Source

Caffeine is a purine alkaloid co-occuring with minor isomeric dimethyl xanthines theobromine and theophylline. Its major sources are tea, coffee, cocoa and cola, which owe their stimulant properties to these water-soluble alkaloids. This alkaloid is found in the leaves, seeds and fruits of 63 different species of plants worldwide.

Caffeine was first isolated in 1821 by the French chemist Pierre Jean Robiquet from coffee. Caffeine acts as a stimulant of the central nervous system (CNS), cardiac muscle and respiratory system as well as a diuretic. As such, it is found to delay fatigue.

The widespread occurrence of caffeine in a variety of plants played a major role in the long-standing popularity of caffeine-containing products. The most important sources of caffeine are coffee (Coffea spp.), tea (Camellia sinensis), guarana (Paullinia cupana), maté (Ilex paraguariensis), cola nuts (Cola vera), and cocoa (Theobroma cacao). The amount of caffeine found in these products varies – the highest amounts are found in guarana (4%–7%), followed by tea leaves (3.5%), maté tea leaves (0.89%–1.73%), coffee beans (1.1%–2.2%), cola nuts (1.5%) and cocoa beans (0.03%).

Uses

Caffeine is used medicinally as a CNS stimulant, usually combined with another therapeutic agent, as in compound analgesic preparations. Caffeine has pharmacologic effects on CNS, heart, peripheral and central vasculature, renal, gastrointestinal and respiratory system. Caffeine competitively inhibits phosphodiesterase resulting in an increase in cyclic AMP and subsequent release of adrenaline. This leads to a stimulation of the CNS, a relaxation of the bronchial smooth muscle, and induction of diuresis as major effects. Caffeine-containing products have been consumed for hundreds of years for their pleasant flavour and stimulating effects.