Evaluation of the free radical scavenging capability of wheat extracts by capillary electrophoresis and multivariate curve resolution.

In the current work, phenolic acids were analysed and their radical scavenging activity evaluated by CE, including the quantification of overlapping peaks by applying the multivariate curve resolution (MCR) method. To investigate radical scavenging activity, the solution of phenolic acids was treated with a stable free 2,2-diphenyl-1-picrylhydrazyl radical of different concentrations and the radical scavenging activity of the reaction mixture was monitored. The radical scavenging reaction was also applied to wheat bran extracts. The overlapping peaks on the electropherograms of both mixtures of standard compounds and extracts of different wheat bran varieties were resolved by using the MCR method, assuming that the overlapping compounds have different UV spectra. MCR enabled the insufficient resolution between syringic and ferulic acids to be effectively resolved.

Variation in the composition of the essential oils, phenolic compounds and mineral elements of Hypericum perforatum L. growing in Estonia.

A comprehensive investigation of the chemical composition of the aerial parts of Hypericum perforatum L. collected in three habitations in Estonia was carried out. An analysis by gas chromatography-mass spectrometry and gas chromatography-flame ionisation detection established the main components of the essential oils. The phenolic compounds both in ethanol and water extracts of the plant were analysed using liquid chromatography-mass spectrometry (LC-MS) and capillary zone electrophoresis. In addition to the earlier published polyphenols, several new phenolic acids and flavonoids, such as quercetin hexoside malonates and an A-type catechin-epicatechin trimer were identified in this Hypericum for the first time. The contents of the pharmaceutically important antidepressants hyperforin and hypericin were also estimated by LC-MS and compared with the data in the literature. The composition of the mineral elements was determined by atomic absorption spectroscopy. The results of the study demonstrate a rather high variability in the content of different substance groups in H. perforatum L. and, hence, the need for a survey of the raw material in the course of selection of raw materials for pharmaceutical preparations.

Enantioselective CE analysis of hepatic ketamine metabolism in different species in vitro.

Ketamine, an injectable anesthetic and analgesic consisting of a racemic mixture of S-and R-ketamine, is routinely used in veterinary and human medicine. Nevertheless, metabolism and pharmacokinetics of ketamine have not been characterized sufficiently in most animal species. An enantioselective CE assay for ketamine and its metabolites in microsomal preparations is described. Racemic ketamine was incubated with pooled microsomes from humans, horses and dogs over a 3 h time interval with frequent sample collection. CE data revealed that ketamine is metabolized enantioselectively to norketamine (NK), dehydronorketamine and three hydroxylated NK metabolites in all three species. The metabolic patterns formed differ in production rates of the metabolites and in stereoselectivity of the hydroxylated NK metabolites. In vitro pharmacokinetics of ketamine N-demethylation were established by incubating ten different concentrations of racemic ketamine and the single enantiomers of ketamine for 8 min and data modeling was based on Michaelis-Menten kinetics. These data revealed a reduced intrinsic clearance of the S-enantiomer in the racemic mixture compared with the single S-enantiomer in human microsomes, no difference in equine microsomes and the opposite effect in canine microsomes. The findings indicate species differences with possible relevance for the use of single S-ketamine versus racemic ketamine in the clinic.

Analysis of the stable free radical scavenging capability of artificial polyphenol mixtures and plant extracts by capillary electrophoresis and liquid chromatography-diode array detection-tandem mass spectrometry.

The oxidation process of phenolic compounds of an artificial mixture consisting of six polyphenols and the extract of eggplant (Solanum melongena) skin was monitored by using capillary zone electrophoresis and liquid chromatography-diode array detection-tandem mass spectrometry. The methods developed enabled simultaneous evaluation of the antioxidative capability of each compound. The above oxidation process was carried out using two radicals, viz. the 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radicals generated via the Fenton reaction. The radical scavenging effects of artificial and natural polyphenol mixtures were compared.

Fraction collection in capillary electrophoresis for various stand-alone mass spectrometers.

A procedure for collecting fractions during capillary electrophoresis for their analysis using various stand-alone instruments is described. The results of a systematic study of the optimization and application of capillary electrophoresis (CE) in conjunction with a reverse-phase high-performance liquid chromatography electrospray ionization quadrupole time of flight-tandem mass spectrometry (RP-HPLC-ESI-Q-TOF-MS/MS) and inductively-coupled mass spectrometry (ICP-MS) to the analysis of the seed extract of the Japanese Pagoda Tree (Sophora japonica) are presented. The off-line coupling of CE to the matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) for the proteins mixture was applied. The cathode end of the capillary was placed inside a stainless steel needle using a coaxial liquid-sheath-flow configuration. The optimization of experimental parameters resulted in an efficient methodology for MS analysis of fractions. Several components contained in the extract of S. japonica were identified, some not previously known. It was demonstrated that low sensitivity, which is a real problem in off-line CE-MS analysis, could be tolerated because of a more flexible optimization of the CE separation conditions and the choice of independent stand-alone instruments for analysis of separated fractions. The estimated limit of detection for CE-RP-HPLC-ESI-Q-TOF-MS was 50 microM of polyphenols and for CE-ICP-MS, 1-100 microg/l.

Evaluation of antioxidative capability of the tomato (Solanum lycopersicum) skin constituents by capillary electrophoresis and high-performance liquid chromatography.

In the current study, phenolic compounds of the tomato (Solanum lycopersicum) skin extract were separated and their composition was determined by capillary electrophoresis and tandem high-performance liquid chromatography diode array detection-mass spectrometry (HPLC-DAD-MS/MS). Both the total phenolic and flavonoid contents of the extract were determined. The antioxidative capability of the extract was measured using a stable free radical 2,2-diphenyl-1-picrylhydrazyl assay. The monitoring of the radical scavenging capability of specific phenolic compounds was carried out both by capillary electrophoresis and HPLC-MS/MS.

Bioactive components of the hop strobilus: comparison of different extraction methods by capillary electrophoretic and chromatographic methods.

In the present study, the composition of the hop strobilus extract by using different extraction methods under different solvent conditions was analysed and compared. Several separation methods were applied to obtaining detailed information about the hop extract: capillary zone electrophoresis (CZE), high-performance liquid chromatography-mass-spectrometry (HPLC-MS/MS) and gas chromatography-mass-spectrometry (GC-MS). The electropherograms of different extracts varied dramatically. The oxidation reaction of the hop strobilus extract was examined.