Caffeine is a central nervous system stimulant that belongs to a class of compounds known as xanthines. Its chemical formula is C₈H₁₀N₄O₂, and it is classified as a methylxanthine. Caffeine is known for its psychoactive properties, which can lead to increased alertness and reduced fatigue. It is believed to act by antagonizing adenosine receptors in the brain, thus promoting wakefulness.
Caffeine is naturally found in various plants, including:
- Coffee beans (Coffea species) - One of the most well-known sources of caffeine, with arabica and robusta being the most commonly cultivated varieties.
- Tea leaves (Camellia sinensis) - Used to produce various forms of tea, including black, green, and oolong, all of which contain caffeine.
- Cacao beans (Theobroma cacao) - Used to make chocolate products; it contains caffeine as well as theobromine, another mild stimulant.
- Guarana berries (Paullinia cupana) - A plant native to the Amazon basin, often used in energy drinks and supplements.
- Yerba mate (Ilex paraguariensis) - A traditional South American drink made from the leaves of this plant, which contains caffeine along with other stimulants.
- Kola nuts (Cola acuminata) - Used to flavor soft drinks and contains caffeine.
These plants have been utilized for centuries for their stimulating effects, and caffeine remains one of the most widely consumed psychoactive substances in the world.