Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The inhibitory effects of five tea polyphenols, namely theaflavin (TF1), theaflavin-3-gallate (TF2), theaflavin-3,3'-digallate (TF3), (-)-epigallocatechin-3-gallate (EGCG), and gallic acid, and propyl gallate (PG) on xanthine oxidase (XO) were investigated. These six antioxidant compounds reduce oxidative stress. Theaflavins and EGCG inhibit XO to produce uric acid and also act as scanvengers of superoxide. TF3 acts as a competitive inhibitor and is the most potent inhibitor of XO among these compounds. Tea polyphenols and PG all have potent inhibitory effects (>50%) on PMA-stimulated superoxide production at 20 approximately 50 microM in HL-60 cells. Gallic acid (GA) showed no inhibition under the same conditions. At 10 microM, only EGCG, TF3, and PG showed significant inhibition with potency of PG > EGCG > TF3. The superoxide scavenging abilities of these six compunds are as follows: EGCG > TF2 > TF1 > GA > TF3 > PG. PG was the most potent inhibitor of PMA-stimulated H(2)O(2) production in HL-60 cells. The order of H(2)O(2) scavenging ability was TF2 > TF3 > TF1 > EGCG > PG > GA. Therefore, the antioxidative activity of tea polyphenols and PG is due not only to their ability to scavenge superoxides but also to their ability to block XO and related oxidative signal transducers.
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PMID:Inhibition of xanthine oxidase and suppression of intracellular reactive oxygen species in HL-60 cells by theaflavin-3,3'-digallate, (-)-epigallocatechin-3-gallate, and propyl gallate. 1089 15

We previously reported that fluvastatin, a potent 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, a strong lipid lowering drug, exerted an anti-atherosclerotic effect at doses insufficient to lower serum lipids in cholesterol fed rabbits. The evidence demonstrated that the superoxide anions from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase plays a critical role in several steps in the development of atherosclerosis. This study was designed to determine the effects of HMG-CoA reductase inhibitors on the production of the superoxide anions of NADPH oxidase in isolated rat peritoneal neutrophils. Fluvastatin (1-10 microM) decreased phorbol 12-myristate 13-acetate (PMA, 10 nM)-dependent reactive oxygen species (ROS) generation in a concentration-dependent manner. It also (10 microM) decreased PMA-dependent O(2) consumption of the rat neutrophils. These effects were reversed by the addition of mevalonate, a metabolite in the HMG-CoA reductase pathway. Treatment with pravastatin did not show any significant changes. Fluvastatin (10 microM) decreased ROS, such as hydroxyl radicals and superoxide anions generated by the Fenton reaction, and by the xanthine-xanthine oxidase system. Rats were treated with either fluvastatin (5 mg/kg per day, p.o.) or pravastatin (5 mg/kg per day, p.o.) for 1 week. Treatment with fluvastatin decreased the PMA-dependent ROS generation. The fluvastatin induced effect on the PMA-dependent ROS generation was reversed by the combined administration with 40 mg/kg mevalonate per day. The antioxidative effect of fluvastatin was thought to have caused not only the scavenging action of the radicals but also to have inhibited ROS generation by inhibiting the NADPH oxidase activity. This antioxidative potential of fluvastatin via the inhibition of NADPH oxidase activity may be profitable in preventing atherosclerosis.
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PMID:Antioxidative potential of fluvastatin via the inhibition of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. 1280 93

Many harmful effects of nitric oxide are caused by the reaction of NO with superoxide anion. The present study was carried out to find out the concomitant production of superoxide and to investigate a suitable inhibitor of NO, which is produced by iNOS. THP-1 cells were differentiated into macrophages by PMA and cytokine. Addition of L-NAME showed decrement in superoxide production. Addition of apocynin, aminoguanidine or ONO 1714 brought about a significant reduction in superoxide production. The expressions of p67 and p47(phox) were reduced by the addition of apocynin, aminoguanidine or ONO 1714 whereas xanthine oxidase and cyclooxygenase did not have a major role in superoxide production. The results of the present study show that iNOS and NADPH oxidase play an important role in superoxide release. It suggests that addition of iNOS inhibitor together with apocynin may be more effective in case of therapeutic application in disease conditions like atherosclerosis.
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PMID:Concomitant production of nitric oxide and superoxide in human macrophages. 1452 19

Mechanism of the action of silybin (1) and its derivatives (2-4), possessing different lipid solubility in PMA-stimulated neutrophils was evaluated. Silybin (1) inhibited the calcium, phosphatidylserine- and diacylglycerol-dependent protein kinase C translocation and the NADPH oxidase activity in PMA-stimulated neutrophils and resulted in decreased apoptosis. Furthermore, silybin (1) inhibited xanthine oxidase activity and hem-mediated oxidative degradation of low-density lipoprotein, as well. Its derivatives (2-4), possessing different lipid-solubility, affected all the studied parameters. The lipid solubility of silybin (1) was enhanced by methylation (5'7'4''trimethylsilybin: 2), whereas a decrease in lipid-solubility by acetylation of compound 2 (5',7,'4"-trimethylsilybin-acetate: 3) or all the hydroxyl groups of silybin (peracetyl-silybin: 4) attenuated the antioxidant capacity by decreasing the inhibition in PKC translocation and NADPH oxidase activation. All the derivatives of silybin (2-4) showed no inhibition in cell free systems; e.g. did not alter the xanthine oxidase activity and the hem-mediated oxidative degradation of LDL. In conclusion, the antioxidant activity of (1) might be due to its ability to inhibit PKC translocation and NADPH oxidase activation in PMA-stimulated neutrophils. The increase of lipid solubility of silybin (1) supports its penetration through cell membrane and enhances its inhibitory effects. This structural modification of (1) might have pharmacological consequences.
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PMID:Effect of silybin on phorbol myristate actetate-induced protein kinase C translocation, NADPH oxidase activity and apoptosis in human neutrophils. 1507 Jan 74

Dang-Gui-Shao-Yao-San (DGSYS) is a mixture of medicinal herbs, which has long been used in traditional Chinese medicine for treating anemia and ovulary disorders. Its preparation comprises Angelicae sinensis (Oliv.) Diels, Ligustucum chuanxiong Hort, Paeonia lactiflora pall, Poria cocos (Schw.) Wolf, Atractylodis macrocephala Koidz and Alisma orientalis (Sam.) Juzep. The present study examined the anti-superoxide formation, free radical scavenging and anti-lipid peroxidation activities of DGSYS by xanthine oxidase inhibition, cytochrome C system with superoxide anion released by the fMLP or PMA activating pathway in human neutrophils, and FeCl2 ascorbic acid-induced lipid peroxidation effects on lipids in rat liver homogenate, respectively. DGSYS showed anti-superoxide formation and free radical scavenging activity in a concentration-dependent manner. It also inhibited PMA- but not fMLP-induced superoxide anion released from human neutrophils. These antioxidant actions of DGSYS showed beneficial cytoprotective effects against lipid peroxidation in rat liver homogenate, human platelet aggregation induced by arachidonic acid (AA) and adenosine diphosphate (ADP) and mitomycin C-mediated hemolytic in human erythrocytes.
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PMID:Antioxidant and antiplatelet effects of dang-gui-shao-yao-san on human blood cells. 1626 87

Structural analogues (flavanone: 2-4 and flavone: 5 and 6, respectively) of silybin (1a) were synthesized and tested for inhibitory activity on O(2)(-) release and PKC translocation in PMA-stimulated neutrophils as well as xanthine oxidase activity in order to identify the molecular structures responsible for the antioxidant property of silybin. Concerning the prevention of hem-mediated oxidative modification of LDL by silybin, the hydroxyl radical scavenging activity of its structural analogues was also determined. We demonstrated that the basic skeleton of 1a (4) is responsible for its inhibitory activity on O(2)(-) release in PMA-stimulated neutrophils via inhibition of PKC translocation, since introduction of a double bound and hydroxyl groups at C-5 and C-7 position (5 and 6) did not result in further increase in inhibition of O(2)(-) release. It has been shown that the presence of the phenolic hydroxyl group at C-5 and C-7 of 1a is essential for the inhibition of xanthine oxidase activity. Moreover, introduction of a double bond into the C-ring of 2 and 3, resulting in flavone derivatives (5 and 6), markedly enhanced the antioxidant effect in all the tested systems. Finally, silybin (1a) and its flavon derivatives (5 and 6) directly scavenged hydroxyl radicals as well. On the basis of these results it might be concluded that different moiety of silybin is responsible for inhibition of overproduction of O(2)(-) in stimulated neutrophils, xanthine oxidase activity, and for prevention of hem-mediated oxidative modification of LDL.
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PMID:Structure prerequisite for antioxidant activity of silybin in different biochemical systems in vitro. 1636 Sep 37

Microglia are resident brain macrophages that become activated and proliferate following brain damage or stimulation by immune mediators, such as IL-1beta or TNF-alpha. We investigated the mechanisms by which microglial proliferation is regulated in primary cultures of rat glia. We found that basal proliferation of microglia was stimulated by proinflammatory cytokines IL-1beta or TNF-alpha, and this proliferation was completely inhibited by catalase, implicating hydrogen peroxide as a mediator of proliferation. In addition, inhibitors of NADPH oxidase (diphenylene iodonium or apocynin) also prevented microglia proliferation, suggesting that this may be the source of hydrogen peroxide. IL-1beta and TNF-alpha rapidly stimulated the rate of hydrogen peroxide produced by isolated microglia, and this was inhibited by diphenylene iodonium, implying that the cytokines were acting directly on microglia to stimulate the NADPH oxidase. Low concentrations of PMA or arachidonic acid (known activators of NADPH oxidase) or xanthine/xanthine oxidase or glucose oxidase (generating hydrogen peroxide) also increased microglia proliferation and this was blocked by catalase, showing that NADPH oxidase activation or hydrogen peroxide was sufficient to stimulate microglia proliferation. In contrast to microglia, the proliferation of astrocytes was unaffected by the presence of catalase. In conclusion, these findings indicate that microglial proliferation in response to IL-1beta or TNF-alpha is mediated by hydrogen peroxide from NADPH oxidase.
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PMID:Microglia proliferation is regulated by hydrogen peroxide from NADPH oxidase. 1639 92

Single-walled carbon nanotubes (SWCNT), nano-cylinders with an extremely small diameter (1-2 nm) and high aspect ratio, have unique physico-chemical, electronic and mechanical properties and may exhibit unusual interactions with cells and tissues, thus necessitating studies of their toxicity and health effects. Manufactured SWCNT usually contain significant amounts of iron that may act as a catalyst of oxidative stress. Because macrophages are the primary responders to different particles that initiate and propagate inflammatory reactions and oxidative stress, we utilized two types of SWCNT: (1) iron-rich (non-purified) SWCNT (26 wt.% of iron) and (2) iron-stripped (purified) SWCNT (0.23 wt.% of iron) to study their interactions with RAW 264.7 macrophages. Ultrasonication resulted in predominantly well-dispersed and separated SWCNT strands as evidenced by scanning electron microscopy. Neither purified nor non-purified SWCNT were able to generate intracellular production of superoxide radicals or nitric oxide in RAW 264.7 macrophages as documented by flow-cytometry and fluorescence microscopy. SWCNT with different iron content displayed different redox activity in a cell-free model system as revealed by EPR-detectable formation of ascorbate radicals resulting from ascorbate oxidation. In the presence of zymosan-stimulated RAW 264.7 macrophages, non-purified iron-rich SWCNT were more effective in generating hydroxyl radicals (documented by EPR spin-trapping with 5,5-dimethyl-1-pyrroline-N-oxide, DMPO) than purified SWCNT. Similarly, EPR spin-trapping experiments in the presence of zymosan-stimulated RAW 264.7 macrophages showed that non-purified SWCNT more effectively converted superoxide radicals generated by xanthine oxidase/xanthine into hydroxyl radicals as compared to purified SWCNT. Iron-rich SWCNT caused significant loss of intracellular low molecular weight thiols (GSH) and accumulation of lipid hydroperoxides in both zymosan-and PMA-stimulated RAW 264.7 macrophages. Catalase was able to partially protect macrophages against SWCNT induced elevation of biomarkers of oxidative stress (enhancement of lipid peroxidation and GSH depletion). Thus, the presence of iron in SWCNT may be important in determining redox-dependent responses of macrophages.
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PMID:Direct and indirect effects of single walled carbon nanotubes on RAW 264.7 macrophages: role of iron. 1652 36

Sphingolipids inhibit the activation of the neutrophil (PMN) NADPH oxidase by protein kinase C pathway. By electron spin resonance spectroscopy (ESR) and chemiluminescence (CL), we studied the effects of sphingosine (SPN) and ceramide analogues on phorbol 12-myristate 13-acetate (PMA, 5x10(-7) M) stimulated PMN (6x10(6) cells). By ESR with spin trapping (100 mM DMPO: 5,5-dimethyl-1-pyrroline-Noxide), we showed that SPN (5 to 8x10(-6) M), C2-ceramide (N-acetyl SPN) and C6-ceramide (N-hexanoyl SPN) at the final concentration of 2x10(-5) and 2x10(-4) M inhibit the production of free radicals by stimulated PMN. The ESR spectrum of stimulated PMN was that of DMPO-superoxide anion spin adduct. Inhibition by 5x10(-6) M SPN was equivalent to that of 30 U/ml SOD. SPN (5 to 8x10(-6) M) has no effect on in vitro systems generating superoxide anion (xanthine 50 mM/xanthine oxidase 110 mU/ml) or hydroxyl radical (Fenton reaction: 88 mM H2O2, 0.01 mM Fe2+ and 0.01 mM EDTA). SPN and N-acetyl SPN also inhibited the CL of PMA stimulated PMN in a dose dependent manner (from 2x10(-6) to 10(-5) M), but N-hexanoyl SPN was less active (from 2x10(-5) to 2x10(-4) M). These effects were compared with those of known PMN inhibitors, superoxide dismutase, catalase and azide. SPN was a better inhibitor compared with these agents. The complete inhibition by SPN of ESR signal and CL of stimulated PMN confirms that this compound or one of its metabolites act at the level of NADPH-oxidase, the key enzyme responsible for production of oxygen-derived free radicals.
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PMID:Effects of sphingosine and sphingosine analogues on the free radical production by stimulated neutrophils: ESR and chemiluminescence studies. 1847 67

Lithospermic acid (LSA) was originally isolated from the roots of Salvia mitiorrhiza, a common herb of oriental medicine. Previous studies demonstrated that LSA has antioxidant effects. In this study, we investigated the in vitro xanthine oxidase (XO) inhibitory activity, and in vivo hypouricemic and anti-inflammatory effects of rats. XO activity was detected by measuring the formation of uric acid or superoxide radicals in the xanthine/xanthine oxidase system. The results showed that LSA inhibited the formation of uric acid and superoxide radicals significantly with an IC50 5.2 and 1.08 microg/ml, respectively, and exhibited competitive inhibition. It was also found that LSA scavenged superoxide radicals directly in the system beta-NADH/PMS and inhibited the production of superoxide in human neutrophils stimulated by PMA and fMLP. LSA was also found to have hypouricemic activity on oxonate-pretreated rats in vivo and have anti-inflammatory effects in a model of gouty arthritis. These results suggested that LSA is a competitive inhibitor of XO, able to directly scavenge superoxide and inhibit superoxide production in vitro, and presents hypouricemic and anti-inflammatory actions in vivo.
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PMID:Lithospermic acid as a novel xanthine oxidase inhibitor has anti-inflammatory and hypouricemic effects in rats. 1869 41


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