An alkaloid is a nitrogen-containing physiologically active compound extracted from plant material. Xanthine alkaloids (xanthines) are intermediates in the degradation of adenosine monophosphate (AMP) to uric acid, being formed by oxidation of hypoxanthine. Xanthines are found in body tissues and fluids, some urinary calculi, and in some plants. They are probably the most widely known and used alkaloids, being constituents of popular daily beverages and foods which include tea, coffee, guarana, maté cola nuts, cola drinks, cocoa, chocolate, yaupon and yoko.
Since high concentrations of some xanthine alkaloids such as caffeine inhibits the growth of plant cells, coffee embryos and other tissues producing caffeine have specific means of avoiding autotoxicity. It is believed that plants producing xanthine alkaloids accumulate these substances as part of a chemical defence system against pests and herbovires.
Xanthine alkaloids include:
- Caffeine (1,3,7-trimethylxanthine)
- Theobromine (3,7-dimethyl-xanthine), close raletive of caffeine
Caffeine and theobromine (methylxanthines) are found in quite a number of plants and have been extracted and used for centuries. Indeed, they are the predominant stimulants consumed by humans. Every time you make a cup of tea or coffee, you perform an aqueous extraction of caffeine. Caffeine is readily soluble in hot water. For this reason it is so easy to separate from black tea leaves by water extraction.
The name theobromine comes from the Greek "theobroma" meaning "food of the Gods." Theobromine which is obtained from cocoa beans is the dominant alkaloid in chocolate, reaching typical ratio of one caffeine for every eight theobromine molecules. Dark chocolate contains 25-30 mg of caffeine and 200-300 mg of theobromine. Both caffeine and theobromine stimulate the CNS and increase blood flow. Theobromine has been used as a drug for its diuretic effect. Because of its ability to dilate blood vessels, this alkaloid also has been used to treat high blood pressure.
Xanthinol Niacinate is a vasodilator drug
Theophylline (1,3-Dimethylxanthine) is a close relative of caffeine and theobromine and a CNS stimulant. Compared to caffeine, it is less active in producing effects of alertness and clearer thinking. Higher doses cause nervousness, restlessness, panic, insomnia and excitement. Theophylline is more capable to produce these adverse effects than caffeine and is more toxic.4
Caffeine, theobromine and theophylline occur naturally in plants. The solubility of these methylxanthines is very low, but it is enhanced by formation of complexes. One of the most notable is the complex of theophylline and ethylenediamine to form the drug aminophylline. Aminophylline (3,7 dihydro-1, 3 dimethyl 1-H purine-2.6 dione plus 1.2 ehtenediamine) is a bronchodilator. In veterinary medicine it is used as a mild diuretic in dogs with congestive heart failure.
- Pentoxifylline is a theophylline derivative that improves blood flow by increasing erythrocyte and leukocyte flexibility. It reduces blood viscosity through a diminuition of fibrinogen; inhibits thromboxane synthesis and platelet adhesiveness to the vessel wall.
- Dimenhydrinate is a theophylline derivative consisting of diphenhydramine and chlorotheophylline. This drug is indicated for the prevention and treatment of nausea, dizziness and vomiting of motion sickness.6
- Dyphylline is a theophylline derivative used as a bronchodilator that relaxes smooth muscles of both bronchial airways and pulmonary blood vessels.7
- 1-Methyl-3-Isobutylxanthine (1-methyl-3-(2-methylpropyl)-7H-purine-2,6-dione); IBMX. It is a theophylline derivative used as a tool in research of the cellular processes.