Efficient syntheses of 3-phosphorylquinolin-4-ones and 3-phosphoryl-1,8-naphthyridin-4-ones

A series of 3-diethoxyphosphorylquinolin-4-ones and 3-diethoxyphosphoryl-1,8-naphthyridin-4-ones containing various substituents at N-1 and C-7 was synthesized in a four-step reaction sequence starting from readily available ethyl 2-chlorobenzoates or ethyl 2-chloronicotinates and diethyl methylphosphonate. Selected quinolinone and naphthyridinone products were transformed into free mono and diacids.     

Application of different modes of thin-layer chromatography and mass spectrometry for the separation and detection of large and small biomolecules

Biomolecules are widespread throughout the world. A biomolecule is any organic molecule produced by a living organism, including large polymeric molecules such as proteins, polysaccharides and nucleic acids. Many sample preparation techniques are used in biomolecule analysis; the method selected depends on the complexity of the sample, the nature of the matrix and the analytes, and the analytical technique available. This review covers the current state of knowledge on thin-layer chromatography and mass spectrometry for qualitative analysis of biomolecules. In the first part of the paper the reader will gain useful information to avoid some problems about performing various modes of thin-layer chromatography combined with mass spectrometry experiments and in the second part he will find useful information for application of these techniques for separation, detection, and qualitative investigation of structures and quantitative determination of biomolecules such as proteins, peptides, oligonucleotides, amino acids, DNA, RNA, and lipids.     

Electronic states of tetrahydrofuran molecules studied by electron collisions

Electronic states of tetrahydrofuran molecules were studied in the excitation energy range 5.5-10 eV using the technique of electron energy loss spectroscopy in the gas phase. Excitation from the two conformations, C(2) and C(s), of the ground state of the molecule are observed in the measured energy loss spectra. The vertical excitation energies of the (3)(n(o)3s) triplet state from the C(2) and C(s) conformations of the ground state of the molecule are determined to be 6.03 ± 0.02 and 6.25 ± 0.02 eV, respectively. The singlet-triplet energy splitting for the n(o)3s configuration is determined to be 0.31 eV. It is also found that excitation from the C(s) conformation of the ground state has a higher cross section than that from the C(2) conformation.     

Application of ultra-performance columns in high-performance liquid chromatography for determination of albendazole and its metabolites in turkeys

Methods for determination of albendazole (ALB), albendazole sulfoxide (SOX) and albendazole sulfone (SON) in turkey blood plasma, using high‐performance liquid chromatography (HPLC) with fluorescence detection, were developed. Moreover, comparison of HPLC columns with ultra‐performance liquid chromatography (UPLC) columns was performed. Albendazol was administered orally in 5‐week‐old birds (n = 18) at a dose of 25 mg/kg b.w. Accuracy and precision of the developed method were satisfactory and stability studies showed acceptable variation (below 15%) in ALB, SOX and SON concentrations when the samples were stored at –75°C for 15 days. UPLC® columns gave higher peaks from typical HPLC columns retaining high quality of analysis. Pharmacokinetic analysis indicated quick elimination of ALB from turkey blood plasma. The mean residence time of SON was at least two times longer than that of SOX and four times longer than that of ALB. The elimination half‐lives for ALB, SOX and SON were 0.7 ± 0.27, 5.37 ± 6.03, 9.17 ± 5.12 h, respectively. The obtained results indicate that the described method allows for precise determination of albendazole and its metabolites in turkey plasma. Moreover, using UPLC columns in HPLC apparatus results in higher sensitivity as compared with the classical HPLC columns. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of volatile organic compounds in human breath for Helicobacter pylori detection by SPME-GC/MS

Helicobacter pylori living in the human stomach release volatile organic compounds (VOCs) that can be detected in expired air. The aim of the study was the application of breath analysis for bacteria detection. It was accomplished by determination of VOCs characteristic for patients with H. pylori and the analysis of gases released by bacteria in suspension. Solid-phase microextraction was applied as a selective technique for preconcentration and isolation of analytes. Gas chromatography coupled with mass spectrometry was used for the separation and identification of volatile analytes in breath samples and bacterial headspace. For data calculation and processing, discriminant and factor analyses were used. Endogenous substances such as isobutane, 2-butanone and ethyl acetate were detected in the breath of persons with H. pylori in the stomach and in the gaseous mixture released by the bacteria strain but they were not identified in the breath of healthy volunteers. The canonical analysis of discrimination functions showed a strong difference between the three examined groups. Knowledge of substances emitted by H. pylori with the application of an optimized breath analysis method might become a very useful tool for noninvasive detection of this bacterium.     

Modern chromatographic and electrophoretic measurements of antidepressants and their metabolites in biofluids

Depression is one of the most frequently occurring psychiatric conditions affecting the economic and social functioning of people all over the world. There are a few classes of drugs commonly used to treat patients with depression disorders. Therapeutic drug monitoring of antidepressants provides the possibility to reduce side effects and optimize the treatment of patients with depression. Hence, there is a need to develop reliable analytical methods for the determination of these agents in biological fluids. Moreover, an important part of understanding the mechanisms of action of these medicines is also associated with the recognition of the metabolites' function because of their potential influence on therapeutic benefits and/or adverse effects. Some of them possess the same primary activity as their parent compounds and may contribute to the therapeutic efficacy whereas the biochemical actions of other metabolites may be different from that of the parent drug. In this review, several validated high-performance liquid chromatographic, gas chromatographic and capillary electrophoretic methods for quantification of antidepressants and their metabolites in biofluids are compared. In addition, the review covers areas such as mechanism of actions, structure-activity relationships and metabolism of the cited antidepressants.     

Synthesis and photochemical characteristics of novel tribenzoporphyrazines possessing peripherally annulated tetrahydrodiazepine and diazepine rings

Novel tribenzoporphyrazines possessing peripherally annulated tetrahydrodiazepine and diazepine rings were synthesized and characterized, and the substituent effects on their absorption spectra in various solvents and on singlet oxygen generation were studied. Solvatochromic effects of tribenzoporphyrazines dissolved in a range of protic and aprotic solvents were evaluated by monitoring the changes in the UV-Vis spectra. The correlation between the Q-band shift towards longer wavelengths and the refractive index of the solvent indicated that the solvatochromic effects are mainly a result of solvation rather than coordination processes. The potential photosensitizing activity of novel tribenzoporphyrazines was evaluated by measuring the ability of singlet oxygen production, which is the result of the interaction between an activated photosensitizer and oxygen. This experiment proves promising photosensitizing activity of novel styryldiazepinotribenzoporphyrazine, which is an efficient singlet oxygen generator with a Φ_Δ value of 0.44, although this value is a little lower than that of zinc phthalocyanine.     

On the homeomorphism groups of manifolds and their universal coverings

Let H _c (M) stand for the path connected identity component of the group of all compactly supported homeomorphisms of a manifold M. It is shown that H _c (M) is perfect and simple under mild assumptions on M. Next, conjugation-invariant norms on H _c (M) are considered and the boundedness of H _c (M) and its subgroups is investigated. Finally, the structure of the universal covering group of H _c (M) is studied.     

Strong Central Limit Theorem for isotropic random walks in {\mathbb{R}^d}

We prove an optimal Gaussian upper bound for the densities of isotropic random walks on ${\mathbb{R}^d}$ in spherical case (d ?? 2) and ball case (d ?? 1). We deduce the strongest possible version of the Central Limit Theorem for the isotropic random walks: if ${\tilde S_n}$ denotes the normalized random walk and Y the limiting Gaussian vector, then ${\mathbb{E} f(\tilde S_{n}) \rightarrow \mathbb{E} f(Y)}$ for all functions f integrable with respect to the law of Y. We call such result a ??Strong CLT??. We apply our results to get strong hypercontractivity inequalities and strong Log-Sobolev inequalities.     

On solving the dual for portfolio selection by optimizing Conditional Value at Risk

This note is focused on computational efficiency of the portfolio selection models based on the Conditional Value at Risk (CVaR) risk measure. The CVaR measure represents the mean shortfall at a specified confidence level and its optimization may be expressed with a Linear Programming (LP) model. The corresponding portfolio selection models can be solved with general purpose LP solvers. However, in the case of more advanced simulation models employed for scenario generation one may get several thousands of scenarios. This may lead to the LP model with huge number of variables and constraints thus decreasing the computational efficiency of the model. To overcome this difficulty some alternative solution approaches are explored employing cutting planes or nondifferential optimization techniques among others. Without questioning importance and quality of the introduced methods we demonstrate much better performances of the simplex method when applied to appropriately rebuilt CVaR models taking advantages of the LP duality.