A rotameric tryptamide alkaloid from the roots of Vepris lecomteana (Pierre) Cheek & T. Heller (Rutaceae).

A rotameric tryptamide alkaloid (1a-1b) was isolated from the methanolic extract of the roots of Vepris lecomteana together with the known compounds anhydroevoxine (2), lecomtequinoline C (3), evoxine (4), N-methylflindersine (5), evoxanthine (6), hesperidin, lupeol, ß-sitosterol and stigmasterol. The previously not reported 7-(3-anilino-2-hydroxyprenyloxy)-8-methoxydictamine (2a) was obtained by opening the epoxide of anhydroevoxine (2). The structures of above compounds were determined by comprehensive spectroscopic analyses of 1D and 2D NMR, EI-/ESI-MS, X-ray crystallography and comparison with the reported data. At room temperature, 1H and 13C NMR spectra show two rotamers (1a and 1b) with integrated intensities of 2/3, whereas at around 60 °C, only the 1b conformer was observed. Furthermore, the crystal structure of 1 was determined by the direct method of single crystal X-ray diffraction. The suggested biosynthesis for the formation of the new rotameric tryptamide alkaloid 1 is presented. Some of the isolated compounds (1, 2 and 2a) were tested in vitro against bacteria, resulting in weak for (1 and 2) to moderate activity for (2a) against Micrococcus luteus and Escherichia coli with MIC values of 15.3 and 15.3 µg/mL, respectively.

Fine-tuning of the automated [18 F]PSMA-1007 radiosynthesis.

Radiolabeled prostate-specific membrane antigen (PSMA) targeting PET-tracers have become desirable radiopharmaceuticals for the imaging of prostate cancer (PC). Recently, the PET radiotracer [18 F]PSMA-1007 was introduced as an alternative to [68 Ga]Ga-PSMA-11, for staging and diagnosing biochemically recurrent PC. We incorporated a one-step procedure for [18 F]PSMA-1007 radiosynthesis, using both Synthra RNplus and GE TRACERlab FxFN automated modules, in accordance with the recently described radiolabeling procedure. Although the adapted [18 F]PSMA-1007 synthesis resulted in repeatable radiochemical yields (55 ± 5%, NDC), suboptimal radiochemical purities of 87 ± 8% were obtained using both modules. As described here, modifications made to the radiolabeling and the solid-phase extraction purification steps reduced synthesis time to 32 minutes and improved radiochemical purity to 96.10%, using both modules, without shearing the radiochemical yield.

Dissipation behaviour and dietary risk assessment of boscalid, triflumizole and its metabolite (FM-6-1) in open-field cucumber based on QuEChERS using HPLC-MS/MS technique.

BACKGROUND: To resist plant diseases, boscalid and triflumizole have been applied to cucumbers frequently. However, the residue and dietary risk assessment of these fungicides in cucumber should be given attention for food safety. RESULTS: An effective and highly sensitive method based on the liquid chromatography-tandem mass spectrometry technique for simultaneous multidetermination of boscalid, triflumizole and its metabolite (FM-6-1) in a cucumber ecosystem was established and validated. Field experiments were conducted in three different locations, where boscalid and triflumizole (35% suspension concentration) were applied at 253 g of active ingredient (a.i.) per hectare (the recommended high dosage) and 379.5 g a.i. ha-1 (1.5 times the recommended high dosage) in each location. The limits of quantification and the limits of detection of the proposed method ranged from 0.01 to 0.05 mg kg-1 and 3.9 × 10-5 to 7.5 × 10-4 mg L-1 respectively. The mean recoveries and relative standard deviations of these compounds were 80-105% and 1.0-6.1% respectively. The dissipation dynamics of compounds followed pseudo-first-order kinetic models remarkably, with a half-value period of 2.3-40.8 days. The residues of boscalid and triflumizole in cucumber at harvest were below 0.66 mg kg-1 and 0.07 mg kg-1 respectively. The results of the dietary risk assessments have shown a low dietary risk of compounds in cucumber with hazard ratios <1 and hazard index <1. CONCLUSION: These results from the experiments are the most important for putting a guide on reasonable usage of these fungicides under the open-field conditions in China. © 2018 Society of Chemical Industry.

Synthesis of carbon-11-labeled isonicotinamides as new potential PET agents for imaging of GSK-3 enzyme in Alzheimer's disease.

The authentic standards 2-(cyclopropanecarboxamido)-N-(4-methoxypyridin-3-yl)isonicotinamide (4a) and 2-(cyclopropanecarboxamido)-N-(4-(4-methoxyphenyl)pyridin-3-yl)isonicotinamide (7a), and their corresponding precursors 2-(cyclopropanecarboxamido)-N-(4-hydroxypyridin-3-yl)isonicotinamide (4b) and 2-(cyclopropanecarboxamido)-N-(4-(4-hydroxyphenyl)pyridin-3-yl)isonicotinamide (7b) were synthesized from methyl 2-aminoisonicotinate and cyclopropanecarbonyl chloride with overall chemical yield 47% in three steps, 22% in four steps, 40% in three steps, and 17% in four steps, respectively. The target tracers 2-(cyclopropanecarboxamido)-N-(4-[11C]methoxypyridin-3-yl)isonicotinamide ([11C]4a) and 2-(cyclopropanecarboxamido)-N-(4-(4-[11C]methoxyphenyl)pyridin-3-yl)isonicotinamide ([11C]7a) were prepared from the precursors (4b and 7b) with [11C]CH3OTf through O-[11C]methylation and isolated by HPLC combined with SPE in 40-50% radiochemical yield, based on [11C]CO2 and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the specific activity (SA) at EOB was 370-1110GBq/µmol with a total synthesis time of ∼40-min from EOB.

Ultrasound assisted combined molecularly imprinted polymer for selective extraction of nicotinamide in human urine and milk samples: Spectrophotometric determination and optimization study.

Ultrasound-assisted dispersive solid phase microextraction followed by UV-vis spectrophotometer (UA-DSPME-UV-vis) was designed for extraction and preconcentration of nicotinamide (vitamin B3) by HKUST-1 metal organic framework (MOF) based molecularly imprinted polymer (MIP). This new material was characterized by FTIR and FE-SEM techniques. The preliminary Plackett-Burman design was used for screening and subsequently the central composite design justifies significant terms and possible construction of mathematical equation which give the individual and cooperative contribution of variables like HKUST-1-MOF-NA-MIP mass, sonication time, temperature, eluent volume, pH and vortex time. Accordingly the optimum condition was set as: 2.0mg HKUST-1-MOF-NA-MIP, 200µL eluent and 5.0min sonication time in center points other variables were determined as the best conditions to reach the maximum recovery of the analyte. The UA-DSPME-UV-vis method performances like excellent linearity (LR), limits of detection (LOD), limits of quantification of 10-5000µgL-1 with R2 of 0.99, LOD (1.96ngmL-1), LOQ (6.53µgL-1), respectively show successful and accurate applicability of the present method for monitoring analytes with within- and between-day precision of 0.96-3.38%. The average absolute recoveries of the nicotinamide extracted from the urine, milk and water samples were 95.85-101.27%.

Aspernigrins with anti-HIV-1 activities from the marine-derived fungus Aspergillus niger SCSIO Jcsw6F30.

Two new 2-benzylpyridin-4-one containing metabolites, aspernigrins C (3) and D (4), together with six known compounds (1, 2, and 5-8), were isolated from the marine-derived fungus Aspergillus niger SCSIO Jcsw6F30. The structures of the new compounds were determined by NMR, MS, and optical rotation analyses. All the isolated compounds were evaluated for their inhibitory activities against infection with HIV-1 SF162 in TZM-bl cells. Malformin C (5) showed the strongest anti-HIV-1 activity with IC50 of 1.4±0.06µM (selectivity index, 11.4), meanwhile aspernigrin C (3) also exhibited potent activity with IC50 of 4.7±0.4µM (selectivity index, 7.5).

[Isolation and structure elucidation of chemical constituents from Pinellia ternata].

OBJECTIVE: To isolate and identify the chemical constituents of ethanol extract of Pinellia ternata. METHODS: The constituents were isolated by silica-gel, Sephadex LH-20 chromatography and HPLC techniques. The structures were identified by spectroscopic analysis including 2D NMR techniques and chemical properties. RESULTS: Nine compounds were obtained and identified as uridine (1), 5'-S-methyl-5'-thioadenosine (2), adenine (3), chrysophanol (4), 5-hydroxymethylfurfural (5), nicotinamide (6), (2S)-1-O-(9Z, 12Z-octadecadienoyl)-3-O-beta-galactopyranosylglycerol (7), daucosterol (8), beta-sitosterol (9). CONCLUSION: Compounds 2, 6, 7 are isolated from this plant for the first time.

Method development and validation for boscalid in blueberries by solid-phase microextraction gas chromatography, and their degradation kinetics.

Analytical method for the residues of boscalid in blueberries was developed. Fungicide residues were determined by solid-phase microextraction (SPME) coupled to gas chromatography with micro-electron capture (µ-ECD) detector. The effect of pH values and fiber coatings were studied. The SPME fiber coating selected was 100 µm PDMS. The method is selective with adequate precision and high accuracy and sensitivity. Recoveries ranged within the 98-104% range, and detection and quantification limits were 1.33 and 4.42 µg/kg, respectively. Statistical parameters indicated the occurrence of matrix effect; consequently calibration was performed on spiked samples. Degradation of boscalid was studied in a blueberry field located in Concordia, Argentina, with fruits from Emerald and Jewel varieties. The degradation of boscalid in both blueberry varieties studied followed a first order rate kinetics and the half-life for boscalid was 5.3 and 6.3 days for Emerald and Jewel cultivars, respectively.

An approach to the chemotaxonomic differentiation of two European dog's mercury species: Mercurialis annua L. and M. perennis L.

Mercurialis annua and M. perennis are medicinal plants used in complementary medicine. In the present work, analytical methods to allow a chemotaxonomic differentiation of M. annua and M. perennis by means of chemical marker compounds were established. In addition to previously published compounds, the exclusive presence of pyridine-3-carbonitrile and nicotinamide in CH(2) Cl(2) extracts obtained from the herbal parts of M. annua was demonstrated by GC/MS. Notably, pyridine-3-carbonitrile was identified for the first time as a natural product. Further chromatographic separation of the CH(2) Cl(2) extracts via polyamide yielded a MeOH fraction exhibiting a broad spectrum of side-chain saturated n-alkylresorcinols. While the n-alkylresorcinol pattern was similar for both plant species, some specific differences were observed for particular n-alkylresorcinol homologs. Finally, the investigation of H(2) O extracts by LC/MS/MS revealed the presence of depside constituents. Whereas, in M. perennis, a mixture of mercurialis acid (=(2R)-[(E)-caffeoyl]-2-oxoglutarate) and phaselic acid (=(E)-caffeoyl-2-malate) could be detected, in M. annua solely phaselic acid was found. By comparison with synthesized enantiomerically pure (2R)- and (2S)-phaselic acids, the configuration of the depside could be determined as (2S) in M. annua and as (2R) in M. perennis.

Multiresidue method for the determination of 13 pesticides in three environmental matrices: water, sediments and fish muscle.

Pesticides residues in aquatic ecosystems are an environmental concern which requires efficient analytical methods. In this study, we proposed a generic method for the quantification of 13 pesticides (azoxystrobin, clomazone, diflufenican, dimethachlor, carbendazim, iprodion, isoproturon, mesosulfuron-methyl, metazachlor, napropamid, quizalofop and thifensulfuron-methyl) in three environmental matrices. Pesticides from water were extracted using a solid phase extraction system and a single solid-liquid extraction method was optimized for sediment and fish muscle, followed by a unique analysis by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Limits of quantification were below 5 ng L(-1) for water (except for fluroxypyr and iprodion) and ranged between 0.1 ng g(-1) and 57.7 ng g(-1) for sediments and regarding fish, were below 1 ng g(-1) for 8 molecules and were determined between 5 and 49 ng g(-1) for the 5 other compounds. This method was finally used as a new routine practice for environmental research.

Simultaneous determination of flonicamid and its metabolites in vegetables using QuEChERS and reverse-phase liquid chromatography-tandem mass spectrometry.

This paper presents a rapid analytical method for the simultaneous determination of flonicamid and its metabolites N-(4-trifluoromethylnicotinoyl) glycine (TFNG), 4-trifluoromethylnicotinic acid (TFNA), and 4-trifluoromethylnicotinamide (TFNA-AM) in vegetables using QuEChERS by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Samples were extracted with acetonitrile. The extract was purified through QuEChERS method with primary secondary amine (PSA) and graphite carbon black (GCB). Then the extract was diluted with 0.1% formic acid in water, and analyzed by LC-MS/MS on a Waters Acquity BEH C18 column with methanol/0.1% formic acid in water as mobile phase with gradient elution. The linearity of the analytical response across the studied range of concentrations (0.20-500 µg/L) was excellent, obtaining correlation coefficients higher than 0.998. No significant matrix effects were observed. Recovery studies were carried out on spiked spinach and cucumber blank samples, at four concentration levels (0.01, 0.05, 0.50 and 2.0 mg/kg) performing six replicates at each level. Mean recoveries of 81.3-94.8% with CVs of 2.4-7.0% were obtained. The method demonstrated to be suitable for the simultaneous determination of flonicamid and its metabolites in vegetables.

Industrial application of green chromatography--I. Separation and analysis of niacinamide in skincare creams using pure water as the mobile phase.

In this work, chromatographic separation of niacin and niacinamide using pure water as the sole component in the mobile phase has been investigated. The separation and analysis of niacinamide have been optimized using three columns at different temperatures and various flow rates. Our results clearly demonstrate that separation and analysis of niacinamide from skincare products can be achieved using pure water as the eluent at 60°C on a Waters XTerra MS C18 column, a Waters XBridge C18 column, or at 80°C on a Hamilton PRP-1 column. The separation efficiency, quantification quality, and analysis time of this new method are at least comparable with those of the traditional HPLC methods. Compared with traditional HPLC, the major advantage of this newly developed green chromatography technique is the elimination of organic solvents required in the HPLC mobile phase. In addition, the pure water chromatography separations described in this work can be directly applied in industrial plant settings without further modification of the existing HPLC equipment.

Interactions between minimum run time, modifier concentration, and efficiency parameters in a high performance liquid chromatography separation.

We modeled and studied the separation of uracil, nicotinamide, resorcinol, theobromine, theophylline, and caffeine on four C-18 columns of different lengths packed with the same stationary phase using water/methanol mobile phase at one temperature. Predictions of retention times and peak widths were compared with experimental results and were found to be sufficiently accurate for performing optimization calculations. With limits set on the required resolution and on maximum values for pressure and flow rate, calculations were performed for numerous virtual column lengths seeking the smallest possible analysis time for each length while allowing methanol concentration and flow rate to vary as required to minimize run time. Predictions were experimentally verified for the column lengths actually available. These calculations revealed the dependence of best-possible analysis time on column length, modifier concentration, flow rate, and pressure for the real system that was modeled, and provided insight into parameter interactions with respect to analysis times meeting the needs and limits specified. We show that when these parameters are considered in concert, rather than individually, conventional guidelines regarding setting their values may not always lead to the optimum.

Separation of flavins and nicotinamide cofactors in Chinese hamster ovary cells by capillary electrophoresis.

Simultaneous extraction, separation and quantitation of reduced nicotinamide adenine dinucleotide (NADH), reduced nicotinamide adenine dinucleotide phosphate (NADPH), flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) in Chinese Hamster Ovary (CHO) cells were investigated. The separation of flavins and nicotinamide cofactors was performed by capillary electrophoresis with laser-induced fluorescence detection at the excitation wavelength of 325 nm. The separation protocol was established by investigating the excitation wavelength, high voltage and effects of buffer nature, pH and concentration. All endogenous fluorophores riboflavin, FAD, FMN, NADH and NADPH show wide linear range of quantitation. The limits of detection for the five compounds ranged from 4.5 to 23 nM. Extraction conditions were optimized for high-efficiency recovery of all endogenous fluorophores from CHO cells. To account for the complex matrix of cell extracts, a standard addition method was used to quantify FAD, FMN, NADH and NADPH in CHO cells. The quantitative results should be useful to reveal the metabolic status of cells. The protocols for extraction, separation and quantitation are readily adaptable to normal and cancer cell lines for the analysis of endogenous fluorophores.

[Fast separation of nicotinamide and nicotinic acid with molecularly imprinted monolithic column].

Nicotinamide has been employed as template for the preparation of molecularly imprinted monolithic polymer (MIP) which was used as liquid chromatographic stationary phase. It showed that the nicotinamide-MIP monolithic column was capable of recognizing the difference between nicotinamide and nicotinic acid, while the non-imprinted polymer had no such ability. The content of organic solvent, flow rate and pH of the mobile phase were investigated in the experiments. The following high performance liquid chromatographic conditions were selected: column, 50 mm x 4.6 mm i.d.; mobile phase, water; flow rate, 7.0 mL/min; experiment temperature, room temperature. The resolution between nicotinamide and nicotinic acid was 1.8. The results showed that the two compounds could be separated by the nicotinamide-MIP monolithic column. The column is very useful for the enrichment and detection of nicotinamide in body fluids.

Separation of water-soluble vitamins via high-performance capillary electrophoresis.

A standard sample and method for performance evaluation in capillary zone electrophoresis is defined. The sample, containing thiamine, nicotinamide and nicotinic acid, was analysed in a 20 mM sodium phosphate buffer pH 7. The impact of pH, buffer type and ionic strength on electroosmotic flow, electrophoretic mobility, and peak shape was investigated. The separation of several water-soluble vitamins in phosphate buffer pH 7 was developed in order to analyse an over-the-counter vitamin preparation. Spectral analysis and peak purity tests were applied on-line for peak identification.

Simultaneous determination of nicotinic acid and its two metabolites in human plasma using solid-phase extraction in combination with high performance liquid chromatography.

A high performance liquid chromatographic method for the simultaneous quantitative determination of nicotinic acid, nicotinamide and nicotinuric acid in human plasma is described. The method is based on solid phase extraction in combination with ion-paired reversed phase high performance liquid chromatography. Recoveries of nicotinic acid, nicotinamide and nicotinuric acid are 92.9, 95.8 and 87.8%, respectively. The procedure shown was applied to the determination of the plasma time-concentration profile of nicotinic acid, nicotinamide and nictotinuric acid after nicotinic acid ingestion in humans.

Rapid and quantitative separation of nicotinamide and its N1-methylated metabolite by Dowex AG50-X4 chromatography.

The use of column chromatography with Dowex AG50-X4 resin has allowed the quantitative separation of nicotinamide from its primary metabolite, N1-methylnicotinamide. Although the sensitivity is similar to earlier high-performance liquid chromatographic methods, this procedure allows multiple assays to be carried out simultaneously in a matter of minutes. This method should be useful to study nicotinamide methyltransferase activity in either whole cells or extracts, and is particularly well suited to screen column fractions for enzyme purification purposes.

Purification procedure for the determination of niacin vitamers in gastrointestinal contents and blood.

A solid phase extraction procedure for subsequent simultaneous HPLC analysis of free nicotinic acid (NIA) and nicotinamide (NAM) in dried or liquid rumen and gastrointestinal contents from sheep is described. Twenty-five mg dried samples were suspended in 1.0 ml of 0.1 mol/l Li2SO4 and centrifuged. The supernatants were passed through two 500 mg solid phase extraction columns (Bond Elut NH2 and Sep Pak C18), mounted in series, and eluted by a four step pH gradient procedure. Recoveries of the two vitameres were between 70 and 75%. Purification was satisfactory when the method was applied to different fractions of rumen content (e.g. to food residues, to a microbial preparation and to rumen fluid), to intestinal contents of sheep and to blood. In rumen fluid no free NIA and NAM was found. Food particles and rumen microbes contained no free NAM.

Chemical identification of a tumor-derived angiogenic factor.

Neoplasms produce substances that induce blood vessel formation (angiogenesis). Fractions from ethanol extracts of the Walker 256 carcinoma were isolated by silica column chromatography and C18 reversed-phase high-performance liquid chromatography. Two of the isolated fractions induced neovascularization when tested in the rabbit corneal micropocket assay. One of the fractions was identified as nicotinamide by desorption-electron impact mass spectrometry, nuclear magnetic resonance spectroscopy, and gas chromatography-mass spectrometry. The second active fraction contained nicotinamide as part of a more complex, as yet unidentified, molecular arrangement. Microgram quantities of commercial nicotinamide induced neovascularization in the corneal micropocket assay and in the chick chorioallantoic membrane assay.