CaffeineA Mini-Report by Tu Anh Le



Name and Structure of Caffeine

pure_caffeine.jpg
Pure caffeine is a bitter white powder.
How did caffeine get its name?
The word "caffeine" came from the German word kaffee and the French word café, each meaning coffee.
The medical name of caffeine, based on its molecular structure, is 1,3,7-trimethylxanthine. It's chemical formula is C8H10N4O2.
caffeine_molecule_structure.jpg
The molecular structure of 1, 3, 7 - trimethylxanthine.

The German chemist Emil Fischer (1852-1919) was the first to work out the molecular structure of caffeine during the 1890s. He first synthesized caffeine from basic raw materials in 1895.
Two years later, he was certain that he finally discovered the structural formula of caffiene.

Caffeine is an alkaloid, a class of naturally occurring compounds containing nitrogen and having the properties of an organic amine base. That is why in its pure form, caffeine is an intensely bitter and white powder. It is odorless and is composed of long hexagonal prisms.

amine_-_purine.jpg
Caffeine is based on the amine, Purine.




How is Caffeine Made?

Caffeine is a drug naturally found in certain leaves, seeds, and fruits of over 60 plants worldwide. Some of these sources are coffee beans, guarana, yerba maté, kola nuts, cacao beans, and tea, with guarana paste (from the Paullinia tree) having the highest concentration of caffeine at 4%. Did you know that caffeine acts as a natural pesticide used to paralyze and kill insects that attempt to eat the plant?
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Guarana Plant


Caffeine is also made in labs and can also be isolated from its natural source by manufacturers and added to energy drinks as an additive or as an ingredient in certain drug products, such as cold and headache remedies.

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Friedrich Ferdinand Runge
The first to isolate caffeine, from Arabian mocha beans, was the German chemist Friedrich Ferdinand Runge in 1819. During the 1820's, scientists identified the stimulating agents in coffee, tea, and chocolate. But they did not realize they had discovered the same ingredient: caffeine! In 1840, two reasearchers named T. Martins and D. Berthemot, working independently showed that all of these active agents were chemically identical to caffeine isolated from coffee beans.

Caffeine can be directly isolated from tea leaves. Caffiene does not exist alone in the tea leaves. It is accompanied by other natural substances from which it must be seperated. Caffiene constitutes only as much as 5% of the weight in leaves and and is water soluble. The main problem here is that Tannins, a derivative of Catechin and Flavonoids, are also water soluble. Fortunately, caffeine is soluble in non-polar organic solvents while tannins are not. Therefore, the isolation of caffeine from tea leaves can be carried-out in the following steps:
steeping_tea.jpg
Isolation of Caffeine from Tea Leaves


  1. Extract the Caffiene and Tannins into the hot water.
  2. Extract the caffiene into a non-polar organic solvent; Methylene Chloride.
  3. Dry the Mthylene Chloride of any remaining water.
  4. Evaporate the Methylene Chloride, leaving impure Caffeine.
  5. Purify the Caffeine by sublimation.

A more detailed laboratory experiment on the Isolation of Caffeine from Tea Leaves can be found here.




How Does Caffeine Affect Us?


Caffeine is quickly and completely removed from the brain. Its effects are short-lived and it tends not to negatively affect concentration or higher brain functions. Yet still, a large majority of us consume considerable amounts of caffeine, either through coffee, tea, energy drinks, or over-the-counter drugs, on a day-to-day basis in order to stay alert and awake. A normal dose of caffeine is generally considered to be 100mg (about half cup of coffee). A low to moderate intake is 130 to 300mg of caffeine a day, while heavy consumption means intaking more than 6 000 mg/day. The lethal dose of caffiene is between 13 to 19 grams. That would be like drinking around 100 cups of coffee in one sitting! caffeine-curve.jpg

On the wary side, consuming as little as 100 mg of caffeine a day may cause the person to become dependent on it. They may develop withdrawal symptoms such as tiredness, irritability, and headaches, if he/she quits caffeine suddenly. So that's the reason why Mom gets so cranky when she doesn't get her coffee!

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Sometimes a little coffee is all it takes to get happy
Caffeine sensitivity (amount of caffeine required to cause an effect in a person) depends on the person. Generally, the smaller the person, the less caffeine needed. People who regularly take in a lot of caffeine soon develop less sensitivity to it. This means that they may require more caffeine to achieve the same effects.

It is important to know that caffeine is an addictive drug. Among its many actions, it operates using the same mechanisms that amphetamines, cocaine, and heroin use to stimulate the brain. Caffeine increases dopamine levels in the same way that amphetamines do. Dopamine is a neurotransmitter that, in certain parts of the brain, activates the pleasure center. In comparison, caffeine's effects are milder than amphetamines, cocaine and heroin, but it is manipulating the same channels in the brain, and that is one of the things that gives caffeine its addictive qualities.

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The effects of osteoporosis on the body.
Caffeine is also a diuretic, meaning that it can cause person to urinate more. This may cause dehydration if large caffeine consumption is taken alongside hot weather, during long workouts, or in situations where copious amounts of sweating is required.

Caffeine can also cause the body to lose calcium, leading to bone loss over time. Drinking caffeine-containg soft drinks instead of milk can have an even greater impact on bone density and can greater the risk of osteoporosis development. Children, teens, and pregnant women should try to limit their caffeine consumption as much as possible. These stages in life require the important growth and development of bones so it is wise to stay away!






How Does Caffeine Keep Us Awake?

Caffeine works by changing the chemistry of the brain by blocking the action of adenosine (a natural brain chemical), the chemical associated with sleep.

Adenosine sends signals that the brain needs to rest. "Since adenosine secretion reflects brain cell activity, rising concentrations of this chemical may be how the organ gauges that it has been burning up its energy reserves and needs to shut down for a while."
(Source: ScienceNewsOnline: Napless cats awaken interest in adenosine) Adenosine is produced through daily activities. Your muscles create adenosine as a byproduct of exercise.

The chemical adenosine
adenosine.gif
Adenosine
binds to the adenosine receptors in the brain. This binding of adenosine causes drowsiness by slowing down nerve cell activity. This also causes blood vessals to dilate in the brain (possibly to let more oxygen in during sleep).

To a nerve cell, caffeine looks like adenosine. Therefore, when you consume caffeine, it binds to the adenosine receptors. The cells cannot sense adenosine anymore because caffeine is taking up all the receptors adenosine binds to. So, instead of slowing down, the cells speed up. You can see that caffeine also causes the brain's blood vessals to constrict because it blocks adenosine's ability to open them up. That's why some headache medicines contain caffeine (like Anacin)-- if you have a vascular headache, the caffeine will close down the blood vessals and relieve it.

With caffeine blocking adenosine, neuron firing in the brain is increased. The pituitary gland sees all of the activity and assumes that some sort of emergency must be occuring. It releases hormones that tell the adrenal glands to produce adrenaline (epinephrine). Adrenaline is, of course, the "fight-or-flight" hormone and has a number of effects on your body.


  • Your pupils dilate
  • Your breathing tubes open up (that's why some people suffering from severe asthma attacks are sometimes injected with epinephrine)
  • Your heart beats faster
  • Blood vessals on the surface contrict to slow blood flow from cuts and also to increase blood flow to muscles; blood pressure rises
  • Blood flow to the stomach slows
  • The liver releases sugar into the bloodstream for extra energy
  • Muscles tighten up ready for action

For all of you that have been wondering all this time, this explains why we are generally more alert when we ingest a fair amount of caffeine.
*sigh* All those energy drinks for those all-nighters...


all-nighter.jpg
Hey, he didn't drink any caffeine. No wonder he fell asleep. Don't worry Ms. Kim, he finished the Chem Project in time!





Another Interesting Fact - Caffeine and Teens: Where Are They Getting All The Caffeine From?


Kidsbucks.jpg
The Starbucks Gift Card is definitely the present to get your average teenager.
It has been addressed by British Columbia's Ministry of Education that school should be more aware of caffeine consumption in teens.

Caffeine will cause the same effects in children and teens as they do in adults but because their smaller size and hormonal changes, too much caffeine may be harder on them. Students get their caffeine in soft drinks, coffee, tea, iced mocha drinks, and other sweet energy drinks such as Monster, Red Bull, and RockStar. Occassionally, the amount of caffeine isn't listed on the label but looking through the ingredient list for natural sources can tell you whether it contains caffeine or not (list of natural sources in section How is Caffeine Made). The Guidelines for Food and Beverage Sales in BC Schools say that schools should only offer choices with less than 15 mg.

Health Canada recommends:


  • 7 - 9 years old: 62.5 mg per day
  • 10 - 12 years old: 85 mg per day
  • Teens: 2 mg/kg of body weight per day


The list (from two different sources) below mentions popular brands and drinks that teens consume on a day-to-day basis.
energy-drinks.jpg
Examples of popular energy drink brands

Drink/Food/Supplement
Amt. of Drink/Food
Amt. of Caffeine
SoBe No Fear
8 ounces
83 mg
Monster energy drink
16 ounces
160 mg
Rockstar energy drink
8 ounces
80 mg
Red Bull energy drink
8.3 ounces
80 mg
Jolt cola
12 ounces
72 mg
Mountain Dew
12 ounces
55 mg
Coca-Cola
12 ounces
34 mg
Diet Coke
12 ounces
45 mg
Pepsi
12 ounces
38 mg
7-Up
12 ounces
0 mg
Brewed coffee (drip method)
5 ounces
115 mg*
Iced tea
12 ounces
70 mg*
Cocoa beverage
5 ounces
4 mg*
Chocolate milk beverage
8 ounces
5 mg*
Dark chocolate
1 ounce
20 mg*
Milk chocolate
1 ounce
6 mg*
Jolt gum
1 stick
33 mg
Cold relief medication
1 tablet
30 mg*
Vivarin
1 tablet
200 mg
Excedrin extra strength
2 tablets
130 mg
*denotes average amount of caffeine
Source: U.S. Food and Drug Administration, National Soft Drink Association, Center for Science in the Public Interest.
<http://kidshealth.org/teen/food_fitness/nutrition/caffeine.html#>

What should our schools do then?The most important thing to do is to offer healthy and affordable ($3 for a juice box is not affordable!) beverage and food choices to aid in the development of children and teens and their healthy choices for the future.





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