Chromatographic analysis of phenethylamine-antihistamine combinations using C8, C18 or cyano columns and micellar sodium dodecyl sulfate-pentanol mixtures

The chromatographic behaviour of binary and ternary mixtures of several phenethylamines (phenylephrine, phenylpropanolamine, ephedrine, pseudoephedrine and methoxyphenamine) and antihistamines (pheniramine, carbinoxamine, doxylamine, chlorpheniramine, dexchlorpheniramine, dexbrompheniramine, diphenhydramine, tripolidine, azatadine and phenyltoloxamine), found in cough-cold pharmaceutical preparations, was studied using C8, C18 and cyano columns, micellar mobile phases of sodium dodecyl sulfate (SDS) and pentanol and UV detection. Using a C8 column and mobile phases of 0.05 mol l-1 SDS-6% v/v pentanol or 0.15 mol l-1 SDS-2% v/v pentanol at pH 7, more than 30 different phenethylamine-antihistamine combinations can be resolved in < 15 min. Intra- and inter-day repeatabilities and reproducibilities evaluated at three different drug concentrations (0.5, 5 and 25 micrograms ml-1, n = 10) were below 1.6, 2.5 and 2.4%, respectively. The drug amounts found in 18 formulations agreed with those declared by the manufacturers within the tolerance limits, and with those obtained using a mobile phase of 55% v/v methanol at pH 7. No interference was observed from other accompanying drugs such as acetylsalicylic acid, ascorbic acid, betamethasone, bromhexine, caffeine, codeine, dextromethorphan, paracetamol, prednisolone, salicylamide and tartrazine. The proposed procedure has the advantage over the conventional aqueous-organic procedure of using a small amount of organic solvent, which is highly retained in the SDS solution. The efficiencies are also greater. On the other hand, in the micellar system, the retentions of phenethylamines and antihistamines are similar, although the compounds can be easily resolved. In contrast, using the methanol-water mobile phase, the phenethylamines are weakly retained, whereas the antihistamines usually show a high retention.     

Solid-phase synthesis and biological evaluation of a teleocidin library--discovery of a selective PKCdelta down regulator

Protein kinaseC (PKC) is linked to the signal-induced modulation of a wide variety of cellular processes, such as growth, differentiation, secretion, apoptosis, and tumor development. The design and synthesis of small molecules that regulate these different cellular signaling systems is at the forefront of modern drug design. Herein we report a) an efficient method for the synthesis of indolactamV (6), a PKC activator, and its N13-des(methyl) analogues (19) using a regioselective organometallic transformation, a convenient aminomalonate derivative (10) to introduce the appropriate functionality and an enantiospecific enzymic hydrolysis as key steps; b) the use of this method in the first solid-phase synthesis of a teleocidin library modifying the N-13, C-12 and C-7 alkyl chains, and, therefore, producing a library of potential activators and/or inhibitors of PKC of the general structure (32); c) the activation of PKC by selected members of the library using a MARCKS translocation in vivo assay system; d) the observation that some of these analogues are nearly as effective as the natural PKC activators phorbol dibutyrate and (-)-indolactam V (6), and e) the observation that some of these analogues have different potential to induce down-regulation of members of the PKC gene family after chronic stimulation.     

Highest-weight representations ofsl(2, ℂ) andsl(3, ℂ) via canonical realizations

The infinite-dimensional representations of thesl(n+1, ) Lie algebras (maximal representations) constructed in our previous paper are studied on the two simplest examplesn = 1,2. The sufficient condition for irreducibility of the maximal representations is proved to be also necessary in these cases. It is further shown, that our method allows us to construct other set of infinite-dimensional highest-weight representations ofsl(3, ), so calledmixed representations which are irreducible in some cases when the maximal as well as the standard highest-weight representations (Verma modules) are reducible.Dedicated to the 25th anniversary of the Joint Institute for Nuclear Research.The authors are grateful to Prof. A. A. Kirillov, Dr. A. U. Klimyk, Dr. W. Lassner and Prof. D. P. Zhelobenko for stimulating discussions.     

The infrared spectra of solid solutions of some iron and chromium oxides

Oxides Fe_2–x Cr _x O₃ (corundum-type) and Fe_3–y ,Cr _y O₄ (spinel-type) were studied by transmission IR spectroscopy. The wavenumbers corresponding to characteristic absorption maxima depend linearly on the composition of both types of solid solutions, i.e. onx andy. The results show that IR spectroscopy can contribute to the analysis of solid solutions of iron and chromium oxides and of the oxidation products of Fe-Cr alloys.The authors are indebted to Ing. P. Holba for the preparation of synthetic oxide samples. The cooperation of Yu. Borodkin and I. Zuika (Riga) who made the measurements in the far IR region is gratefully acknowledged.     

Production of lepton pairs in processes with hadronic jets

We propose a model for the production of extra (additional) lepton pairs in deep inelastic lepton-hadron scattering, e⁺e^– annihilation and large p_T processes. Extra lepton pairs are supposed to be originated by annihilations of quarks and antiquarks created during the space-time evolution of quark initiated jets. This mechanism yields predominantly dileptons with rather low masses. Predictions following from the model are compared with the recent data on trimuon production in neutrino-nucleon interactions. It is also suggested that internal hard processes can lead to dileptons with both small and large masses. The latter mechanism has rather small cross section but it is particularly interesting from the point of view of the simple quark-parton model.Dedicated to Academician Václav Votruba on the occasion of his seventieth birthday.     

Influence of the overall pressure on electrical conductivity of the amorphous semiconductor Ge15Te81S2As2

The experimental results obtained with the chalcogenide glass Ge₁₅Te₈₁S₂As₂ with imposed overall pressure up to 700 MPa are presented. The material exhibits the switching effect and the memory effect. It is shown that the overall pressure changes remarkably d.c. electrical conductivity of the amorphous semiconductor. It is assumed that the changes in conductivity are caused by changes in activation energy. The changes in activation energy within the range of considered pressures are, as follows from our measurements, E/p–10·95×10^–5 eV/MPa +p × 10·41 W 10^–7 eV/MPa². The assumption of the activation energy dependence on pressurep are confirmed also by measurements of dependence In vs. 1/T at various pressures.     

Field and temperature dependence of magnetization of U3P4

Conclusions We conclude that the occurrence of a maximum in the magnetization versus temperature curve observed under certain circumstances on U₃P₄ is not connected with its intrinsic magnetic structure, but substantially depends on the form in which the material is studied (polycrystalline powder, single crystal, single crystal powders with various dimensions of grains). This phenomenon seems to be affected by quenching of the state from the region of low anisotropy at higher temperature in the small particles with a strong tendency to single domain behaviour and thus it may be a consequence of rotation magnetization process in the fields relatively small for U₃P₄. The assertion about transitions between magnetic ordering, sometimes proposed in the literature on the basis of observed anomalies in the temperature course of magnetization without simultaneous confirmation by neutron diffraction, should be accepted with some reservation, especially in the case of simple uranium compounds. However, another situation arises for pseudobinary alloys of ferro- and antiferromagnetic components (e.g. UP_0·75S_0·25) where such transitions were confirmed both by magnetic methods and by neutron diffraction studies [13].The authors would like to express their thanks to Ing. A.Meovský for careful preparation of samples.     

Optical absorption in vitreous GeSb2Se4

Optical absorption of vitreous GeSb₂Se₄ was studied in spectral region 0.7–25 μm. At low absorption levels near the edge the absorption coefficient K depends exponentially on energy. At high absorption levels the quadratical energy dependence of K is observed. In the present work we determined the optical energy gap E^opt_g = 1.29 eV and discussed the temperature dependence of the absorption coefficient. Measured reflectivity curves were used to estimate the value of the refractive index of GeSb₂Se₄ ($\text{n = 3.13–3.56}\text{at}\text{h}\text{?}\text{ω = 1.00–1.70}\text{eV}$). Vitreous GeSb₂Se₄ is also transparent in the spectral interval 2–15.7 μm.     

Effect of Biodegradable Coatings on the Growth of Aspergillus flavus In Vitro,on Maize Grains,and on the Quality of Tortillas during Storage

The fungus Aspergillus flavus causes serious damage to maize grains and its by-products, such as tortilla. Currently, animal and plant derivatives, such as chitosan and propolis, and plant extract residues, respectively, are employed as alternatives of synthetic fungicides. The objective of this research was to evaluate the efficacy of several formulations based on propolis-chitosan-pine resin extract on the in vitro growth of A. flavus, the growth of maize grain plantlets and the quality of stored tortillas at 4 and 28 °C. The most outstanding formulation was that based on 59.7% chitosan + 20% propolis nanoparticles + 20% pine resin extract nanoparticles; since the in vitro conidia germination of A. flavus did not occur, disease incidence on grains was 25–30% and in tortillas, 0% infection was recorded, along with low aflatoxin production (1.0 ppb). The grain germination and seedling growth were markedly reduced by the nanocoating application. The percentage weight loss and color of tortillas were more affected by this coating compared to the control, and the rollability fell within the scale of non-ruptured at 4 °C and partially ruptured at 28 °C. The next step is to evaluate the toxicity of this formulation.     

An efficient method for computing the QTAIM topology of a scalar field: The electron density case

An efficient method for computing the quantum theory of atoms in molecules (QTAIM) topology of the electron density (or other scalar field) is presented. A modified Newton–Raphson algorithm was implemented for finding the critical points (CP) of the electron density. Bond paths were constructed with the second‐order Runge–Kutta method. Vectorization of the present algorithm makes it to scale linearly with the system size. The parallel efficiency decreases with the number of processors (from 70% to 50%) with an average of 54%. The accuracy and performance of the method are demonstrated by computing the QTAIM topology of the electron density of a series of representative molecules. Our results show that our algorithm might allow to apply QTAIM analysis to large systems (carbon nanotubes, polymers, fullerenes) considered unreachable until now. © 2012 Wiley Periodicals, Inc.