Methylxanthine

The structure of xanthine.

Xanthines are a group of alkaloids that are commonly used for their effects as mild stimulants and as bronchodilators, notably in treating the symptoms of asthma.

Methylated xanthine derivatives include caffeine, theophylline, and theobromine (found mainly in chocolate). These drugs inhibit phosphodiesterase and antagonise adenosine.

The core compound, xanthine, is a product on the pathway of purine degradation and is converted to uric acid by the action of the xanthine oxidase enzyme. Some people lack sufficient xanthine oxidase, and thus xanthine, cannot be converted to uric acid. This, rare, inherited disease is called xanthinuria. Those with the disease thus have higher than usual concentrations of xanthine in their blood and urine which can lead to health problems such as renal failure. There is no specific treatment, sufferers are advised by doctors to avoid foods high in purine and to maintain a high fluid intake.

Xanthines are purine derivatives and found very rarely in constituents of nucleic acids.