How do you start the day? A cup of heterocyclic alkaloid! “A what?” you may ask. Many of us stumble, sleepily to the kitchen each morning for a good old cup of coffee. In so doing, you are taking in caffeine, the active ingredient in your morning ritual.
Caffeine is a heterocyclic alkaloid, which by definition means a nitrogen-containing organic compound with a two-ringed or dual-cyclic structure. This molecule naturally occurs in many plant species as a secondary metabolite. Secondary metabolites are compounds produced during metabolism that are not essential for the normal growth and functioning of the organism. In plants, caffeine acts to reduce herbivory and acts as an antibiotic and antifungal agent. Some species from which caffeine is derived include coffee beans, tea leaves, cocoa seeds, cola nuts, and yoco bark to name just a few.
Caffeine in its pure form appears as a white, crystalline powder. Its chemical formula is C8H10N4O2 and has the chemical name 1,3,7-trimethylxanthine. Some physical properties include:
Boiling point: 178 C
Melting point: 238 C
Density: 1.2 g/cm^3
Molecular weight: 194.19 g/mol
The most notable characteristic of caffeine is its pharmacological effects on humans. Caffeine acts as a stimulant, a drug that acts on the nervous system creating alertness and a sense of heightened energy. Caffeine acts on the brain and body cells by blocking adenosine receptors. These receptors normally bind adenosine, another heterocyclic alkaloid. Adenosine acts as a signal, which slows cell activity especially in nerve cells. However, when bound to caffeine, the opposite affect occurs increasing cell activity thus explaining caffeine’s stimulant action. Caffeine stimulates the release of epinephrine (adrenaline) and dopamine, which act to increase heart rate, blood pressure, urine production, and the release of glucose into the blood from the liver.
Effects of caffeine are short-lived in the body since it is quickly metabolized. With continued use, a tolerance to caffeine’s effects can occur. Also, if individuals with this tolerance do not consume caffeine, it can lead to withdrawal symptoms such as headache. Caffeine overdose can cause nervousness, agitation, insomnia, trembling of the hands, and even extreme symptoms such as hallucinations. If too much caffeine is consumed, as with caffeine pills, it can lead to death.
A normal dose of caffeine is considered to be between 50 to 100 milligrams, the amount taken in from a single cup of coffee. The amount of caffeine in coffee does vary based on the species of coffee used and the amount of roasting since roasting reduces caffeine content. Dark roasts therefore have less caffeine per cup than light roasts. Teas usually contain less caffeine than coffee. Soft drinks and energy drinks contain from 25 to 400 milligrams, respectively.
The next time you order a soft drink, tea, or coffee or eat a piece of chocolate, remember the heterocyclic alkaloid that will give you that boost of energy. Whether we utilize it for medicinal effects or because we simply love that morning coffee, caffeine has become an important part of our lives.