Determination of trace elements in Rheum moorcroftianum by AAS

Micro and macro elements such as Zn, Cu, Mn, Fe, Co, Na, K, Ca and Li were detected from Rheum moorcroftianum Royle, a plant used in folk medicines. Altitudinal and seasonal variation of these trace elements in cultivated and wild roots and leaves of R. moorcroftianum were quantified by atomic absorption spectroscopy. The highest concentrations of Zn, Cu, Mn, Fe, Co, Na, K, Ca and Li were found to be 376.0?±?0.9, 83.0?±?4.6, 322.0?±?6.0, 920.0?±?1.9, 72.0?±?1.5, 402.0?±?7.8, 10,235.0?±?7.0, 12,336.0?±?2.6 and 59.9?±?0.3 mg?kg(-1), respectively, in all the samples analysed.     

Cu–ZnO nanocrystallites by aqueous thermolysis method

ZnO and different atomic percentages of Cu-doped ZnO nanocrystallites have been prepared by aqueous thermolysis method using Glycine as a fuel and encapsulating agent. Mechanism and formation of intermediate products have been given for the first time. All the findings given are for samples annealed at 800?°C. XRD of nanocrystalline ZnO and Cu?CZnO has been indexed to hexagonal wurtzite structure. Influence of temperature on thermal properties of gel precursor and Cu-doped ZnO nanoparticles have been investigated using thermogravimetric and differential thermal analysis. Accordingly, samples have been annealed at different temperatures. Infrared studies revealed formation of Cu?CZnO nanoparticles and removal of organic matter at higher temperature.     

EccA1, a component of the Mycobacterium marinum ESX-1 protein virulence factor secretion pathway, regulates mycolic acid lipid synthesis

Pathogenic mycobacteria, which cause multiple diseases including tuberculosis, secrete factors essential for disease via the ESX-1 protein export system and are partially protected from host defenses by their lipid-rich cell envelopes. These pathogenic features of mycobacterial biology are believed to act independently of each other. Key ESX-1 components include three ATPases, and EccA1 (Mycobacterium marinum MMAR_5443; M.?tuberculosis Rv3868) is the least characterized. Here we show that M.?marinum EccA1's ATPase activity is required for ESX-1-mediated protein secretion, and surprisingly for the optimal synthesis of mycolic acids, integral cell-envelope lipids. Increased mycolic acid synthesis defects, observed when an EccA1-ATPase mutant is expressed in an eccA1-null strain, correlate with decreased in?vivo virulence and intracellular growth. These data suggest that two mycobacterial virulence hallmarks, ESX-1-dependent protein secretion and mycolic acid synthesis, are critically linked via EccA1.     

Copper-mediated coupling of aminopurines and aminopyrimidines with arylboronic acids

Selective N-arylation of aminopurines and aminopyrimidines 1-3 with arylboronic acids 4-6 was explored using copper(II) acetate and the corresponding N-arylated purine and pyrimidine derivatives 7-15 were obtained in moderate to good yields.     

A simple,selective and rapid validated method for estimation of anastrazole in human plasma by liquid chromatography–tandem mass spectrometry and its application to bioequivalence study

A rapid, simple and specific method for estimation of anastrazole in human plasma was validated using letrozole as internal standard. The analyte and internal standard were extracted from plasma using simple solid‐phase extraction. The compound were separated on a reverse‐phase column with an isocratic mobile phase consisting of 0.1% formic acid in water and acetonitrile (12 : 88, v/v) and detected by tandem mass spectrometry in positive ion mode. The ion transitions recorded in multiple reaction monitoring mode were m/z 294.1 → 225.1 for anastrazole and m/z 286.1 → 217.1 for internal standard. Linearity in plasma was observed over the concentration range 0.3–30 ng/mL for anastrazole. The mean recovery for anastrazole was 83.7% with a lower limit of quantification of 0.3 ng/mL. The coefficient of variation of the assay was less than 6.8% and the accuracy was 96.1–102.2%. The validated method was applied to a bioequivalence study of 1 mg anastrazole tablet in healthy human volunteers. Copyright © 2009 John Wiley & Sons, Ltd.     

An Efficient Low‐Temperature Stille–Migita Cross‐Coupling Reaction for Heteroaromatic Compounds by Pd–PEPPSI–IPent

The reactivity of Pd–PEPPSI (Pyridine, Enhanced, Precatalyst, Preparation, Stabilization, and Initiation) precatalysts in the Stille–Migita cross‐coupling reaction between heteroaryl stannanes and aryl or heteroaryl halides was evaluated. In general, Pd–PEPPSI–IPent (IPent=diisopentylphenylimidazolium derivative) demonstrated high efficiency over a variety of challenging aryl or heteroaryl halides with thiophene‐, furan‐, pyrrole‐, and thiazole‐based organostannanes when compared with Pd–PEPPSI–IPr (IPr=diisopropylphenylimidazolium derivative). The transformations proceeded at appreciably lower temperatures (30–80 °C) than triarylphosphine‐based Pd catalysts, improving the scope of this useful carbon–carbon bond‐forming process.     

Effect of ionic micellar medium on kinetics and mechanism of oxidation of bovine serum albumin: A pulse radiolysis study

Effect of protein–micelle interaction on bovine serum albumin (BSA) oxidation by trichloromethyl peroxyl radical (CCl₃O₂^·) in anionic sodium dodecyl sulfate (SDS) and cationic cetyltrimethyl ammonium bromide (CTAB) micellar media has been studied using nanosecond pulse radiolysis technique. Viscosity measurement and light scattering studies have suggested that SDS and CTAB micelles produce BSA–micelle aggregates of different sizes and polydispersity. Oxidation kinetics and transients have been affected both by anionic SDS and cationic CTAB micelles but in a different manner. Tryptophanyl-CCl₃O₂^· adduct radical to tyrosyl radical transformation in BSA has been observed in anionic SDS micelles but not in cationic CTAB micelles. Similar studies have also been done with tryptophan and tyrosine amino acids, which undergo oxidation in BSA. The study suggests that Coulombic and hydrophobic interactions between micelles and protein affect the structure of the protein to shield its functional amino acids, like tryptophan and tyrosine, to neutral oxidizing radical.     

Error minimization in the envelope method for the determination of optical constants of a thin film

The algorithm for the determination of optical constants of a weakly absorbing thin film from the envelope method has been modified to minimize the error in the estimated values of extinction coefficient (k) as a function of wavelength. The refinement procedure is based on an extension of interference order adjustment method used for improving the estimated values of film thickness d and wavelength‐dependent refractive index n from the envelope method. The proposed modification when applied to a hypothetical as well as an experimental film is found to work well over a wide spectral region. Copyright © 2010 John Wiley & Sons, Ltd.     

A Convenient Synthesis of Aryl‐Substituted N‐Carbamoyl/N‐Thiocarbamoyl Narcotine and Related Compounds

The reaction of nornarcotine and 5‐bromonornarcotine, synthesized from noscapine, with suitable aromatic isocyanates or isothiocyanates provides a general method for the synthesis of aryl‐substituted N‐carbamoyl or N‐thiocarbamoylnarcotine and related compounds. Similarly, 15a has been prepared via the reduction of the lactone ring moiety of noscapine. Also, an improved procedure, which utilizes narcotine N‐oxide⋅HCl for generation of nornarcotine, is described.