Editing Alkaloid (section)

==Distribution in nature==
[[File:Strychnos nux-vomica - Köhler–s Medizinal-Pflanzen-266.jpg|thumb|[[Strychnine tree]]. Its seeds are rich in [[strychnine]] and [[brucine]].]]

Alkaloids are [[anabolism|generated]] by various living organisms, especially by [[Vascular plant|higher plants]]&nbsp;– about 10 to 25% of those contain alkaloids.<ref>[[#Aniszewski|Aniszewski]], p. 13</ref><ref>[[#Orekhov|Orekhov]], p. 11</ref> Therefore, in the past the term "alkaloid" was associated with plants.<ref name="Hesse 4">[[#Hesse|Hesse]], p.4</ref>

The alkaloids content in plants is usually within a few percent and is inhomogeneous over the plant tissues. Depending on the type of plants, the maximum concentration is observed in the leaves (for example, [[black henbane]]), [[fruit]]s or [[seed]]s ([[Strychnine tree]]), root (''[[Rauvolfia serpentina]]'') or bark ([[cinchona]]).<ref>[[#Grinkevich|Grinkevich]], pp. 122–123</ref> Furthermore, different tissues of the same plants may contain different alkaloids.<ref>[[#Orekhov|Orekhov]], p. 12</ref>

Beside plants, alkaloids are found in certain types of [[fungus]], such as [[psilocybin]] in the fruiting bodies of the genus ''[[Psilocybe]]'', and in animals, such as [[bufotenin]] in the skin of some toads<ref name="Hesse 5" /> and a number of insects, markedly ants.<ref name=":1">{{Cite journal|last1=Touchard|first1=Axel|last2=Aili|first2=Samira|last3=Fox|first3=Eduardo|last4=Escoubas|first4=Pierre|last5=Orivel|first5=Jérôme|last6=Nicholson|first6=Graham|last7=Dejean|first7=Alain|date=2016-01-20|title=The Biochemical Toxin Arsenal from Ant Venoms|journal=Toxins|volume=8|issue=1|pages=30|doi=10.3390/toxins8010030|pmid=26805882|pmc=4728552|issn=2072-6651|doi-access=free}}</ref> Many marine organisms also contain alkaloids.<ref>[[#Fattorusso|Fattorusso]], p. XVII</ref> Some [[amines]], such as [[adrenaline]] and [[serotonin]], which play an important role in higher animals, are similar to alkaloids in their structure and biosynthesis and are sometimes called alkaloids.<ref>[[#Aniszewski|Aniszewski]], pp. 110–111</ref>