Alkaloids are chemical compounds that can be made naturally. They contain basic nitrogen atoms and make up various stimulating compounds.
‘He smiled at my vehemence. “Perhaps you are right, Watson,” he said. “I suppose that its influence is physically a bad one. I find it, however, so transcendently stimulating and clarifying to the mind that its secondary action is a matter of small moment.”’ ― Arthur Conan Doyle, The Sign of Four
The name comes from the word ‘alkaline’ and was used to describe any alkaline containing nitrogen.
Alkaloids are made by a large variety of organisms, such as bacteria, fungi, plants, and animals and are part of the group of natural products (also known as secondary metabolites).
Many alkaloids can be purified from basic substances by acid-base extraction. Also, many alkaloids are toxic to other organisms.
All of the following alkaloids are produced by flowering plants. Because of their bitter taste, the alkaloids are one of the main ways plants reduce or avoid being eaten by herbivores:
- Cocaine, used as an anaesthetic and a stimulant, is an illegal drug when it is not used medically.
- Caffeine, used as a stimulant, is used as something addictive in coffee or tea. In this case and the following, herbivores can eat the leaves but they get heart palpitations if they eat too many.
- Nicotine, used as a stimulant in cigarettes, can also be used to treat certain forms of epilepsy.
- Morphine is widely used to subdue severe pain. In a special slow-release form, it is sometimes used to help people get away drug addiction.
- Quinine, used to treat certain forms of malaria, is sometimes used to give food a bitter taste.
- Curare, the poison dart substance, is originally a plant product from Strychnos toxifera, which is later concentrated in poison dart frogs.
- Strychnine and Brucine are toxic alkaloids produced by Strychnos nux-vomica.