Alkaloids are a class of organic compounds with nitrogen in a heterocyclic ring. Alkaloids often have
pharmacological effects on humans. Alkaloids are found primarily in plants and
are especially common in certain families of flowering plants. Examples of
alkaloids: nicotine, morphine, cocaine.
- Morphine is a powerful narcotic used for the relief of pain, though its addictive properties limit its usefulness.
- Ergonovine (from the fungus Claviceps purpurea) and ephedrine (from Ephedra species) act as blood-vessel constrictors. Ergonovine is used to reduce uterine hemorrhage after childbirth, and ephedrine is used to relieve the discomfort of common colds, sinusitis, hay fever, and bronchial asthma.
- Cocaine (from Erythroxylon coca) is a very potent local anesthetic.
- Quinine (from Cinchona species) is a powerful antimalarial agent that was formerly the drug of choice for treating that disease, though it has been largely replaced by less toxic and more effective synthetic drugs.
- Two alkaloids, vincristine and vinblastine (from Vinca rosea), are widely used as chemotherapeutic agents in the treatment of many types of cancer.
- Nicotine obtained from the tobacco plant (Nicotiana tabacum) is the principal alkaloid and chief addictive ingredient of the tobacco smoked in cigarettes, cigars, and pipes.