Xanthine (3,7-dihydro-purine-2,6-dione), is a purine

Purine

A purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines, including substituted purines and their tautomers, are the most widely distributed kind of nitrogen-containing heterocycle in nature....

 base

Base (chemistry)

For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...

 found in most human body tissues and fluids and in other organisms. A number of stimulant

Stimulant

Stimulants are psychoactive drugs which induce temporary improvements in either mental or physical function or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others...

s are derived from xanthine, including caffeine

Caffeine

Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...

 and theobromine

Theobromine

Theobromine , also known as xantheose, is a bitter alkaloid of the cacao plant, with the chemical formula C7H8N4O2. It is found in chocolate, as well as in a number of other foods, including the leaves of the tea plant, and the kola nut...

.

Xanthine is a product on the pathway of purine degradation.

• It is created from guanine
  Guanine
  Guanine is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine . In DNA, guanine is paired with cytosine. With the formula C5H5N5O, guanine is a derivative of purine, consisting of a fused pyrimidine-imidazole ring system with...
  
   by guanine deaminase
  Guanine deaminase
  Guanine deaminase is an enzyme which converts guanine to xanthine.-External links:...
  
  .
• It is created from hypoxanthine
  Hypoxanthine
  Hypoxanthine is a naturally occurring purine derivative. It is occasionally found as a constituent of nucleic acids where it is present in the anticodon of tRNA in the form of its nucleoside inosine. It has a tautomer known as 6-Hydroxypurine. Hypoxanthine is a necessary additive in certain cell,...
  
   by xanthine oxidoreductase.
• It is also created from xanthosine
  Xanthosine
  Xanthosine is a nucleoside derived from xanthine and ribose.-See also:* Xanthosine monophosphate* Xanthosine diphosphate* Xanthosine triphosphate...
  
   by purine nucleoside phosphorylase
  Purine nucleoside phosphorylase
  Purine nucleoside phosphorylase also known as PNPase and inosine phosphorylase is an enzyme that in humans is encoded by the NP gene.- Function :Purine nucleoside phosphorylase is an enzyme involved in purine metabolism...
  
  (PNP).

Xanthine is subsequently converted to uric acid

Uric acid

Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates such as ammonium acid urate. Uric acid is created when the body breaks down purine nucleotides. High blood concentrations of uric acid...

 by the action of the xanthine oxidase

Xanthine oxidase

Xanthine oxidase Xanthine oxidase Xanthine oxidase (XO (sometimes 'XAO'), a form of xanthine oxidoreductase that generates reactive oxygen species. Is an enzyme that catalyzes the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid...

 enzyme.

Studies reported in 2008, based on ¹²C/¹³C isotopic ratios of organic compounds found in the Murchison meteorite

Murchison meteorite

The Murchison meteorite is named after Murchison, Victoria, in Australia. It is one of the most studied meteorites due to its large mass , the fact that it was an observed fall, and it belongs to a group of meteorites rich in organic compounds....

, suggested that xanthine and related chemicals, including the RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

 component uracil

Uracil

Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine, cytosine, and guanine. In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine.Uracil is a common and...

, were formed extraterrestrially.