Albert de Maguncia

The cafeine is a Méthylxanthine present in many food like the grains of Café, the The, the Cacao (Chocolat), the Nut of cola, the Maté or Guarana granulates it. It is well-known for its properties of Stimulant of the central Nervous system and the cardiovascular system. It belongs to the composition of drinks like the Cola (Coca-Cola) or the drink énergisante Red Bull.

Discovered

Cafeine, in the past called guaranine , was discovered in 1819 by Friedrich Ferdinand Runge and Von Giese and was described in 1821 per Pierre Joseph Pelletier and Pierre Jean Robiquet. The theine , discovered in 1827 by Oudry, was shown, in 1838, identical to cafeine. The difference in effect between and coffee is primarily explained by the fact why the contains a great quantity of Tanin S, which slows down the assimilation of cafeine. This is why its effect is softer and more progressive, although it is about the same substance.

Chemical composition

Cafeine - C₈H₁₀N₄O₂, or 1,3,7-tri methyl Xanthine or 3,7-dihydro-1,3,7-trimethyl-1H- Purin -2,6-dione - is a molecule of the family of the Méthylxanthine S, which also includes/understands the Théophylline and the Théobromine. In its pure form, it consists of a white powder of an extremely bitter taste.

A normal cup of Café filter contains from 80 to 130 cafeine Mg. An amount from 30 to 40 G of Espresso, as for it, contains approximately 100 of them, reaching the 130 Mg. Pills Stimulant be can contain up to 200 Mg each one of it.

Mechanism of action

Cafeine inhibits the Phosphodiestérase, person in charge of the inactivation of the AMPc. The increase in the intracellular rate of AMPc amplifies its actions of “second messenger”, which makes it responsible for the principal pharmacological actions of cafeine.

Effects of cafeine

In a general way, cafeine is a psychostimulant which has for principal effects to accelerate the cardiac rhythm at the end of a few minutes then to cause a feeling of alarm clock.

Cafeine involves a vasodilatation. It presents effects to the level of the systems cardiovascular, respiratory and gastro-intestinal. Moreover, it acts on the level of the skeletal muscles, of renal blood flow, the Glycogénolyse and the Lipolyse.

A too important cafeine catch can lead to an intoxication. These symptoms are insomnia, the nervousness, the excitation, flushing cutaneous (a very red face), the increase in the Diurèse, and disorders gastrointestinaux. At certain people, they can appear after a catch as weak as 250 Mg per day. More than one gram per day can generate involuntary muscular contractions, thoughts and matter décousus, cardiac arrhythmia as well as a psychomotor agitation. The symptoms of the intoxication to cafeine are similar to those of the Panique and a generalized Anxiété. The LD₅₀ of cafeine by ingestion in the rat is of 192 mg/kg. Although this value cannot be directly extrapolated with the human one, one can make the assumption that the ingestion of approximately 10 G of cafeine at the adult man, is approximately 100 coffee cups, would be lethal in 50% of the cases. Cafeine is consequently classified in the category of the fairly toxic substances.

On the central nervous system

It is thought that cafeine acts on the Cerveau mainly by Antagonisme of the Adénosine, i.e. cafeine blocks its receiving S. the Adénosine, when it is fixed on the receivers of the nervous cells, decreases the activity of the cell via the Protéines G which remain fixed at the receiving S and cannot thus start the chain reaction which leads to the activity of the cell; that occurs for example during the Sommeil. Cafeine the molecule, structurally similar to the Adenosine, does not decrease the activity of the cells; on the contrary, it is fixed at the receivers and prevents the action of adenosine.

The increase in the nervous activity which results from it starts the release of Adrénaline, a hormone which causes several effects such as the increase of the cardiac rhythm (Chronotrope +), of the contractility of the heart (Inotrope +), of the blood Pressure, of the contribution of Sang to the Muscle S, the reduction in the contribution of Sang to the others Organe S (except the Cerveau) and the release of Glucose by the Foie, by Néoglucogénèse for example.

In addition, cafeine increases the levels of Dopamine (a Neurotransmetteur) in the Cerveau, as Amphétamines would do it for example.

The effects of cafeine, contrary to those of the alcohol or others Stimulant S of the central Nervous system, are of short duration. Who more is, cafeine does not affect the concentration or other higher mental functions.

Consumption continues cafeine ends up revealing a Addiction related to the excess of receivers to the Adénosine and the lack of receivers to the Dopamine. At the time of weaning, the body becomes hypersensitive with the Adénosine, which makes increase the blood Pressure in a dramatic way and can generate very strong headaches and other symptoms like the Bradycardie; the lack of Dopamine can generate a depressive state and a clear reduction in the cerebral performances, this is why one always recommends a progressive weaning spread out over several weeks, even several months. However, contrary to other stimulants of the central nervous system, cafeine does not act directly on the Noyau accumbens, person in charge of the psychological Addiction.

Recent studies suggest that the cafeine contribution by the Café could decrease the risk to contract the Parkinson's disease, but a thorough study is necessary.

Studies prove nevertheless the positive effects of cafeine. A study on 2.000 premature pleasing thinking that cafeine would have a positive role on the respiratory functions.

Pharmacokinetic

Cafeine very quickly and completely is absorbed by the digestive Tract, and arrives at the brain as of the 5th minute following ingestion. It is comparable to 75% after fifteen minutes and the plasmatic peak is reached at the end of one hour. Its Demi-vie is from 4 to 6 a.m.

Cafeine diffuses quickly in the extra-vascular medium. It is only slightly related to circulating proteins of plasma (approximately 15%). It passes the hemato-encephalic Barrière thanks to its resemblance to adenosine. Its concentration in the céphalo-rachidian liquid is equal to that of plasma.

The passage in the mother's milk is also important, the concentration is worth 50% of the plasmatic Concentration of the mother. In the adult, cafeine is almost completely metabolized at the hepatic level by Oxydation, Déméthylation and Acétylation.

Cafeine cannot be detected in the organization after more 24:00 after the last cafeine catch, that it is by globular Analyze of blood or by chemical examination of the Urine.

Cafeine in food

Extraction of the cafeine of a drink

The extraction of the cafeine of an unspecified drink is not something that no matter who can only make at home. Indeed, it is difficult to know the exact quantity of cafeine which contains even a coffee prepared consequently anybody in the same way each day.

The extraction can be made according to three processes:

an extraction by an organic solvent (generally a chlorinated solvent), which benefits from differential solubility (coefficient of division). The solvent is then eliminated by distillation;
an extraction by supercritical fluid (of carbon dioxide);
an extraction with water.

The first method, which cannot avoid residual solvent traces, tends to being replaced by the second. The last is the least effective and denatures the taste.

A Café known as “decaffeinated” is not it in fact not completely; for the majority of the marks, five to ten coffee cups “decaffeinated” per day get a cafeine amount equivalent to that of two coffee cafeine cups, according to a study North-American which tested the coffees of nine marks by Chromatographie in gas phase: except a mark, all contained of 8,6 Mg with 13,9 cafeine Mg. According to Dr. Mark S. Gold, professor of psychiatry at the University of Florida, this quantity is sufficient to cause a physical dependence with the coffee in certain consumers.

Note

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