A crystalline compound found in blood and urine which is an intermediate in the metabolic breakdown of nucleic acids to uric acid.
A purine derivative; chemical formula: C₅H₄N₄O₂
- ‘Xanthine oxidase catalyses the oxidation of xanthine and hypoxanthine to uric acid and is a well-known producer of superoxide radicals.’
- ‘It appears that the purine metabolic system in humans has found a way to avoid the overproduction of uric acid by downregulating the Xor gene expression, the product converting hypoxanthine to xanthine and further xanthine to uric acid.’
- ‘Xanthine oxidase activity was evaluated by the spectrophotometric measurement of the formation of uric acid from xanthine.’
- ‘Stones can be composed of calcium, oxalate, urate, cystine, xanthine, phosphate, or all of these.’
- ‘Red beets, another highly colored vegetable, get their scarlet color from a combination of the purple pigment cyanin and the yellow pigment xanthin.’
- 1.1count noun Any of the derivatives of xanthine, including caffeine and related alkaloids.
- ‘Methyl xanthines (caffeine, theophylline and theobromine) are found in seeds and leaves of a variety of unrelated plant species, including coffee, tea, cocoa, cola and mate.’
- ‘Ephedrine and the xanthines, such as caffeine and theophylline, increase metabolic rate.’
- ‘The main components of this tea are natural xanthines such as caffeine, theobromine, theophylline and tanni.’
- ‘Ice cream gives a little calcium, and chocolate offers plant chemicals called xanthins that can be healthful in moderation.’
- ‘From that time forward into the present, methyl xanthines have been used, most often in the form of theophylline or the water-soluble, related compound aminophylline, for the treatment of asthma.’
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