xanthine


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xanthine

 [zan´thēn]
a purine compound found in most bodily tissues and fluids; it is a precursor of uric acid. Methylated xanthine compounds such as caffeine, theobromine, and theophylline are used for their bronchodilator effects.

xan·thine (Xan),

(zan'thēn),
Oxidation product of guanine and hypoxanthine, precursor of uric acid; occurs in many organs and in the urine, occasionally forming urinary calculi; elevated in molybdenum cofactor deficiency and in xanthinuria.

xanthine

/xan·thine/ (-thēn) a purine base found in most body tissues and fluids, certain plants, and some urinary calculi; it is an intermediate in the degradation of AMP to uric acid. Methylated xanthine compounds (e.g., caffeine, theobromine, theophylline) are used for their bronchodilator effect. Abbreviated X.

xanthine

(zăn′thēn′, -thĭn)
n.
1. A yellowish-white, crystalline purine base, C5H4N4O2, that is a precursor of uric acid and is found in blood, urine, muscle tissue, and certain plants.
2. Any of several derivatives of this compound.

xanthine

[zan′thīn]
Etymology: Gk, xanthos, yellow
a nitrogenous by-product of the metabolism of nucleoproteins. It is normally found in the muscles, liver, spleen, pancreas, and urine. xanthic, adj.

xan·thine

(zan'thēn)
Oxidation product of guanine and hypoxanthine, precursor of uric acid; occurs in many organs and in the urine, occasionally forming urinary calculi.

xanthine

a purine compound found in most bodily tissues and fluids; it is a precursor of uric acid. Xanthine compounds such as theophylline have diuretic properties.

xanthine calculi
see xanthine urolith.
dimethyl xanthine
theobromine.
xanthine oxidase
key enzyme in the pathway for purine breakdown. Catalyzes the conversion of hypoxanthine to xanthine and then to uric acid. Generates hydrogen peroxide, which can be a generator of free radicals in biological systems through reactions with superoxide ions.
trimethyl xanthine
caffeine.
References in periodicals archive ?
Like iron, copper, zinc, manganese, and cobalt, molybdenum (Mo) can be utilized as a stably bound, variably coordinated cofactor in proteins, in mammals, Mo is found in three different enzymes: aldehyde oxidoreductase (AOR), sulfite oxidase (SOX), and xanthine oxidoreductase (XOR).
Xanthine oxidase activity was expressed as percent inhibition of xanthine oxidase, calculated as (1 - B/A) x100, where A is the change in absorbance of the assay without the plant extract (Dabs.
Superoxide anion XDH: Xanthine dehydrogenase XO: Xanthine oxidase XOR: Xanthine oxidoreductase.
6 g) exhibited significant xanthine oxidase inhibition activity at 150 ug/ml as compared to the reference standard allopurinol 67.
The increase in XOR activity detected in atherosclerosis patients reflects the detail that the catabolic pathway is increased in a way to produce hypoxanthine and xanthine in order to permit its readiness to recycle to IMP.
Mutational analysis of the xanthine dehydrogenase gene in a Turkish family with autosomal recessive classical xanthinuria.
When perfusion of ischemic organ is restored hypoxanthine is oxidized to xanthine by the enzyme xanthine oxidase, releasing free oxygen radicals which cause cell membrane damage by peroxidizing fatty acids found in the structure of phospholipid layer of cell membranes [3].
Should monotherapy with a xanthine oxidase inhibitor be insufficient to reach target, the TFP recommended the addition of a uricosuric agent, such as probenecid, losartan, or fenofibrate to the xanthine oxidase inhibitor.
In higher organisms, they fall into only two categories: xanthine dehydrogenases are involved in metabolic pathways; sulfite oxidases catalyse a small but important set of reactions involved in brain development.
Mixed-function oxygenase (MFO) enzymes are mostly represented by cytochrome P- 450s, Aryl hydrocarbon hydroxylase and xanthine oxidase which play a crucial role in the biotransformation, metabolism, and detoxification of xenobiotics and foreign compounds that are introduced in our body system.