Editing Alkaloid (section)

==Biological role==
Alkaloids are among the most important and best-known [[secondary metabolites]], i.e. biogenic substances not directly involved in the normal [[cell growth|growth]], [[Biological development|development]], or [[reproduction]] of the organism. Instead, they generally mediate ecological [[biological interaction|interactions]], which may produce a selective advantage for the organism by increasing its [[survivability]] or [[fecundity]]. In some cases their function, if any, remains unclear.<ref>[[#Aniszewski|Aniszewski]], p. 142</ref> An early hypothesis, that alkaloids are the final products of [[nitrogen]] [[metabolism]] in plants, as [[urea]] and [[uric acid]] are in mammals, was refuted by the finding that their concentration fluctuates rather than steadily increasing.<ref name="Meyers"/>

Most of the known functions of alkaloids are related to protection. For example, [[aporphine]] alkaloid [[liriodenine]] produced by the [[Liriodendron tulipifera|tulip tree]] protects it from parasitic mushrooms. In addition, the presence of alkaloids in the plant prevents insects and [[chordate]] animals from eating it. However, some animals are adapted to alkaloids and even use them in their own metabolism.<ref>[[#Hesse|Hesse]], pp. 283–291</ref> Such alkaloid-related substances as [[serotonin]], [[dopamine]] and [[histamine]] are important [[neurotransmitter]]s in animals. Alkaloids are also known to regulate plant growth.<ref>[[#Aniszewski|Aniszewski]], pp. 142–143</ref> One example of an organism that uses alkaloids for protection is the ''[[Utetheisa ornatrix]]'', more commonly known as the ornate moth. Pyrrolizidine alkaloids render these larvae and adult moths unpalatable to many of their natural enemies like coccinelid beetles, green lacewings, insectivorous hemiptera and insectivorous bats.<ref>W.E. Conner (2009). ''Tiger Moths and Woolly Bears—behaviour, ecology, and evolution of the Arctiidae''. New York: Oxford University Press. pp. 1–10. {{ISBN|0195327373}}.</ref> Another example of alkaloids being utilized occurs in the [[Agonopterix alstroemeriana|poison hemlock moth]] (''Agonopterix alstroemeriana).'' This moth feeds on its highly toxic and alkaloid-rich host plant [[Conium maculatum|poison hemlock]] (''Conium maculatum'') during its larval stage. ''A. alstroemeriana'' may benefit twofold from the toxicity of the naturally-occurring alkaloids, both through the unpalatability of the species to predators and through the ability of ''A. alstroemeriana'' to recognize ''[[Conium maculatum]]'' as the correct location for oviposition.<ref>{{Cite journal|last1=Castells|first1=Eva|last2=Berenbaum|first2=May R.|date=June 2006|title=Laboratory Rearing of Agonopterix alstroemeriana, the Defoliating Poison Hemlock (Conium maculatum L.) Moth, and Effects of Piperidine Alkaloids on Preference and Performance|url=http://ddd.uab.cat/record/125702|journal=Environmental Entomology|volume=35|issue=3|pages=607–615|via=ResearchGate|doi=10.1603/0046-225x-35.3.607|s2cid=45478867|doi-access=free}}<!--http://ddd.uab.cat/record/125702--></ref> A [[fire ant]] [[venom]] alkaloid known as [[solenopsin]] has been demonstrated to protect queens of [[Red imported fire ant|invasive fire ants]] during the foundation of new nests, thus playing a central role in the spread of this pest ant species around the world.<ref>{{Cite journal|last1=Fox|first1=Eduardo G. P.|last2=Wu|first2=Xiaoqing|last3=Wang|first3=Lei|last4=Chen|first4=Li|last5=Lu|first5=Yong-Yue|last6=Xu|first6=Yijuan|date=2019-02-01|title=Queen venom isosolenopsin A delivers rapid incapacitation of fire ant competitors|journal=Toxicon|volume=158|pages=77–83|doi=10.1016/j.toxicon.2018.11.428|pmid=30529381|bibcode=2019Txcn..158...77F |s2cid=54481057|issn=0041-0101}}</ref>