an efficient one-pot oxidation/condensation tandem process has been developed for the synthesis of 2-substituted benzimidazole derivatives from benzylic alcohols and 1,2-phenylenediamine with use of urea-hydrogen peroxide/silica phosphoric acid  as a bifunctional catalyst. this method provides a rapid and efficient access to 2-substituted benzimidazoles.

The aim of this research is to determine whether oxidative stress induces cellular senescence in human retinal pigment epithelial cells. Cultured ARPE19 cells were subjected to different concentrations of hydrogen peroxide to induce oxidative stress. Cells were seeded into 24-well plates with hydrogen peroxide added to cell medium and incubated at 37°C + 5% CO2 for a 90-minute period [at 0, 300...

Reactive oxygen species (ROS) such as superoxide radical anion, singlet oxygen, hydrogen peroxide and hydroxyl radical are products of oxidative metabolism (Kourie, 1998). Low levels of ROS contribute to important signaling pathways to regulate key biological responses, including cell migration, mitosis and apoptosis (Goldschmidt-Clermont & Moldovan, 1999). For instance, endogenous oxidants pro...

We constructed and characterized a Xanthomonas campestris pv. phaseoli oxyR mutant. The mutant was hypersensitive to H2O2 and menadione killing and had reduced aerobic plating efficiency. The oxidants' induction of the catalase and ahpC genes was also abolished in the mutant. Analysis of the adaptive responses showed that hydrogen peroxide-induced protection against hydrogen peroxide was lost, ...

Lactoperoxidase and thiocyanate were shown to protect Escherichia coli and three oral streptococcal species from the bactericidal effect of hydrogen peroxide under aerobic conditions. Lactoperoxidase in the absence of thiocyanate was also protective for two of the bacterial species in a dilution medium but potentiated hydrogen peroxide toxicity for the other two under the same conditions. The p...

A new method for the determination of glutathione peroxidase activity in erythrocytes was developed. The present method was applied to the measurement of hydrogen peroxide removal rates by glutathione peroxidase in erythrocytes at 70 microM hydrogen peroxide under simulated in vivo conditions. The removal rates by glutathione peroxidase in mouse erythrocytes were twenty-times faster than those ...

The results of research carried out on rats, assessing the influence of chronic intoxication with ethanol, methanol, and ethylene glycol on hydrogen peroxide concentration in internal organs – brain, lungs, liver, kidney, and heart – are presented in this paper. It was shown that the organ most exposed to the detrimental activity of ethanol, methanol, and ethylene glycol is the heart: the great...

Understanding intracellular redox chemistry requires new tools for the site-specific visualization of intracellular oxidation. We have developed a spatially-resolved intracellular sensor of hydrogen peroxide, HyPer-Tau, for time-resolved imaging in live cells. This sensor consists of a hydrogen peroxide-sensing protein tethered to microtubules. We demonstrate the use of the HyPer-Tau sensor for...

To determine the regulatory role of p72syk in lymphocyte activation, peripheral blood lymphocytes were treated with 10 mM hydrogen peroxide. Hydrogen peroxide induced a rapid elevation of p72syk activity (4-6-fold) and a dramatic increase in tyrosine phosphorylation of a number of cellular proteins, including phospholipase C gamma 1 (PLC gamma 1) and p72syk. Monoclonal antibodies to PLC gamma 1...

Szucs (1913) reported that hydrogen peroxide increased the permeability of the living cell. Following up a previous observation [Bokorny, 1886], he found that if threads of Spirogyra were treated first with hydrogen peroxide and then with ferrous sulphate solutions, a dark precipitate appeared within the cells. He concluded that the hydrogen peroxide had so increased the permeability of the cel...