Caffeine's Cousins

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Caffeine isn't the only methylxanthine consumed by humans--it's just the most famous. Coffee and tea also contain very small amounts of a methylxanthine called theophylline. Cacao products (that is, chocolate in all its guises) contain yet another methylxanthine called theobromine:

As you can see, both theophylline and theobromine are dimethylxanthines. Unlike caffeine, the molecules have only two methyl groups attached to their xanthine skeleton. You can also see that these compounds are extremely similar to each other: they contain exactly the same number and kinds of atoms. They differ only in the position of one of the methyl groups. In a beautiful example of how shape is everything in chemistry, this seemingly trivial difference produces striking differences in the way the two substances affect the brain. Theophylline is roughly as potent as caffeine; theobromine is seven times weaker than either.

Theophylline is perhaps best known for its medicinal qualities. Because it very effectively relaxes the bronchial passageways, it is often the drug of choice for treating asthma and other breathing difficulties, such as congestion caused by pet allergies. Indeed, allergy sufferers who are unaware of theophylline's similarity to caffeine may find themselves wide awake at night or unusually jittery if they take their medication and also drink their usual coffee, tea, or cola.

Caffeine opens up bronchial passages also--though less dramatically than theophylline-- and this particular attribute is part of the story behind one of the most famous coffee slogans of all time.

Theodore Roosevelt was prone to asthma attacks when he was a boy. His doctors recommended small doses of coffee to arrest these attacks, which started Roosevelt on a habit that grew over time into a legendary appetite (Seigel 1989). His coffee mugs were said to more closely resemble vats than cups. In 1907, coffee merchant Joel Clark set up a booth to display his wares at a country fair to which Roosevelt was paying a visit. When Roosevelt walked by his booth, Clark thrust a cup of his coffee at him--a cup the president promptly drained in a gulp. Setting down the empty cup, Roosevelt turned to the people around him and declared the coffee "good to the last drop," thus giving Clark and his brand of coffee--Maxwell House--a slogan that lives to this day.

Caffeine's other cousin, the relatively weak theobromine, is consumed by countless millions every day. Most people know that chocolate contains a small amount of caffeine--roughly 20 milligrams in a 1-ounce portion. That's not much--only one-fifth the amount in an average cup of coffee. But most people don't realize chocolate also contains theobromine. In fact, theobromine is seven times more abundant than caffeine in chocolate--about 130 milligrams in a 1-ounce piece. This abundance neatly compensates for theobromine's lack of raw pharmacological punch. Basically, when theobromine's influence is added to caffeine's, a 1-ounce piece of chocolate can be said to have the stimulating power of roughly 40 milligrams of caffeine, about the same as that found in a cup of tea (Gilbert 1992).

If it were only asthmatics who needed to appreciate theophylline, or "chocoholics" who needed to think about theobromine, these two methylxanthines would be mere curiosities to most other people. But, in fact, these two substances play an important role in the lives of everyone who drinks coffee, tea, colas, or any other caffeine-containing beverage.

pp. 116-119 Buzz: The Science and Lore of Alcohol and Caffeine by Stephen Braun(1997)

Image retrieved from Extracting native mate plant material using supercritical CO2 conditions to obtain a mate formulation comprising at least one at level one predetermined characteristic on September 7, 2014.

Caffeine, theobromine, theophylline, molecule