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)

Plasmalogens have been determined in blood plasma, arterial and myocardial tissue of rats intubated with an atherogenic diet (vitamin D2 + cholesterol). These lipids are significantly decreased in arterial tissue after the administration of these substances for 5 consecutive days. Folic acid involved in the synthesis of plasmalogens and a powerful inhibitor of xanthine oxidase, on the contrary, increases enormously the concentration of plasmalogens in arterial tissue even with an atherogenic diet.
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PMID:Plasmalogens in arterial wall. 90 37

Although folate deficiency and increased requirements for folate are observed in most alcoholics, the possibility that acetaldehyde generated from ethanol metabolism may increase folate catabolism has not been previously demonstrated. Folate cleavage was studied in vitro during the metabolism of acetaldehyde by xanthine oxidase, measured as the production of p-aminobenzoylglutamate from folate using h.p.l.c. Acetaldehyde/xanthine oxidase generated superoxide, which cleaved folates (5-methyltetrahydrofolate greater than folinic acid greater than folate) and was inhibited by superoxide dismutase. Cleavage was increased by addition of ferritin and inhibited by desferrioxamine (a tight chelator of iron), suggesting the importance of catalytic iron. Superoxide generated from the metabolism of ethanol to acetaldehyde in the presence of xanthine oxidase in vivo may contribute to the severity of folate deficiency in the alcoholic.
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PMID:Cleavage of folates during ethanol metabolism. Role of acetaldehyde/xanthine oxidase-generated superoxide. 253 25

We have examined the effects of folate compounds and the folate analog amethopterin (methotrexate) as inhibitors of mammalian xanthine oxidase and have found that they offer potent inhibition of the enzyme. We have compared the inhibitory potency of folic acid and its coenzyme derivative tetrahydrofolic acid to that of allopurinol, a known inhibitor of xanthine oxidase, and have demonstrated that folic acid and tetrahydrofolic acid are severalfold more potent than allopurinol as inhibitors of xanthine oxidase. Comparative inhibition constants calculated were 5.0 X 10(-7) M for folic acid. 1.25 X 10(-6) M for tetrahydrofolic acid, and 4.88 X 10(-6) M for allopurinol. Incubation of xanthine oxidase with folic acid at a concentration of 10(-6) M abolished 94% of the enzymic activity within 1 min of incubation with the enzyme. At the same concentration, allopurinol was almost ineffective as an inhibitor of xanthine oxidase. The substrate xanthine protected the enzyme against total inhibition by folic acid. Reversibility of the enzymic inhibition by folic acid was demonstrated. Folic acid-inactivated enzyme was totally regenerated either by filtration through Sephadex G-200 or by precipitation with ammonium sulfate. 2-Amino-4-hydroxypteridine was a poor substrate for the enzyme but a potent inhibitor for the oxidation of xanthine by the enzyme. The inhibition constant calculated was 1.50 X 10(-6) M. In the presence of an excess of xanthine oxidase, neither folic acid nor tetrahydrofolic acid and allopurinol exhibited any change in intensity of their absorbance or in the wavelength of their maximal absorbance that might have been suggestive of substrate utility. The folate analog amethopterin was also determined a potent inhibitor of mammalian xanthine oxidase. The inhibition constant calculated was 3.0 X 10(-5) M.
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PMID:Inhibition of mammalian xanthine oxidase by folate compounds and amethopterin. 660 20

PGA administered in doses up to 1000 mg orally a day did not significantly lower the serum urate concentration nor decrease the urinary urate or total oxypurine excretion in five hyperuricemic subjects. The folate was well absorbed, as reflected by marked increases in the serum and erythrocyte folate concentrations, and up to 50% of the administered folate could be recovered in the urine. There was no evidence of clinical or laboratory toxicity at these high doses of folate. PGA is a weak inhibitor of human liver xanthine oxidase in vitro, and much of its inhibitory effect is secondary to trace contamination by pterin-6-aldehyde, a potent inhibitor of the enzyme.
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PMID:Failure of folic acid (pteroylglutamic acid) to affect hyperuricemia. 689 65

Folic acid was irradiated under cooling at 10 degrees C in a slightly alkaline solution with a ceramics radiator (surface temperature: 68 degrees C). The difference spectra of the folate against the non-irradiated one showed a red shift. The difference absorbance of the peak at the wavelength above 320 nm increased with the radiation time. Affinity of the irradiated folate (FA(+)), which is a competitive inhibitor, to the irradiated xanthine oxidase (XO(+)) more increased than the irradiated substrate with increasing temperature of the reaction, while the affinity to the non-irradiated enzyme (XO(-)) significantly decreased. The difference of the standard entropy change in the FA(+)/XO(-) system to that in the non-irradiated FA(-)/XO(-) system, i.e., delta (delta Ss) gave a large negative value, while delta (delta Ss) of the FA(-)/XO(+) system gave a large positive value. An increase in the delta (delta Ss) of the FA(+)/XO(+) system overcame an increase in the enthalpy difference delta (delta Hs) of the system, and then the free-energy difference delta (delta Gs) resulted in the most negative value. This means that the driving force by the reaction system depends on an entropy effect. These results indicate that the red shift of the spectra of FA(+) is due to a solvent ordering effect obtained by the radiation, and that the affinity of the FA(+) to the active center of XO(+) increases when XO has also received the ordering effect.
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PMID:Non-thermal effect of ceramics radiation on folate structure and on xanthine oxidase inhibition by folate. 812 Jun 67

15-Deoxy-delta(12,14)-prostaglandin J(2) (15dPGJ(2) has been recently proposed as a potent anti-inflammatory agent. However, the mechanisms by which 15dPGJ(2) mediates its therapeutic effects in vivo are unclear. We demonstrate that 15dPGJ(2) at micromolar (2.5-10 microm) concentrations induces the expression of heme oxygenase-1 (HO-1), an anti-inflammatory enzyme, at both mRNA and protein levels in human lymphocytes. In contrast, troglitazone and ciglitazone, two thiazolidinediones that mimic several effects of 15dPGJ(2) through their binding to the peroxisome proliferator-activated receptor (PPAR)-gamma, did not affect HO-1 expression, and the positive effect of 15dPGJ(2) on this process was mimicked instead by other cyclopentenone prostaglandins (PG), such as PGD(2) (the precursor of 15dPGJ(2)) and PGA(1) and PGA(2) which do not interact with PPAR-gamma. Also, 15dPGJ(2) enhanced the intracellular production of reactive oxygen species (ROS) and increased xanthine oxidase activity in vitro. Inhibition of intracellular ROS production by N-acetylcysteine, TEMPO, Me(2)SO, 1,10-phenanthroline, or allopurinol resulted in a decreased 15dPGJ(2)-dependent HO-1 expression in the cells. Furthermore, buthionine sulfoximine, an inhibitor of reduced glutathione synthesis, or Fe(2+)/Cu(2+) ions enhanced the positive effect of 15dPGJ(2) on HO-1 expression. On the other hand, the inhibition of phosphatidylinositol 3-kinase or p38 mitogen-activated protein kinase, or the blockade of transcription factor NF-kappaB activation, hindered 15dPGJ(2)-elicited HO-1 expression. Collectively, the present data suggest that 15dPGJ(2) anti-inflammatory actions at pharmacological concentrations involve the induction of HO-1 gene expression through mechanisms independent of PPAR-gamma activation and dependent on ROS produced via the xanthine/xanthine oxidase system and/or through Fenton reactions. Both phosphatidylinositol 3-kinase and p38 mitogen-activated protein kinase signaling pathways also appear implicated in modulation of HO-1 expression by 15dPGJ(2).
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PMID:15-deoxy-delta 12,14-prostaglandin J2 induces heme oxygenase-1 gene expression in a reactive oxygen species-dependent manner in human lymphocytes. 1502 26

Hyperhomocysteinemia, a condition of elevated blood homocysteine (Hcy) levels, is a metabolic disease. It is a common clinical finding in patients with chronic kidney diseases and occurs almost uniformly in patients with end-stage renal disease. Hyperhomocysteinemia is also a risk factor for cardiovascular disease. Our recent studies indicate that hyperhomocysteinemia can lead to renal injury by inducing oxidative stress. Oxidative stress is one of the important mechanisms contributing to Hcy-induced tissue injury. Folic acid supplementation is regarded as a promising approach for prevention and treatment of cardiovascular disease associated with hyperhomocysteinemia due to its Hcy-lowering effect. However, its effect on the kidney is not clear. The aim of this study was to examine the effect of folic acid supplementation on Hcy-induced superoxide anion production via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the kidney during hyperhomocysteinemia. Hyperhomocysteinemia was induced in male Sprague-Dawley rats fed a high-methionine diet for 12 wk with or without folic acid supplementation. A group of rats fed a regular diet was used as control. There was a significant increase in levels of superoxide anions and lipid peroxides in kidneys isolated from hyperhomocysteinemic rats. Activation of NADPH oxidase was responsible for hyperhomocysteinemia-induced oxidative stress in the kidney. Folic acid supplementation effectively antagonized hyperhomocysteinemia-induced oxidative stress via its Hcy-lowering and Hcy-independent effect. In vitro study also showed that 5-methyltetrahydrofolate, an active form of folate, effectively reduced Hcy-induced superoxide anion production via NADPH oxidase. Xanthine oxidase activity was increased and superoxide dismutase (SOD) activity was decreased in the kidney of hyperhomocysteinemic rats, which might also contribute to an elevation of superoxide anion level in the kidney. Folic acid supplementation attenuated xanthine oxidase activity and restored SOD activity in the kidney of hyperhomocysteinemic rats. These results suggest that folic acid supplementation may offer renal protective effect against oxidative stress.
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PMID:Folic acid supplementation inhibits NADPH oxidase-mediated superoxide anion production in the kidney. 2098 Apr 7