Colourimetric and spectroscopic discrimination between nucleotides and nucleosides using para-sulfonato-calix[4]arene capped silver nanoparticles

The complexation of nucleosides and nucleotides by hybrid nanoparticles capped by para-sulfonato-calix[4]arene shows clear discrimination between purine and pyrimidine based molecules. For the pyrimidine nucleotides there is appearance of a new absorption band around 550 nm, and a colour change from yellow to orange red and pink.     

Joule-Thomson coefficients and Joule-Thomson inversion curves for pure compounds and binary systems predicted with the group contribution equation of state VTPR

In this work the accuracy of the prediction of Joule-Thomson coefficients for the gases CO₂ and Ar and the binary systems CO₂-Ar and CH₄-C₂H₆ was examined using the group contribution equation of state VTPR. Furthermore the experimental and correlated data of Joule-Thomson inversion curves of a few compounds including carbon dioxide, nitrogen, benzene, toluene, methane, ethane, ethylene, propyne, and SF₆ were compared with the results of the group contribution equation of state VTPR, the Soave-Redlich-Kwong (SRK), the Peng-Robinson (PR) and the Helmholtz equation of state (HEOS). Moreover, Joule-Thomson inversion curves for pure fluids, binary (CH₄-C₂H₆, N₂-CH₄, CO₂-CH₄), and ternary systems (CO₂-CH₄-N₂, CH₄-C₂H₆-N₂, CO₂-CH₄-C₂H₆) were calculated with VTPR and compared to the results of SRK, PR, HEOS and the molecular simulation results of Vrabec et al. It was found that the calculated values for the Joule-Thomson coefficients and Joule-Thomson inversion curves are in good agreement with the experimental findings.     

Convenient Synthesis of 3,5‐Disubstituted Isoxazoles

α,β‐Unsaturated oximes obtained from the corresponding α,β‐unsaturated ketones on treatment with 2 equivalents of manganese dioxide in refluxing chloroform gives 3,5‐disubstituted isoxazoles in good yields.     

Investigation of low-abundant in vitro metabolites of stable isotope-labelled BAL4815 by accurate mass capillary-LC-ESI-qTof-MS and MS/MS

The metabolic profile of BAL4815, an antifungal azole drug, was determined using in vitro rat hepatocyte incubations and subsequent analysis by capillary LC-qTof-MS and MS/MS including accurate mass determination. For the detection of the metabolites, a mixture of the drug and its deuterium-labelled analogue was used for incubations. Metabolic stability of BAL4815 was high in cultured rat hepatocytes. However, several low-abundant metabolites were detected by the use of capillary LC-qTof-MS and manual investigation of the data. The peak intensity of the most abundant metabolite was close to the limit of detection. Except for an apparent oxidation product, the masses of the other detected metabolites could not be assigned to a single and frequently occurring biotransformation. Accurate mass determination and possible elemental compositions suggested that metabolism occurred through a combination of glutathionylation and defluorination. This was verified using accurate mass MS/MS. The use of accurate mass measurements and the derived suggestions for the elemental compositions were essential to elucidate this atypical metabolic pathway. A mass accuracy better than 8 ppm could be achieved for most assigned MS and MS/MS signals with intensities less than 6 cps in the spectra.     

Synthesis and radioprotective study of new siladithioacetals and germadithioacetals

A series of organosilicon and organogermanium compounds derived from cysteamine, methylcysteamine and 2‐[1‐(1‐naphthyl)ethyl]‐2‐imidazoline have been prepared and their radiopharmacological properties (radioprotective activity and toxicity) have been determined in mice. A number of these new organometallic derivatives have been found to possess radioprotective activity. We have also noted a notable decrease of the toxicity and a fairly large increase in the radioprotective activity in comparison with the unsubstituted organic molecules. Copyright © 2003 John Wiley & Sons, Ltd.     

In vitro antitumour activity of some organogermanium radioprotectors

Four germanium derivatives of 2,2′‐oxydiethanethiol and 2,2′‐thiodiethanethiol have been synthesized and characterized by ¹H and ¹³C NMR, mass spectroscopy and elemental analysis. The antitumour activity of one of them is comparable to those of cis‐platin and etoposide. Copyright © 2003 John Wiley & Sons, Ltd.     

Rapid discovery of inhibitors of <Emphasis Type="Italic">Toxoplasma gondii</Emphasis> using hybrid structure-based computational approach

Toxoplasma (T.) gondii, the causative agent of toxoplasmosis, is a ubiquitous opportunistic pathogen that infects individuals worldwide, and is a leading cause of severe congenital neurologic and ocular disease in humans. No vaccine to protect humans is available, and hypersensitivity and toxicity limit the use of the few available medicines. Therefore, safer and more effective medicines to treat toxoplasmosis are urgently needed. Using the Hybrid Structure Based (HSB) method, we have previously identified small molecule inhibitors of P. falciparum that seem to target a novel protein–protein interaction between the Myosin tail interacting protein and myosin light chain. This pathway has been hypothesized to be involved in invasion of host erythrocytes by the parasite and is broadly conserved among the apicomplexans. Guided by similar computational drug design approaches, we investigated this series of small molecules as potential inhibitors of T. gondii. Compound C3-21, identified as the most active inhibitor in this series, exhibited an IC₅₀ value ~500 nM against T. gondii. Among the 16 structural analogs of C3-21 tested thus far, nine additional compounds were identified with IC₅₀ values <10.0 μM. In vitro assays have revealed that C3-21 markedly limits intracellular growth of T. gondii tachyzoites, but has no effect on host cell human foreskin fibroblasts (HFF) at concentrations more than a log greater than the concentration that inhibits the parasites.     

Wallpaper functions

Instead of making wallpaper by repeating copies of a motif, we construct wallpaper functions. These are functions on ² that are invariant under the action of one of the 17 planar crystallographic groups. We also construct functions with antisymmetries, and offer a complete analysis of types. Techniques include exhibiting bases for various spaces of wallpaper functions, and an algebraic definition of equivalence of pattern type.     

Synthesis and study of optical and electrical characteristics of a hybrid structure of single wall carbon nanotubes and silver nanoparticles

Ag nanoparticles of average size 20 nm have been deposited on SWCNT surfaces following a very lucid wet chemical process. The SWCNT/Ag nanohybrid material has been characterized using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD) analysis and Raman spectroscopy. Both optical and electrical properties of the hybrid have been studied. The hybrid material has been synthesized at 60 °C and treated to higher temperatures. About three-fold increase in photoluminescence (PL) emission intensity has been achieved when the hybrid sample has been treated to 500 °C. DC conductivity at varying temperatures from 77–473 K has been studied. The conductivity of Ag-decorated SWCNTs increased up to 1.76 times of that of pristine SWCNT at a low temperature of 180 K. This hybrid material can find wide application as conducting filler in polymer composite which other filler materials seldom possess.