Methylxanthines

Methylxanthines are purine derivatives that are biosynthesized by enzymatic methylation of free xanthine on N-1,N-3 and/or N-7. Naturally occurring methylxanthines are caffeine, theobromine, theophylline are plant constituents. They are used as pharmaceuticals in various areas.

Methylxanthines have, among other things, centrally stimulating effects; they have a dilatatory effect on skin and blood vessels. They also have bronchodilatory and diuretic effects. They exert their effect by inhibiting adenosine receptors (ATP receptors). In higher doses methylxanthines act as non-selective phosphodiesterase inhibitors.

The following substances belong to the methylxanthines (see structural formulae):

• Theophylline
• Theobromine
• Caffeine

Another methylxanthine used therapeutically is aminophylline, a complex of theophylline and ethylenediamine.