Linking - Xanthine
Information Portal (U.S. National Library of Medicine) - 3-Methylxanthine
Bank - 3-Methylxanthine
(Kyoto Encyclopedia of Genes and Genomes) - 3-Methylxanthine
theobromine and theophylline are chemical compounds
with closely related structures and similar pharmacological
properties. They are all members of the class of compounds
known as methylxanthines which are mild stimulants.
They occur in many common food plants such as coffee,
tea, cocoa, maté and cola. From time to time,
they have been linked with a range of conditions including
heart disease and high blood pressure. Some people are
concerned that children may be consuming excessive amounts.
As a result of this interest, a vast amount of research
has been carried out, mainly on caffeine with less on
theobromine. Caffeine is the compound that is consumed
in the largest quantities, although intakes average
only 2.4 to 4.5 mg per day in typical Europeans.
The methylxanthine caffeine has many pharmacological effects, most of which can
be linked to blockade of adenosine receptors, inhibition of phosphodiesterases,
and augmentation of calcium-dependent release of calcium from intracellular
stores. A variety of xanthines have been developed as potent and/or
selective antagonists for adenosine receptors. Several xanthines have been
developed that are more potent and more selective inhibitors of cyclic
nucleotide phosphodiesterase than caffeine or theophylline. Caffeine remains
the xanthine of choice for activation of intracellular calcium-sensitive calcium
release channels although millimolar concentrations are required, which can have
effects on other aspects of calcium regulation.