Search results for "Hypoxanthine"
showing 5 items of 25 documents
Effect of flupirtine on cell death of human umbilical vein endothelial cells induced by reactive oxygen species.
1999
Abstract Flupirtine (KATADOLON®), known as a nonopiate centrally acting analgesic drug, was tested as to its potential to prevent apoptosis of human endothelial cells induced by reactive oxygen species (ROS). It was found that Flupirtine displayed no effect on viability and cell proliferation of human umbilical vein endothelial cells (HUVEC) up to a concentration of 10 μg/mL. Apoptosis, induced by ROS and generated by hypoxanthine/xanthine oxidase (EC 1.1.3.22) (HX/XOD) or t-butyl hydroperoxide, was reduced after preincubation with Flupirtine for 3 hr by 35% and 41%, respectively. The maximal cytoprotective effect against apoptosis was observed at a drug concentration of 1 to 3 μg/mL. Flow …
NMR Quantification of Tautomeric Populations in Biogenic Purine Bases
2009
Purine bases such as purine, adenine, hypoxanthine, and mercaptopurine are known to exist in several tautomeric forms. Characterization of their tautomeric equilibria is important not only for predicting the regioselectivity of their N-alkylation reactions but also for gaining knowledge of the patterns with which these compounds of significant biological activity form hydrogen bonds with their biological targets. Low-temperature 1H- and 13C-NMR spectroscopy were used to investigate the tautomeric equilibria for purine and some purine derivatives in methanol and N,N-dimethylformamide solutions. The N(7)H and N(9)H tautomeric forms were quantified by integrating the individual 1H NMR signals …
Sulfotransferase-mediated activation of mutagens studied using heterologous expression systems
1998
Abstract Sulfation is a common final step in the biotransformation of xenobiotics and is traditionally associated with inactivation. However, the sulfate group is electron-withdrawing and may be cleaved off heterolytically in some molecules leading to electrophilic cations which may form adducts with DNA and other important cellular structures. Since endogenous sulfotransferases do not appear to be expressed in indicator cells of standard mutagenicity tests, rat and human sulfotransferases have been stably expressed in his−Salmonella typhimurium strain TA1538 and Chinese hamster V79 cells. Using these recombinant indicator cells, sulfotransferase-dependent genotoxic activities were detected…
Complex formation of hypoxanthine and 6-mercaptopurine with Cd(II) ion
1984
Reaction of Cd(II) ion with hypoxanthine (H2 Y) and with 6-mercaptopurine (H2 MP) in dioxane-water (50%) leads to the formation of CdY·2H2O and Cd(HMP)2·2H2O, respectively. In methanolic medium Cd(II) and H2 MP give Cd(MP)·H2O. These compounds have been characterized by chemical analysis, IR spectra and thermogravimetric analysis. The stability constant of CdY complex at 25±0.1 °C and 1M ionic strength with NaClO4 in dioxane-water medium is log β=10.25±0.05.
Xanthine oxidase catalyzes the oxidation of retinol.
2007
In mammals, xanthine oxidase (E.C. 1.17.3.2) catalyzes the hydroxylation of a wide variety of heterocyclic substrates such as purines, pyrimidines, and pterins, in addition to aldehydes [1] as all-trans-retinaldehyde [2-5]. Here, we show that buttermilk xanthine oxidase was capable to oxidizing all-trans-retinol (t-ROL) to all-trans-retinaldehyde (t-RAL) that was successively oxidized to all-trans-retinoic acid (t-RA). A rise in the enzyme activity, when t-ROL-CRBP complex was assayed, with respect to the free t-ROL, was observed. Furthermore, treatment of the enzyme with Na2S and glutathione resulted in a significant increment in catalytic activity toward t-ROL and t-RAL, due to the recons…