释义 |
xanthine /ˈzanθiːn /noun [mass noun] Biochemistry1A 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.
1.1 [count noun] Any of the derivatives of this, 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.
Origin Mid 19th century: from xanthic + -ine4. |