Liquid Chromatographic Mass Spectrometric Technique Research Articles

Metabolite Profiling by Hyphenated Liquid Chromatographic Mass Spectrometric Technique (HPLC-DAD-ESI-Q-TOF-MS/MS) and Neurobiological Potential of Haplophyllum sahinii and H. vulcanicum Extracts.

In the current study, the ethanol extracts of flower, stem, and root parts of two endemic Turkish species, e. g., Haplophyllum sahinii O. Tugay & D. Ulukuş and H. vulcanicum Boiss. & Heldr., were screened against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) associated with Alzheimer's disease as well as tyrosinase (TYR) linked to Parkinson's disease using ELISA microplate assay at 200 μg/mL. Among the extracts, the highest inhibition was caused by the stem extract of H. sahinii against BChE (IC50 =64.93±1.38 μg/mL). Consistently, all of the extracts were found to exert a selective inhibition towards BChE to some extent. It was only the root extract of H. vulcanicum that could inhibit AChE at low level (IC50 =203.18±5.33 μg/mL). None of the extracts displayed an inhibition over 50 % against TYR. Metabolite profiling of the extracts was achieved by a highly hyphenated liquid chromatographic mass spectrometric technique (HPLC-DAD-ESI-Q-TOF-MS/MS), which revealed the presence of furoquinoline (β-fagarine, γ-fagarine) and amide (tubasenicine, tubacetine) alkaloids; furano- (rutamarin), pyrano- (xanthyletine), and geranyloxy coumarins; phenylpropanoid (secoisolariciresinol), arylnaphthalene (mono-O-acetyldiphyllin apioside), and dibenzylbutyrolactone (kusunokinin, haplomyrfolin) lignans. Several important differences were observed between the extracts analyzed. β-Fagarine was the major alkaloid in H. vulcanicum, whereas γ-fagarine was present only in the roots of both Haplophyllum species; moreover, secoisolariciresinol and secoisolariciresinol dimethyl ether were the main lignans in the stems and flowers. This is the first study identifying ChE and TYR inhibitory effect and metabolic profiles of H. vulcanicum and H. sahinii.

Comparative pharmacokinetics of three triterpene acids in rat plasma after oral administration of Poria extract and its formulated herbal preparation: GuiZhi-FuLing capsule

A sensitive liquid chromatographic-mass spectrometric technique coupled with liquid–liquid extraction method was developed and validated for simultaneous determination of dehydro-tumulosic acid, tumulosic acid and polyporic acid C in rat plasma. The analytes were separated on a Kromasil C 18 column with a total running time of 12.5 min. Author had compared the pharmacokinetics of dehydro-tumulosic acid, tumulosic acid and polyporic acid C after oral administration of the extract of Poria and its formulated herbal preparation (GuiZhi-FuLing capsule). The improved pharmacokinetic profiles of the three compounds were found in the GuiZhi-FuLing capsule, indicating the more effective absorption and the slower elimination, compared with the Poria extract. Furthermore, this study revealed that as far as the Poria extract was concerned, it is very valuable to be used as a clinical instruction of GF capsule.

An improved assay for platelet-activating factor using HPLC-tandem mass spectrometry

We describe an improved assay for platelet-activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) using HPLC-tandem mass spectrometry (LC-MS/MS). The present method can readily detect as little as 1 pg (1.9 fmol) of PAF, a significant improvement over previously described LC-MS/MS methods, and gives a linear response up to 1,000 pg of PAF. Our method also overcomes the artifacts from isobaric lipids that have limited the usefulness of certain existing LC-MS/MS assays for PAF. In the course of these studies, we detected three novel lipid species in human neutrophils. One of the novel lipids appears to be a new molecular species of PAF, and the other two have chromatographic and mass spectrometric properties consistent with stearoyl-formyl-glycerophosphocholine and oleoyl-formyl-glycerophosphocholine. These observations identify previously unknown potential interferences in the measurement of PAF by LC-MS/MS. Moreover, our data suggest that the previously described palmitoyl-formyl-glycerophosphocholine is not unique but rather is a member of a new and poorly understood family of formylated lipids.

Organic pollutants in biological waste water treatment. Results of mass and tandem mass spectrometry of the flow injection mode compared with liquid chromatographic examinations: Polar compounds under positive ionization

Polar pollutants in the waste water of the Thessaloniki waste water treatment plant were qualitatively examined by substance-specific detection and identification methods. Many pollutants contained in the inflow could even be observed in the effluent together with their metabolites. To characterize these difficult to degrade and non-removable compounds, screening methods applying flow injection analysis and liquid chromatographic-mass spectrometric techniques, both in combination with soft ionizing interfaces like atmospheric pressure chemical ionization and electrospray ionization in the positive mode were used. After concentration by SPE, selective elution was performed prior to flow injection analysis or LC both in combination with MS detection. For identification of polar waste-water constituents tandem mass spectrometry by collision-induced dissociation and source CID were applied. Results obtained by substance-specific MS detection techniques are compared and discussed.

Sensitive and specific determination of midazolam and 1-hydroxymidazolam in human serum by liquid chromatography–electrospray mass spectrometry

A liquid chromatographic–mass spectrometric technique was designed for the determination of the anaesthetic benzodiazepine midazolam (MID) and its active metabolite 1-hydroxymidazolam (1-OHM), with the aim of conducting pharmacokinetic/pharmacodynamic studies. MID and 1-OHM were extracted from alkalinised (pH 9.5) spiked and clinical serum samples using a single step, liquid–liquid extraction procedure with diethyl ether–2-propanol (98:2, v/v). The chromatographic separation was performed on a Nucleosil C 18, 5 μm (150×1 mm I.D.) column, using a gradient of acetonitrile in 5 m M ammonium formate, pH 3.0 as the mobile phase, delivered at a flow-rate of 50 μl/min. The compounds were ionised in the ionspray source of an atmospheric pressure mass spectrometer, fragmented by in-source collisions and the pseudomolecular and fragment ions detected in the selected ion monitoring mode. The recovery was between 79 and 87% for MID, between 83 and 87% for 1-OHM and 81.5% for methylclonazepam. The limit of detection was 0.2 μg/l for MID and 0.5 μg/l for 1-OHM, the limit of quantitation (LOQ) was 0.5 μg/l for both. Linearity was verified from these LOQs up to 2000 μg/l and the method was found accurate and precise over this range. It was successfully applied to a preliminary study to establish the concentration versus time curve of MID and 1-OHM in a patient administered midazolam by continuous infusion.

Determination of Vincristine and Vinblastine in Catharanthus roseus Plants by High Performance Liquid Chromatography/ Electrospray Ionization Mass Spectrometry

A reversed phase high performance liquid chromatographic/ mass spectrometric (LC-MS) method with an electrospray ion source was used in this study to determine the concentration of two dimeric alkaloids, vinblastine and vincristine, in nearisogenic lines of Catharanthus leaves. A linear gradient of 25 mM ammonium acetate in methanol (solution A) and the same concentration in water (solution B) served as the mobile phase. A C18 column was used to separate those two compounds from other components in the extracted plant samples. Mass spectra generated by the electrospray ionization source were dominated by protonated molecules with little or no fragmentation being observed under the experimental conditions applied. Since very little fragmentation occurred. the method exhibited enhanced sensitivity over other LC-MS techniques. Product-ion mass spectra of vincristine and vinblastine were produced in a single quadrupole mass spectrometer through collision-induced dissociation (CID) between the capillary exit and first skimmer of the electrospray source. CID spectra can be used to unequivocally differentiate between vincristine, vinblastine and other alkaloids.

High-performance liquid chromatographic-mass spectrometric analysis of oligosaccharides from enzymatic digestion of glycosaminoglycans: Application to human samples

Glycosaminoglycan contents were evaluated in plasma and urine samples from volunteers treated intravenously with a mixture of dermatan sulphate and heparin, combining a novel liquid chromatographic-mass spectrometric technique for the determination of oligosaccharides from glycosaminoglycans with a classical technique for the extraction of glycosaminoglycans from biological samples (precipitation with cetylpyridinium chloride). In plasma samples dermatan sulphate and heparin can be measured for 2 h after treatment; urine excretion was detectable for 24 h. These results suggest that this novel approach is promising for future studies on the pharmacokinetics of glycosaminoglycans, although some technical aspects need further improvement, mainly regarding the procedures for sample clean-up; cetylpiridinium precipitations is a complex procedure and the recovery is limited.