Alkaloid
From Wikipedia, the free encyclopedia
An alkaloid is, strictly speaking, a naturally occurring amine produced by a plant,[1] but amines produced by animals and fungi are also called alkaloids. Many alkaloids have pharmacological effects on humans and animals. The name derives from the word alkaline; originally, the term was used to describe any nitrogen-containing base. Alkaloids are usually derivatives of amino acids, and many have a bitter taste. They are found as secondary metabolites in plants (e.g. potatoes and tomatoes), animals (e.g. shellfish) and fungi. Many alkaloids can be purified from crude extracts by acid-base extraction.
While many alkaloids are poisonous, some are used medicinally as analgesics (pain relievers) or anaesthetics, particularly morphine and codeine, and for other uses.
[edit] Alkaloid classifications
Alkaloids are usually classified by their common molecular feet, based on the metabolic pathway used to construct the molecule. When not much was known about the biosynthesis of alkaloids, they were grouped under the names of known compounds, even some non-nitrogenous ones (since those molecules' structures appear in the finished product; the opium alkaloids are sometimes called "phenanthrenes", for example), or by the plants or animals they were isolated from. When more is learned about a certain alkaloid, the grouping is changed to reflect the new knowledge, usually taking the name of a biologically-important amine that stands out in the synthesis process.
- Pyridine group: piperine, coniine, trigonelline, arecaidine, guvacine, pilocarpine, cytisine, nicotine, sparteine, pelletierine.
- Pyrrolidine group: hygrine, cuscohygrine, nicotine
- Tropane group: atropine, cocaine, ecgonine, scopolamine
- Quinoline group: quinine, quinidine, dihydroquinine, dihydroquinidine, strychnine, brucine, veratrine, cevadine
- Isoquinoline group: The opium alkaloids (morphine, codeine, thebaine, papaverine, narcotine, sanguinarine, narceine, hydrastine, berberine)
- Phenethylamine group: mescaline, ephedrine
- Indole group:
- Tryptamines: DMT, N-methyltryptamine, psilocybin, serotonin
- Ergolines: the ergot alkaloids (ergine, ergotamine, lysergic acid, etc.)
- Beta-carbolines: harmine, yohimbine, reserpine, emetine
- Purine group:
- Terpenoid group:
- Vinca alkaloids: vinblastine, vincristine. They are antineoplastic and binds free tubulin dimers thereby disrupting balance between microtuble polymerization and delpolymerization resulting in arrest of cells in metaphase.
[edit] References
- ^ Carey, Francis A. [1987] (2006). Organic Chemistry, 6th ed., New York: McGraw Hill, 954. ISBN 0-07-282837-4. “(Strictly speaking, these compounds are not classified as alkaloids because they are not isolated from plants.)”
