We have studied the effect of oxidant stress on human lymphocyte cytotoxicity. Lymphocyte cultures maintained good viability after incubation with xanthine and xanthine oxidase. an enzyme system known to generate several highly reactive oxygen compounds. We demonstrated that these lymphocytes were viable after exposure to an in vitro oxidant stress but had a significant impairment in both antib...

The molybdoenzyme, xanthine oxidoreductase (XOR), has been much studied, largely because of its ready availability on a large scale from cows' milk [ l ] . It catalyses the oxidation of a wide range of substrates, most notably hypoxanthine and xanthine, generating xanthine and uric acid respectively, in the process of purine catabolism. The enzyme is a homodimer of 150 kDa subunits and exists i...

At pH 7.0, in air, 20% of the total electron flux through xanthine oxidase can be accounted for in terms of the univalent reduction of oxygen. The fraction of the total flux of electrons which traversed the univalent pathway to oxygen was increased by raising the pH and by raising the oxygen tension. It was further shown that at any given pH and oxygen tension, the amount of tmivalently reduced...

Caffeine and theobromine are members of the xanthine family. Coffee soft drinks contain caffeine, whereas, in cacao, is main ingredient. The mineral contents tooth which sucked caffeine-containing dam’s milk were decreased. To determine if caffeine would affect enamel, dams fed with a pups killed first second molars extracted. Enamel was exposed to acid solution dissolved minerals from enamel m...

Abbreviations: LDL-C: Low-density-lipoprotein cholesterol; HDL-C: High-density lipoprotein cholesterol; BPH: Benign prostatic hypertrophy; PARP: ADP ribose polymerase; H2O2: Hydrogen peroxide; X: Xanthine; XO: Xanthine oxidase; BDNF: Brain-derived neurotrophic factor; pCREB: Phosphorylated cAMP response element binding-protein; pERK: Phosphorylated extracellular signal-regulated kinase; NO: Nit...

By A. MAzUR AND A. CARLETON T HE RESULTS of studies in our laboratory’ lend support to the hypothesis that the release of iron from ferritin stores in the liver is mediated by the enzyme xanthine oxidase acting as a dehydrogenase. In this reaction the reduced enzyme, formed as a result of oxidation of xanthine or hypoxanthine to uric acid, is reoxidized by some of the ferric iron of ferritin wh...

Endogenous and exogenous accumulation of nucleobases was observed when Escherichia coli entered the stationary phase. The onset of the stationary phase was accompanied by excretion of uracil and xanthine. Except for uracil and xanthine, other nucleobases (except for minor amounts of hypoxanthine), nucleosides, and nucleotides (except for cyclic AMP) were not detected in significant amounts in t...

An attempt has been made to search for xanthine oxidase (XO) inhibitors from the root extracts of Tephrosia purpurea Linn. which is traditionally used in folk medicine in India. Root extracts were screened for in vitro antioxidant and xanthine oxidase inhibitory activity. Antioxidant activity was measured using ABTS, DPPH, FRAP and ORAC methods. The enzyme inhibitory activity was tested on puri...

complex reacted rapidly with 02-. in a catalytic manner. The rate constant for O,-* dismutation was determined by competition of the iron porphyrin with Nitro Blue Tetrazolium in a xanthine/xanthine oxidase system at pH 10.1 ; a value of 3 x ~O'M-' .s-' at 20°C was obtained. The iron porphyrin had no effect on xanthine oxidase activity. Under our reaction conditions, at least 14 molecules of Oz...