"This article is about the chemical compounds alkaloids. For the
pharmaceutical companyin the Republic of Macedoniasee Alkaloid (company).
Alkaloids are naturally occurring
chemical compounds containing basic nitrogenatoms. [GoldBookRef|title=alkaloids|file=A00220|year=1995] The name derives from the word alkalineand was used to describe any nitrogen-containing base. Alkaloids are produced by a large variety of organisms, including bacteria, fungi, plants, and animals and are part of the group of natural products(also called secondary metabolites). Many alkaloids can be purified from crude extracts by acid-base extraction. Many alkaloids are toxic to other organisms. They often have pharmacological effects and are used as medications and recreational drugs. Examples are the local anestheticand stimulant cocaine, the stimulant caffeine, nicotine, the analgesic morphine, or the antimalarial drug quinine. Some alkaloids have a bitter taste.
Alkaloids are usually classified by their common molecular precursors, based on the
metabolic pathwayused to construct the molecule. When not much was known about the biosynthesisof 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.
Pyridinegroup: piperine, coniine, trigonelline, arecoline, arecaidine, guvacine, cytisine, lobeline, nicotine, anabasine, sparteine, pelletierine.
Pyrrolidinegroup: hygrine, cuscohygrine, nicotine
Tropanegroup: atropine, cocaine, ecgonine, scopolamine, catuabine
Quinolinegroup: quinine, quinidine, dihydroquinine, dihydroquinidine, strychnine, brucine, veratrine, cevadine
Isoquinolinegroup: opium alkaloids ( papaverine, narcotine, narceine), sanguinarine, hydrastine, berberine, emetine, berbamine, oxyacanthine
Phenanthrene alkaloids: The opiumalkaloids ( morphine, codeine, thebaine)
Phenethylaminegroup: mescaline, ephedrine, dopamine
Tryptamines: serotonin, DMT, 5-MeO-DMT, bufotenine, psilocybin
Ergolines (the ergotalkaloids): ergine, ergotamine, lysergic acid, LSD
Beta-carbolines: harmine, harmaline, tetrahydroharmine
Vinca alkaloids: vinblastine, vincristine
Mitragyna speciosa" alkaloids: mitragynine, 7-hydroxymitragynine
Tabernanthe iboga" alkaloids: ibogaine, voacangine, coronaridine, 18-methoxycoronaridine
Strychnos nux-vomica" alkaloids: strychnine, brucine
Xanthines: caffeine, theobromine, theophylline
Steroidalkaloids (containing a steroid skeleton in a nitrogen containing structure):
solanum(e.g. potato and tomato) alkaloids ( solanidine, solanine, chaconine)
veratrumalkaloids ( veratramine, cyclopamine, cycloposine, jervine, muldamine) [ http://www.ansci.cornell.edu/plants/toxicagents/steroid.html,]
*** newt alkaloids (
* Quaternary ammonium compounds:
muscarine, choline, neurine
capsaicin, cynarin, phytolaccine, phytolaccotoxin
Low-molecular weight alkaloids without
hydrogen bonddonors such as hydroxy groups are often liquid at room temperature, examples are nicotine, sparteine, coniine, and phenethylamine.
The basicity of alkaloids depends on the
lone pairs of electrons on their nitrogenatoms. As organic bases, alkaloids form salts with mineral acids such as hydrochloric acidand sulfuric acidand organic acids such as tartaric acidor maleic acid. These salts are usually more water-soluble than their free baseform.
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