 11.34% while accuracy (relative error, RE%) ranged from -6.01% to 4.92% and -3.97% to 4.39%, respectively. Interestingly, the expression of the γ-aminobutyric acid (GABA) receptor subunits (GABAAα1, GABAAα5 and GABAAμ1) mRNAs was enhanced in the rat hippocampal neurons treated with swertisin as analyzed by real-time polymerase chain reaction. Moreover, the method was successfully applied to determine the pharmacokinetic of swertisin in rats after tail vein injection with 4.0 mg/kg of the compound. Our results provide useful pharmacokinetic information for swertisin in vivo and suggest that the sedative function of this compound may be through inducing the expression of the GABAA receptor subunits. [ABSTRACT FROM AUTHOR]

Aging is an inevitable condition leading to health deterioration and death. Regular physical exercise can moderate the metabolic phenotype changes of aging. However, only a small number of metabolomics-based studies provide data on the effect of exercise along with aging. Here, urine and whole blood samples fromWistar rats were analyzed in a longitudinal study to explore metabolic alterations due to exercise and aging. The study comprised three different programs of exercises, including a life-long protocol which started at the age of 5 months and ended at the age of 21 months. An acute exercise session was also evaluated. Urine and whole blood samples were collected at different time points and were analyzed by LC-MS/MS (Liquid Chromatography-tandem Mass Spectrometry). Based on their metabolic profiles, samples from trained and sedentary rats were differentiated. The impact on the metabolome was found to depend on the length of exercise period with acute exercise also showing significant changes. Metabolic alterations due to aging were equally pronounced in sedentary and trained rats in both urine and blood analyzed samples. [ABSTRACT FROM AUTHOR]

To investigate the pharmacokinetic (PK) interaction between telmisartan (Tel) and pitavastatin (Pit), a rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometric assay method had been successfully established and fully validated for the simultaneous quantification of Tel and Pit in rat plasma. A simple protein precipitation procedure was adopted for the sample preparation with satisfactory extraction recovery for both analytes and the internal standard. The samples were chromatographed on an Inertsil ODS-3 C18 column (100 mm × 2.1 mm, 2 μm) using a mixture of acetonitrile and 10 mM ammonium acetate containing 0.1% formic acid (60: 40, v/v) as the mobile phase at a flow rate of 0.4 mL/min. The calibration curves obtained were linear (r > 0.99) over the concentration range of 2–200 ng/mL for Tel and 1–100 ng/mL for Pit, respectively. The validated method was successfully applied to the PK study and the data did not reveal any evidence for the potential drug–drug interaction (DDI) between Tel and Pit. This information would provide the evidence for clinical rational use of Tel and Pit, and this study might be applied in therapeutic drug monitoring in patients receiving Tel/Pit combinations or single drug. [ABSTRACT FROM AUTHOR]

Capilliposide B, a novel oleanane triterpenoid saponin isolated from Lysimachia capillipes Hemsl, showed significant anti-tumor activities in recent studies. To characterize the excretion of Capilliposide B, a reliable liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was developed and validated for simultaneous determination of Capilliposide B and its active metabolite, Capilliposide A in rat urine and feces. Sample preparation using a solid-phase extraction procedure was optimized by acidification of samples at various degrees, providing extensive sample clean-up with a high extraction recovery. In addition, rat urinary samples were pretreated with CHAPS, an anti-adsorptive agent, for overcoming nonspecific analytes adsorption during sample storage and process. The method validation was conducted over the curve range of 10.0–5000 ng/ml for both analytes. The intra- and inter-day precision and accuracy of the QC samples showed ≤11.0% RSD and −10.4–12.8% relative error. The method was successfully applied to an excretion study of Capilliposide B following intravenous administration. [ABSTRACT FROM AUTHOR]

An amide derivative of gallic acid (GA), 3,4,5-trihydroxy-N-(8-hydroxyquinolin-2-yl)benzamide) (SG-HQ2) was recently synthesized, and its inhibitory actions were previously shown on histamine release and pro-inflammatory cytokine expression. In this study, a simultaneous quantification method was developed for the determination of SG-HQ2 and its possible metabolite, GA, in rat plasma using liquid chromatography with a tandem mass spectrometry (LC–MS/MS). After simple protein precipitation with acetonitrile including diclofenac (internal standard, IS), the analytes were chromatographed on a reversed phased column with a mobile phase of acetonitrile and water (60:40, v/v, including 0.1% formic acid). The ion transitions of the precursor to the product ion were principally protonated ion [M+H] + at m / z 313.2 → 160.6 for SG-HQ2, and deprotonated ions [M−H] − at m / z 168.7 → 124.9 for GA and 296.0 → 251.6 for the IS. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This method was successfully applied to a pharmacokinetic study of SG-HQ2 after intravenous administration in rats. [ABSTRACT FROM AUTHOR]

A fast, selective and sensitive procedure for quantitation of the camphor-based anti-influenza agent camphecene in whole rat blood was developed and validated using dried blood spots and LC–MS/MS. The method was validated according to recommendations of the FDA and EMA in terms of selectivity, linearity, accuracy, precision, recovery, matrix factor, stability, and carry-over. Sample preparation included spotting 20 μL of whole blood taken from the tail vein onto the paper, drying and extracting the analyte, followed by evaporation of the solvent and analysis of the residue. HPLC separations were run on a reversed-phase microcolumn; the time of analysis was less than 2 min. MS/MS detection was performed on a triple quadrupole mass-spectrometer using multiple reaction monitoring (MRM) mode. Transitions 196.4 → 122.2/153.3 and 152.2 → 93.1/107.2 were monitored for camphecene and 2-adamantylamine hydrochloride (internal standard), respectively. The intra- and inter-day precisions and accuracies, matrix factor, carry-over and recovery were within acceptable limits. Despite low extraction recovery (less than 2%), the sensitivity of the method was enough to detect the analyte in the concentration range 50–2500 ng/mL. The application of the method was shown in pharmacokinetic studies of camphecene in rats at a dose of 10 mg/kg. [ABSTRACT FROM AUTHOR]

It has been proved that the purine metabolic pathway has been implicated in various biological disorders including gout, diabetes, coronary heart diseases, and neurodegenerative diseases. The analysis of the purine metabolic pathway in organisms reveals important alterations under different physiological and pathological conditions, which contributes to the pathological study, diagnosis, and therapy of related diseases. In the present study, an ultra-high performance liquid chromatography with ultraviolet and tandem mass spectrometry (UHPLC-UV–MS/MS) method was developed for conducting the comprehensive analysis of the metabolite profiles of the purine pathway in rat plasma through a single analysis. The purine metabolites including adenosine-5′-monophosphate, guanosine-5′-monophosphate, adenosine, inosine, guanosine, inosine-5′-monophosphate, deoxyadenosine, deoxyguanosine, deoxyinosine, xanthine, hypoxanthine, and uric acid, were separated and quantified in the short running time of 10 min. After rapid chromatographic separation achieved by an Agilent Zorbax SB-Aq column, high concentration of uric acid and the remaining purine metabolites at lower levels were respectively detected by ultraviolet detector and triple quadruple mass spectrometry within a single analysis. The proposed method was validated by applying charcoal-stripped plasma as a matrix and it was proved to be linear ( R 2 > 0.982), accurate (with a relative error for accuracy < ± 15% and the relative standard deviation for intra- and inter-run precision <11%) and reproducible (with a matrix effect ranging between 86.49% and 111.44% with a maximum RSD of 8.69%). As a result, the method was successfully applied to the quantification of the endogenous purine metabolites in rat plasma. It was found that the concentration levels of the purine metabolites may keep a physiological balance as an integrated system in normal individuals and the concentration level of uric acid in rat plasma was 64 μM which was more than 200 times greater than the other purine metabolites. The established method and the measurement of the concentration of these purines in normal rat plasma may help the investigation of the action mechanisms between purine disorders and related diseases. [ABSTRACT FROM AUTHOR]

In the current work, a rapid, specific, sensitive and validated liquid chromatography tandem mass-spectrometric method was developed for the quantification of ponatinib (PNT) in human plasma and rat liver microsomes (RLMs) with its application to metabolic stability. Chromatographic separation of PNT and vandetanib (IS) were accomplished on Agilent eclipse plus C18 analytical column (50 mm × 2.1 mm, 1.8 μm particle size) maintained at 21±2°C. Flow rate was 0.25 mLmin-1 with run time of 4 min. Mobile phase consisted of solvent A (10 mM ammonium formate, pH adjusted to 4.1 with formic acid) and solvent B (acetonitrile). Ions were generated by electrospray (ESI) and multiple reaction monitoring (MRM) was used as basis for quantification. The results revealed a linear calibration curve in the range of 5–400 ngmL-1 (r2 ≥ 0.9998) with lower limit of quantification (LOQ) and lower limit of detection (LOD) of 4.66 and 1.53 ngmL-1 in plasma, 4.19 and 1.38 ngmL-1 in RLMs. The intra- and inter-day precision and accuracy in plasma ranged from1.06 to 2.54% and -1.48 to -0.17, respectively. Whereas in RLMs ranged from 0.97 to 2.31% and -1.65 to -0.3%. The developed procedure was applied for quantification of PNT in human plasma and RLMs for study metabolic stability of PNT. PNT disappeared rapidly in the 1st 10 minutes of RLM incubation and the disappearance plateaued out for the rest of the incubation. In vitro half-life (t1/2) was 6.26 min and intrinsic clearance (CLin) was 15.182± 0.477. [ABSTRACT FROM AUTHOR]

We established and validated a specific and sensitive analytical method for the determination of 1-vinyl-2-pyrrolidone (VP) as 1-vinyl-2-pyrrolidone-mercapturic acid (VPMA) in urine using an electrospray liquid chromatography tandem mass spectrometry (ESI-LC/MS/MS) column switching method. An online solid phase extraction (SPE) for sample cleanup was performed by column switching to a restricted access material and back-flushing to the analytical column. A Phenomenex Luna C8 column was used for sample separation (150 mm; ID 4,6 mm; 3 μm). D4-VPMA served as an isotope labeled internal standard and was detected in negative multiple-reaction monitoring (MRM) mode. The Limit of quantification (LOQ) for VPMA was 1.5 μg/L, the intra-day precision of three concentrations (2 μg/L, 75 μg/L and 400 μg/L) of spiked urine samples ranged from 2.7 to 7.3%, the inter-day precision from 3.4 to 14.4%. The accuracy ranged from 6.2 to 9.0%, for the intra-day experiments and from 0.3 to 6.9% for the inter-day experiments. The method was applied to urines of Sprague-Dawley rats exposed to VP as a proof of principle of VPMA as a potential biomarker. [ABSTRACT FROM AUTHOR]

Aromatase (ARO) is a cytochrome P450 enzyme that accounts for local estrogen production in the brain. The goal of this study was to develop a microsomal based assay to sensitively and reliably detect the low levels of ARO activity in different brain regions. Enzyme activity was detected based on the conversion of testosterone to estradiol. Quantity of estradiol was measured using ultra performance liquid chromatography–mass spectrometry. Detection was linear over a range of 2.5–200 pg/ml estradiol, and was reproducible with intra- and inter-assay coefficients of variation (CV) <15%. Estradiol production using isolated microsomes was linear with time up to 30 min as well as linearly related to amount of microsome. Substrate concentration curves revealed enzymatic kinetics (hippocampus: V max and K m : 0.57 pmol estradiol/h per mg microsome and 48.58 nM; amygdala: V max and K m : 1.69 pmol estradiol/h per mg microsome and 48.4 nM; preoptic area: V max and K m : 0.96 pmol estradiol/h per mg microsome and 44.31 nM) with testosterone used at a saturating concentration of 400 nM. Anastrozole treatment blocked ARO activity in hippocampal and ovarian microsomes, indicating that the assay is specific for ARO. Also, we showed that the distribution of the long form ARO mRNA (CYP19A1) in different regions of the brain is correlated with ARO activity, with highest levels in the amygdala, followed by preoptic area and hippocampus. In the frontal cortex, very little long form ARO mRNA, and little to no ARO activity, were detected. These findings demonstrate that the microsomal incubation (MIB) assay is a sensitive and reliable method for quantifying ARO activity in discrete brain regions. [ABSTRACT FROM AUTHOR]

A rapid and sensitive ultra-fast liquid chromatography tandem mass spectrometry method, followed by simple protein precipitation and solid-phase extraction, has been developed and validated for the quantitative determination of four azo dyes (Para red, Solvent yellow 2, Solvent red 1 and Sudan red 7B) in rat plasma using D5-Sudan I as the internal standard. The optimal separation was accomplished on an Agilent Eclipse Plus C18 column (100 ? 2.1 mm, 1.8 µm) with gradient elution using the mobile phase including acetonitrile and water (containing 0.1% formic acid). The flow rate was 0.45 mL/min. The detection was conducted by means of electrospray ionization mass spectrometry in positive ion mode with multiple reaction monitoring. The calibration curves showed good linearity, with correlation coefficients >0.998 for all of the analytes within the concentration range. The lower limits of quantification (LLOQs) of Para red, Solvent yellow 2, Solvent red 1 and Sudan red 7B in rat plasma were 1.0, 0.1, 0.1 and 0.1 µg/L, respectively. The intra- and interday relative standard deviations were ≤9.6 and ≥12.4%, respectively, and the accuracy was in the range of -5.8 to -9.5%. The average recoveries were between 81.49 and 118.65%, and the matrix effects were satisfactory in the biological matrices. The fully validated method has been successfully applied in measuring levels of the four azo dyes in rat plasma following oral administration of 20.0 mg/kg of analytes in rats, which was suitable for the pharmacokinetic studies of the azo dyes. [ABSTRACT FROM AUTHOR]

A rapid and sensitive bioassay based on liquid chromatography-tandem mass spectrometry (LC-MS-MS) has been developed and validated to measure arbutin in rat plasma. Sample preparation of plasma after the addition of indapamide as internal standard (IS) involved solid-phase extraction (SPE) on C18 cartridges. Reversed-phase chromatography using acetonitrile and 0.5% formic acid solution (pH 2.56) was used for separation in a run time of 4.0 min. The analytes were detected in the negative ion mode using selective reaction monitoring (SRM) of the transitions at m/z 271.2→107.8 for arbutin and 364.3→189.0 for indapamide. The method has the following performance characteristics: a reliable response range of 7.5-5250.0 ng/mL with correlation coefficients (r) of >0.995. The lower limit of quantitation (LLOQ) was 7.5 ng/mL. The intra- and inter-day precision and accuracy of the quality control (QC) samples at low, medium and high concentration levels showed ≤8.79% relative standard deviation (RSD) and −1.15 to 1.49% relative error (RE). The method was successfully applied to a pharmacokinetic study to measure arbutin in rats after extracts of Vaccinium vitis-idaea was orally administered. [ABSTRACT FROM AUTHOR]

An UPLC-MS/MS method for the quantification of indirubin in lithium heparinized rat plasma was developed and validated according to current international guidelines. Indirubin was extracted from rat plasma by using Waters Ostro™ pass-through sample preparation plates. The method was validated with a LLOQ of 5.00 ng/mL and an ULOQ of 500 ng/mL. The calibration curve was fitted by least-square quadratic regression, and a weighting factor of 1/X was applied. Recoveries of indirubin and I.S. were consistent and ≥75.5%. Stability studies demonstrated that indirubin was stable in lithium heparinized rat plasma for at least 3 freeze/thaw cycles, for 3 h at RT, for 96 h in the autosampler at 10 °C, and for 84 days when stored below −65 °C. Preliminary pharmacokinetic (PK) data were obtained from Sprague Dawley rats after intravenous administration of indirubin (2 mg/kg b.w.) and blood sampling up to 12 h after injection. PK parameters were determined by non-compartmental analysis. Indirubin had a half-life (t 1/2 ) of 35 min, and a relatively high clearance (CL) of 2.71 L/h/kg. [ABSTRACT FROM AUTHOR]

Ziyuglycoside I is one of the major active ingredients in Sanguisorba officinalis , a popular medicinal plant in China. In the present study, the metabolites of ziyuglycoside I in rat liver microsome and intestinal flora were identified and structurally characterized, and the metabolic rules were summed based on the LC–Q-TOF/MS system. Then, the metabolites in rat excreta samples were rapidly screened and identified according to the in vitro metabolic rules. Finally, ziyuglycoside I was incubated with fresh liver/lung/kidney/stomach homogenates to further explore the source of the metabolites and reveal the possible metabolic organs involved. Four metabolites in liver microsome were identified as M0-Glu, M0-CH 2 OH, M0-Glu + CH 3 , M0-Glu-Ara + CH 3 . In intestinal flora incubation system, 6 degradation products including M0-Glu-Ara + O, M0-Ara, M0-Glu-COOH, M0-Glu, M0-Glu-Ara + O and M0-Ara + H 2 O were tentatively identified by interpretation of their accurate MS 1 and MS 2 data. Fifteen metabolites in rat urine and feces were identified, and most of the metabolites were attributed to the transformation in liver microsome and intestinal flora. Specifically, more than a dozen of new metabolites were identified in rat fresh tissues, and ziyuglycoside II was confirmed as the major metabolite in rats. [ABSTRACT FROM AUTHOR]

A rapid, sensitive and selective ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) method has been developed for the simultaneous determination and pharmacokinetic investigation of Tetramethylpyrazine (TMP) and Ferulic acid (FA) in rat striatum. The method was validated over the concentration range of 1.15–505 ng/mL for TMP and 3.23–101 ng/mL for FA, with a lower limit of quantitation (LLOQ) of 1.15 ng/mL and 3.23 ng/mL, respectively. This method can be successfully applied in pharmacokinetic studies of TMP and FA in striatum of awake and anesthetic rats. The cerebral blood flow velocity (CBF) during middle cerebral artery occlusion (MCAO) was monitored by Laser speckle contrast imaging, to observe whether the compatibility of TMP and FA could improve CBF against cerebral ischemia/reperfusion (I/R) injury. Infarct volume was examined to evaluate severity of ischemic brain injury. The pharmacokinetic study indicated that T 1/2, C max, MRT and AUC 0-inf were changed after combined administration of TMP and FA, when compared with either drug alone both in awake and anesthetic groups. The pharmacodynamics results showed that co-administration of drugs could enhance the CBF during middle cerebral artery occlusion and reduced the infarct volume. Taken together, the compatibility treatment of TMP and FA might be a promising therapeutic strategy for ischemic stroke. Further study is required to optimize the compatibility proportion. [ABSTRACT FROM AUTHOR]

4-Methoxydiphenylmethane (4-MDM), a selective augmenter of Leukotriene A 4 Hydrolase (LTA 4 H), is a new anti-inflammatory compound for potential treatment of chronic obstructive pulmonary disease (COPD). Currently, there is no liquid chromatography tandem mass spectrometric (LC–MS/MS) method for the quantification of 4-MDM. A major barrier for developing the LC–MS/MS method is the inability of electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) to ionize 4-MDM due to its hydrophobicity and lack of any functional group for ionization. With the advent of atmospheric pressure photoionization (APPI) technique, many hydrophobic compounds have been demonstrated to ionize by charge transfer reactions. In this study, a highly sensitive ultrapressure liquid chromatography tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC–APPI-MS/MS) for the quantifications of 4-MDM in rat plasma has been developed and validated. 4-MDM was extracted from the plasma by solid phase extraction (SPE) and separated chromatographically using a reverse phase C 8 column. The photoionization (PI) was achieved by introducing anisole as a dopant to promote the reaction of charge transfer. The assay with a linear range of 5 (LLOQ)–400 ng mL −1 met the regulatory requirements for accuracy, precision and stability. The validated assay was employed to quantify the plasma concentrations of 4-MDM after an oral dosing in Sprague Dawley (SD) rats. [ABSTRACT FROM AUTHOR]

Compound feed is particularly vulnerable to multi-mycotoxin contamination. A method for the determination of 12 mycotoxins; enniatins A, A1, B, B1; aflatoxins B1, B2, G1, G2; OTA; ZEA; T-2 and HT-2 by liquid chromatography-tandem mass spectrometry has been developed and applied for the analysis of laboratory rat commercial feeds. The method trueness was checked by recovery assays at three different spiked levels (n = 9). Recoveries ranged from 73% to 112%, and the intra-day and inter-day precision were lower than 9% and 13%, respectively. Limits of quantitation were lower than 15 μg/kg. Twenty-seven laboratory rats feed samples showed multi-contamination by at least three up to six different mycotoxins. ENNs B and B1, followed by ZEA were the most prevalent mycotoxins. T-2, HT-2, and OTA were not detected. ZEA showed the highest concentration levels reaching 492 μg/kg. The results underline the importance of implementing mycotoxin regular surveillance programs for laboratory animal feeds. [ABSTRACT FROM PUBLISHER]

Phellodendrine, a quaternary ammonium alkaloid extracted from the dried bark of Phellodendrom chinensis Schneid and Phellodendrom amurense Rupr, has the effect of suppressing cellular immune response, reducing blood pressure and antinephritis. However, few investigations have been conducted for the pharmacokinetic study of phellodendrine. Thus, a rapid, simple and reliable ultra-high performance liquid chromatography–tandem quadrupole mass spectrometry (UHPLC–QQQ MS/MS) method has been established for quantification of phellodendrine in rat plasma and tissues by using magnoflorine as internal standard. The chromatographic separation was achieved on an Agilent ZORBAX SB-C18 column (4.6 mm × 50 mm, 1.8 μm) by gradient elution using 0.1% aqueous formic acid (A) and methanol (B). Triple quadrupole mass detection with multiple reaction monitoring mode was used to monitor the ion transitions, at m / z 342.20 → 192.20 for phellodendrine and m / z 342.20 → 58.20 for internal standard, respectively. The developed method was fully validated and successfully applied to the pharmacokinetics and tissue distribution study of phellodendrine after intravenous administration. The lower limits of quantification were 0.5 ng/mL for plasma samples, 2.5 ng/g for brain and 1 ng/g for other tested tissues. Precisions and accuracy values were within the Food and Drug Administration acceptance criteria, the recovery and matrix effects were between 87.8–113.5%. The area under the curve (AUC 0−t ) ranged from 15.58 to 57.41 mg/L min and Cmax were between 1.63–4.93 mg/L. The results showed that phellodendrine was eliminated in 120 min in plasma and most of tissues and the highest concentrations of phellodendrine were found in the kidney. This study may provide a basis for the further study of phellodendrine. [ABSTRACT FROM AUTHOR]

A rapid and specific LC-MS-MS method has been developed for simultaneous analysis of quercetin and naringenin in rat plasma. The method was applied to the pharmacokinetics studies of quercetin and naringenin after oral administration of Pollen Typhae extract. The samples were prepared by the protein precipitation method. The analysis was carried out on an ACQUITY UPLC™BEH C18 column with gradient elution using mobile phase, which included acetonitrile and water (containing 0.1% formic acid). The flow rate was 0.4 mL/min. All analytes including internal standard (IS) were monitored by selected reaction monitoring with an electrospray ionization source. Linear responses were obtained for quercetin ranging from 0.5 to 100 ng/mL and naringenin ranging from 5 to 1000 ng/mL. The intra- and interday precisions (RSD) were less than 10.78 and 11.20%. The extraction recovery of the analytes was acceptable. Stability studies showed that quercetin and naringenin were stable in the preparation and analytical process. The validated method was successfully used to determine the concentration-time profiles of quercetin and naringenin. [ABSTRACT FROM AUTHOR]

A rapid, sensitive and selective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) was developed and validated for the determination and pharmacokinetic investigation of apremilast in rat plasma. Sample preparation was accomplished through a simple one-step deproteinization procedure with 0.2 mL of acetonitrile to a 0.1 mL plasma sample. Plasma samples were separated by UPLC on an Acquity UPLC BEH C18 column using a mobile phase consisting of acetonitrile-0.1% formic acid in water with gradient elution. The total run timewas 3.0 min, and the elution of apremilast was at 1.27 min. The detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction-monitoring mode using the respective transitions m/z 461.3→257.1 for apremilast and m/z 237.2→194.2 for carbamazepine (internal standard). The calibration curve was linear over the range of 0.1-100 ng/mL with a lower limit of quantitation of 0.1 ng/mL. The mean recovery of apremilast in plasmawas in the range of 83.2-87.5%. Both intraday and interday precision were <9.6%. This method was successfully applied in the pharmacokinetic study after oral administration of 6.0 mg/kg apremilast in rats. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are organic chemicals that were traditionally produced and widely used in industry as mixtures and are presently formed as byproducts of pigment and dye manufacturing. They are known to persist and bioaccumulate in the environment. Some have been shown to induce liver cancer in rodents. Although the mechanism of the toxicity of PCBs is unknown, it has been shown that they increase oxidative stress, including lipid peroxidation. We hypothesized that oxidative stress-induced DNA damage could be a contributor for PCB carcinogenesis and analyzed several DNA adducts in female Sprague-Dawley rats exposed to 3,3',4,4',5-pentachlorobiphenyl (PCB 126), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), and a binary mixture (PCB 126 + 153) for 14, 31, and 53 wks. Eight adducts were measured to profile oxidative DNA lesions, including 8-oxo-deoxyguanosine (8-oxo-dG), 1,N 6-ethenodeoxyadenosine (1,N 6-edA), N ²,3-ethenoguanine (N ²,3-eG), 1,N ²-ethenodeoxyguanosine (1,N ²-edG), as well as malondialdehyde (M1dG), acrolein (AcrdG), crotonaldehyde (CrdG), and 4-hydroxynonenal-derived dG adducts (HNEdG) by LC-MS/MS analysis. Statistically significant increases were observed for 8-oxo-dG and 1,N 6-edA concentrations in hepatic DNA of female rats exposed to the binary mixture (1000 ng/kg/day + 1000 μg/kg/day) but not in rats exposed to PCB 126 (1000 ng/kg/day) or PCB 153 (1000 μg/kg/day) for 14 and 31 wks. However, exposure to PCB 126 (1000 ng/kg/day) for 53 wks significantly increased 8-oxo-dG, 1,N 6-edA, AcrdG, and M1dG. Exposure to PCB 153 (1000 μg/kg/day) for 53 wks increased 8-oxo-dG, and 1,N 6-edA. Exposure to the binary mixture for 53 wks increased 8-oxo-dG, 1,N 6-edA, AcrdG, 1,N ²-edG, and N ²,3-eG significantly above control groups. Increased hepatic oxidative DNA adducts following exposure to PCB 126, PCB 153, or the binary mixture shows that an increase in DNA damage may play an important role in hepatic toxicity and carcinogenesis in female Sprague-Dawley rats. [ABSTRACT FROM AUTHOR]

Tamoxifen (TAM) is a non-steroidal estrogen receptor antagonist that enhances erlotinib (ERL)-induced cytotoxicity in the treatment of NSCLC. ERL and TAM are metabolized by CYP3A4 enzymes. In addition, both drugs have the potential of altering the enzymatic activity through either inhibition (ERL) or induction (TAM). Thus it was expected that pharmacokinetics (PK) drug–drug interactions (DDIs) could be encountered following their co-administration. In this respect, a bioanalytical UPLC–MS/MS method has been developed and validated for the simultaneous determination of ERL and TAM in rat plasma samples, using ondansetron (OND) as an internal standard (IS). Plasma samples were prepared using mixed mode cationic solid phase extraction (SPE) STRATA™ −X-C 33 μm cartridges with good extraction recovery of both drugs from rat plasma (E r % from −13.92 to −3.32). The drugs were separated on a Waters BEH™ C18 column with an isocratic elution using a mobile phase composed of a mixture of acetonitrile and water, each with 0.15% formic acid, in the ratio of 80: 20, v/v. Quantitation was carried out using the positive ionization mode with multiple reaction monitoring (MRM) at m / z 394.20 > 278.04 (ERL), m / z 372.25 > 72.01 (TAM), and m / z 294.18 > 170.16 (OND). The method was fully validated as per the FDA guidelines over the concentration range of 0.2–50 ng/mL with very low lower limit of quantification (LLOQ) of 0.2 ng/mL for both ERL and TAM. The intra- and inter-day assay precision (in terms of relative standard deviation, RSD) and accuracy (in terms of percentage relative error, % E r ) were evaluated for both drugs and the calculated values evaluated at four different concentration levels were within the acceptable limits (<15%) for concentrations other than LLOQ and 20% for LLOQ. The method was successfully applied to the study of possible PK-DDI following the oral administration of ERL and TAM in a combination, compared to their single administration. [ABSTRACT FROM AUTHOR]

Gout is a common metabolic disorder caused by the deposition of monosodium urate crystals within joints. A new kind of xanthine oxidase inhibitor, WSJ-537, was developed as a potential drug. In order to investigate the pharmacokinetic behavior in vivo , a liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for determination the concentration of WSJ-537 in rat plasma was developed. After extraction by protein precipitation method with acetonitrile, the chromatographic separation was accomplished on a Venusil ASB C 18 column(2.1 mm × 50 mm, 3 mm)at a flow rate of 0.3 mL min −1 with the mobile phase consisting of acetonitrile-ammonium acetate (33:67, v/v ). An electrospray ionization (ESI) source was applied and operated in the positive ion mode. The plasma concentration was detected by multiple reactions monitoring (MRM) mode with the target fragment ions m / z 410.2 → m / z 368.1 for WSJ-537 and m / z 244.1 → m / z 185.0 for the IS. Good linearity was observed in the range of 20–800 ng mL −1 (r = 0.9947). The recovery of WSJ-537 in rats plasma was more than 85%. This method was suitable for pharmacokinetic studies after oral administration of 10 mg/kg WSJ-537 in rats. [ABSTRACT FROM AUTHOR]

Clinical studies suggest a link between depression and dysfunctional tryptophan (TRP) metabolism. Even though depression is twice as prevalent in women as men, the impact of the estrous cycle on TRP metabolism is not well-understood. Here we investigated 13 kynurenine and serotonin metabolites in female Flinders Sensitive Line (FSL) rats, a genetic rat model of depression. FSL rats and controls (Flinders Resistant Line rats), 12–20 weeks old, were subject to the forced swim test (FST), a commonly used measure of depression-like behavior. Open field was used to evaluate locomotor ability and agoraphobia. Subsequently, plasma and hemispheres were collected and analyzed for their content of TRP metabolites using liquid chromatography-tandem mass spectrometry. Vaginal saline lavages were obtained daily for ⩾2 cycles. To estimate the effects of sex and FST we included plasma from unhandled, naïve male FSL and FRL rats. Female FSL rats showed a depression-like phenotype with increased immobility in the FST, not confounded by anxiety. In the brain, 3-hydroxykynurenine was increased whereas anthranilate and 5-hydroxytryptophan were decreased. In plasma, anthranilate and quinolinate levels were lower in FSL rats compared to the control line, independent of sex and FST. The estrous cycle neither impacted behavior nor TRP metabolite levels in the FSL rat. In conclusion, the female FSL rat is an interesting preclinical model of depression with altered TRP metabolism, independent of the estrous cycle. The status of the pathway in brain was not reflected in the plasma, which may indicate that an inherent local, cerebral regulation of TRP metabolism occurs. [ABSTRACT FROM AUTHOR]

N-Acetylcysteine (NAC) is the N-acetyl derivative of the amino acid L-cysteine and is extensively used as a medicine to treat a variety of diseases. High-throughput ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) method has been developed for the quantitative assessment of N-acetyl-L-cysteine. The method was further applied to study the distribution of the intraperitoneal injected drug into different tissues and plasma of Wistar rats, including liver, kidney, heart, lungs and spleen. The drug was having highest concentration in plasma and liver followed by kidney, lungs, heart and spleen. Method validation studies suggested being linear in the range of 1-15 µg mL-1 for liver, kidney, heart, lungs and spleen and 1-120 µg mL-1 for the plasma. The limit of detection and limit of quantitation were found to be 0.20 and 0.66 ug mL-1, respectively. The recovery studies suggested that in all the cases, the obtained recovery was in the range of 98.51-101.88%. Our analyses provide a validated UPLC-MS method for the determination of NAC and its successful application for the analysis in plasma and tissues obtained from Wistar rats. [ABSTRACT FROM AUTHOR]

We used mass spectrometry to quantitate production of angiotensinogen metabolites in renal artery of 3- and 7-monthold Wistar-Kyoto (WKY) and Spontaneously Hypertensive Rats (SHR). Tissue fragments were incubated for 15 min in oxygenated buffer, with added angiotensin I. Concentrations of angiotensins I (ANG I), II (ANG II), III (ANG III), IV (ANG IV), angiotensin (1-9) [ANG (1-9)], angiotensin (1-7) [ANG (1-7)], and angiotensin (1-5) [ANG (1-5)], excreted into the buffer during experiment, were measured using liquid chromatographymass spectrometry (LC/MS) and expressed per mg of dry tissue. Effects of pretreatment with 10 μM perindoprilat on the production of ANG I metabolites were quantitated. Background production of any of ANG I metabolites differed neither between WKY and SHR rats nor between 3- and 7-month-old rats. Perindoprilat pretreatment of renal arteries resulted, as expected, in decrease of ANG II production. However, renal arteries of 7-month-old SHR rats were resistant to ACE inhibitor and did not change ANG II production in response to perindoprilat. In renal arteries, taken from 3-month-old rats, pretreated with perindoprilat, incubation with ANG I, resulted in the level of ANG (1-9) significantly higher in SHR than WKY rats. Our conclusion is that in SHR rats, sensitivity of renal artery ACE to perindoprilat inhibition changes with age. [ABSTRACT FROM AUTHOR]