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- Published: 2011-02-05
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- Author: bodysuppsvideos
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Xanthine is a product on the pathway of purine degradation.
Xanthine is subsequently converted to uric acid by the action of the xanthine oxidase enzyme.
Methylxanthines affect not only the airways but stimulate heart rate, force of contraction, cardiac arrhythmias at high concentrations. In the CNS they increase alertness, stimulate the respiratory centre, and are used for treatment of infantile apnea. In high doses they can lead to convulsions that are resistant to anticonvulsants. Methylxanthines induce acid and pepsin secretions in the GI tract. Methylxanthines are metabolized by Cytochrome P450 in the liver. Methylated xanthines include caffeine, aminophylline, IBMX, paraxanthine, pentoxifylline , theobromine, and theophylline. These drugs act as both # competitive nonselective phosphodiesterase inhibitors which raise intracellular cAMP, activate PKA, inhibit TNF-alpha and leukotriene synthesis, and reduce inflammation and innate immunity and # nonselective adenosine receptor antagonists which inhibit sleepiness-inducing adenosine. But different analogues show varying potency at the numerous subtypes, and a wide range of synthetic xanthines (some nonmethylated) have been developed searching for compounds with greater selectivity for phosphodiesterase enzyme or adenosine receptor subtypes. Xanthines are also found very rarely as constituents of nucleic acids.
{| class="wikitable sortable" |+ Selected Xanthines !Name!!R1!!R2!!R3!!IUPAC nomenclature!!Found In |- |Caffeine||CH3||CH3||CH3||1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione||Coffee, Guarana, Yerba mate, Tea, Kola |- |Theobromine||H||CH3||CH3||3,7-dihydro-3,7-dimethyl-1H-purine-2,6-dione||Chocolate, Yerba mate |- |Theophylline||CH3||CH3||H||1,3-dimethyl-7H-purine-2,6-dione||Tea, chocolate, Yerba mate |- |Xanthine||H||H||H||3,7-dihydro-purine-2,6-dione||plants, animals |}
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