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4-Benzyl-1,2,4-triazin-3,5(2H,4H)-dione (3-benzyl-6-azauracil, 2), and 2,4-dibenzyl-1,2,4- triazin-3,5(2H,4H)-dione (1,3-dibenzyl-6-azauracil, 3) were synthesized by the reaction of 1,2,4-triazin-3,5(2H,4H)-dione (6-azauracil, 1) with benzyl bromide and potassium carbonate in dry acetone via the 18-crown-6-ether catalysis. In these reaction methods, we developed more convenient and efficient methodologies to afford compounds 2 and 3 in good yields. These compounds were characterized by ¹H- and 13C-NMR, MS spectrum, IR spectroscopy and elemental analysis. The structure of 2 was verified by 2D-NMR measurements, including gHSQC and gHMBC measurements. A single-crystal X-ray diffraction experiment indicated that compound 3, with the molecular formula C17H15N3O2, crystallized from a CH3OH/CH2Cl2 diffusion solvent system in a monoclinic space group P21/c with a = 13.7844(13), b = 8.5691(8), c = 13.0527(12) Å, b = 105.961(2)°, V = 1482.3(2) ų, Z = 4, resulting in a density Dcalc of 1.314 g/cm³. The crystal structure of compound 3 is tightly stabilized by contact with five other molecules from the six short contacts formed by intermolecular C-O...H-Car, C-H...Car, and weakly π...π stacking interactions. The dihedral angle 31.90° is formed by the mean planes of the benzene rings of the N-2 and N-4 benzyl groups. [ABSTRACT FROM AUTHOR]

The article presents a case study that investigates whether an exposure to aluminum, gallium, indium, arsenic, and antimony stimulates lipid peroxidation in workers in the optoelectronic industry. Researchers use inductively coupled plasma mass spectrometry in analyzing the whole blood and urine samples of 103 exposed electronic industry workers and 67 referents, while in determining malondialdehyde (MDA), they use high-performance liquid chromatography. Results show that the mean plasma MDA level in the 103 workers was significantly higher compared to the 67 referents. Furthermore, it has been found that MDA can be induced by gallium and arsenic exposure.

A direct arylation of pyrazolo[1,5-a]pyridines with aryl iodides selectively occurring at the C-3 and C-7 positions via palladium-catalyzed C-H activation is described. In these reactions, (a) cesium(I) fluoride and (b) silver(I) carbonate were employed as the additive to afford 3- and 7-arylated pyrazolo[1,5-a]pyridines, respectively, in modest to good yields. These reactions showed good compatibility with functional groups, and the catalytic mechanisms of these reactions were proposed. Finally, the synthetic application on the potent p38 kinase inhibitors was demonstrated. [ABSTRACT FROM AUTHOR]

Here we present the in vitro selection of a novel nbozyine specific for Zn2+-dependent catalysis on hydrolysis of a phosphorothiolate thiolester bond. The ribozyme, called the TWI7 ribozyme, was evolved and selected from an artificial RNA pool covalently linked to a biotin-containing substrate through the phosphorothiolate thiolester bond. The secondary structure for the evolved ribozyme consisted of three major helices and three loops. Biochemical and chemical studies of ribozyme-catalyzed reaction products provided evidence that the ribozyme specifically catalyzes hydrolysis of the phosphorothiolate thiolester linkage. A successfiil ribozyme construct with active catalysis in trans further supported the determined ribozynse structure and indicated the potential of the ribozysne for multiple-substrate turnover. The ribozyme also requires Zn2+ and Mg2+ for maximal catalysis. The TW17 ribozyme, in the presence of Zn2+ and Mg2+, conferred a rate enhancement of at least S orders of magnitude when compared to the estimated rate of the uncatalyzed reaction. The ribozyme completely lost catalytic activity in the absence of Zn2+, like Zn2+-dependent protein hydrolases. The discovery and characterization of the TWI7 ribozyme suggest additional roles for Zn2+ in ribozyme catalysts. [ABSTRACT FROM AUTHOR]