Editing Alkaloid (section)

== Classifications ==
[[File:Nicotine.svg|class=skin-invert-image|thumb|160px|The [[nicotine]] molecule contains both [[pyridine]] (left) and [[pyrrolidine]] rings (right).]]

Compared with most other classes of natural compounds, alkaloids are characterized by a great structural diversity. There is no uniform classification.<ref name="ref15">[[#Hesse|Hesse]], p. 11</ref> Initially, when knowledge of chemical structures was lacking, botanical classification of the source plants was relied on. This classification is now considered obsolete.<ref name=xumuk.ru /><ref>[[#Orekhov|Orekhov]], p. 6</ref>

More recent classifications are based on similarity of the carbon skeleton (''e.g.'', [[indole]]-, [[isoquinoline]]-, and [[pyridine]]-like) or biochemical precursor ([[ornithine]], [[lysine]], [[tyrosine]], [[tryptophan]], etc.).<ref name=xumuk.ru /> However, they require compromises in borderline cases;<ref name="ref15" /> for example, [[nicotine]] contains a pyridine fragment from [[nicotinamide]] and a [[pyrrolidine]] part from ornithine<ref>[[#Aniszewski|Aniszewski]], p. 109</ref> and therefore can be assigned to both classes.<ref name="ref19">[[#Dewick|Dewick]], p. 307</ref>

Alkaloids are often divided into the following major groups:<ref>[[#Hesse|Hesse]], p. 12</ref>

# "True alkaloids" contain [[nitrogen]] in the [[heterocycle]] and originate from [[amino acid]]s.<ref  
name="ref21">[[#Plemenkov|Plemenkov]], p. 223</ref> Their characteristic examples are [[atropine]], [[nicotine]], and [[morphine]]. This group also includes some alkaloids that besides the nitrogen heterocycle contain [[terpene]] (''e.g.'', [[evonine]]<ref>[[#Aniszewski|Aniszewski]], p. 108</ref>) or peptide fragments (''e.g.'' [[ergotamine]]<ref name="ref23">[[#Hesse|Hesse]], p. 84</ref>). The piperidine alkaloids [[coniine]] and [[coniceine]] may be regarded as true alkaloids (rather than pseudoalkaloids: see below)<ref name="ref24">[[#Hesse|Hesse]], p. 31</ref> although they do not originate from amino acids.<ref name="ref25">[[#Dewick|Dewick]], p. 381</ref>
# "Protoalkaloids", which contain [[nitrogen]] (but not the nitrogen heterocycle) and also originate from amino acids.<ref name="ref21" /> Examples include [[mescaline]], [[adrenaline]] and [[ephedrine]].
# [[Polyamine]] alkaloids – derivatives of [[putrescine]], [[spermidine]], and [[spermine]].
# Peptide and [[cyclopeptide]] alkaloids.<ref name="ref27">{{cite journal|author1=Dimitris C. Gournelif |author2=Gregory G. Laskarisb |author3=Robert Verpoorte |title = Cyclopeptide alkaloids|doi = 10.1039/NP9971400075|journal = Nat. Prod. Rep.|year = 1997|volume = 14|pages = 75–82|pmid = 9121730|issue = 1}}</ref>
# Pseudoalkaloids – alkaloid-like compounds that do not originate from amino acids.<ref>[[#Aniszewski|Aniszewski]], p. 11</ref> This group includes [[terpene]]-like and [[steroid]]-like alkaloids,<ref>[[#Plemenkov|Plemenkov]], p. 246</ref> as well as [[purine]]-like alkaloids such as [[caffeine]], [[theobromine]], [[theacrine]] and [[theophylline]].<ref name="ref30">[[#Aniszewski|Aniszewski]], p. 12</ref> Some authors classify [[ephedrine]] and [[cathinone]] as pseudoalkaloids. Those originate from the amino acid [[phenylalanine]], but acquire their nitrogen atom not from the amino acid but through [[transamination]].<ref name="ref30" /><ref name="ref31">[[#Dewick|Dewick]], p. 382</ref>

Some alkaloids do not have the carbon skeleton characteristic of their group. So, [[galanthamine]] and homoaporphines do not contain [[isoquinoline]] fragment, but are, in general, attributed to isoquinoline alkaloids.<ref>[[#Hesse|Hesse]], pp. 44, 53</ref>

Main classes of monomeric alkaloids are listed in the table below:
<!--the table is translated from the ru.wiki article. Please fix translation glitches -->
{| Class = "wikitable skin-invert-image"
|-
! Class
!Major groups
!Main synthesis steps
!Examples
|-
| colspan="4"  style="text-align:center; background:# DADADA;"|''Alkaloids with nitrogen heterocycles (true alkaloids)''
|-
| [[Pyrrolidine]] derivatives<ref name="ref34">[[#Plemenkov|Plemenkov]], p. 224</ref>
[[File:Pyrrolidine structure.svg|50px|center]]
|
| [[Ornithine]] or [[arginine]] → [[putrescine]] → N-methylputrescine → N-methyl-Δ<sup>1</sup>-pyrroline<ref name="ref35">[[#Aniszewski|Aniszewski]], p. 75</ref>
| [[Cuscohygrine]], [[hygrine]], hygroline, stachydrine<ref name="ref34" /><ref>[[#Orekhov|Orekhov]], p. 33</ref>
|-
| Rowspan = "2"|[[Tropane]] derivatives<ref name="ref38">{{Cite web |url=http://www.xumuk.ru/encyklopedia/2/4609.html |title=Chemical Encyclopedia: Tropan alkaloids |work=xumuk.ru}}</ref>
[[File:Tropane numbered.svg|100px|center]]
| Atropine group<br /><small>Substitution in positions 3, 6 or 7 </small>
| Rowspan = "2"|[[Ornithine]] or [[arginine]] → [[putrescine]] → N-methylputrescine → N-methyl-Δ<sup>1</sup>-pyrroline<ref name = "ref35 "/>
| [[Atropine]], [[scopolamine]], [[hyoscyamine]]<ref name="ref34" /><ref name="ref38" /><ref>[[#Hesse|Hesse]], p. 34</ref>
|-
| Cocaine group<br /> <small>Substitution in positions 2 and 3 </small>
| [[Cocaine]], [[ecgonine]]<ref name="ref38" /><ref>[[#Aniszewski|Aniszewski]], p. 27</ref>
|-
| Rowspan = "4"|[[Pyrrolizidine]] derivatives<ref name="ref45">{{Cite web |url=http://www.xumuk.ru/encyklopedia/2/3370.html |title=Chemical Encyclopedia: Pyrrolizidine alkaloids |work=xumuk.ru}}</ref>
[[File:Pyrrolizidine.svg|80px|center]]
| Non-esters
| Rowspan = "3"|In plants: [[ornithine]] or [[arginine]] → [[putrescine]] → [[homospermidine]] → [[retronecine]]<ref name="ref35" />
| [[Retronecine]], heliotridine, laburnine<ref name="ref45" /><ref>[[#Plemenkov|Plemenkov]], p. 229</ref>
|-
| Complex [[esters]] of monocarboxylic acids
| Indicine, lindelophin, sarracine<ref name="ref45" />
|-
| Macrocyclic diesters
| [[Platyphylline]], trichodesmine<ref name="ref45" />
|-
| 1-aminopyrrolizidines ([[Loline alkaloids|lolines]])
| In [[Neotyphodium|fungi]]: [[Proline|<small>L</small>-proline]] + [[homoserine|<small>L</small>-homoserine]] → ''N''-(3-amino-3-carboxypropyl)proline → norloline<ref name="Blankenship">{{cite journal|vauthors=Blankenship JD, Houseknecht JB, Pal S, Bush LP, Grossman RB, Schardl CL |year= 2005|title=Biosynthetic precursors of fungal pyrrolizidines, the loline alkaloids|journal=ChemBioChem|volume=6|pages=1016–1022|pmid=15861432|doi=10.1002/cbic.200400327|issue=6|s2cid= 13461396}}</ref><ref name="Faulkner et al. 2006">{{cite journal|vauthors=Faulkner JR, Hussaini SR, Blankenship JD, Pal S, Branan BM, Grossman RB, Schardl CL |year= 2006|title=On the sequence of bond formation in loline alkaloid biosynthesis|journal=ChemBioChem|volume=7|pages=1078–1088|pmid=16755627|doi=10.1002/cbic.200600066|issue=7|s2cid= 34409048}}</ref>
|Loline, ''N''-formylloline, ''N''-acetylloline<ref name="Schardl et al. 2007">{{cite journal|vauthors=Schardl CL, Grossman RB, Nagabhyru P, Faulkner JR, Mallik UP |year=2007|title=Loline alkaloids: currencies of mutualism|journal = [[Phytochemistry (journal)|Phytochemistry]]|volume=68|pages=980–996|doi=10.1016/j.phytochem.2007.01.010|pmid=17346759|issue=7|bibcode=2007PChem..68..980S }}</ref>
|-
| Rowspan = "2"|[[Piperidine]] derivatives<ref>[[#Plemenkov|Plemenkov]], p. 225</ref>
[[File:Piperidin.svg|50px|center]]
|
| [[Lysine]] → [[cadaverine]] → Δ<sup>1</sup>-piperideine<ref>[[#Aniszewski|Aniszewski]], p. 95</ref>
| [[Sedamine]], lobeline, anaferine, [[piperine]]<ref name="ref24" /><ref>[[#Orekhov|Orekhov]], p. 80</ref>
|-
|
| [[Caprylic acid|Octanoic acid]] → coniceine → [[coniine]]<ref name="ref25" />
| [[Coniine]], coniceine<ref name="ref25" />
|-
| Rowspan = "5"|[[Quinolizidine]] derivatives<ref name="ref57">{{Cite web |url=http://www.xumuk.ru/encyklopedia/2/5011.html |title=Chemical Encyclopedia: Quinolizidine alkaloids |work=xumuk.ru}}</ref><ref>[[#Saxton|Saxton]], Vol. 1, p. 93</ref>
[[File:Quinolizidine.svg|80px|center]]
| [[Lupinine]] group
| Rowspan = "5"|[[Lysine]] → [[cadaverine]] → Δ<sup>1</sup>-piperideine<ref>[[#Aniszewski|Aniszewski]], p. 98</ref>
| [[Lupinine]], nupharidin<ref name="ref57" />
|-
| [[Cytisine]] group
| [[Cytisine]]<ref name="ref57" />
|-
| [[Sparteine]] group
| [[Sparteine]], [[lupanine]], [[anahygrine]]<ref name="ref57" />
|-
| [[Matrine]] group.    
| Matrine, oxymatrine, allomatridine<ref name="ref57" /><ref>[[#Saxton|Saxton]], Vol. 1, p. 91</ref><ref>{{cite journal|author = Joseph P. Michael|title = Indolizidine and quinolizidine alkaloids|doi = 10.1039/b208137g|pmid = 14620842|journal=Nat. Prod. Rep.|year = 2002|volume = 19|issue = 5|pages = 458–475}}</ref>
|-
| [[Ormosanine]] group
| Ormosanine, piptantine<ref name="ref57" /><ref>[[#Saxton|Saxton]], Vol. 1, p. 92</ref>
|-
| [[Indolizidine]] derivatives<ref>[[#Dewick|Dewick]], p. 310</ref>
[[File:Indolizidine.svg|80px|center]]
|
| [[Lysine]] → δ-semialdehyde of [[alpha-Aminoadipic acid|α-aminoadipic acid]] → [[pipecolic acid]] → 1 indolizidinone<ref>[[#Aniszewski|Aniszewski]], p. 96</ref>
| [[Swainsonine]], [[castanospermine]]<ref>[[#Aniszewski|Aniszewski]], p. 97</ref>
|-
| Rowspan = "4"|[[Pyridine]] derivatives<ref name="ref72">[[#Plemenkov|Plemenkov]], p. 227</ref><ref name="ref73">{{Cite web |url=http://www.xumuk.ru/encyklopedia/2/3336.html |title=Chemical Encyclopedia: pyridine alkaloids |work=xumuk.ru}}</ref>
[[File:Pyridine.svg|50px|center]]
| Simple derivatives of pyridine
| Rowspan = "3"|[[Nicotinic acid]] → dihydronicotinic acid → 1,2-dihydropyridine<ref name="ref74">[[#Aniszewski|Aniszewski]], p. 107</ref>
| [[Trigonelline]], [[ricinine]], [[arecoline]]<ref name="ref72" /><ref name="ref76">[[#Aniszewski|Aniszewski]], p. 85</ref>
|-
| Polycyclic noncondensing pyridine derivatives
| [[Nicotine]], [[nornicotine]], [[anabasine]], anatabine<ref name="ref72" /><ref name="ref76" />
|-
| Polycyclic condensed pyridine derivatives
| [[Actinidine]], [[gentianine]], pediculinine<ref>[[#Plemenkov|Plemenkov]], p. 228</ref>
|-
| [[Sesquiterpene]] pyridine derivatives
| [[Nicotinic acid]], [[isoleucine]]<ref name="Aniszewski 110"/>
| Evonine, hippocrateine, triptonine<ref name="ref73" /><ref name="ref74" />
|-
| Rowspan = "26"|[[Isoquinoline]] derivatives and related alkaloids<ref name="Hesse 36">[[#Hesse|Hesse]], p. 36</ref>
[[File:Isoquinoline numbered.svg|90px|center]]
| Simple derivatives of isoquinoline<ref name="XimE: izoxinolin">{{Cite web |url=http://www.xumuk.ru/encyklopedia/1642.html |title=Chemical Encyclopedia: isoquinoline alkaloids |work=xumuk.ru}}</ref>
| Rowspan = "26"|[[Tyrosine]] or [[phenylalanine]] → [[dopamine]] or [[tyramine]] (for alkaloids Amarillis)<ref>[[#Aniszewski|Aniszewski]], pp. 77–78</ref><ref name="Begley">[[#Begley|Begley]], Alkaloid Biosynthesis</ref>
| [[Salsoline]], lophocerine<ref name="Hesse 36"/><ref name="XimE: izoxinolin"/>
|-
| Derivatives of 1- and 3-isoquinolines<ref name="Saxton 122">[[#Saxton|Saxton]], Vol. 3, p. 122</ref>
| N-methylcoridaldine, noroxyhydrastinine<ref name="Saxton 122"/>
|-
| Derivatives of 1- and 4-phenyltetrahydroisoquinolines<ref name="XimE: izoxinolin"/>
| Cryptostilin<ref name="XimE: izoxinolin"/><ref name="Hesse 54">[[#Hesse|Hesse]], p. 54</ref>
|-
| Derivatives of 5-naftil-isoquinoline<ref name="ref83">[[#Hesse|Hesse]], p. 37</ref>
| Ancistrocladine<ref name="ref83" />
|-
| Derivatives of 1- and 2-benzyl-izoquinolines<ref>[[#Hesse|Hesse]], p. 38</ref>
| [[Papaverine]], [[laudanosine]], sendaverine
|-
| [[Cularine]] group<ref name="ref86">[[#Hesse|Hesse]], p. 46</ref>
| Cularine, yagonine<ref name="ref86" />
|-
| [[Pavine (molecule)|Pavine]]s and isopavines<ref name="ref88">[[#Hesse|Hesse]], p. 50</ref>
| Argemonine, [[amurensine]]<ref name="ref88" />
|-
| Benzopyrrocolines<ref name="ref90">{{cite journal|author = Kenneth W. Bentley|title = β-Phenylethylamines and the isoquinoline alkaloids|doi = 10.1039/NP9971400387|journal=Nat. Prod. Rep.|year = 1997|volume = 14|pages = 387–411|pmid = 9281839|issue = 4|url=http://chemistry.mdma.ch/hiveboard/rhodium/pdf/archive/merbst/phenethylamines%20and%20isoquinolines%202001.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://chemistry.mdma.ch/hiveboard/rhodium/pdf/archive/merbst/phenethylamines%20and%20isoquinolines%202001.pdf |archive-date=2022-10-09 |url-status=live}}</ref>
| Cryptaustoline<ref name="XimE: izoxinolin"/>
|-
| Protoberberines<ref name="XimE: izoxinolin"/>
| [[Berberine]], [[canadine]], ophiocarpine, mecambridine, corydaline<ref name="ref91">[[#Hesse|Hesse]], p. 47</ref>
|-
| Phthalidisoquinolines<ref name="XimE: izoxinolin"/>
| [[Hydrastine]], [[narcotine]] (Noscapine)<ref>[[#Hesse|Hesse]], p. 39</ref>
|-
| Spirobenzylisoquinolines<ref name="XimE: izoxinolin"/>
| Fumaricine<ref name="ref88" />
|-
| [[Psychotria ipecacuanha|Ipecacuanha]] alkaloids<ref name="ref94">[[#Hesse|Hesse]], p. 41</ref>
| Emetine, protoemetine, ipecoside<ref name="ref94" />
|-
| Benzophenanthridines<ref name="XimE: izoxinolin"/>
| Sanguinarine, oxynitidine, corynoloxine<ref name="ref96">[[#Hesse|Hesse]], p. 49</ref>
|-
| [[Aporphine]]s<ref name="XimE: izoxinolin"/>
| [[Glaucine]], coridine, liriodenine<ref>[[#Hesse|Hesse]], p. 44</ref>
|-
| Proaporphines<ref name="XimE: izoxinolin"/>
| Pronuciferine, glaziovine<ref name="XimE: izoxinolin"/><ref name="ref90" />
|-
| Homoaporphines<ref name="ref99">[[#Saxton|Saxton]], Vol. 3, p. 164</ref>
| Kreysiginine, multifloramine<ref name="ref99" />
|-
| Homoproaporphines<ref name="ref99" />
| Bulbocodine<ref name="ref86" />
|-
| [[Morphine]]s<ref name="ref103">[[#Hesse|Hesse]], p. 51</ref>
| [[Morphine]], [[codeine]], [[thebaine]], [[sinomenine]],<ref name="ref104">[[#Plemenkov|Plemenkov]], p. 236</ref> [[heroin]]
|-
| Homomorphines<ref>[[#Saxton|Saxton]], Vol. 3, p. 163</ref>
| Kreysiginine, androcymbine<ref name="ref103" />
|-
| Tropoloisoquinolines<ref name="XimE: izoxinolin"/>
| Imerubrine<ref name="XimE: izoxinolin"/>
|-
| Azofluoranthenes<ref name="XimE: izoxinolin"/>
| Rufescine, imeluteine<ref>[[#Saxton|Saxton]], Vol. 3, p. 168</ref>
|-
| [[Amaryllis]] alkaloids<ref>[[#Hesse|Hesse]], p. 52</ref>
| [[Lycorine]], ambelline, tazettine, [[galantamine]], montanine<ref>[[#Hesse|Hesse]], p. 53</ref>
|-
| [[Erythrina alkaloids]]<ref name="Hesse 54"/>
| Erysodine, erythroidine<ref name="Hesse 54"/>
|-
| [[Phenanthrene]] derivatives<ref name="XimE: izoxinolin"/>
| Atherosperminine<ref name="XimE: izoxinolin"/><ref name="ref91" />
|-
| [[Protopine]]s<ref name="XimE: izoxinolin"/>
| [[Protopine]], oxomuramine, corycavidine<ref name="ref96" />
|-
| Aristolactam<ref name="XimE: izoxinolin"/>
| Doriflavin<ref name="XimE: izoxinolin"/>
|-
| [[Oxazole]] derivatives<ref name="Plemenkov 241">[[#Plemenkov|Plemenkov]], p. 241</ref>
[[File:Oxazole structure.svg|80px|center]]
|
| [[Tyrosine]] → [[tyramine]]<ref>[[#Brossi|Brossi]], Vol. 35, p. 261</ref>
| Annuloline, halfordinol, texaline, texamine<ref>[[#Brossi|Brossi]], Vol. 35, pp. 260–263</ref>
|-
| [[Isoxazole]] derivatives
[[Image:isoxazole structure.png|80px|center]]
|
|[[Ibotenic acid]] → [[Muscimol]]
|Ibotenic acid, Muscimol
|-
| [[Thiazole]] derivatives<ref name="ref114">[[#Plemenkov|Plemenkov]], p. 242</ref>
[[File:Thiazole structure.svg|80px|center]]
|
| [[1-Deoxy-D-xylulose 5-phosphate]] (DOXP), [[tyrosine]], [[cysteine]]<ref>[[#Begley|Begley]], Cofactor Biosynthesis</ref>
| Nostocyclamide, thiostreptone<ref name="ref114" /><ref>{{cite journal|author = John R. Lewis|title = Amaryllidaceae, muscarine, imidazole, oxazole, thiazole and peptide alkaloids, and other miscellaneous alkaloids|journal = Nat. Prod. Rep.|year = 2000|volume = 17|pages = 57–84|pmid = 10714899|issue = 1|doi = 10.1039/a809403i}}</ref>
|-
| Rowspan = "3"|[[Quinazoline]] derivatives<ref>{{Cite web |url=http://www.xumuk.ru/encyklopedia/2/5003.html |title=Chemical Encyclopedia: Quinazoline alkaloids |work=xumuk.ru}}</ref>
[[File:Quinazoline numbered.svg|90px|center]]
| 3,4-Dihydro-4-quinazolone derivatives
| Rowspan = "3"|[[Anthranilic acid]] or [[phenylalanine]] or [[ornithine]]<ref>[[#Aniszewski|Aniszewski]], p. 106</ref>
| [[Febrifugine]]<ref name="ref120">[[#Aniszewski|Aniszewski]], p. 105</ref>
|-
| 1,4-Dihydro-4-quinazolone derivatives
| Glycorine, arborine, glycosminine<ref name="ref120" />
|-
| Pyrrolidine and piperidine quinazoline derivatives
| [[Vazicine]] (peganine)<ref name="Plemenkov 241"/>
|-
| [[Acridine]] derivatives<ref name="Plemenkov 241"/>
[[File:Acridine.svg|100px|center]]
|
| [[Anthranilic acid]]<ref>{{cite journal|author = Richard B. Herbert|title = The biosynthesis of plant alkaloids and nitrogenous microbial metabolites|journal=Nat. Prod. Rep.|year = 1999|volume = 16|issue = 2|pages = 199–208|doi = 10.1039/a705734b|last2 = Herbert|first2 = Richard B.|last3 = Herbert|first3 = Richard B.}}</ref>
| Rutacridone, [[acronicine]]<ref>[[#Plemenkov|Plemenkov]], pp. 231, 246</ref><ref>[[#Hesse|Hesse]], p. 58</ref>
|-
| Rowspan = "4"|[[Quinoline]] derivatives<ref>[[#Plemenkov|Plemenkov]], p. 231</ref><ref name="ref126">{{Cite web |url=http://www.xumuk.ru/encyklopedia/2/5014.html |title=Chemical Encyclopedia: Quinoline alkaloids |work=xumuk.ru}}</ref>
[[File:Quinoline numbered.svg|90px|center]]
| Simple derivatives of quinoline derivatives of [[2–quinolone]]s and [[4-quinolone]]
| Rowspan = "3"|[[Anthranilic acid]] → 3-carboxyquinoline<ref name="ref127">[[#Aniszewski|Aniszewski]], p. 114</ref>
| Cusparine, [[echinopsine]], evocarpine<ref name="ref126" /><ref>[[#Orekhov|Orekhov]], p. 205</ref><ref>[[#Hesse|Hesse]], p. 55</ref>
|-
| Tricyclic terpenoids
| Flindersine<ref name="ref126" /><ref name="ref131">[[#Plemenkov|Plemenkov]], p. 232</ref>
|-
| Furanoquinoline derivatives
| [[Dictamnine]], fagarine, [[skimmianine]]<ref name="ref126" /><ref>[[#Orekhov|Orekhov]], p. 212</ref><ref>[[#Aniszewski|Aniszewski]], p. 118</ref>
|-
| [[Quinine]]s
| [[Tryptophan]] → [[tryptamine]] → [[strictosidine]] (with [[secologanin]]) → korinanteal → [[cinhoninon]]<ref name="Begley"/><ref name = " ref127 "/>
| [[Quinine]], [[quinidine]], [[cinchonine]], cinhonidine<ref name="ref131" />
|-
| Rowspan = "10"|[[Indole]] derivatives<ref name="ref104" />
[[File:Indole numbered.svg|100px|center]]
{{See also|indole alkaloids}}
| colspan="3" style="text-align:center;"|''Non-isoprene indole alkaloids''
|-
| Simple indole derivatives<ref name="ref140">[[#Aniszewski|Aniszewski]], p. 112</ref>
| Rowspan = "3"|[[Tryptophan]] → [[tryptamine]] or [[5-Hydroxytryptophan]]<ref name="ref141">[[#Aniszewski|Aniszewski]], p. 113</ref>
| [[Serotonin]], [[psilocybin]], [[dimethyltryptamine]] (DMT), [[bufotenin]]<ref>[[#Hesse|Hesse]], p. 15</ref><ref>[[#Saxton|Saxton]], Vol. 1, p. 467</ref>
|-
| Simple derivatives of [[beta-carboline|β-carboline]]<ref>[[#Dewick|Dewick]], pp. 349–350</ref>
| Harman, [[harmine]], [[harmaline]], eleagnine<ref name="ref140" />
|-
| Pyrroloindole alkaloids<ref name="ref152">[[#Aniszewski|Aniszewski]], p. 119</ref>
| [[Physostigmine]] (eserine), etheramine, physovenine, eptastigmine<ref name="ref152" />
|-
| colspan="3" style="text-align:center;"|''Semiterpenoid indole alkaloids''
|-
| [[Ergoline|Ergot alkaloids]]<ref name="ref104" />
| [[Tryptophan]] → chanoclavine → agroclavine → elimoclavine → [[paspalic acid]] → [[lysergic acid]]<ref name="ref152" />
| [[Ergotamine]], ergobasine, ergosine<ref>[[#Hesse|Hesse]], p. 29</ref>
|-
| colspan="3" style="text-align:center;"|''Monoterpenoid indole alkaloids''
|-
| ''Corynanthe'' type alkaloids<ref name="ref141" />
| Rowspan = "3"|[[Tryptophan]] → [[tryptamine]] → [[strictosidine]] (with [[secologanin]])<ref name="ref141" />
| Ajmalicine, sarpagine, vobasine, [[ajmaline]], [[yohimbine]], [[reserpine]], [[mitragynine]],<ref>[[#Hesse|Hesse]], pp. 23–26</ref><ref>[[#Saxton|Saxton]], Vol. 1, p. 169</ref> group [[strychnine]] and ([[Strychnine]] [[brucine]], aquamicine, [[vomicine]]<ref>[[#Saxton|Saxton]], Vol. 5, p. 210</ref>)
|-
| [[Iboga]]-type alkaloids<ref name="ref141" />
| [[Ibogamine]], [[ibogaine]], [[voacangine]]<ref name="ref141" />
|-
| [[Aspidosperma]]-type alkaloids<ref name="ref141" />
| [[Vincamine]], [[vinca alkaloid|''vinca'' alkaloids]],<ref name = CurrMedChem-VA /><ref name = MoleculesReview /> vincotine, aspidospermine<ref>[[#Hesse|Hesse]], pp. 17–18</ref><ref>[[#Dewick|Dewick]], p. 357</ref>
|-
| [[Imidazole]] derivatives<ref name="Plemenkov 241"/>
[[File:Imidazole structure.svg|50px|center]]
|
| Directly from [[histidine]]<ref name="Aniszewski 104">[[#Aniszewski|Aniszewski]], p. 104</ref>
| [[Histamine]], [[pilocarpine]], pilosine, [[stevensine]]<ref name="Plemenkov 241"/><ref name="Aniszewski 104"/>
|-
| [[Purine]] derivatives<ref>[[#Hesse|Hesse]], p. 72</ref>
[[File:9H-Purine.svg|90px|center]]
|
| [[Xanthosine]] (formed in purine biosynthesis) → 7 methylxantosine → [[7-methylxanthine]] → [[theobromine]] → [[caffeine]]<ref name="Begley"/>
| [[Caffeine]], [[theobromine]], [[theophylline]], [[saxitoxin]]<ref>[[#Hesse|Hesse]], p. 73</ref><ref>[[#Dewick|Dewick]], p. 396</ref>
|-
| colspan="4"  style="text-align:center; background:# DADADA;"|''Alkaloids with nitrogen in the side chain (protoalkaloids)''
|-
| β-[[Phenylethylamine]] derivatives<ref name="ref90" />
[[File:Phenylethylamine numbered.svg|110px|center]]
|
| [[Tyrosine]] or [[phenylalanine]] → [[dioxyphenilalanine]] → [[dopamine]] → [[adrenaline]] and [[mescaline]] [[tyrosine]] → [[tyramine]] phenylalanine → 1-phenylpropane-1,2-dione → [[cathinone]] → [[ephedrine]] and [[pseudoephedrine]]<ref name="Aniszewski 110"/><ref name="ref31" /><ref>{{Cite web |url=http://www.plantcyc.org:1555/PLANT/NEW-IMAGE?type=NIL&object=PWY-5883 |title=PlantCyc Pathway: ephedrine biosynthesis |archive-url=https://web.archive.org/web/20111210040135/http://www.plantcyc.org:1555/PLANT/NEW-IMAGE?type=NIL&object=PWY-5883 |archive-date=December 10, 2011 }}</ref>
| [[Tyramine]], [[ephedrine]], [[pseudoephedrine]], [[mescaline]], [[cathinone]], [[catecholamines]] ([[adrenaline]], [[noradrenaline]], [[dopamine]])<ref name="Aniszewski 110"/><ref>[[#Hesse|Hesse]], p. 76</ref>
|-
| [[Colchicine]] alkaloids<ref name="ref179">{{Cite web |url=http://www.xumuk.ru/encyklopedia/2069.html |title=Chemical Encyclopedia: colchicine alkaloids |work=xumuk.ru}}</ref>
[[File:Colchicine.svg|120px|center]]
|
| [[Tyrosine]] or [[phenylalanine]] → [[dopamine]] → [[autumnaline]] → [[colchicine]]<ref>[[#Aniszewski|Aniszewski]], p. 77</ref>
| [[Colchicine]], colchamine<ref name="ref179" />
|-
| [[Muscarine]]<ref name="ref182">[[#Hesse|Hesse]], p. 81</ref>
[[File:Muscarine.svg|100px|center]]
|
| [[Glutamic acid]] → 3-ketoglutamic acid → muscarine (with [[pyruvic acid]])<ref>[[#Brossi|Brossi]], Vol. 23, p. 376</ref>
| [[Muscarine]], allomuscarine, epimuscarine, epiallomuscarine<ref name="ref182" />
|-
| Benzylamine<ref name="ref185">[[#Hesse|Hesse]], p. 77</ref>
[[File:Benzylamine.svg|90px|center]]
|
| [[Phenylalanine]] with [[valine]], [[leucine]] or [[isoleucine]]<ref>[[#Brossi|Brossi]], Vol. 23, p. 268</ref>
| [[Capsaicin]], [[dihydrocapsaicin]], nordihydrocapsaicin, [[vanillylamine]]<ref name="ref185" /><ref>[[#Brossi|Brossi]], Vol. 23, p. 231</ref>
|-
| colspan="4"  style="text-align:center; background:# DADADA;"|''Polyamines alkaloids''
|-
| [[Putrescine]] derivatives<ref name="ref189">[[#Hesse|Hesse]], p. 82</ref>
[[File:Putrescine.svg|90px|center]]
|
| Rowspan = "3"|[[ornithine]] → [[putrescine]] → [[spermidine]] → [[spermine]]<ref>{{Cite web|url=http://www.chem.qmul.ac.uk/iubmb/enzyme/reaction/misc/spermine.html/|title=Spermine Biosynthesis|website=www.qmul.ac.uk|archive-url=https://web.archive.org/web/20031113075753/http://www.chem.qmul.ac.uk/iubmb/enzyme/reaction/misc/spermine.html/ |archive-date=13 November 2003 }}</ref>
| Paucine<ref name="ref189" />
|-
| [[Spermidine]] derivatives<ref name="ref189" />
[[File:Spermidine.svg|110px|center]]
|
| Lunarine, codonocarpine<ref name="ref189" />
|-
| [[Spermine]] derivatives<ref name="ref189" />
[[File:Spermine.svg|130px|center]]
|
| Verbascenine, aphelandrine<ref name="ref189" />
|-
| colspan="4"  style="text-align:center; background:# DADADA;"|''Peptide (cyclopeptide) alkaloids''
|-
| Rowspan = "2"|Peptide alkaloids with a 13-membered cycle<ref name="ref27" /><ref name="ref196">[[#Plemenkov|Plemenkov]], p. 243</ref>
| Nummularine C type
| Rowspan = "8"|From different amino acids<ref name="ref27" />
| Nummularine C, Nummularine S<ref name="ref27" />
|-
| [[Ziziphine]] type
| Ziziphine A, sativanine H<ref name="ref27" />
|-
| Rowspan = "5"|Peptide alkaloids with a 14-membered cycle<ref name="ref27" /><ref name="ref196" />
| Frangulanine type
| Frangulanine, scutianine J<ref name="ref196" />
|-
| Scutianine A type
| Scutianine A<ref name="ref27" />
|-
| Integerrine type
| Integerrine, discarine D<ref name="ref196" />
|-
| Amphibine F type
| Amphibine F, spinanine A<ref name="ref27" />
|-
| Amfibine B type
| Amphibine B, lotusine C<ref name="ref27" />
|-
| Peptide alkaloids with a 15-membered cycle<ref name="ref196" />
| Mucronine A type
| Mucronine A<ref name="ref23" /><ref name="ref196" />
|-
| colspan="4"  style="text-align:center; background:# DADADA;"|''Pseudoalkaloids ([[terpenes]] and [[steroids]])''
|-
| Diterpenes<ref name="ref23" />
[[File:Isoprene.svg|80px|center]]
| Lycoctonine type
| [[Mevalonic acid]] → [[Isopentenyl pyrophosphate]] → [[geranyl pyrophosphate]]<ref>{{Cite web |url=http://www.xumuk.ru/encyklopedia/2/4392.html |title=Chemical Encyclopedia: Terpenes |work=xumuk.ru}}</ref><ref>[[#Begley|Begley]], Natural Products: An Overview</ref>
| [[Aconitine]], [[delphinine]]<ref name="ref23" /><ref>{{cite journal|author = Atta-ur-Rahman and M. Iqbal Choudhary|title = Diterpenoid and steroidal alkaloids|journal=Nat. Prod. Rep.|year = 1997|volume = 14|pages = 191–203|pmid = 9149410|issue = 2|doi = 10.1039/np9971400191}}</ref>
|-
| [[Steroidal alkaloid]]s<ref>[[#Hesse|Hesse]], p. 88</ref>
[[File:Cyclopentenophenanthrene.svg|100px|center]]
|
| [[Cholesterol]], [[arginine]]<ref>[[#Dewick|Dewick]], p. 388</ref>
| [[Solanidine]], [[cyclopamine]], [[batrachotoxin]]<ref>[[#Plemenkov|Plemenkov]], p. 247</ref>
|}