An
alkaloid is a
nitrogenous organic
molecule that has a
pharmacological effect on
humans and other
animals. The name derives from the word alkaline; originally, the term was used to describe any nitrogen-containing
base (an
amine in modern terms). Alkaloids are found as
secondary metabolites in
plants (e.g., in
potatoes and
tomatoes), animals (e.g., in
shellfish) and
fungi, and can be extracted from their sources by treatment with
acids (usually
hydrochloric acid or
sulfuric acid, though organic acids such as maleic acid and
citric acid are sometimes used).
Even though many alkaloids are
poisonous (such as
strychnine or
coniine), some are used in medicine as
analgesics (pain relievers) or anaesthetics, particularly
morphine and
codeine. Most alkaloids have a very bitter taste.
Alkaloid classifications
Alkaloids are usually classified by their common molecular precursors, based on the biological 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.
- Indole group:
- * Tryptamines: DMT, NMT, psilocybin, serotonin
- * Ergolines: the ergot alkaloids (ergine, ergotamine, lysergic acid, etc.), LSD
- * Beta-carbolines: harmine, yohimbine, reserpine, emetine
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da:Alkaloid
de:Alkaloide
eo:Alkaloido
fr:Alcaloïde
it:Alcaloide
lt:Alkaloidas
nl:Alkaloïde
ja:アルカロイド
pl:Alkaloid
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uk:Алкалоїди