Chromatographic profiles of tryptophan and kynurenine enantiomers derivatized with (S)‐4‐(3‐isothiocyanatopyrrolidin‐1‐yl)‐7‐(N,N‐dimethylaminosulfonyl)‐2,1,3‐benzoxadiazole using LC–MS/MS on a triazole‐bonded column

d ‐ and l ‐Tryptophan (Trp) and d ‐ and l ‐kynurenine (KYN) were derivatized with a chiral reagent, (S )‐4‐(3‐isothiocyanatopyrrolidin‐1‐yl)‐7‐(N,N‐dimethylaminosulfonyl)‐2,1,3‐benzoxadiazole (DBD‐PyNCS), and were separated enantiomerically by high‐performance liquid chromatography (HPLC) equipped with a triazole‐bonded column (Cosmosil HILIC) using tandem mass spectrometric (MS/MS) detection. Effects of column temperature, salt (HCO₂NH₄) concentration, and pH of the mobile phase in the enantiomeric separation, followed by MS detection of (S )‐DBD‐PyNCS‐d ,l ‐Trp and ‐d ,l ‐KYN, were investigated. The mobile phase consisting of CH₃CN/10 mM ammonium formate in H₂O (pH 5.0) (90/10) with a column temperature of 50–60 °C gave satisfactory resolution (R s) and mass‐spectrometric detection. The enantiomeric separation of d ,l ‐Trp and d ,l ‐KYN produced R s values of 2.22 and 2.13, and separation factors (α) of 1.08 and 1.08, for the Trp and KYN enantiomers, respectively. The proposed LC–MS/MS method provided excellent detection sensitivity of both enantiomers of Trp and KYN (5.1–19 nM).     

Analysis of Oxcarbazepine and the 10‐Hydroxycarbazepine Enantiomers in Plasma by LC‐MS/MS: Application in a Pharmacokinetic Study

Oxcarbazepine is a second‐generation antiepileptic drug indicated as monotherapy or adjunctive therapy in the treatment of partial seizures or generalized tonic–clonic seizures in adults and children. It undergoes rapid presystemic reduction with formation of the active metabolite 10‐hydroxycarbazepine (MHD), which has a chiral center at position 10, with the enantiomers (S)‐(+)‐ and R‐(?)‐MHD showing similar antiepileptic effects. This study presents the development and validation of a method of sequential analysis of oxcarbazepine and MHD enantiomers in plasma using liquid chromatography with tandem mass spectrometry (LC‐MS/MS). Aliquots of 100 μL of plasma were extracted with a mixture of methyl tert‐butyl ether: dichloromethane (2:1). The separation of oxcarbazepine and the MHD enantiomers was obtained on a chiral phase Chiralcel OD‐H column, using a mixture of hexane:ethanol:isopropanol (80:15:5, v/v/v) as mobile phase at a flow rate of 1.3 mL/min with a split ratio of 1:5, and quantification was performed by LC‐MS/MS. The limit of quantification was 12.5 ng oxcarbazepine and 31.25 ng of each MHD enantiomer/mL of plasma. The method was applied in the study of kinetic disposition of oxcarbazepine and the MHD enantiomers in the steady state after oral administration of 300 mg/12 h oxcarbazepine in a healthy volunteer. The maximum plasma concentration of oxcarbazepine was 1.2 µg/mL at 0.75 h. The kinetic disposition of MHD is enantioselective, with a higher proportion of the S‐(+)‐MHD enantiomer compared to R‐(?)‐MHD and an AUC^0‐12 _{S‐(+)/R‐(?)} ratio of 5.44. Chirality 25:897–903, 2013. © 2013 Wiley Periodicals, Inc.     

Analysis of sesquiterpene lactones in Eupatorium lindleyanum by HPLC‐PDA‐ESI‐MS/MS

Introduction – The aerial part Eupatorium lindleyanum is commonly used as an antipyretic and detoxicant clinically in traditional Chinese medicine. Our previous research showed that germacrane sesquiterpene lactones were its main active constituents, so the development of rapid and accurate methods for the identification of the sesquiterpene lactones is of great significance. Objective – To develop an HPLC‐PDA‐ESI‐MS/MS method capable for simple and rapid analysis of germacrane sesquiterpene lactones in the aerial part E. lindleyanum. Methodology – High‐performance liquid chromatography‐photodiode array detection‐electrospray ionization‐tandem mass spectrometry was used to analyze germacrane sesquiterpene lactones of Eupatorium lindleyanum. The fragmentation behavior of germacrane sesquiterpene lactones in a Micromass Q/TOF Mass Spectrometer was discussed, and 9 germacrane sesquiterpene lactones were identified by comparison of their characteristic data of HPLC and MS analyses with those obtained from reference compounds. Results – The investigated germacrane sesquiterpene lactones were identified as eupalinolides C (1), 3β‐acetoxy‐8β‐(4′‐hydroxy‐tigloyloxy)‐14‐hydroxy‐costunolide (2), eupalinolides A (3), eupalinolides B (4), eupalinolides E (5), 3β‐acetoxy‐8β‐(4′‐oxo‐tigloyloxy)‐14‐hydroxy‐heliangolide (6), 3β‐acetoxy‐8β‐(4′‐oxo‐ tigloyloxy)‐14‐hydroxy‐costunolide (7), hiyodorilactone B (8), and 3β‐acetoxy‐8β‐(4′‐hydroxy‐tigloyloxy)‐ costunolide (9). Compounds 6, 7 and 9 were reported for the first time. Conclusion – HPLC‐PDA‐ESI‐MS/MS provides a new powerful approach to identify germacrane sesquiterpene lactones in E. lindleyanum rapidly and accurately. Copyright © 2009 John Wiley & Sons, Ltd.     

Analysis of sesterterpenoids from Aspergillus terreus using ESI‐QTOF and ESI‐IT

Introduction – Biosynthesis of terretonin was studied due to the interesting skeleton of this series of sesterterpenoids. Very recently, López‐Gresa reported two new sesterterpenoids (terretonins E and F) which are inhibitors of the mammalian mitochondrial respiratory chain. Mass spectrometry (MS), especially tandem mass spectrometry, has been one of the most important physicochemical methods for the identification of trace natural products due to it rapidity, sensitivity and low levels of sample consumption. The potential application prospect and unique skeleton prompted us to study structural characterisation using MS. Objective – To obtain sufficient information for rapid structural elucidation of this class of compounds using MS. Methodology – The elemental composition of the product ions was confirmed by low‐energy ESI‐CID‐QTOF‐MS/MS analyses. The fragmentation pathways were postulated on the basis of ESI‐QTOF‐MS/MS/MS and ESI‐IT‐MSⁿ spectra. Common features and major differences between ESI‐QTOF‐MS/MS and IT‐MSⁿ spectra were compared. For ESI‐QTOF‐MS/MS/MS experiments, capillary exit voltage was raised to induce in‐source dissociation. Ammonium acetate or acetic acid were added into solutions to improve the intensity of [M + H]⁺. The collision energy was optimised to achieve sufficient fragmentation. Some fragmentation pathways were unambiguously proposed by the variety of abundance of fragment ions at different collision energies even without MSⁿ spectra. Results – Fragmentation pathways of five representative sesterterpenoids were elucidated using ESI‐QTOF‐MS/MS/MS and ESI‐IT‐MSⁿ in both positive‐ and negative‐ion mode. The key group of characterising fragmentation profiles was ring B, and these fragmentation patterns are helpful to identify different types of sestertepenoids. Conclusion – Complementary information obtained from fragmentation experiments of [M + H]⁺ (or [M + NH₄]⁺) and [M ? H]^? precursor ions is especially valuable for rapid identification of this kind of sesterterpenoid.     

A comparison of MS/MS‐based,stable‐isotope‐labeled,quantitation performance on ESI‐quadrupole TOF and MALDI‐TOF/TOF mass spectrometers

The peptide‐based quantitation accuracy and precision of LC‐ESI (QSTAR Elite) and LC‐MALDI (4800 MALDI TOF/TOF) were compared by analyzing identical Escherichia coli tryptic digests containing iTRAQ‐labeled peptides of defined abundances (1:1, 2.5:1, 5:1, and 10:1). Only 51.4% of QSTAR spectra were used for quantitation by ProteinPilot Software versus 66.7% of LC‐MALDI spectra. The average protein sequence coverages for LC‐ESI and LC‐MALDI were 24.0 and 18.2% (14.9 and 8.4 peptides per protein), respectively. The iTRAQ‐based expression ratios determined by ProteinPilot from the 57 467 ESI‐MS/MS and 26 085 MALDI‐MS/MS spectra were analyzed for measurement accuracy and reproducibility. When the relative abundances of peptides within a sample were increased from 1:1 to 10:1, the mean ratios calculated on both instruments differed by only 0.7–6.7% between platforms. In the 10:1 experiment, up to 64.7% of iTRAQ ratios from LC‐ESI MS/MS spectra failed S/N thresholds and were excluded from quantitation, while only 0.1% of the equivalent LC‐MALDI iTRAQ ratios were rejected. Re‐analysis of an archived LC‐MALDI sample set stored for 5 months generated 3715 MS/MS spectra for quantitation, compared with 3845 acquired originally, and the average ratios differed by only 3.1%. Overall, MS/MS‐based peptide quantitation performance of offline LC‐MALDI was comparable with on‐line LC‐ESI, which required threefold less time. However, offline LC‐MALDI allows the re‐analysis of archived HPLC‐separated samples.     

Bottom‐up proteome analysis of E. coli using capillary zone electrophoresis‐tandem mass spectrometry with an electrokinetic sheath‐flow electrospray interface

The Escherichia coli proteome was digested with trypsin and fractionated using SPE on a C18 SPE column. Seven fractions were collected and analyzed by CZE‐ESI‐MS/MS. The separation was performed in a 60‐cm‐long linear polyacrylamide‐coated capillary with a 0.1% v/v formic acid separation buffer. An electrokinetic sheath‐flow electrospray interface was used to couple the separation capillary with an Orbitrap‐Velos operating in higher‐energy collisional dissociation mode. Each CZE‐ESI‐MS/MS run lasted 50 min and total MS time was 350 min. A total of 23 706 peptide spectra matches, 4902 peptide IDs, and 871 protein group IDs were generated using MASCOT with false discovery rate less than 1% on the peptide level. The total mass spectrometer analysis time was less than 6 h, the sample identification rate (145 proteins/h) was more than two times higher than previous studies of the E. coli proteome, and the amount of sample consumed (<1 μg) was roughly fourfold less than previous studies. These results demonstrate that CZE is a useful tool for the bottom‐up analysis of prokaryote proteomes.     

Preparative isolation and purification of four flavonoids from the petals of nelumbo nucifera by high‐speed counter‐current chromatography

Introduction – Flavonoids, the primary constituents of the petals of Nelumbo nucifera, are known to have antioxidant properties and antibacterial bioactivities. However, efficient methods for the preparative isolation and purification of flavonoids from this plant are not currently available. Objective – To develop an efficient method for the preparative isolation and purification of flavonoids from the petals of N. nucifera by high‐speed counter‐current chromatography (HSCCC). Methodology – Following an initial clean‐up step on a polyamide column, HSCCC was utilised to separate and purify flavonoids. Purities and identities of the isolated compounds were established by HPLC‐PAD, ESI‐MS, ¹H‐NMR and ¹³C‐NMR. Results – The separation was performed using a two‐phase solvent system composed of ethyl acetate–methanol–water–acetic acid (4 : 1 : 5 : 0.1, by volume), in which the upper phase was used as the stationary phase and the lower phase was used as the mobile phase at a flow‐rate of 1.0 mL/min in the head‐to‐tail elution mode. Ultimately, 5.0 mg syringetin‐3‐O‐β‐d‐glucoside, 6.5 mg quercetin‐3‐O‐β‐d‐glucoside, 12.8 mg isorhamnetin‐3‐O‐β‐d‐glucoside and 32.5 mg kaempferol‐3‐O‐β‐d‐glucoside were obtained from 125 mg crude sample. Conclusion – The combination of HSCCC with a polyamide column is an efficient method for the preparative separation and purification of flavonoids from the petals of N. nucifera. Copyright © 2009 John Wiley & Sons, Ltd.     

A laser ablation ICP‐MS based method for multiplexed immunoblot analysis: applications to manganese‐dependent protein dynamics of photosystem II in barley (Hordeum vulgare L.)

Manganese (Mn) constitutes an essential co‐factor in the oxygen‐evolving complex of photosystem II (PSII). Consequently, Mn deficiency reduces photosynthetic efficiency and leads to changes in PSII composition. In order to study these changes, multiplexed protein assays are advantageous. Here, we developed a multiplexed antibody‐based assay and analysed selected PSII subunits in barley (Hordeum vulgare L.). A selection of antibodies were labelled with specific lanthanides and immunoreacted with thylakoids exposed to Mn deficiency after western blotting. Subsequently, western blot membranes were analysed by laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS), which allowed selective and relative quantitative analysis via the different lanthanides. The method was evaluated against established liquid chromatography electrospray ionization tandem mass spectrometry (LC‐ESI‐MS/MS) methods, based on data‐dependent acquisition (DDA) and selected reaction monitoring (SRM). Manganese deficiency resulted in a general decrease in PSII protein abundances, an effect that was shown to be reversible upon Mn re‐supplementation. Specifically, the extrinsic proteins PsbP and PsbQ showed Mn‐dependent changes in abundances. Similar trends in the response to Mn deficiency at the protein level were observed when comparing DDA, SRM and LA‐ICP‐MS results. A biologically important exception to this trend was the loss of PsbO in the SRM analysis, which highlights the necessity of validating protein changes by more than one technique. The developed method enables a higher number of proteins to be multiplexed in comparison to existing immunoassays. Furthermore, multiplexed protein analysis by LA‐ICP‐MS provides an analytical platform with high throughput appropriate for screening large collections of plants.     

Ultra‐performance convergence chromatography with tandem mass spectrometry‐assisted method for rapid enantioseparation and determination of fluazifop‐butyl in tobacco and soil

A quick, green, and sensitive method for chiral separation and determination of fluazifop‐butyl enantiomers in tobacco and soil was established by ultra‐performance convergence chromatography with tandem mass spectrometry (UPC²‐MS/MS). The baseline separation was obtained on an ACQUITY UPC² Trefoil CEL2 column in 4 minutes with CO₂ and methanol as mobile phase. Column temperature, auto back pressure regulator pressure (ABPR), and modifier solvent were optimized to obtain the best separation efficiency. Under the optimal conditions, the recoveries of both enantiomers were 82.8% to 99.5% with relative standard deviations (RSDs) less than 5.5% at three different concentration levels in two matrices. Good coefficients of determination (R² ≥ 0.9976) were achieved over the concentration range of 10 to 500 ng/mL. The limits of detection (LODs) for all enantiomers in the two matrices varied from 1.6 to 2.1 μg/kg, and the limits of quantification (LOQs) did not exceed 7.0 μg/kg. The proposed method was then successfully applied to analyze authentic samples, confirming that it was a green, convenient, and reliable strategy for the analysis of fluazifop‐butyl enantiomers in tobacco and soil.     

Bioimaging of multiple elements by high‐resolution LA‐ICP‐MS reveals altered distribution of mineral elements in the nodes of rice mutants

Inter‐vascular transfer in rice (Oryza sativa) nodes is required for delivering mineral elements to developing tissues, which is mediated by various transporters in the nodes. However, the effect of these transporters on distribution of mineral elements in the nodes at a cellular level is still unknown. Here, we established a protocol for bioimaging of multiple elements at a cellular level in rice node by laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS), and compared the mineral distribution profile between wild‐type (WT) rice and mutants. Both relative comparison of mineral distribution normalized by endogenous ¹³C and quantitative analysis using spiked standards combined with soft ablation gave valid results. Overall, macro‐nutrients such as K and Mg were accumulated more in the phloem region, while micro‐nutrients such as Fe and Zn were highly accumulated at the inter‐vascular tissues of the node. In mutants of nodal Zn transporter OsHMA2, Zn localization pattern in the node tissues did not differ from that of WT; however, Zn accumulation in the inter‐vascular tissues was lower in uppermost node I but higher in the third upper node III compared with the WT. In contrast, Si deposition in the mutants of three nodal Si transporters Lsi2, Lsi3 and Lsi6 showed different patterns, which are consistent with the localization of these transporters. This improved LA‐ICP‐MS analysis combined with functional characterization of transporters will provide further insight into mineral element distribution mechanisms in rice and other plant species.     

Discovery and identification of serum potential biomarkers for pulmonary tuberculosis using iTRAQ‐coupled two‐dimensional LC‐MS/MS

Pulmonary tuberculosis (TB) caused by Mycobacterium tuberculosis is a chronic disease. Currently, there are no sufficiently validated biomarkers for early diagnosis of TB infection. In this study, a panel of potential serum biomarkers was identified between patients with pulmonary TB and healthy controls by using iTRAQ‐coupled 2D LC‐MS/MS technique. Among 100 differentially expressed proteins screened, 45 proteins were upregulated (>1.25‐fold at p < 0.05) and 55 proteins were downregulated (<0.8‐fold at p < 0.05) in the TB serum. Bioinformatics analysis revealed that the differentially expressed proteins were related to the response to stimulus, the metabolic and immune system processes. The significantly differential expression of apolipoprotein CII (APOCII), CD5 antigen‐like (CD5L), hyaluronan‐binding protein 2 (HABP2), and retinol‐binding protein 4 (RBP4) was further confirmed using immunoblotting and ELISA analysis. By forward stepwise multivariate regression analysis, a panel of serum biomarkers including APOCII, CD5L, and RBP4 was obtained to form the disease diagnostic model. The receiver operation characteristic curve of the diagnostic model was 0.98 (sensitivity = 93.42%, specificity = 92.86%). In conclusion, APOCII, CD5L, HABP2, and RBP4 may be potential protein biomarkers of pulmonary TB. Our research provides useful data for early diagnosis of TB.     

Over 4100 protein identifications from a Xenopus laevis fertilized egg digest using reversed‐phase chromatographic prefractionation followed by capillary zone electrophoresis–electrospray ionization–tandem mass spectrometry analysis

A tryptic digest generated from Xenopus laevis fertilized embryos was fractionated by RPLC. One set of 30 fractions was analyzed by 100‐min CZE‐ESI‐MS/MS separations (50 h total instrument time), and a second set of 15 fractions was analyzed by 3‐h UPLC‐ESI‐MS/MS separations (45 h total instrument time). CZE‐MS/MS produced 70% as many protein IDs (4134 versus 5787) and 60% as many peptide IDs (22 535 versus 36 848) as UPLC‐MS/MS with similar instrument time (50 h versus 45 h) but with 50 times smaller total consumed sample amount (1.5 μg versus 75 μg). Surprisingly, CZE generated peaks that were 25% more intense than UPLC for peptides that were identified by both techniques, despite the 50‐fold lower loading amount; this high sensitivity reflects the efficient ionization produced by the electrokinetically pumped nanospray interface used in CZE. This report is the first comparison of CZE‐MS/MS and UPLC‐MS/MS for large‐scale eukaryotic proteomic analysis. The numbers of protein and peptide identifications produced by CZE‐ESI‐MS/MS approach those produced by UPLC‐MS/MS, but with nearly two orders of magnitude lower sample amounts.     

O‐Glycosylated 24 kDa human growth hormone has a mucin‐like biantennary disialylated tetrasaccharide attached at Thr‐60

MS was used to characterize the 24 kDa human growth hormone (hGH) glycoprotein isoform and determine the locus of O‐linked oligosaccharide attachment, the oligosaccharide branching topology, and the monosaccharide sequence. MALDI‐TOF/MS and ESI‐MS/MS analyses of glycosylated 24 kDa hGH tryptic peptides showed that this hGH isoform is a product of the hGH normal gene. Analysis of the glycoprotein hydrolysate by high‐performance anion‐exchange chromatography with pulsed amperometric detection and HPLC with fluorescent detection for N‐acetyl neuraminic acid (NeuAc) yielded the oligosaccharide composition (NeuAc₂, N‐acetyl galactosamine₁, Gal₁). After β‐elimination to release the oligosaccharide from glycosylated 24 kDa hGH, collision‐induced dissociation of tryptic glycopeptide T6 indicated that there had been an O‐linked oligosaccharide attached to Thr‐60. The sequence and branching structure of the oligosaccharide were determined by ESI‐MS/MS analysis of tryptic glycopeptide T6. The mucin‐like O‐oligosaccharide sequence linked to Thr‐60 begins with N‐acetyl galactosamine and branches in a bifurcated topology with one appendage consisting of galactose followed by NeuAc and the other consisting of a single NeuAc. The oligosaccharide moiety lies in the high‐affinity binding site 1 structural epitope of hGH that interfaces with both the growth hormone and the prolactin receptors and is predicted to sterically affect receptor interactions and alter the biological actions of hGH.     

Structural Characterisation of Alkaloids in Leaves and Roots of Stephania kwangsiensis by LC‐QTOF‐MS

Introduction

The tuberous roots of Stephania kwangsiensis, which contain bioactive alkaloids, are used as a traditional Chinese medicine. Overexploitation of the roots has made the plant increasingly rare, and the abundant leaves of the same plant may offer a potential alternative. However, there is insufficient phytochemical information for a comparison of alkaloid compositions in the two parts.

Objective

To characterise and compare the alkaloids in the leaves and roots of S. kwangsiensis.

Methods

The alkaloids in S. kwangsiensis were characterised using high pressure liquid chromatography coupled with positive electrospray ionisation quadrupole time‐of‐flight tandem mass spectrometry (HPLC‐(+)ESI‐QTOF‐MS/MS). The alkaloid compositions in the leaves and roots were compared by visual inspection combined with principal component analysis (PCA) of the HPLC‐MS data.

Results

Seventy‐five alkaloids comprising aporphine‐, proaporphine‐, protoberberine‐, benzylisoquinoline‐, bisbenzylisoquinoline‐ and morphine‐type alkaloids were identified or tentatively identified in the roots and leaves of S. kwangsiensis. Sixty‐three of these alkaloids have not been previously reported in this species, and three have not been previously reported in the literature. The roots and leaves had similarities in alkaloid composition but differences in the peak intensities of most alkaloids. The PCA revealed that the samples were clustered into two distinct groups, which corresponded to leaves and roots.

Conclusion

This study further clarified the chemical constituents in the roots of S. kwangsiensis, and revealed that diverse alkaloids were also present in the leaves. The comparative chemical profiling of the two parts provides useful information on their potential medicinal use. Copyright © 2017 John Wiley & Sons, Ltd.     

A simple and efficient frit preparation method for one‐end tapered‐fused silica‐packed capillary columns in nano‐LC‐ESI MS

A novel frit preparation method for one‐end tapered‐fused silica‐packed capillary columns in nano‐LC‐ESI MS was developed. A hollow‐fused silica capillary column with a tapered tip as nano‐spray emitter was filled with 5 μm C₁₈ beads, and then a sintered frit about 0.25 mm in length was prepared at the tip by butane flame. A stainless steel protection tube with 0.5 mm id was used to control the length of the frit and to protect the packed C₁₈ beads behind the sintered frit during the sintering. C₁₈ sintered frits were evaluated by BSA tryptic digests with nano‐LC‐LTQ. The sintered frits did not produce post‐column band broadening due to very small volume (about 0.2 nL) and did not produce adsorption to sample. The sintered frit columns had good separation reproducibility and separation performance compared with self‐assembled particles frit columns and commercial columns.     

Transformation of Arsenobetaine and Growth of Bacteria on Zeolitic Tuffs

Arsenobetaine (AsB) is a known organoarsenical of harmless toxicity. It is formed mainly by the metabolization of arsenate in marine organisms such as fish, mollusks and crustaceans. Preliminary investigations have shown that AsB can be degraded in contact with zeolites used as feed additives. Employing high‐performance liquid chromatography (HPLC) combined with simultaneous parallel electrospray ionization (ESI) and inductively coupled plasma mass spectrometric (ICP‐MS) detection, the formation of degradation products was monitored over fifty days in batch reactors containing AsB and clinoptilolites in an aqueous solution. After a 50‐day contact with different natural Mexican zeolites, the AsB concentration decreased by 37 to 100 %. In contrast, no degradation products of AsB were detected after contact with a synthetic clinoptilolite. The formation of dimethyl (1‐carboxymethyl) arsine and arsenate proceeded with different yields in the set of four natural zeolites. To search for the presence of bacteria on the zeolites as an alternative explanation for the metabolism of AsB in our experiments, the growth of microorganisms was studied on two natural clinoptilolites from Hungary and Mexico after severe acid wash. After 10 days of cultivation in iron and sulfur media, almost a threefold increase of the microbial population was observed. In further experiments on the retention of inorganic arsenic, one sample retained, for example, 25 μg/g As(V) and 2.5 μg/g As(III) from a 400 μg/L arsenic solution.     

NMR,HS‐SPME‐GC/MS,and HPLC/MSn Analyses of Phytoconstituents and Aroma Profile of Rosmarinus eriocalyx

In this work, a comprehensive study on the chemical constituents of the aerial parts of Rosmarinus eriocalyx (Lamiaceae), an aromatic shrub traditionally consumed as a food and herbal remedy in Algeria, is presented. The aroma profile was analysed by headspace solid phase microextraction (HS‐SPME) coupled with gas chromatography‐mass spectrometry (GC/MS), whereas the crude extract constituents were analyzed by ¹H‐NMR and by high performance liquid chromatography coupled with mass spectrometry (HPLC/MSⁿ). Thirty‐nine volatile compounds, most of them being monoterpenes, have been identified, with camphor, camphene, and α‐pinene as the most abundant constituents. ¹H‐NMR analysis revealed the presence of phenolic compounds and betulinic acid while HPLC/MSⁿ allowed the identification of glycosilated and aglyconic flavonoids as well as phenylpropanoid derivatives. Some of these constituents, namely as betulinic acid, rosmanol, and cirsimaritin were reported for the first time in R. eriocalyx.     

UHPLC/HR‐ESI‐MS/MS Profiling of Phenolics from Tunisian Lycium arabicum Boiss. Antioxidant and Anti‐lipase Activities’ Evaluation

This study was performed in the aim to evaluate nine different extracts from Tunisian Lycium arabicum for their total phenolic and total flavonoid contents, phytochemical analyses as well as their antioxidant and anti‐lipase activities. The in vitro antioxidant property was investigated using three complementary methods (DPPH, ferric reducing antioxidant power (FRAP), and β‐carotene‐linoleic acid bleaching assays) while anti‐lipase activity was evaluated using 4‐methylumbelliferyl oleate method. From all of the tested extracts the most potent found to be the polar MeOH extracts especially those of stems and leaves. In order to investigate the chemical composition of these extracts and possible correlation of their constituents with the observed activities, an UHPLC/HR‐ESI‐MS/MS analysis was performed. Several compounds belonging to different chemical classes were tentatively identified such as rutin and kampferol rutinoside, the major constituents of the leaves, and N‐caffeoyltyramine, lyciumide A, N‐dihydrocaffeoyltyramine as well as fatty acids: trihydroxyoctadecadienoic acid and hydroxyoctadecadienoic acid isomers were detected abundantly in the stems. These results showed that the MeOH extracts of stems and leaves of L. arabicum can be considered as a potential source of biological active compounds.     

Study of the Se-containing metabolomes in Se-rich yeast by size-exclusion-cation-exchange HPLC with the parallel ICP MS and electrospray orbital ion trap detection

Strong cation exchange HPLC with the parallel ICP MS and electrospray hybrid linear ion trap quadrupole orbital trap mass spectrometry (ESI Orbitrap MS) detection was developed for the study of the metabolomic pattern of selenium in selenium-rich yeast. The mobile phase composition (gradient of ammonium formate in 20% methanol) was optimized to obtain separation in conditions guaranteeing the identical ICP MS sensitivity during the entire chromatographic run and the compatibility with electrospray ionization. Twenty seven Se-containing metabolites observed in the HPLC-ICP MS chromatogram were identified by ESI Orbitrap MS based on the Se isotopic pattern, the accurate molecular mass, and the multistage fragmentation patterns. The method allowed for the first time the correlation of the differences observed in HPLC-ICP MS chromatography of water extracts of Se-rich yeast samples from different manufacturers with the identity of the eluted compounds determined by ESI MS.