Unadulterated caffeine appears like a white powdery substance something similar to cornstarch and tastes bitter. The white coffee powder is somewhat soluble in water at body temperature and dissolves completely in water when heated to boiling point. In 1820, caffeine was first isolated from coffee and seven years later in 1827 from tea and named theine. Soon after this, researchers found out that the properties of coffee and tea to change moods and behaviour is actually owing to the presence of caffeine in these substances. In fact, caffeine is known by two different technical names. While the full name of this chemical substance is 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione, the more familiar technical name of caffeine is 1,3,7-trimethylxanthine. Actually, these two technical names describe the chemical structure of the caffeine molecule.

In order to comprehend the consequences of caffeine, it is essential to provide a concise preamble to purine as well as compounds related to it. In effect, purine is the parent amalgam of all these chemicals as well as several other chemicals present in our body. When xanthine or dioxypurine is scrutinized closely, it will be seen that they are actually purine possessing two oxygen atoms. In addition, it will also be found that that caffeine or trimethylxanthine is actually xanthine having three methyl groups. One methyl group comprises of a solitary carbon atom as well as three hydrogen atoms. In fact, the '1,3,7' portion in caffeine's technical name actually denotes the positions of the methyl groups as they are numbers in the purine arrangement.

Pure purine is not naturally present in the human body. When the chemical constituents present in the purine family are disintegrated, it produces xanthine as a transitional product. Later, the liver transforms xanthine into uric acid that is present in exceptionally high intensity in the human body. While uric acid is known to be related with an ailment called gout, this chemical substance is believed to be responsible for the longer span of life of the humans, compared to other mammals.

Adenine and guanine are two most significant purines present in the human body. Along with cytosine and thymine, these two purines encompass the four fundamental letters of the genetic alphabet, also called code, present in the cells of every living organism. In fact, this code decides on each and everything inherited by an individual, including his or her belonging to the human species to the color of their eye. This code is 'read' or interpreted in the three categories of purines, every one chemically attached to an elongated thread of molecules. In fact, two such strands of molecules along with their purines comprise the DNA (deoxyribonucleic acid) double helix. Genes are actually series of the group of three purines present in particular sites on the chromosomes - arrangements made up of DNA.

One of the vital processes in cell reproduction as well as the entire organism involves the replication of DNA. It is important to note that caffeine is able to get in the way of the process involving duplication of DNA and result in errors in the reproduction of the cell, as it has a lot of resemblance with the vital elements of the genetic code. And such errors may lead to cancers, tumors and even genetic imperfections.

Xanthine molecules or two dimethylxanthines, such as theobromine and theophylline possess two methyl groups instead of the usual three methyl groups present in other xanthine. Both the dimethylxanthines generate consequences that are same as those produced by caffeine. However, theobromine is considered to be comparatively less potent as it does not possess more than 10 per cent of the invigorating results of either caffeine or theophylline. While theobromine is not present in coffee, it is found in different proportions in kola nuts and cocoa products and in very small amounts in tea. The strength of theobromine in cocoa is usually seven times more than that of caffeine. Owing to this factor, despite the fact that the content of caffeine in cocoa products is comparatively less, consumption of these products will produce significant effects that are genuinely like caffeine.

Although very small quantities of theophylline are present in tea along with caffeine and theobromine, it is likely to have a potent invigorating impact on the heart as well as on breathing compared to caffeine. In fact, theophylline is often the preferred drug while treating ailments accompanied by breathing problems - for instance, bronchitis, asthma and emphysema. It may be noted that the theophylline is actually caffeine derived from coffee or tea.

Since caffeine is somewhat soluble in water it is actually found in the different parts of our body wherever water is present, i.e. in almost all places of the body. In addition, caffeine is able to pass through the cell membranes without any effort. Owing to these properties of caffeine, once the ingested chemical substance is hastily and entirely soaked up by the stomach and the intestines, it quickly assimilates into the bloodstream and is distributed to the different organs of the body, inclusive of the brain, the testes and the ovaries. What seems to be worse is the fact the when women consume caffeine during pregnancy, the chemical substance also passes on to all the organs of the fetus. From the bloodstream, caffeine is eventually transported to the liver, which breaks down the chemical substance into different products called metabolites by means of a process known as metabolism. These metabolites are finally eliminated from the body by means of urination. These metabolites comprise theophylline, theobromine and a third dimethylxanthine called paraxanthine.

It may be noted here that the concentration of paraxanthine in the body is comparatively high after a person has consumed products containing caffeine. Nevertheless, when the blood goes through the liver once again, this substance is disintegrated into 1-methylxanthine. Although methylxanthine usually comprises just around 20 per cent of the caffeine dose, it is the principal metabolite of caffeine present in our urine. The remaining methylxanthine present in the ingested caffeine is converted into one of at least 12 other products of caffeine metabolism. Since caffeine moves in both directions across the cell membranes so effortlessly, the kidneys are unable to expel this chemical substance from the body by means of urination. It is important to mention that if the body did not metabolize caffeine into different compounds, such as 1-methylxanthine, which is unable to penetrate the cell membranes of the kidneys as well as into the bloodstream again, once a cup of coffee is consumed by a person, the caffeine content in it would remain in his or her body for a number of days.

It has been often found that the metabolites of some drugs have more potent effect compared to the original drug consumed. In fact, paraxanthine, particularly 1-methylxanthine, is much more identical to adenine and guanine compared to caffeine. While it is yet to be ascertained as to how precisely and how much the metabolites of caffeine add to the chemical compound's consequences, it is very likely that paraxanthine as well as 1-methylxanthine have significant functions in the simulating properties of the drug in the nervous system. The invigorating consequences of caffeine entail the exploits of adenosine - a chemical substance present in considerable amount in our body. The adenosine molecules are made up of a purine that is connected to a form of sugar and is a component of a larger molecule that provides energy that is requisite for the functioning of the cells.

In addition, adenosine also plays a significant role in controlling the different processes in the body, especially the communication of different signals by the nerves. Often adenosine and similar substances are also injected into the body and when they are injected in large measures, they are likely to result in a stupor and also induce sleep. Adenosine is also capable to widening the blood vessels, denigrate spasms or seizures, weaken the ability of the gastrointestinal organs to contract (gastrointestinal motility), slow down the body's response to stress and decrease the blood pressure, rate of heart beat as well as body temperature.

Apart from the other properties of adenosine, this chemical substance also has the aptitude to slow down the discharge of neurotransmitters - chemicals produced by the nerve cells to communicate with one another. In order to accomplish this, adenosine ought to initially attach itself to particular receptor locations on the exterior of the nerve cells. Since the structure of adenosine is very much akin to caffeine, this chemical substance also attaches itself to the receptors and in the process, caffeine thwarts adenosine from attaching to the surface of the nerve cells. Interestingly enough, scientists have discovered that compared to adenosine, paraxanthine as well as 1-methylxanthine are both doubly effectual in binding with adenosine receptors. Hence, it is believed that it is possible to augment the effect of caffeine in invigorating the brain when this chemical substance naturally present in our body is metabolized to produce either paraxanthine or 1-methylxanthine.

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