N-Nitrosamine formation from chloramination of two common ionic liquids

Ionic liquids (ILs) are a class of solvents increasingly used as "green chemicals." Widespread applications of ILs have led to concerns about their accidental entry to the environment. ILs have been assessed for some environmental impacts; however, little has been done to characterize their potential impacts on drinking water if ILs accidentally enter surface water. IL cations are often aromatic or alkyl quaternary amines that resemble structures of previously confirmed N-nitrosamine (NA) precursors. Therefore, this study has evaluated two common ILs, 1-ethyl-3-methylimidazolium bromide (EMImBr) and 1-ethyl-1-methylpyrrolidinium bromide (EMPyrBr), for their NA formation potential. Each IL species was reacted with pre-formed monochloramine under various laboratory conditions. The reaction mixtures were extracted using liquid-liquid extraction and analyzed for NAs using high performance liquid chromatography tandem mass spectrometry. At low concentration of IL (250 μmol/L), the yields of NAs (NMEA or NPyr) increased with increasing doses of monochloramine from both IL species. The total NA yield was as high as 2.5 ± 0.3 ng/mg from EMImBr, and as high as 8.6 ± 0.8 ng/mg from EMPyrBr. At high concentration of IL (5 mmol/L), the NA yield reached a maximum at 2.5 mmol/L NH₂Cl, and then decreased with subsequent increases in the reactant concentrations, demonstrating ILs' solvent effects. This study re-emphasizes the importance of preventing discharge of ILs to water bodies to prevent secondary impacts on drinking water.

Comparative pharmacokinetics of quercitrin, astragalin, afzelin and taxifolin in plasma after oral administration of Polygonum orientale inflorescence in sham-operated and myocardial ischemia-reperfusion injury rats

The study aimed to compare the pharmacokinetic properties of quercitrin, astragalin, afzelin and taxifolin, four major bioactive components of Polygonum orientale inflorescence extracts, between sham-operated and myocardial ischemia-reperfusion injury (MIRI) rats.Rats were divided into two groups: MIRI model and sham-operated. The blood samples were collected according to the time schedule. The levels of quercitrin, astragalin, afzelin and taxifolin in the plasma at designated time points were determined using an HPLC-MS/MS method. Various pharmacokinetic parameters were estimated from the plasma concentration versus time data using non-compartmental methods. After the administration of the Chinese herb Polygonum orientale inflorescence extracts, the C_max, AUC, as well as MRT, increased, while CL decreased, in MIRI model compared to the sham-operated animals.These results suggest that the pathological damage of ischemia-reperfusion had a significant impact on the pharmacological effects of Polygonum orientale inflorescence extracts on ischemic heart disease.The method had been successfully applied to evaluate the pharmacokinetics of quercitrin, astragalin, afzelin and taxifolin in rat plasma after the oral administration of Chinese herb Polygonum orientale inflorescence extracts in rats.

Simultaneous Quantitative Analysis of Six Isothiazolinones in Water-Based Adhesive Used for Food Contact Materials by High-Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS)

In this study, a target analytical approach using high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was developed to simultaneously determine six isothiazolinones containing 2-Methylisothiazol-3(2H)-one (MI), 5-Chloro-2-methyl-4-isothiazolin-3-one (CMI), 1,2-benzisothiazolin-3-one (BIT), 2-Octyl-3(2H)-isothiazolinone (OIT), Dichlorooctylisothiazolinone (DCOIT), and 2-methyl-1,2-benzisothiazolin-3-one (MBIT) in water-based adhesive used for food contact materials. The main factors affecting extraction efficiency such as extraction method, extraction time, extraction solvent, and solid–liquid ratio have been evaluated by using real adhesive samples. Multiple-reaction monitoring (MRM) was used for the qualitative and quantitative analyses of targeted isothiazolinones. This method was demonstrated as an effective and reliable technique for detecting multiple isothiazolinones with satisfactory recoveries (81.5~107.3%), and the limits of detection (LOD) and quantification (LOQ) were obtained at a low level. This method was validated and applied to the determination of six isothiazolinones in commercial water-based adhesives. The present results revealed that these adhesives contained a combination of isothiazolinones (BIT, MI, CMI, and MBIT) with the concentration ranging from 2.27 to 123.5 mg/kg. To our knowledge, it is the first time it has been reported that MBIT was detected in water-based adhesives used for food contact materials, which requires a further investigation for its migration to food and the risk to human health.

An HPLC-MS/MS method for quantitation of trelagliptin and application in a comparative pharmacokinetic study

Aim: A sensitive HPLC-MS/MS approach was established to quantify trelagliptin and explore the pharmacokinetic characteristics in rats for up to 7 days. Meanwhile, the pharmacokinetic differences of trelagliptin were investigated for the first time. Results/methodology: The ion pairs of m/z 358.2→341.2 for trelagliptin and m/z 340.3→116.1 for alogliptin (internal standard) were detected in positive mode. Trelagliptin displayed a good linearity in the range of 4-4000 ng/ml (r² = 0.9997) with a mean recovery rate of 86.9-94.1%. Discussion/conclusion: Compared with normal groups, the T1/2, apparent volume of distribution, area under the curve and bioavailability in model rats were significantly increased while the apparent plasma clearance decreased. The approach is proved to be straightforward and appropriate for quantitation of trelagliptin and application in pharmacokinetics studies.

Antiproliferative and antioxidant effect of polar hemp extracts (Cannabis sativa L., Fedora cv.) in human colorectal cell lines

Total phenolic content and antioxidant activity of polar extracts of edible resources from Fedora hemp cultivar (Cannabis sativa L.), namely seed, flour and oil, were evaluated. The main components in the polar extracts were identified using HPLC-DAD and HPLC-ESI-MS/MS. As expected, the molecular profile of components from seeds and flour was strictly similar, dominated by N-trans-caffeoyltyramine. The profile of oil polar extracts contained hydroxycinnamic acid derivatives and cannabinoids at lower extent. While the extracts from hemp seed and flour did not interfere with growth of Caco-2 and HT-29 cell, the one from oil (150 µg/mL) significantly reduced cell viability after 24 h of treatment. This effect was associated with the activation of apoptotic cell death and was independent from the antioxidant capacity of the oil polar extract. Notably, HT-29 cells differentiated with sodium butyrate were not sensitive to the cytotoxic effect of the oil extract.

Evaluation, characterization, expression profiling, and functional analysis of DXS and DXR genes of Populus trichocarpa

1-Deoxy-D-xylulose-5-phosphate synthasse (DXS) and 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) are key enzymes in terpenoid biosynthesis. DXS catalyzes the formation of 1-deoxy-D-xylulose 5-phosphate (DXP) from pyruvate and D-glyceraldehyde-3-phosphate. DXR catalyzes the formation of 2-C-methyl-D-erythritol 4-phosphate (MEP) from DXP. Previous studies of the DXS and DXR genes have focused on herbs, such as Arabidopsis thaliana, Salvia miltiorrhiza, and Amomum villosum, but few studies have been conducted on woody plants. For that reason, we chose Populus trichocarpa as a model woody plant for investigating the DXS and DXR genes. PtDXS exhibited the highest expression level in leaves and the lowest expression in roots. PtDXR showed maximum expression in young leaves, and the lowest expression in mature leaves. The expression profiles revealed by RT-PCR following different elicitor treatments such as abscisic acid, NaCl, PEG₆₀₀₀, H₂O₂, and cold stress showed that PtDXS and PtDXR were elicitor-responsive genes. Our results showed that the PtDXS gene exhibited diurnal changes, but PtDXR did not. Moreover, overexpression of PtDXR in transgenic poplars improved tolerance to abiotic and biotic stresses. Those results showed that the PtDXR encoded a functional protein, and widely participates in plant growth and development, stress physiological process.

Novel LC-MS/MS method for analysis of metformin and canagliflozin in human plasma: application to a pharmacokinetic study

Highly sensitive and selective liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous estimation of the recently approved oral hypoglycemic mixture; metformin (MET) and canagliflozin (CFZ) in human plasma using propranolol HCl (PPL) and tadalafil (TDF) as internal standards (IS), respectively. Analytes were extracted using protein precipitation induced by acetonitrile then liquid-liquid extraction was performed using ethyl acetate. Reversed phase HPLC was carried out using C18 analytical column (50 mm × 4.6 mm i.d., 5 µm) with a simple isocratic mobile phase composed of 0.1% formic acid and acetonitrile (60:40, v/v). Detection was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring (MRM), with the transitions of m/z 130.2 → 60.1, m/z 462.3 → 191.0, m/z 260.2 → 183.0 and m/z 390.2 → 268.2 for MET, CFZ, PPL and TDF, respectively, in the positive ion mode. The analysis was carried out within 5 min over a linear concentration range of 50-5000 ng/mL for MET and 10-1000 ng/mL for CFZ. The method was validated in accordance with the FDA guidelines for bioanalytical method. All obtained recoveries were higher than 90.0% while the accuracy was in the range of 88.14-113.05% and the relative standard deviation was below 10.0% for all investigated drugs by the proposed method. The achieved promising results has allowed for the successful application of the developed LC-MS/MS method to a pharmacokinetic study of the target drugs after their oral administration to Egyptian healthy volunteers. The pharmacokinetic study was accomplished after the agreement of the ethics committee.

Determination of Florfenicol, Thiamfenicol and Chloramfenicol at Trace Levels in Animal Feed by HPLC⁻MS/MS

Administration of florfenicol and thiamfenicol through medicated feed is permitted within the European Union, always following veterinary prescription and respecting the withdrawal periods. However, the presence of low levels of florfenicol, thiamfenicol, and chloramfenicol in non-target feed is prohibited. Since cross-contamination can occur during the production of medicated feed and according to Annex II of the European Regulation 2019/4/EC, the control of residue levels of florfenicol and thiamfenicol in non-target feed should be monitored and avoided. Based on all the above, a sensitive and reliable method using liquid chromatography tandem mass spectrometry was developed for the simultaneous detection of chloramfenicol, florfenicol, and thiamfenicol at trace levels in animal feed. Analytes were extracted from minced feed with ethyl acetate. Then, the ethyl acetate was evaporated, the residue was resuspended in Milli-Q water and the extract filtered. The method was in-house validated at carryover levels, with concentration ranging from 100 to 1000 µg/kg. The validation was conducted following the European Commission Decision 2002/657/EC and all performance characteristics were successfully satisfied. The capability of the method to detect amfenicols at lower levels than any prior perspective regulation literature guarantees its applicability in official control activities. The developed method has been applied to non-compliant feed samples with satisfactory results.

Folate content analysis of wheat cultivars developed in the North China Plain

Folates are essential micronutrients in the human diet. Germplasm rich in folates can be used as genetic resource for diet and breeding to produce new varieties with enhanced folates. To investigate the natural variation of folates among wheat cultivars and identify high folate materials for breeding, we studied the grain folate contents of 360 wheat samples consisting of 315 wheat genotypes grown in North China using the high performance liquid chromatography coupled with mass spectrometry (HPLC-MS/MS) method. The total folate content among wheat genotypes ranged from 10.15 ± 2.86 to 91.44 ± 5.64 µg per 100 g grains, thus showing a remarked variation. Fifty-two wheat cultivars, such as Henong58-3, were identified as good sources of folates. 5-Formyltetrahydrate and 5-methyltetrahydrate were found to be the two major folate derivatives in wheat germplasm. In addition, we found that environment factor also had significant effect on folate production. This investigation can help wheat breeders for folate improvement.

Schizophrenia: recent advances in LC-MS/MS methods to determine antipsychotic drugs in biological samples

Schizophrenia is one of the most debilitating and costly illnesses worldwide. First-generation antipsychotics such as chlorpromazine and haloperidol succeeded in controlling the positive symptoms of schizophrenia, but had significant extrapyramidal effects that led to the search for new agents and the release of second-generation (or atypical) antipsychotics. These drugs had a lower risk of adverse motor symptoms. Therapeutic drug monitoring has become a useful tool to optimize schizophrenia treatment and HPLC-MS/MS has been considered the primary technique to monitor antipsychotics. This review comprises three sections: schizophrenia pathophysiology and treatment; recent advances in LC-MS/MS methods designed to measure levels of antipsychotics and their metabolites in plasma samples (selectivity, matrix effect and sensitivity); and the importance of therapeutic drug monitoring.

HPLC-MS/MS-based analysis of everolimus in rabbit aqueous humor: pharmacokinetics of in situ gel eye drops of suspension

Aim: Everolimus is an inhibitor of mTOR which is derived from rapamycin. Its high corneal permeability and bioavailability makes it an effective treatment for ocular disorders. To study the pharmacokinetics of in situ gel eye drops of everolimus suspension after ocular administration in rabbit aqueous humor, we developed a rapid and reliable HPLC-MS/MS method. Methodology/results: Ascomycin was selected as the internal standard. HPLC-MS/MS method was used to investigate the concentration-time relationship of everolimus in rabbit aqueous humor through protein precipitation technique. The validated results showed good linearity, accuracy and precision. Conclusion: The method developed in this study is rapid, sensitive and reliable for the determination of the concentration of everolimus in rabbit aqueous humor.

QuEChERS and HPLC-MS/MS Combination for the Determination of Chloramphenicol in Twenty Two Different Matrices

A simple method for the determination of chloramphenicol in 22 matrices was prepared based on the QuEChERS and HPLC-MS/MS combination. Following a hydrolysis step, the homogenized samples were extracted and partitioned after adding sodium chloride with acetonitrile. Chloramphenicol was analysed by HPLC-MS/MS in negative electrospray mode by monitoring the daughter ions m/z: 321→194 and 321→152. The limit of decision (CCα) was calculated at the range of 0.10 μg kg⁻¹ to 0.15 μg kg⁻¹ and detection capability (CCβ) from 0.12 μg kg⁻¹ to 0.18 μg kg⁻¹. Validation results showed that this method is suitable for the determination and confirmation of chloramphenicol in various matrices.

Exercise Training Impacts Cardiac Mitochondrial Proteome Remodeling in Murine Urothelial Carcinoma

Cardiac dysfunction secondary to cancer may exert a negative impact in patients’ tolerance to therapeutics, quality of life, and survival. The aim of this study was to evaluate the potential therapeutic effect of exercise training on the heart in the setting of cancer, after diagnosis. Thus, the molecular pathways harbored in heart mitochondria from a murine model of chemically-induced urothelial carcinoma submitted to 8-weeks of high intensity treadmill exercise were characterized using mass spectrometry-based proteomics. Data highlight the protective effects of high intensity exercise training in preventing left ventricle diastolic dysfunction, fibrosis, and structural derangement observed in tumor-bearing mice. At the mitochondrial level, exercise training counteracted the lower ability to produce ATP observed in the heart of animals with urothelial carcinoma and induced the up-regulation of fatty acid oxidation and down-regulation of the biological process “cardiac morphogenesis”. Taken together, our data support the prescription of exercise training after cancer diagnosis for the management of disease-related cardiac dysfunction.

Rapid HPLC-ESI-MS/MS Analysis of Neurotransmitters in the Brain Tissue of Alzheimer's Disease Rats before and after Oral Administration of Xanthoceras sorbifolia Bunge

In order to explore the potential therapeutic effect of Xanthoceras sorbifolia Bunge. against Alzheimer’s disease, an HPLC-MS/MS method has been developed and validated for simultaneous determination in rat brain of eight neurotransmitters, including dopamine, norepinephrine, 5-hydroxy-tryptamine, acetylcholine, l-tryptophan, γ-aminobutyric acid, glutamic acid and aspartic acid with a simple protein precipitation method for sample pre-treatment. The brain samples were separated on a polar functional group embedded column, then detected on a 4000 QTrap HPLC-MS/MS system equipped with a turbo ion spray source in positive ion and multiple reaction monitoring mode. The method was fully validated to be precise and accurate within the linearity range of the assay, and successfully applied to compare the neurotransmitters in the rat brain from four groups of normal, Alzheimer’s disease, and the oral administration group of X. sorbifolia extract and huperzine. The results indicated that brain levels of dopamine, norepinephrine and acetyl choline all decreased in the AD rats, while l-tryptophan showed an opposite trend. After administration of the Xanthoceras sorbifolia extract and huperzine, the level of acetyl choline and tryptophan returned to normal. Combination of the metabolic analysis, the results indicated that acetyl choline and l-tryptophan could be employed as therapy biomarkers for AD, and the results shown that the crude extract of the husks from Xanthoceras sorbifolia might ameliorate the impairment of learning and memory in the Alzheimer’s disease animal model with similar function of AchEI as huperzine. The established method would provide an innovative and effective way for the discovery of novel drug against Alzheimer’s disease, and stimulate a theoretical basis for the design and development of new drugs.

Development and application of a HPLC-MS/MS method for quantitation of fucosylated chondroitin sulfate and fucoidan in sea cucumbers

Fucosylated chondroitin sulfate (FCS) and fucoidan (FUC) are two main bioactive polysaccharides in sea cucumbers. A novel method for quantitation of FCS and FUC was developed by detecting chondroitin disaccharide and fucose produced through acid hydrolysis using HPLC-MS/MS. The present method showed satisfactory performance for both saccharides. It was applied to assay sea cucumbers (Stichopus japonicus) reared in pond grow-out or bottom sowing, and the results were compared with those obtained by traditional HPLC method and 1,9-dimethylmethylene blue test, which could only provide the total sea cucumber polysaccharide (SCP) contents. No difference of total SCP content was observed between sea cucumbers reared through different ways, while a higher ratio of FCS to FUC of sea cucumbers of pond grow-out was revealed by the present method. Thus, this novel method is potential to quantify the two polysaccharides and could be a powerful tool for quality evaluation of sea cucumbers.

Development and validation of a liquid chromatography-tandem mass spectrometry assay for the quantification of lurbinectedin in human plasma and urine

Lurbinectedin is a novel highly selective inhibitor of RNA polymerase II triggering caspase-dependent apoptosis of cancerous cells. This article describes the development and validation of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay to quantify lurbinectedin in human plasma and urine. Plasma samples were pre-treated with 1 M aqueous ammonia after which they were brought onto supported liquid extraction (SLE) columns. Lurbinectedin was eluted from the columns using tert-butyl methyl ether (TBME). Urine was first diluted in plasma and lurbinectedin was extracted from this matrix by liquid-liquid extraction using TBME. Samples were measured by LC-MS/MS in the positive electron ion spray mode. The method was linear over 0.1-100 ng/mL and 1-1000 ng/mL in plasma and urine, respectively, with accuracies and precisions within ±15% (20% for LLOQ) and below 15% (20% for LLOQ), respectively. The method was developed to support a mass balance study in which patients received a dose of 5 mg lurbinectedin.

Association of serum levels of perfluoroalkyl substances (PFASs) with the metabolic syndrome (MetS) in Chinese male adults: A cross-sectional study

As extensively used chemicals in a variety of consumer products, perfluoroalkyl substances (PFASs) are ubiquitous and could bring significant risk to human health. However, the effect of PFASs on metabolic syndrome (MetS) is not fully understood. In 2015, a preliminary cross-sectional study was undertaken. A total of 148 male subjects including 81 affected by MetS and 67 non-MetS participants as the reference were recruited from Physical Examination Center affiliated to Capital Medical University, China. Serum levels of perfluorohexane sulfonic acid (PFHxS), perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) were significantly higher in the subjects with MetS. Logistic regression results showed that concentration of PFNA in serum was associated with 10.9-fold [95% confidence interval (CI), 2.00-59.1] increased risk of MetS. Moreover, increased serum PFNA concentrations were associated with high blood pressure [both for systolic and diastolic blood pressure (SBP and DBP); odds ratio (OR) 7.52 (95%CI, 1.34-42.1) for SBP and 7.27 (95%CI, 1.17-45.1) for DBP], hypertriglyceridemia [13.2 (95%CI, 2.34-74.2)] and obesity [13.3 (95%CI, 2.38-74.4)], respectively. After adjustment by age in logistic regression models, serum levels of PFOA were associated with 29.4-fold (95%CI, 2.90-299.7) increased risk of MetS. Increased PFOA levels were also correlated with MetS [29.4 (95%CI, 2.9-299.7)], SBP [10.8 (95%CI, 1.31-90.0)], hypertriglyceridemia [16.6 (95%CI, 1.92-147.1)], and obesity [46.7 (95%CI, 4.47-487.7)] with adjustment for age. This study suggests bodily retention of PFASs and its association with MetS. Further clinical and animal studies are warranted to clarify the putative causal relationship.

Studies on the metabolism of paeoniflorin in human intestinal microflora by high performance liquid chromatography/electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometry and quadrupole time-of-flight mass spectrometry

In this study, a high performance liquid chromatography/electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometry and quadrupole time-of-flight mass spectrometry (HPLC-ESI-FT-ICR MS and HPLC-ESI-QTOF MS²) based on chemical profiling method was established to study the metabolites of paeoniflorin in human intestinal microflora (HIM). By virtue of the high resolution, high speed of HPLC and the accurate mass measurement of FT-ICR MS and QTOF MS², 31 metabolites in methyl tert-butyl ether (MTBE) layer were detected, and the structures of 16 metabolites were identified. Among them, 13 metabolites (including two new compounds) were found for the first time in HIM transformation in vitro. The results indicated that metabolic pathways of paeoniflorin in HIM contained extensive metabolic reactions. The hydrolysis, oxidization and conjugation were major metabolic pathways, and the glycosidic linkage, ester bond, benzene ring and pinane of the structure were metabolic sites. These results would contribute to better understanding the metabolic mechanism of paeoniflorin, thereby to in-depth study and development of paeoniflorin in medicine.

A simple and sensitive HPLC-MS/MS method for quantification of eggmanone in rat plasma and its application to pharmacokinetics

Allosteric phosphodiesterase 4 (PDE4) inhibitors are highly sought after due to their important anti-inflammatory and anti-cancer therapeutic effects. We recently identified Eggmanone, an extraordinarily selective allosteric PDE4 inhibitor displaying favorable drug properties. However, a specific analytic method of Eggmanone in serum and its pharmacokinetics have not been reported yet. In this study, we developed a rapid and sensitive high performance liquid chromatography-mass spectrometric (HPLC-MS/MS) method to determine Eggmanone concentrations in rat plasma. This assay method was validated in terms of specificity, linearity, sensitivity, accuracy, precision, matrix effect, recovery and stability, and was applied to a pharmacokinetic study in rats following intravenous injection of Eggmanone at doses of 1 and 3 mg/kg. The lower limit of quantification (LLOQ) of this assay was 5 ng/mL and the linear calibration curve was acquired with R² > 0.99 between 5 and 1000 ng/m. The intra-day and inter-day precision was evaluated with the coefficient of variations less than 11.09%, whereas the mean accuracy ranged from 98.38% to 105.13%. The assay method exhibited good recovery and negligible matrix effect. The samples were stable under all the experimental conditions. The plasma concentrations of Eggmanone were detected and quantified over 24 h with the terminal elimination half-live of 3.57 ± 1.80 h and 5.92 ± 3.34 h for the low dose (1 mg/kg) and high dose (3 mg/kg) respectively. In summary, the present method provides a robust, fast and sensitive analytical approach for quantification of Eggmanone in plasma and was successfully applied to a pharmacokinetic study in rats.

Determination of fenticonazole in human plasma by HPLC-MS/MS and its application to pharmacokinetic studies

Two simple and sensitive high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) methods were developed and validated for the determination of fenticonazole in human plasma after percutaneous and intravaginal administration. Mifepristone was used as an internal standard (IS), and simple protein precipitation by acetonitrile containing 2% acetic acid was utilized for extracting the analytes from the plasma samples. Chromatographic separation was performed on a Kinetex XB-C₁₈ column. The quantitation was performed by a mass spectrometer equipped with an electrospray ionization source in multiple reactions monitoring (MRM) positive ion mode using precursor-to-product ion transitions of m/z 455.2-199.1 for fenticonazole and m/z 430.2-372.3 for mifepristone. The validated linear ranges were 5-1000 pg/mL and 0.1-20 ng/mL fenticonazole in plasma for the methods A and B, respectively. For the two methods, the accuracy data ranged from 85% to 115%, the intra- and inter-batch precision data were less than 15%, the recovery data were more than 90%, and no matrix interference was observed. The methods A and B were successfully validated and applied to the pharmacokinetic studies of fenticonazole gel in Chinese healthy volunteers after percutaneous and intravaginal administration, respectively.

Simultaneous determination of synthetic food additives in kimchi by liquid chromatography-electrospray tandem mass spectrometry

A new analytical method was developed for the simultaneous determination of seven food additives (Ponceau 4R, Allura Red AC, Amaranth, 4-hydroxymethyl benzoic acid, ethyl-4-hydroxybenzoate, butyl-4-hydroxybenzoate, and saccharin sodium) in kimchi using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry. The linearity, sensitivity, selectivity, precision, and accuracy of the method were validated. The limit of detection was 0.00004-0.24 μg/mL, and the limit of quantification was 0.00012-0.8 μg/mL. Recoveries ranged from 85.65 to 120.82%. The method was successful and may help to ensure food safety.

Identification of potential genes that contributed to the variation in the taxoid contents between two Taxus species (Taxus media and Taxus mairei)

Taxol is currently a valuable anticancer drug; however, the accumulated mixture of taxoids can vary greatly among Taxus species. So far, there is very little genomic information for the genus Taxus, except for Taxus baccata. Transcriptome analysis is a powerful approach to explore the different regulatory mechanisms underlying the taxoid biosynthesis pathway in Taxus species. First, we quantified the variation in the taxoid contents between Taxus media and Taxus mairei. The contents of paclitaxel and 10-deacetylpaclitaxel in T. media are higher than that in T. mairei. Then, the transcriptome profiles of T. media and T. mairei were analyzed to investigate the altered expressions. A total of 20,704 significantly differentially expressed genes (DEGs), including 9865 unigenes predominantly expressed in T. media and 10,839 unigenes predominantly expressed in T. mairei, were identified. In total, 120 jasmonic acid-related DEGs were analyzed, suggesting variations in 'response to JA stimulus' and 'JA biosynthetic process' pathways between T. media and T. mairei. Furthermore, a number of genes related to the precursor supply, taxane skeleton formation and hydroxylation, and C13-side chain assembly were also identified. The differential expression of the candidate genes involved in taxoid biosynthetic pathways may explain the variation in the taxoid contents between T. media and T. mairei.

Development of a linear dual column HPLC-MS/MS method and clinical genetic evaluation for tramadol and its phase I and II metabolites in oral fluid

Tramadol is a centrally acting synthetic opioid analgesic and has received special attention due to its abuse potential and unexpected responses induced by CYP2D6 polymorphism. Oral fluid is an advantageous biofluid for drug analysis due to non-invasive sampling and high correlation of drug concentrations with plasma. However, few studies have been performed on distribution of tramadol and its metabolites in oral fluid. In the present study, a linear dual column HPLC-MS/MS method was developed and fully validated for the simultaneous determination of tramadol and its phase I [O-desmethyltramadol (ODMT), N-desmethyltramadol (NDMT) and N,O-didesmethyltramadol (NODMT)] and II metabolites in oral fluid. Furthermore, the distribution of tramadol and its metabolites, in relation to CYP2D6 genetic variations, in oral fluid was investigated following a clinical study including 23 subjects with CYP2D6*wt/*wt, CYP2D6*10/*10 or CYP2D6*5/*5. The validation results of selectivity, matrix effect, linearity, precision and accuracy were satisfactory. Pharmacokinetic parameters, such as C_ss,max and AUC_0-τ of tramadol, NDMT and NODMT, in the CYP2D6*10/*10 group were significantly higher than those in the CYP2D6*wt/*wt group. Moreover, the ratios of ODMT/tramadol, NDMT/tramadol and NODMT/NDMT correlated well with the CYP2D6 genotypes. We demonstrated that oral fluid is a promising biofluid for pharmacokinetic evaluation in relation to genetic variations.

Quantification of amlodipine in dried blood spot samples by high performance liquid chromatography tandem mass spectrometry

A sensitive and specific method, utilising high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was developed for the quantitative determination of amlodipine in dried blood spot (DBS) samples. Chromatographic separation was achieved using a Waters XBridge C18 column with gradient elution of a mixture of water and acetonitrile containing 0.1% formic acid (v/v). Amlodipine was quantified using a Waters Quattro Premier mass spectrometer coupled with an electro-spray ionization (ESI) source in positive ion mode. The MRM transitions of 408.9 m/z→238.1m/z and 408.9→294.0 m/z were used to quantify and qualify amlodipine, respectively. The method was validated across the concentration range of 0.5-30ng/mL by assessing specificity, sensitivity, linearity, precision, accuracy, recovery and matrix effect according to the Food and Drug Administration (FDA) guidelines. This method was also validated clinically within a large pharmacoepidemiological study in which amlodipine blood concentration was determined in patients who had been prescribed this medication.

Simultaneous quantification of five biflavonoids in rat plasma by LC-ESI-MS/MS and its application to a comparatively pharmacokinetic study of Selaginella doederleinii Hieron extract in rats

Selaginella doederleinii Hieron is a widely used as folk Chinese medicine for treatment of different cancers. Our previous investigations have confirmed that the total biflavonoids in ethyl acetate extract from S. doederleinii (SDEA) have favorable anticancer potentials. However, the in vivo process of its bioactive ingredients remains unknown. In this paper, a sensitive and reliable method was developed for simultaneous quantification of main five biflavonoids, including amentoflavone, robustaflavone, 2″,3″-dihydro-3',3″-biapigenin, 3',3″-binaringenin and delicaflavone in the ethyl acetate extract of S. doederleinii (SDEA extract) in rat plasma by high-performance liquid chromatography with electrospray ionization-mass spectrometry (HPLC-ESI-MS/MS). Chromatographic separation was performed using an Ultimate^® XB-C18 (100×2.1mm, 3.5μm) with gradient elution of water (0.5% acetic acid) and acetonitrile at 0.2mL/min. All analytes with internal standard (chrysin) were detected using selective reaction monitoring (SRM) in negative ionization mode. The method showed a good linearity over a wide concentration range (r²>0.99). The limits of quantification for the biflavonoids were less than 10ng/mL. The developed method was applied to the comparatively pharmacokinetic study of the five biflavonoids after oral or intravenous administration of SDEA extract in rats. In addition, in silico assessments of permeability and solubility of these biflavonoids were also performed to understand their poor bioavailability. It is the first time to report the in vivo process profiles of the biflavonoids of SDEA extract in rats.