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
xan·thine (z n th n , -th n)n. 1. A yellowish-white crystalline purine base that is a precursor of uric acid and is found in blood, urine, and muscle tissue. 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.
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.
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