Caffeine molecule is the most consumed psychoactive substance (a substance that stimulates the central nervous system) and therefore a drug. It was estimated that about 80% of the world’s population consume caffeine every day. Caffeine is so popular, because of its stimulating effect on the brain. The consumption of caffeine may alleviate fatigue, increase the feeling of wakefulness and improve concentration and focusing.
However, according to the researches 5 grams of caffeine molecule (equivalent to 30-40 cups of regular coffee) may cause the death of the consumer.
The substance is well-known as caffeine, although its chemical name is 1,3,7-Trimethyl-3,7-dihydro-1H-purine-2,6-dione or 1,3,7-trimethyl xanthine.
Chemical structure and properties
The chemical formula of caffeine is C8H10N4O2 (caffeine molecule anhydrous) or C8H10N4O2.H2O. Caffeine molecule is a water soluble unionized alkaloid (methylxanthine) with an average mass of 194.191 Da.
Caffeine appears as a white, odorless powder or crystals with a bitter taste. Boiling point is at 178°C (352° F at 760 mm Hg) and melting point at 238 °C (460° F). Soluble in ethyl acetate, pyrrole and slightly in ethanol. 1 g of caffeine dissolves in 46 ml of water.
The molecule is stable. Toxic nitrogen oxide fumes are produced when caffeine is heated to decomposition.
The absorption of caffeine depends on the way of consumption/intake. It was estimated that caffeine delivered with coffee ingestion has the biggest bioavailability of about 99%. The blood saturation of caffeine is detected in 39-42 minutes after the consumption of 200 mg of caffeine cup of coffee. The same results are seen when the same amount of caffeinated energy drink is consumed. 90% of caffeine is absorbed when derived by caffeine capsules. The highest level of caffeine in the blood is detected about 84-120 minutes after the capsules were swallowed.
In general caffeine delivered as liquid provides the best absorption of the substance.
The absorption rates, however, may be decreased if the person’s stomach is full.
The half-life of caffeine is about 4-6 hours. This means that usually the effect of caffeine molecule consumption lasts approximately 4-6 hours. The caffeine half-life may last longer in those who have liver disorders, infants and pregnant women.
Caffeine is metabolized in the liver, although less than 3% of caffeine remain unchanged. CYP1A2 gene is responsible for this process (95%). The caffeine metabolism is processed via N-3 demethylation to paraxanthine (70-80%), 1-N- demethylation to theobromine (7-8%), 7-N-demethylation to theophylline (7-8%) and C-8 hydroxylation to 1,3,7-trimethyluric acid (15%).
Caffeine metabolites are excreted with urine. Clearance values for caffeine molecule is approximately 1 – 3 mg/kg/min
Mechanism of action
A substance chemically is similar to adenosine, an agent that makes a person feel tired. In the body, this compound slows down nerve activity and therefore promotes sleep. Adenosine influences on the blood and oxygen supply to the brain by dilatation of the vessels. The level of adenosine in the body increases gradually during the day and it is suggested that this substance is responsible for the need to sleep.
Caffeine binds to the adenosine receptors in the brain and this way stimulates the central nervous system.
At the same time caffeine influences on a hormonal balance causing the growth of adrenaline level and the alertness increases Another effect – feeling of arousal – is connected with the increasing level of dopamine in the brain after the consumption of caffeine.
Caffeine may relax smooth muscle and stimulate the myocardium.
Caffeine can be synthesized from uric acid, although it occurs naturally in the leaves, seeds, or fruit of more than 60 plant species, including:
- Coffee beans (Caffea Arabica and C. robusta);
- Tea leaves (Thea sinensis and other spp.);
- Kola nuts (Cola acuminate and other spp.);
- Cacao beans (Theobroma cacao and other spp.);
- Guarana (Paulliania cupana);
- Yerba mate;
- Yoco (Paulliniayoco);
The amount of caffeine included in some common foods and beverages are:
- Coffee, brewed – 102 -200 milligrams per cup;
- Coffee, instant – 27-173 milligrams per cup;
- Coffee, decaffeinated – 3-12 milligrams per cup;
- Tea, instant – 28 milligrams per cup;
- Tea, canned iced – 22-36 milligrams per 12 ounces;
- Caffeine-containing cola and other soft drinks – 36-71 milligrams per 12 ounces;
- Cocoa – 3 – 13 milligrams per cup;
- Chocolate, milk – 3-6 milligrams per ounce;
- Chocolate, bittersweet – 25 milligrams per ounce;
Caffeine is used as a flavor for food and a food additive as well as a component of several pharmaceutical formulations.