Chemometric Comparison of Thin-Layer Chromatography,Gradient High-Performance Liquid Chromatography,and Computational Methods for Lipophilicity Assessment of Model Compounds

JPC – Journal of Planar Chromatography – Modern TLC - Thin-layer chromatography (TLC) on two adsorbents (RP18 and CN) and with six modifiers (acetonitrile, acetone, dioxane, propan...     

Capillary electrophoresis of microbial aggregates

Uncontrolled aggregation of bacterial cells is a significant disadvantage of electrophoretic separations. Various aspects of the electrophoretic behavior of different strains of Gram‐positive Bacillus cereus, Bacillus subtilis, Sarcina lutea, Staphylococcus aureus(1), and Micrococcus luteus bacteria and Gram‐negative Escherichia coli bacteria were investigated in this study. Our findings indicate that bacteria can be rapidly analyzed by CZE with surface charge modification by calcium ions (Ca²⁺). Bound Ca²⁺ ions increase zeta potential to more than 2.0 mV and significantly reduce repulsive forces. Under the above conditions, bacterial cells create compact aggregates, and fewer high‐intensity signals are observed in electropherograms. The above can be attributed to the bridging effect of Ca²⁺ between bacterial cells. CE was performed to analyze bacterial aggregates in an isotachophoretic mode. A single peak was observed in the electropherogram.     

Application of PLE for the determination of essential oil components from Thymus vulgaris L

Essential plants, due to their long presence in human history, their status in culinary arts, their use in medicine and perfume manufacture, belong to frequently examined stock materials in scientific and industrial laboratories. Because of a large number of freshly cut, dried or frozen plant samples requiring the determination of essential oil amount and composition, a fast, safe, simple, efficient and highly automatic sample preparation method is needed.Five sample preparation methods (steam distillation, extraction in the Soxhlet apparatus, supercritical fluid extraction, solid phase microextraction and pressurized liquid extraction) used for the isolation of aroma-active components from Thymus vulgaris L. are compared in the paper. The methods are mainly discussed with regard to the recovery of components which typically exist in essential oil isolated by steam distillation.According to the obtained data, PLE is the most efficient sample preparation method in determining the essential oil from the thyme herb. Although co-extraction of non-volatile ingredients is the main drawback of this method, it is characterized by the highest yield of essential oil components and the shortest extraction time required. Moreover, the relative peak amounts of essential components revealed by PLE are comparable with those obtained by steam distillation, which is recognized as standard sample preparation method for the analysis of essential oils in aromatic plants.     

Application of liquid chromatography-tandem mass spectrometry method for the simultaneous quantitative analysis of propentofylline and its chiral metabolite M1 in rats

A sensitive and selective liquid chromatographic–electrospray ionization mass spectrometric method for the simultaneous determination of propentofylline and enantiomers of its active metabolite M1 in rat serum, cortex and hippocampus was developed and validated according to GLP procedures. Sample preparations were carried out by liquid–liquid extraction using diethyl ether after the addition of the internal standard (pentoxifylline). The dried residue was reconstituted in mobile phase and injected onto a Chiralpak AD column (10 µm, 250 × 4.6 mm i.d.). The limit of quantification for propentofylline in serum, cortex and hippocampus was set at 0.25 ng/mL and for enantiomers of its metabolite M1 at 1.25 ng/mL. The established LC/ESI‐MS/MS method has been successfully applied to an initial pharmacokinetic study of propentofylline and also to assessment of distribution of parent drug and enantiomers of its pharmacologically active metabolite M1 to cortex and hippocampus after intravenous administration of propentofylline to rats at a dose of 5 mg/kg. Copyright © 2010 John Wiley & Sons, Ltd.     

New one-pot technique to introduce charged nanoparticles into a lyotropic liquid crystal matrix

We present a new method to incorporate hydrophilic charged nanoparticles into the lyotropic liquid crystal (LLC) template. This method is based on the effect of the polymer-induced phase separation (PIPS) and consists of two steps. In the first step, the nanoparticles are mixed with a surfactant micellar solution. In the second step, upon addition of polymer, phase separation is induced and the LLC phase doped with the nanoparticles is formed. Columnar hexagonal and lamellar LLC templates are obtained with the PIPS method. The ordering of the LLC phase can be controlled by the amount of polymer added to induce phase separation. The method works both for the system of nonionic surfactants and polymers and ionic surfactants and polyelectrolytes. We demonstrate that the PIPS method enables the fabrication of the LLC templates doped with positively or negatively charged nanoparticles as well as with a mixture of oppositely charged nanoparticles in arbitrary proportions.     

Evaluation of Two Techniques for Extraction of Cortisol from Human Saliva

The aim of the study was to compare two kinds of extraction of cortisol from human saliva. The first was made with dichloromethane and the second by solid-phase extraction. Saliva was sampled in the evening into plastic tubes then cortisol was extracted and analyzed by LC with detection at 240 nm. The limit of detection was 1 ng mL^?1 for extraction with dichloromethane and 3 ng mL^?1 for SPE extraction. Both methods of extraction were applied to the analysis of saliva samples without any interference peaks.     

Stinging Nettle (Urtica dioica L.) as a Functional Component in Durum Wheat Pasta Production: Impact on Chemical Composition,In Vitro Glycemic Index,and Quality Properties

Stinging nettle (Urtica dioica L.) is a good source of biologically active compounds with proven beneficial health effects. This study aimed to investigate the effect of nettle herb supplementation on chemical composition, including the content of selected minerals and pigments, the in vitro glycemic response, and the cooking and sensory quality of extruded pasta. Tagliatelle-shaped pasta was produced under semi-technical scale by partial replacement of durum wheat semolina with 0, 1, 2, 3, 4, and 5% of lyophilized nettle. The partial substitution with freeze-dried nettle caused a statistically significant (p ≤ 0.05) increase in the content of minerals, especially calcium, iron, potassium, and magnesium in the products. The calcium content in the pasta fortified with 5%-addition of stinging nettle was 175.9 mg 100 g⁻¹ and this concentration was 5.8 times higher than in the control sample. At the same time, high content of chlorophylls and carotenoids (237.58 µg g⁻¹ and 13.35 µg g⁻¹, respectively) was noticed. Enriching pasta with a 0–5% addition of stinging nettle resulted in a statistically significant (p ≤ 0.05) increase in the content of the total dietary fiber (TDF) (from 5.1 g 100 g⁻¹ to 8.82 g 100 g⁻¹) and the insoluble dietary fiber (IDF) (from 2.29 g 100 g⁻¹ to 5.63 g 100 g⁻¹). The lowest hydrolysis index of starch (HI = 17.49%) and the lowest glycemic index (GI = 49.31%) were noted for the pasta enriched with 3% nettle.     

Development of a High-Fibre Multigrain Bar Technology with the Addition of Curly Kale

The aim of this study was to find the effect of kale and dietary fibre (DF) on the physicochemical properties, nutritional value and sensory quality of multigrain bars. A recipe of multigrain bars was prepared with the addition of fresh kale (20% and 30%) and DF preparations (apple, blackcurrant, chokeberry and hibiscus). The bars were baked at 180 °C for 20 min. These snack bars, based on pumpkin seeds, sunflower seeds, flaxseed and wholegrain oatmeal, are a high-calorie product (302–367 kcal/100 g). However, the composition of the bars encourages consumption. In addition to the ability to quickly satisfy hunger, such bars are rich in many natural ingredients that are considered pro-health (high fibre content (9.1–11.6 g/100 g), protein (11.2–14.3 g/100 g), fat (17.0–21.1 g/100 g, including unsaturated fatty acids), carbohydrates (20.5–24.0 g/100 g), as well as vitamins, minerals and a large number of substances from the antioxidant group. The addition of kale caused a significant increase of water content, but reduction in the value of all texture parameters (TPA profiles) as well as calorific values. The content of polyphenols was strongly and positively correlated with the antioxidant activity (r = 0.92). In the bars with 30% addition of kale (422 mg GA/100 g d.m.), the content of polyphenols was significantly higher than based ones (334 mg GA/100 g d.m.). Bars with the addition of the DF were characterized by a higher antioxidant activity, and the content of carotenoids, chlorophyll A and B and polyphenols. High sensory quality was demonstrated for all (from 4.8 to 7.1 on a 10-point scale). The addition of fibre preparations was also related to technological aspects and allows to create attractive bars without additional chemicals.     

Au@Pt Core-Shell Nanoparticle Bioconjugates for the Therapy of HER2+ Breast Cancer and Hepatocellular Carcinoma. Model Studies on the Applicability of 193mPt and 195mPt Radionuclides in Auger Electron Therapy

^193mPt and ^195mPt radionuclides are therapeutically attractive Auger electron emitters with notably high Auger electron yield per decay. The present paper summarizes the first step of research on the applications of core-shell (Au@Pt) nanoparticles for electron Auger therapy of HER2+ (human epidermal growth factor receptor 2) breast cancer and hepatocellular carcinoma. Gold nanoparticles (30 nm) were synthesized covered with a platinum shell at high efficiency (>80%) and were further evaluated for in vitro studies such as binding affinity, internalization and cytotoxicity. To find the mechanism(s) responsible for platinum cytotoxicity in HepG2 cells, the platinum concentration in isolated cell nuclei and cytoplasm was determined using ICP-MS (inductively coupled plasma mass spectrometry). Lack of platinum in cell nuclei suggests that the cytotoxic effect is associated with the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Studies carried out on the SKOV-3 cell line with the use of a synthesized targeting bioconjugate (Au@Pt-PEG-trastuzumab) revealed a high affinity of this preparation to HER2+ cells, its internalization, its placement in the perinuclear area and partial intranuclear location. The specific binding for HER2 negative cells, MDA-MB-231, was negligible and Au@Pt-PEG-trastuzumab did not enter these cells. The results obtained are promising and warrant future investigation of Auger electron therapy using ^193mPt and ^195mPt based radiopharmaceuticals.     

Revisiting Thin-Layer Chromatography as a Lipophilicity Determination Tool. Part II — Is Silica Gel a Reliable Adsorbent for Lipophilicity Estimation?

JPC – Journal of Planar Chromatography – Modern TLC - Lipophilicity is often estimated by thin-layer chromatography (TLC) as a fundamental property related to biological and...