Advanced UPLC-MS/MS Method for the Quantification of SIPI6398 in Rat Plasma and Its Pharmacokinetic Characterization.

SIPI6398 is a novel anti-schizophrenia agent with a new mechanism of action and demonstrates better target selectivity and safety compared to its competitors. However, few in vivo studies on the pharmacokinetics and bioavailability of SIPI6398 have been performed. A rapid and simple ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) approach was developed for accurate quantification of SIPI6398 in rat plasma. A simple protein precipitation of acetonitrile-methanol (9 : 1, v/v) was used to treat plasma. Chromatography was performed on a UPLC HSS T3 column (50 mm × 2.1 mm, 1.8 µm) at a flow rate of 0.4 ml/min. The mobile phase consisted of acetonitrile-water (with 0.1% formic acid) and gradient elution was used, and the elution time was 4 minutes. Quantitative analysis was performed using electrospray ionization (ESI) in positive ion detection mode with multiple reaction monitoring (MRM) mode. To evaluate the pharmacokinetics and bioavailability, SIPI6398 was administered to rats in two different ways: oral (4 mg/kg) and intravenous (2 mg/kg) administration. The calibration curve for the UPLC-MS/MS approach shows excellent linearity in the range of 1-2000 ng/mL with an r value above 0.99. The precision, accuracy, recovery, matrix effect, and stability results all meet the criteria established for biological analytical methods. The UPLC-MS/MS method was successfully applied it to pharmacokinetics study of SIPI6398. The bioavailability of SIPI6398 was calculated to be 13.2%. These studies have the potential to contribute towards a more comprehensive comprehension of the pharmacokinetics and bioavailability of SIPI6398.

Pharmacokinetics of Ziyuglycoside I and Ziyuglycoside II in Rat Plasma by UPLC-MS/MS.

Ziyuglycoside I and ziyuglycoside II are important active components of Sanguisorba officinalis L., which have excellent pharmacological effects, such as antioxidant and anticancer effects. However, the bioavailability of ziyuglycoside I and ziyuglycoside II has not been reported. This work aims to establish a UPLC-MS/MS method to study the pharmacokinetics of ziyuglycoside I and ziyuglycoside II in rats under different administration routes (intragastric and intravenous administration) and to calculate the bioavailability. The concentration of ziyuglycoside I and ziyuglycoside II in rat plasma in the range of 2-2000 ng/mL showed a good linear relationship (r > 0.99). The intra-day accuracies of ziyuglycoside I and ziyuglycoside II ranged from 87% to 110%, and the inter-day accuracies ranged from 97% to 109%. The intra-day precision was less than 15% and the inter-day precision was less than 14%. The matrix effects ranged from 88% to 113%. The recoveries were all above 84%. The developed UPLC-MS/MS method for the determination of ziyuglycoside I and ziyuglycoside II in rat plasma was applied to pharmacokinetics. The bioavailability of ziyuglycoside I and ziyuglycoside II was measured at 2.6% and 4.6%, respectively.

[Characteristics and Source Analysis of Carbonaceous Aerosols in PM2.5 in Huaxi District, Guiyang].

Carbonaceous aerosol, as an important component of atmospheric aerosol, has a significant impact on atmospheric environmental quality, human health, and global climate change. To investigate the characteristics and sources of carbonaceous aerosol in atmospheric fine particulate matter (PM2.5) in Huaxi District of Guiyang, an in-situ observational study was conducted during different seasons in 2020, and the carbonaceous components of PM2.5 were measured using a thermal-optical carbon analyzer (DRI Model 2015). The results of the study showed that the average concentrations of PM2.5, total carbonaceous aerosol (TCA), organic carbon (OC), secondary organic carbon (SOC), and elemental carbon (EC) concentrations during the observation period were (39.7±22.3), (14.1±7.2), (7.6±3.9), (4.4±2.6), and (2.0±1.0) µg·m-3, respectively, and the mean value of OC/EC was (3.9±0.8). ρ(PM2.5), ρ(TCA), ρ(OC), ρ(SOC), and ρ(EC) showed a seasonal variation pattern with the highest in winter [(52.6±28.6), (17.0±9.6), (9.1±5.2), (6.1±3.9), and (2.4±1.2) µg·m-3, respectively] and the lowest in summer [(25.1±7.1), (11.6±3.6), (6.3±1.9), (3.7±1.2), and (1.6±0.6) µg·m-3, respectively]. The seasonal variation in OC/EC showed summer (4.2±0.8) > winter (3.8±0.9) > autumn (3.8±0.5) > spring (3.7±0.9), indicating the presence of SOC generation in all seasons in Huaxi District. SOC showed a significant correlation with OC (R2 =0.9), and the SOC concentration tended to increase with the increase in atmospheric oxidation. OC showed a good correlation with EC in all seasons, with the highest in autumn (R2 =0.9) and lower correlations in the other three seasons (R2 ranged from 0.74 to 0.75), indicating a common source. According to OC/EC ratio range, it was preliminarily determined that carbonaceous aerosol came from vehicle exhaust emissions, coal burning emissions, and biomass combustion emissions. In order to further quantify the contribution of major emission sources to carbonaceous aerosol, the results of this study using PMF to analyze the sources of carbonaceous aerosol showed that the main sources of carbonaceous aerosol in Huaxi District of Guiyang were coal combustion sources (29.3%), motor vehicle emission sources (21.5%), and biomass combustion sources (49.2%).

Development of an ultra-high-performance liquid chromatography-tandem mass spectrometry method for the simultaneous determination of crassicauline A, fuziline, karacoline, and songorine in rat plasma and application in their pharmacokinetics.

In this paper, an ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for quantifying the levels of crassicauline A, fuziline, karacoline, and songorine in rat plasma. After processing the rat plasma, the proteins in the plasma were separated by extracting the analytes with acetonitrile-methanol (9:1, v/v). The chromatographic column used was the UPLC HSS T3 column, and the mobile phase (methanol-water with 0.1% formic acid) under a gradient elution profile was used to separate the four compounds, with elution times for each analyte being less than 5 min. Electrospray ionization in positive-ion mode and operating in multiple reaction monitoring mode was used for quantitative analysis. Crassicauline A, fuziline, karacoline, and songorine were administered to 48 rats (n = 6 per group) orally (5 mg/kg) and intravenously (0.5 mg/kg). The standard curves demonstrated excellent linearity in the range of 1-2500 ng/mL, wherein all r values were greater than 0.99. The UPLC-MS/MS method for the determination of crassicauline A, fuziline, karacoline, and songorine in rat plasma was successfully applied in determining their pharmacokinetics parameters, from which their oral bioavailabilities were calculated to be 18.7%, 4.3%, 6.0%, and 8.4%, respectively.

Abnormalities of serum lipid metabolism in patients with acute paraquat poisoning caused by ferroptosis.

As the mechanism of paraquat (PQ) poisoning is still not fully elucidated, and no specific treatment has been developed in medical practice, the management of PQ poisoning continues to present a medical challenge. In this study, the objective was to investigate the early metabolic changes in serum metabolism and identify the key metabolic pathways involved in patients with PQ poisoning. Quantitative analysis was conducted to determine the relevant metabolites. Additionally, experiments were carried out in both plasma and cell to elucidate the mechanisms underlying metabolic disorder and cell death in PQ poisoning. The study found that polyunsaturated fatty acids (PUFAs) and their metabolites, such as arachidonic acid (AA) and hydroxy eicosatetraenoic acids (HETEs), were significantly increased by non-enzymatic oxidative reaction. Reactive oxygen species (ROS) production increased rapidly at 2 h after PQ poisoning, followed by an increase in PUFAs at 12 h, and intracellular glutathione, cysteine (Cys), and Fe2+ at 24 h. However, at 36 h later, intracellular glutathione and Cys decreased, HETEs increased, and the expression of SLC7A11 and glutathione peroxidase 4 (GPX4) decreased. Ultrastructural examination revealed the absence of mitochondrial cristae. Deferoxamine was found to alleviate lipid oxidation, and increase the viability of PQ toxic cells in the low dose. In conclusion, unsaturated fatty acids metabolism was the key metabolic pathways in PQ poisoning. PQ caused cell death through the induction of ferroptosis. Inhibition of ferroptosis could be a novel strategy for the treatment of PQ poisoning.

A polymeric nitrogen N[Formula: see text]-N[Formula: see text] system with enhanced stability at low pressure.

Postulated in 1992 and synthesized in 2004 above 2000 K and 110 GPa, the singly-bonded nitrogen cubic gauche crystal (cg-PN) is still considered to be the ultimate high energy density material (HEDM). The search however has continued for a method to synthesize cg-PN at more ambient conditions or find HEDMs which can be synthesized at lower pressure and temperature. Here, using ab initio evolutionary crystal prediction techniques, a simpler nitrogen-based molecular crystal consisting of N[Formula: see text] and N[Formula: see text] molecules is revealed to be a more favorable polynitrogen at lower pressures. The energetic gain of  534 meV/atom over cg-PN and  138 meV/atom over the N[Formula: see text] molecular crystal at zero pressure makes the N[Formula: see text]-N[Formula: see text] system more appealing. Dynamical and mechanical stabilities are investigated at 5 and 0 GPa, and vibrational frequencies are assessed for its Raman and IR spectra. The prospects of an experimental synthesis of the N[Formula: see text]-N[Formula: see text] polymeric system compared to cg-PN is higher because the C[Formula: see text] symmetry of N[Formula: see text] within this crystal would be easier to target from the readily available N[Formula: see text] azides and the observed N[Formula: see text] and N[Formula: see text] radicals.

Determination of isoscoparin in mouse blood using UPLC-MS/MS and its pharmacokinetics.

This study developed a UPLC-MS/MS method to detect isoscoparin in mouse blood, determined the pharmacokinetics of isoscoparin in mice after intravenous (5 mg/kg) and intragastric (20 mg/kg) administration, and calculated the absolute bioavailability. A HSS T3 column was used for separation, and the column temperature was set at 40°C. The mobile phases were acetonitrile and 0.1% formic acid, and the gradient elution procedure was used. The blood sample was treated with protein precipitant with acetonitrile-methanol (9:1, v/v). Multiple reaction monitoring mode was used for quantitative analysis in electrospray positive-ion mode. It showed a good linear relationship in the range of 1-4000 ng/mL (r > 0.998); the intra-day and inter-day precision was <12%, and the accuracy was 86-112%. The recovery was >68%, and the matrix effect was 86-90%. The half-life of isoscoparin was relatively short in mice, and the bioavailability was 2.6%. The developed UPLC-MS/MS method was rapid, sensitive, and suitable for the pharmacokinetics of isoscoparin in mice.

Development of a UPLC-MS/MS method for the determination of narciclasine and 7-deoxynarciclasine in mouse blood and its application in pharmacokinetics.

In this study, we used ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to measure the concentration of narciclasine and 7-deoxynarciclasine in mouse blood after intravenous (i.v.) and oral administration (p.o.), and we used this method to investigate their pharmacokinetics profiles in mice. Chromatographic separation of the analytes was achieved using a UPLC HSS T3 column (2.1 mm × 100 mm, 1.8 µm) with a mobile phase consisting of acetonitrile-water (0.1% formic acid) by gradient elution. Electrospray ionization (ESI positive-ion mode)-tandem mass spectrometry in multiple reaction monitoring (MRM) mode was employed for quantitative analysis of the analytes in mouse blood samples. Twelve mice were administered narciclasine and 7-deoxynarciclasine (2 mg/kg) intravenously (iv), while the other twelve mice were administered narciclasine and 7-deoxynarciclasine (10 mg/kg) orally. The mouse blood was withdrawn from the caudal vein to be processed, after which the blood was analyzed by UPLC-MS/MS, and the corresponding data were fitted using the Drug and Statistics (DAS) software. Standard curves of narciclasine and 7-deoxynarciclasine were generated over the concentration range of 5-5000 ng/mL. The intra-day accuracy of narciclasine and 7-deoxynarciclasine was 90-105%, and the corresponding inter-day accuracy was 87-108%. The intra-day precision was less than 13%, while the inter-day precision was less than 14%. Matrix effects were also observed (between 94% and 104%), and the recovery calculated was higher than 70%. The developed and validated UPLC-MS/MS method was then successfully applied in determining the mouse pharmacokinetics of narciclasine and 7-deoxynarciclasine. From this, thebioavailabilityofnarciclasine and 7-deoxynarciclasinewasdetermined to be 10.3%and35.4%, respectively.

Development and Validation of a UPLC-MS/MS Method for the Quantitative Determination and Pharmacokinetic Analysis of Cirsimarin in Rat Plasma.

Cirsimarin is a bioactive antilipogenic flavonoid isolated from the cotyledons of Abrus precatorius and represents one of the most abundant flavonoids present in this plant species. Cirsimarin exhibits excellent antioxidant, lipolysis, and other biological properties; it can effectively trigger lipid movement and demonstrates antiobesity effects. In this work, an ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of cirsimarin in rat plasma after intravenous administration. A standard curve of cirsimarin in blank rat plasma was generated over the concentration range of 1-3000 ng/mL. Six rats were administered cirsimarin intravenously (1 mg/kg). The method only required 50 µL of plasma for sample preparation, and the plasma proteins were precipitated with acetonitrile to pretreat the plasma sample. The precisions of cirsimarin in rat plasma were less than 14%, while the accuracies varied between 92.5% and 107.3%. In addition, the matrix effect varied between 103.6% and 107.4%, while the recoveries were greater than 84.2%. This UPLC-MS/MS method was then applied in measuring the pharmacokinetics of cirsimarin in rats. The AUC(0-t) values of cirsimarin from the pharmacokinetic analysis were 1068.2 ± 359.2 ng/mL·h for intravenous administration. The half-life (t 1/2) was 1.1 ± 0.4 h (intravenous), indicating that the metabolism of the compound was quick in the rats. Exploring the pharmacokinetics of cirsimarin in vivo can help better understand its metabolism.

Pharmacokinetics of yunaconitine and indaconitine in mouse blood by UPLC-MS/MS.

Yunaconitine and indaconitine are active ingredients from the rhizomes of Aconitum plants. In this study, an ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed to measure the concentrations of the yunaconitine and indaconitine in mouse blood, and the method was applied in measuring the pharmacokinetics of the two alkaloids after oral and intravenous administration. A UPLC HSS T3 column (2.1 mm × 100 mm, 1.8 µm particle size) was used for chromatographic separation by gradient elution using acetonitrile-water (0.1% formic acid) as the mobile phase at a flow rate of 0.4 mL/min. Multiple reaction monitoring (MRM) mode and electrospray ionization (ESI) (positive-ion mode) were used to monitor the transitions of each analyte by tandem mass spectrometry for quantitative analysis. Yunaconitine and indaconitine were administered to the mice orally at 2 mg/kg and intravenously at 0.05 mg/kg. Blood was collected at various time intervals, and the blood samples were processed after collection and analyzed by UPLC-MS/MS. The standard curve generated for each analyte was linear over the concentration range of 0.5-500 ng/mL. The intra-day and inter-day accuracy of yunaconitine and indaconitine were 90%-103% and 86%-106%, respectively, and the precision (RSD, %) was less than 15% for both intra-day and inter-day measurements. The matrix effect ranged from 96% to 109%, and the recovery was higher than 72%. The UPLC-MS/MS method developed herein was successfully applied to measuring the pharmacokinetic parameters of yunaconitine and indaconitine in mice after intravenous and oral administration. The bioavailability of yunaconitine and indaconitine were 27.4% and 25.8%, respectively.

A practical way to enhance the synthesis of N8- from an N3- precursor, studied by both computational and experimental methods.

Polymeric nitrogen (PN) belongs to a general family of materials containing all-nitrogen molecules or clusters. Although it is rare and challenging to synthesize PN members, they are attracting increasing scientific attention due to their high energy storage capacity and possible use as a green catalyst. A few theoretical calculations predicted the possible PN phases from N2 gas, but they all require extremely high pressures and temperatures to synthesize. In this work, a practical way to synthesize N8 polymeric nitrogen from an N3- precursor is elucidated using density functional theory calculations. The detailed mechanism, , is determined. The calculated energy barriers indicate that the first step is the rate-limiting step. This result guides us to rationally synthesize N8 under UV (254 nm) irradiation, chosen based on the calculated absorption spectrum for the azide anion. As expected, UV irradiation enhances N8 yields by nearly four times. This provides an interesting route to the scalable synthesis of high energy density N8 compounds.

Pharmacokinetics of 10-Hydroxy Mesaconitine in Rat Plasma by Ultra-Performance Liquid Chromatography-Tandem Quadrupole Mass Spectrometry.

Mesaconitine is the predominant active ingredient in Aconitum carmichaelii Debx. The compound 10-hydroxy mesaconitine is one known metabolite of mesaconitine and is toxic. In order to better understand its pharmacokinetics, UPLC-MS/MS was used in this paper to measure the concentration of 10-hydroxy mesaconitine in the plasma of rats after oral (5 mg/kg) and intravenous (0.1 mg/kg) administration of 10-hydroxy mesaconitine. The concentrations of 10-hydroxy mesaconitine in rat plasma measured in the standard curve covered the range of 0.3-60 ng/mL. The intraday and interday precisions of the samples of 10-hydroxy mesaconitine in rat plasma were lower than 15%. In addition, the accuracies ranged between 96.0% and 109.3%, the matrix effects ranged between 88.9% and 98.1%, and the recoveries were all higher than 79.1%. The AUC(0 - t) values were 23.6 ± 5.9 and 207.6 ± 72.9 ng/mL·h for intravenous and oral administration, respectively, and the bioavailability of 10-hydroxy mesaconitine was 17.6%. Lastly, t 1/2 was 1.3 ± 0.6 h and 3.1 ± 0.4 h for intravenous and oral administration, respectively.

Predicting the crystal structure of [Formula: see text] high energy density material using ab initio evolutionary algorithms.

[Formula: see text] is the first successfully synthesized salt that has a polymeric nitrogen moeity ([Formula: see text]). Although 12 other [Formula: see text] salts followed, with [Formula: see text] and [Formula: see text] being the most stable, the crystal structure of [Formula: see text] remains unknown. Currently, it is impossible to experimentally determine the structures of [Formula: see text] due to its marginal stability and explosive nature. Here, following an ab initio evolutionary prediction and using only the stoichiometry of [Formula: see text] as a starting point, we were able to reveal the crystal structure of this high energy density material (HEDM). The [Formula: see text] symmetry of the [Formula: see text] cation, as suggested from earlier investigations, is confirmed to be the symmetry adopted by this polymeric nitrogen within the crystal. This result gave full confidence in the validity of this crystal prediction approach. While stability of the [Formula: see text] within the crystal is found to be driven by electronic considerations, the marginal stability of this HEDM is found to be related to a partial softening of its phonon modes.

Development of a simple and rapid UPLC-MS/MS method for determination of 8-deacetyl-yunaconitine in rat plasma and its application to pharmacokinetics.

In this paper, UPLC-MS/MS was used to determine 8-deacetyl-yunaconitine in the plasma of rats after oral and intravenous administration. Six rats were orally (po) administered 8-deacetyl-yunaconitine (5 mg/kg), while another six rats were intravenously (iv) administered the drug (0.1 mg/kg). A standard curve of known concentrations of 8-deacetyl-yunaconitine in rat plasma was generated over the range of 0.3-600 ng/mL. The intra-day and inter-day precision of 8-deacetyl-yunaconitine in rat plasma was lower than 15 %, while the accuracy ranged between 97.7 % and 105.5 %. In addition, the matrix effect ranged between 95.3 % and 105.6 %, while the recovery was greater than 82.8 %. This determined method was then applied in measuring the pharmacokinetics of 8-deacetyl-yunaconitine in rats. The AUC(0-t) values were 73.0 ± 24.6 and 1770.0 ± 530.6 ng/mL h for intravenous and oral administration, respectively, and the bioavailability was 48.5 %. The half-life (t1/2) was determined to be 4.5 ± 1.7 h and 3.2 ± 0.7 h for intravenous and oral administration, respectively, indicating that the metabolism of the xenobiotic was quick in the rats.

Simultaneous Determination of Six Uncaria Alkaloids in Mouse Blood by UPLC-MS/MS and Its Application in Pharmacokinetics and Bioavailability.

A specific ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed for the simultaneous determination of six Uncaria alkaloids in mouse blood with midazolam as the internal standard (IS). Only 20 µL blood was needed for sample preparation, and the protein was precipitated with acetonitrile. The UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 µm) was used for chromatographic separation. The mobile phase consisted of 0.1% formic acid and acetonitrile with gradient elution within 5.5 min. Multiple reaction monitoring (MRM) and the positive electrospray ionization model were used for quantitative analysis. The accuracy of the UPLC-MS/MS method ranged from 86.5% to 110.4%. The precision for intraday and interday was ≤15% each. The mean recovery and the matrix effects were found to be 64.4-86.8% and 94.1-109.4%, respectively. The calibration curves in blood were linear in the range of 1-1000 ng/mL with a favorable correlation coefficient (r 2) of 0.995. The pharmacokinetic results showed that six Uncaria alkaloids metabolized rapidly in mice with a half-life between 0.6 h and 4.4 h. The bioavailability of corynoxeine, isocorynoxeine, rhynchophylline, isorhynchophylline, hirsutine, and hirsuteine was 27.3%, 32.7%, 49.4%, 29.5%, 68.9%, and 51.0%, respectively, which showed satisfactory oral absorption of each alkaloid.

Toxicokinetics of 11 Gelsemium Alkaloids in Rats by UPLC-MS/MS.

Gelsemium elegans (Gardn. & Champ.) Benth. is a plant belonging to the genus Gelsemium (family Gelsemiaceae), and its main components are alkaloids. It is a Chinese traditional medicinal plant and notoriously known as a highly toxic medicine. However, a method has not yet been found for the simultaneous detection of 11 Gelsemium alkaloids in rat plasma, and the toxicokinetics of 11 Gelsemium alkaloids after intravenous administration has not been reported. In this work, we have developed a sensitive and rapid method of ultraperformance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) for the detection of 11 Gelsemium alkaloids in rat plasma. The toxicokinetic behavior was also investigated, so as to provide a reference of the scientific properties of Gelsemium elegans and improve the efficacy and safety of drugs. Sixty-six Sprague-Dawley rats were randomly divided into 11 groups, six rats in each group. Each group was intravenously given one alkaloid (0.1 mg/kg), respectively. A Waters UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 µm) was used for chromatographic separation. Methanol and water (containing 0.1% formic acid) were used for the mobile phase with gradient elution. Multiple reactions were monitored, and positive electrospray ionization was used for quantitative analysis. The precision was less than 16%, and the accuracy was between 86.9% and 113.2%. The extraction efficiency was better than 75.8%, and the matrix effects ranged from 88.5% to 107.8%. The calibration curves were in the range of 0.1-200 ng/mL, with a correlation coefficient (R 2) greater than 0.995. The UPLC-MS/MS method was successfully applied to the toxicokinetics of 11 Gelsemium alkaloids in rats after intravenous administration (0.1 mg/kg for each alkaloid). The results of the toxicokinetics provide a basis for the pharmacology and toxicology of Gelsemium alkaloids and scientific evidence for the clinical use of Gelsemium alkaloids.

Simultaneous Determination of Ropivacaine and 3-Hydroxy Ropivacaine in Cerebrospinal Fluid by UPLC-MS/MS.

In this paper, a UPLC-MS/MS method was developed for the determination of ropivacaine and its metabolite 3-hydroxy ropivacaine in cerebrospinal fluid. The cerebrospinal fluid was processed by ethyl acetate liquid-liquid extraction. The multiple reaction monitoring (MRM) mode was used for quantitative analysis by monitoring the transitions of m/z 275.3 → 126.2 for ropivacaine, m/z 291.0 → 126.0 for 3-hydroxy ropivacaine, and m/z 290.2 → 198.2 for the internal standard. Standard curves for ropivacaine and 3-hydroxy ropivacaine in cerebrospinal fluid were conducted over the concentration range of 0.2-2000 ng/mL, demonstrating excellent linearity, and the lower limit of quantification was 0.2 ng/mL. The intraday precision of ropivacaine and 3-hydroxy ropivacaine was less than 11%, while the interday precision was less than 7%. The accuracy ranged between 87% and 107%, the average extraction efficiency was higher than 79%, and the matrix effect was between 89% and 98%. The developed method was then applied to a case of suspected poisoning of ropivacaine.

Bioavailability and Pharmacokinetics of Anisatin in Mouse Blood by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry.

BACKGROUND: Anisatin is a neurotoxic sesquiterpene dilactone wildly found in plants of the family Illiciaceae. Due to morphological similarities among Illiciaceae fruits, fatal poisonings are frequent. OBJECTIVE: This study is aimed at developing a rapid, simple ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to determine anisatin's bioavailability in mouse blood and the method's application to pharmacokinetics. METHODS: Blood samples were preprocessed by protein precipitation using acetonitrile. Salicin (internal standard, IS) and anisatin were gradient-eluted by a mobile phase of methanol and water (0.1% formic acid) in a UPLC BEH C18 column. This step involved using an electrospray ionization source of anisatin at a mass-to-charge ratio (m/z) of 327.1 → 127.0 and IS at m/z 285.1 → 122.9 in the negative ion mode with multiple reaction monitoring. RESULTS: The calibration curve ranged from 1 to 2000 ng/ml (r > 0.995), with the method's accuracy ranging from 86.3% to 106.9%. Intraday and interday precision were lower than 14%, and the matrix effect was between 93.9% and 103.3%. The recovery rate was higher than 67.2%. CONCLUSIONS: The developed UPLC-MS/MS method was successfully used for a pharmacokinetic study of oral (1 mg/kg) and intravenous (0.5 mg/kg) administration of anisatin to mice-the absolute bioavailability of anisatin in the mouse blood was 22.6%.

Metabolic and transcriptional changes in seminal plasma of asthenozoospermia patients.

This study was designed to investigate the metabolic and transcriptional alterations in seminal fluid caused by asthenozoospermia (AS). To address these issues, a method of metabonomics based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and real-time quantitative PCR (RT-qPCR) was performed to identify some crucial biomarkers and transcription levels of the enzymes in seminal fluid. Seminal fluid samples were collected from 87 AS patients and 73 healthy males with normozoospermia. The quantitative analysis by UPLC-MS/MS showed that 19 metabolites in seminal plasma were associated with AS, and they were involved in several metabolic pathways, such as energy metabolism, purine metabolism, methionine cycle, and branched chain amino acid metabolism. Among these metabolites, the levels of citric acid, malic acid, succinic acid, and pyruvic acid, which are related to energy metabolism, were collectively reduced in the AS group, whereas the lactic acid level was enhanced. These results indicated that lesser energy source (adenosine triphosphate) was produced through the anaerobic glycolysis pathway rather than via aerobic catabolism of suger and tricarboxylic acid cycle, resulting in reduced power of sperms. Meanwhile, partial least squares discriminant analysis showed significant differences in metabolic profiles between the AS and control groups. In addition, RT-qPCR results revealed that the expression levels of four genes encoding fructokinase citrate synthase, succinate dehydrogenase, and spermine synthase, which were related to energy metabolism, were decreased in the AS group. The 23 descriptors with differential expression in AS may be valuable for the diagnosis and sequential study on AS. These results will help highlight the role of sperm inactivity in AS pathogenesis.

Quantitative determination of talatisamine and its pharmacokinetics and bioavailability in mouse plasma by UPLC-MS/MS.

Talatisamine, as the efficacy ingredient of Aconitum, was known as a novel specific blocker for the delayed rectifier K+ channels in rat hippocampal neurons. In this study, a rapid, selective and reproducible UPLC-MS/MS separation method was established and fully validated for the quantitative determination of talatisamine levels in ICR (Institute of Cancer Research) mouse blood. A total of 24 healthy male ICR mice were divided into four groups that was administered talatisamine via intravenous at a dose of 1 mg/kg and oral administration of three doses (2, 4, 8 mg/kg). All blood samples were protein precipitate by using acetonitrile with an internal standard (IS) deltaline. The effective chromatographic separation was carried out through an UPLC BEH C18 analytical column (2.1 mm × 50 mm, 1.7 µm) with an initial mobile phase that consisted of acetonitrile and 10 mmol/L ammonium acetate aqueous solution (containing 0.1% formic acid) with a gradient elution pumped at a flow rate of 0.4 mL/min. Also, an electrospray ionization (ESI) was applied to quantify the talatisamine in the positive ions mode. The method validation demonstrated good linearity over the range of 1-1000 ng/mL (r2 ≥ 0.9993) for talatisamine in mouse blood with a lower limit of quantification (LLOQ) at 1 ng/mL. The accuracy values of the method were within 89.4% to 113.3%, and the matrix effects were between 103.2% and 106.3%. The mean extraction recoveries for talatisamine obtained from four concentrations of QC blood samples were exceeded 71.7%, and the relative standard deviation (RSD) both of intra- and inter-day precision values for replicate quality control samples did not exceed 15% respectively for all analytes during the assay validation. This method was successfully applied to the evaluation of the pharmacokinetic of talatisamine, regardless of intragastric or intravenous administration in mice. Based on the pharmacokinetics data, the bioavailability of talatisamine in mice was >65.0% after oral administration, exhibiting an excellent oral absorption.