Composition,Anti-MRSA Activity and Toxicity of Essential Oils from Cymbopogon Species

Many of the essential oils obtained from medicinal plants possess proven antimicrobial activity and are suitable for medicinal purposes and applications in the food industry. The aim of the present work was the chemical analysis of 19 essential oils (EOs) from seven different Cymbopogon species (C. nardus, C. citratus, C winterianus, C. flexuosus, C. schoenanthus, C. martinii, C. giganteus). Five different chemotypes were established by GC/MS and TLC assay. The EOs, as well as some reference compounds, i.e., citronellol, geraniol and citral (neral + geranial), were also tested for their antimicrobial and antibiofilm activity against methicillin-resistant Staphylococcus aureus (MRSA) by the microdilution method and direct bioautography. The toxicity of EOs was evaluated by Danio rerio ‘Zebrafish’ model assay. All examined EOs showed moderate to high activity against MRSA, with the highest activity noted for C. flexuosus—lemongrass essential oil, both in microdilution and direct autobiography method. Significant difference in the toxicity of the examined EOs was also detected.     

Phase and Element Contents of the cBN Based Composites as Estimated by XPS

X-ray photoelectron spectroscopy (XPS) is used to estimate phase and element contents of the composites based on cubic boron nitride. A composite is a mixture of several compounds and the use of traditional X-ray diffraction for phase analysis in many cases can be difficult. By using XPS, we were able to evaluate the atomic concentration of elements and the content of different compounds of each element. SEM and XPS showed that samples are heterogeneous. The TiB₂ phase, expecting from thermodynamic calculations, was formed in both investigated samples of cBN/Ti₃SiC₂/TiC but in different amount. The Ti₃SiC₂ additive was found more chemically active then TiC.     

Preparation and characterisation of monolayers and Langmuir–Blodgett films of liquid crystal mixed with cubic silsesquioxanes

Polyhedral oligomeric silesquioxanes (POSS) with eight polyether substituents were mixed with the liquid crystal (LC) 4-octyloxy-4′-cyanobiphenyl and spread at the air/water interface. The surface pressure-area and surface potential-area isotherms were recorded for different weight ratios of both components. The obtained results showed that POSS molecules had beneficial influence on LC monolayer improving its stability and rigidity. Moreover, it was found that some LC–POSS mixtures collapse reversibly and form multilayer films on the top of LC monolayer. On the other hand, interfacial dilatational and shear rheology indicated decrease of elasticity of the films after mixing. Brewster angle microscopy revealed multilayer structure of the condensed film and formation of net-like structures in the expanded film. These films were successfully transferred on solid substrates using the Langmuir–Blodgett technique. The scanning electron microscopy images confirmed the film deposition and formation of networks by POSS–LC mixtures. These findings may be useful in the fabrication of electronic devices based on LCs.     

Thiazolidine-4-carboxylic acid and 2-aminothiazoleethanoic acid as ligands. The synthesis, magnetic, e.p.r. and spectral properties of copper(II) complexes

Summary Two complexes formed from Cu^II acetate and thiazolidine-4-carboxylic acid (4-TCA) and 2-amino-4-thiazoleethanoic acid (ATAA) have been prepared and characterized by magnetic and spectroscopic techniques. The influence of the nature of ligands and solvents upon Cu^II e.p.r. properties was investigated for these compounds, Spin-Hamiltonian parameters from these data enabled suggestions concerning the structure of these complexes and the binding ability of the ligands.     

Application of Organolithium and Related Reagents in Synthesis, Part 29 [1]. A Concise Regiospecific Conversion of Benzoic Acids into 5-(2-Carboxyphenyl)-5-phenylpent-2-enoic Acids

A convenient two-step protocol preparation of ortho-alkylated (substituent with the carbomethoxy group at the end of five carbon atoms alkyl chain) aromatic carboxylic acids from benzoic acids anilides is described. Ortho-lithiation of benzanilides and subsequent reaction of the generated bis(N- and C-ortho-)-lithiated anilides with aromatic aldehydes provided 3-arylphthalides. In the next step, these phthalides were converted into 5-(2-carboxyphenyl)-5-phenylpent-2-enoic acids by treatment with 1-methoxy-1-trimethylsilyloxybuta-1,3-diene.     

Reproducible tritium generation in electrochemical cells employing palladium cathodes with high deuterium loading

Reproducible tritium generation well above background has been observed in tightly closed D₂SO₄-containing cells in four out of four Pd wire cathodes of one type. Tritium analysis was performed before and after each experiment on the Pd, the electrolyte and the gas in the head space. No tritium generation was observed in four identical Pd cathodes in H₂SO₄ cells operated at the same time under the same conditions. A cyclic loading-unloading regime with low current densities, rather than the usual continuous constant current regime, was employed to attain D/Pd and H/Pd loadings of 1±0.05 reproducibly. D/Pd loadings greater than 0.8±0.05 appear to be necessary to generate tritium. The largest amount of tritium, generated in 7 days of continuous electrolysis, was 2.1 × 10¹¹ tritium atoms, compared with a background of 4 × 10⁹ tritium atoms. The concentration of tritium and its axial distribution in the Pd were determined and concentrations of up to 9 × 10¹⁰ atoms/g Pd were found compared with a maximum background of 5 × 10⁸ atoms g⁻¹. The T/D ratio in the Pd is about 100 times larger than in the electrolyte or gas and indicates that tritium generation occurs in the Pd interior rather than at its surface. No tritium generation was observed in two other types of Pd electrodes in D₂SO₄, despite the attainment of D/Pd ratios near 1:1. Thus high D/Pd ratios appear to be a necessary but not sufficient condition for tritium generation in D₂SO₄ electrolysis.     

Selection of the sample composition for the selective preconcentration of some platinum group metal ions by Donnan dialysis

The possibility of selective preconcentration of platinum group metal ions by Donnan dialysis was investigated. The effect of sample matrix (glycine) on self diffusion of the following platinum group metal ions Pt(IV), Pd(II), Rh(III), Ir(III) and Ir(IV) was determined. To separate a sample from the receiver electrolyte (0.5M NH₄Cl), anion or cation-exchange membrane were used. Excellent selective preconcentration of Pd(II) in the sample and Ir(III) in the receiver solution was achieved. Experiments performed enable to draw some conclusion on the charge sign of glycinepalladium complexes.     

Testing for Drugs in Hair – a Review of Chromatographic Procedures

This article reviews the analysis of drugs and drug metabolites in hair by chromatographic procedures, including the pretreatment steps, and the extraction methods. The general tendency in the last years, to highly sophisticated techniques (GC–MS–NCI, HPLC–MS, GC–MS–MS) illustrates the constant fight for sensitivity.