3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||152.11 g/mol|
|1 g/ 14.5 L @ 16 °C|
1 g/1.4 L @ 100 °C
|NFPA 704 (fire diamond)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Xanthine (// or //; archaically xanthic acid; systematic name 3,7-dihydropurine-2,6-dione) is a purine base found in most human body tissues and fluids and in other organisms. Several stimulants are derived from xanthine, including caffeine, theophyline, and theobromine.
- It is created from guanine by guanine deaminase.
- It is created from hypoxanthine by xanthine oxidoreductase.
- It is also created from xanthosine by purine nucleoside phosphorylase.
Use and manufacturing
Derivatives of xanthine (known collectively as xanthines) are a group of alkaloids commonly used for their effects as mild stimulants and as bronchodilators, notably in the treatment of asthma or influenza symptoms. In contrast to other, more potent stimulants like sympathomimetic amines, xanthines mainly act to oppose the actions of adenosine, and increase alertness in the central nervous system.
Due to widespread effects, the therapeutic range of xanthine is narrow, making it a merely second-line asthma treatment. The therapeutic level is 10-20 micrograms/mL blood; signs of toxicity include tremor, nausea, nervousness, and tachycardia/arrhythmia.
Methylated xanthines (methylxanthines), which include caffeine, aminophylline, IBMX, paraxanthine, pentoxifylline, theobromine, and theophylline, affect not only the airways but stimulate heart rate, force of contraction, and cardiac arrhythmias at high concentrations. In high doses, they can lead to convulsions that are resistant to anticonvulsants. Methylxanthines induce gastric acid and pepsin secretions in the gastrointestinal tract. Methylxanthines are metabolized by cytochrome P450 in the liver.
- competitive nonselective phosphodiesterase inhibitors which raise intracellular cAMP, activate PKA, inhibit TNF-α and leukotriene synthesis, and reduce inflammation and innate immunity and
- nonselective adenosine receptor antagonists  which inhibit sleepiness-inducing adenosine.
However, 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.
|Name||R1||R2||R3||R8||IUPAC nomenclature||Found in|
|Caffeine||CH3||CH3||CH3||H||1,3,7-Trimethyl-1H-purine-2,6(3H,7H)-dione||Coffee, guarana, yerba mate, tea, kola, guayusa, holly|
|Theobromine||H||CH3||CH3||H||3,7-Dihydro-3,7-dimethyl-1H-purine-2,6-dione||Cacao (chocolate), yerba mate, kola, guayusa, holly|
|Theophylline||CH3||CH3||H||H||1,3-Dimethyl-7H-purine-2,6-dione||Tea, cacao (chocolate), yerba mate, kola|
|Paraxanthine||CH3||H||CH3||H||1,7-Dimethyl-7H-purine-2,6-dione||Animals that have consumed caffeine|
|8-Chlorotheophylline||CH3||CH3||H||Cl||8-Chloro-1,3-dimethyl-7H-purine-2,6-dione||Synthetic pharmaceutical ingredient|
|8-Bromotheophylline||CH3||CH3||H||Br||8-Bromo-1,3-dimethyl-7H-purine-2,6-dione||Pamabrom diuretic medication|
|Diprophylline||CH3||CH3||C3H7O2||H||7-(2,3-Dihydroxypropyl)-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione||Synthetic pharmaceutical ingredient|
|Uric acid||H||H||H||O||7,9-Dihydro-1H-purine-2,6,8(3H)-trione||Byproduct of purine nucleotides metabolism and a normal component of urine|
Speculation on origin
Studies reported in 2008, based on 12C/13C isotopic ratios of organic compounds found in the Murchison meteorite, suggested that xanthine and related chemicals, including the RNA component uracil, were formed extraterrestrially. In August 2011, a report, based on NASA studies with meteorites found on Earth, was published suggesting xanthine and related organic molecules, including the DNA and RNA components adenine and guanine, were found in outer space.
- Merck Index, 11th Edition, 9968.
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- Martins, Z.; Botta, O.; Fogel, M. L.; Sephton, M. A.; Glavin, D. P.; Watson, J. S.; Dworkin, J. P.; Schwartz, A. W.; Ehrenfreund, P. (2008). "Extraterrestrial nucleobases in the Murchison meteorite". Earth and Planetary Science Letters. 270 (1–2): 130–136. arXiv:0806.2286. Bibcode:2008E&PSL.270..130M. doi:10.1016/j.epsl.2008.03.026.
- AFP Staff (13 June 2008). "We may all be space aliens: study". AFP. Archived from the original on June 17, 2008. Retrieved 2011-08-14.
- Callahan, M. P.; Smith, K. E.; Cleaves, H. J.; Ruzicka, J.; Stern, J. C.; Glavin, D. P.; House, C. H.; Dworkin, J. P. (2011). "Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases". Proceedings of the National Academy of Sciences. 108 (34): 13995–8. Bibcode:2011PNAS..10813995C. doi:10.1073/pnas.1106493108. PMC 3161613. PMID 21836052.
- Steigerwald, John (8 August 2011). "NASA Researchers: DNA Building Blocks Can Be Made in Space". NASA. Retrieved 2011-08-10.
- ScienceDaily Staff (9 August 2011). "DNA Building Blocks Can Be Made in Space, NASA Evidence Suggests". ScienceDaily. Retrieved 2011-08-09.