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Why is this substance in two groups? __meco 01:34, 15 July 2006 (UTC)

Because it has both a pyridine and a pyrrolidene group. Look at the molecule. —Keenan Pepper 02:13, 15 July 2006 (UTC)
I'm not chemically conversant. I understand however that it's correct the way it currently reads. __meco 18:48, 15 July 2006 (UTC)


I added an example and citation of an organism that uses alkaloids for protection: Utetheisa ornatrix to “The Biological Role” section. Kzyoung (talk) 20:18, 14 November 2013 (UTC)


The {{Commons}} box looks awful at the top. Can we please not put it there? —Keenan Pepper 09:52, 4 August 2006 (UTC)

Moved back to where it belongs - bottom of article. __meco 11:32, 4 August 2006 (UTC)

LSD an alkaloid?[edit]

it does not appear naturally, so why is it included here? if noone objects, I'll remove it. -- Rwst 08:07, 7 August 2006 (UTC)

I'm certainly no authority, however, if LSD is removed on the grounds of it being synthetic, then others must also be removed, for instance MDMA. __meco 23:08, 7 August 2006 (UTC)
Historically to be considered an alkaloid a chemical had to:

1 come from a plant 2 contain at least 1 nitrogen atom in its structure 3 have a physiological effect on animals

A minor synthetic change doesn't matter,

Heroin is not found in nature, but is a simple derivative of morphine, and is an alkaloid.

So is LSD. (talk)jimmy2000 Dec 2011 —Preceding undated comment added 07:51, 4 December 2011 (UTC).

the suffix "ine"[edit]

The article on cocaine has "The name comes from the name of the coca plant plus the alkaloid suffix -ine". Can this suffix use be confirmed and documented here? TIA

Jerome Potts 03:35, 21 August 2006 (UTC)

I think noting that many trivial names for alkaloids end in "-ine" is probably uncontroversial enough to be added without a source, although sourcing it would be preferable. We could say something like "many alkaloids have names ending in -amine or simply -ine" for example. Calling "-ine" the alkaloid suffix might not be the best practice though, as many synthetic amines end in "ine" (e.g. drugs with names ending in "amine" or "-caine"). The use of "-in" would be good to document also. Names with "-in", when they occur, seem to be applied to alkaloids discovered in animals (bufotenin aka bufotenine) or fungi (psilocybin), but I think "-ine" may even be more common.--Eloil 01:42, 26 April 2007 (UTC)


I'm adding Category: Chemistry to this article, for obvious reasons. Mihovil 18:42, 30 August 2006 (UTC)

There's no reason to. It's already in Category:Chemistry via Category:AlkaloidsCategory:Organic compoundsCategory:Organic chemistryCategory:Chemistry. If you really want to put it in another category, why not something more specific, like Category:Amines? —Keenan Pepper 04:42, 31 August 2006 (UTC)


What about pyrrolizidine alkaloids? Does this category merit a mention in the list of alkaloid groups? They are of interest for their hepatotoxicity and have already been mentioned in a number of other articles- for example, borage, comfrey, fuki, Roger Adams. Krnntp 17:20, 1 September 2006 (UTC)

It certainly does. As do the quinolizidines (e.g. the amphibian-derived homopumiliotoxins)Pikiwedian 08:39, 20 December 2006 (UTC)

Alkaloid metabolic pathways[edit]

I am a novice on this area but would like someone to direct me what to analyse for (not myself but competent biochemists) if I would like to look at the metabolites of an alkaloid, mesembrine. If I want to see if it was taken up in animal metabolic pathways when consumed, what would I look for. or if I need to analyse for residues. Could anyone give me clues? PstrydomPstrydom 13:59, 19 October 2006 (UTC)pstrydom

Examples in classification section[edit]

The classification section could use a bit of cleanup. It is not clear that the examples given are not exhaustive. Also, what are the criteria for choosing specific compounds to list as examples? If it is by their importance, I would suggest adding Synephrine. With the FDA's restrictions on Ephedrine, Synephrine is becoming a popular alternative despite the fact that it may be just as dangerous. 03:20, 2 November 2006 (UTC)

Template help[edit]

If anyone has time, the {{Alkaloids}} would really benefit from your expertise. Thanks! :) Willow 19:07, 27 January 2007 (UTC)

alkaloid definition[edit]

Currently the article opens as follows:

An alkaloid, strictly speaking, is a naturally-occurring amine produced by a plant,[1] but amines produced by animals and fungi are also called alkaloids. (...) The name derives from the word alkaline; originally, the term was used to describe any nitrogen-containing base.

The wording of the first sentence seems to suggest that the "strict" definition (must be found in plants) is the most correct somehow, but the third sentence suggests that this interpretation was predated by a much broader one (any nitrogen-containing base). My feeling is that we should go by usage and not by someone's conservative interpretation of what should "strictly" be called an alkaloid. If "alkaloid" is widely used in scientific literature to describe nitrogen-containing bases that have been found in animals or fungi but not (or not yet) in plants, then I think those chemicals are alkaloids. This usage might be considered mildly controversial by some, which is worth noting, but I don't think we're justified in implying it's not "strictly" correct.

from Wiktionary:alkaloid:

Any of many organic heterocyclic bases, that occur in nature and often have medicinal properties.

The "heterocyclic" qualifier is interesting. Phenethylamine alkaloids like mescaline have only carbons in their rings, and I'd guess there are many other example non-heterocyclic alkaloids. Are there alkaloids with no rings at all? It seems like most have some type of ring structure. --Eloil 09:51, 1 April 2007 (UTC)

Yes, please try to clarify. I read this article to try and understand what an alkaloid is, but the definition is WAY to loose to be useful. By the current definition, why wouldn't an amino acid be called an alkaloid? ike9898 (talk) 22:36, 21 February 2008 (UTC)
An alkaloid always has some type of physiological effect on animals.

So amino acid's generally don't meet that definition. (talk)jimmy2000 dec 2011

there is a whole class of alkaloids called protoalkaloids that contains nitrogen atom but not in a heterocyclic ring--7amada'sback:) (talk) 17:59, 5 January 2009 (UTC)


Mesembrine is Alkaloid which can be added. —Preceding unsigned comment added by (talk) 17:36, 7 June 2008 (UTC)

Classificating list[edit]

I think the classification in the article needs some revising. Namely, the quaternary ammonium salts are listed as if they were part of steroids... and they aren't:) In either way they're not terpenoids so they would better fit under separate entry somewhere below. And also the Indolic alkaloids. Reserpine and yohimbine have no more relation to beta-carbolines than to simple tryptamines. They'd better be listed as a separate subgroup amongst other indoles, possibly "Yohimbans". Mytraginine has also much similarity to that particular structure. Vinca alkaloids are too indolic, so why not place them as a sub to indoles? Same about Strychnine and Ibogaine, they deserve a mention as structurally unrelated Indoles. And also, capsaicin is not an alkaloid at all, it's a vanilloid, not an amine (it's rather an amide) and thus not basic. Correct me if I'm wrong. Angsaar (talk) 20:26, 18 July 2008 (UTC)


Fixed that, now saying it is a "steroid alkaloid", containing both a nitrogen, and a steroid skeleton as components of the structure. Linking them to "steroid" is misleading. (talk) 11:13, 5 August 2008 (UTC)

Phenanthrene alkaloids[edit]

Regardless of the synthesis pathway, these three differ so much from the structure of the other isoquinoline alkaloids, that a separate category is justified. (talk) 12:26, 5 August 2008 (UTC)


I have seen the discussion about amides, leading to removal of colchicine. I think that is overzealous, piperine is an amid too, capsaicin too. (talk) 12:38, 5 August 2008 (UTC)

A more appropriate definition of alkaloids includes the amides. This seems to be in line with current nomenclature. Colchicine should be put back. The xanthines are also alkaloids after all. piperine and capsaicin belong in too. (talk) 04:59, 9 September 2008 (UTC)

See here,+Isolation,+Synthesis+and+Biology&sig=ACfU3U2ItEZqMh72a8Xc_AZGEijQ-i-A_Q

and here

Cacycle: your edit reverted for that reason. (talk) 05:25, 9 September 2008 (UTC)

Arbitrarily loosening the definition of alkaloids in the way you propose it would make the term mostly synonymous with natural product and would clearly not reflect the well-established past and current use. Citing books on alkaloids that also include a few non-alkaloids or a sloppy use by certain authors and even teachers does in no way warrant such a change. Therefore, capsaicin and piperine should not be in the list. It would make more sense to add a short line that these and a few other compounds are often mentioned in the context of alkaloids. Cacycle (talk) 03:48, 10 September 2008 (UTC)

I would not call the loosening of the definition arbitrary. First we would have to verify the correctness of the current definition in the alkaloid entry. I have given two book references you call sloppy. There are many more. IMO alkaloids are "nitrogen containing small molecules, naturally occuring in plants, animals and fungi, developed for defense, characterized by high physiological activity". This narrows the definition sufficiently from "natural products". In this sense the common amino acids would not be alkaloids, but "domoic acid" would be. Colchicine, piperine and capsaicin would be. The concept is a practical one, I want readers to find things where they expect them, and where they find them in scientific literature. The concept is not only a practical one but also a historical one. The line I follow here is historically founded, I don't want a new but incompatible definition, but we will do what the majority of literature does, even if it appears sloppy. After all the concept of alkaloids was introduced historically, to cover the active nitrogen containing plant substances after they were investigated, it is an ad hoc approach to nomenclature of already existing discoveries, and of a developing topic. If the books count piperine and colchicine as alkaloids, then we do too. (talk) 21:50, 10 September 2008 (UTC)

To give my two cents in this debate, I'd suggest to go with common usage, which is indeed rather loose and often in the eye of the beholder. The term "alkaloid" is one given to a compound to categorize it in the broadest sense, mainly by dint of its being an organic compound with at least one nitrogen atom. Compounds that fall into this category and are well characterized and widely known, such as amino acids or nucleotides, could rightly also be called alkaloids, but to do so would goes against common usage, as laymen and experts alike usually call them by their rightful names. Natural products encompass a myriad of other non-alklaloid compounds, such as terpenes, flavonoids, phenylpropanoids, and so on, so using a looser definition of alkaloid will do little to soften the concept of what an alkaloid is. I'm an ardent supporter of rigorous definitions, but to try this here will be met with as much success as casting a jellyfish IMO. Malljaja (talk) 23:17, 10 September 2008 (UTC)
Please read Wikipedia:No original research, it is not our job here to make up or tweak definitions to our likening. We should instead refer to explicit definitions from reliable sources. If there is considerable disagreement between reliable sources, we should state so in the article.
Here is what IUPHAR IUPAC says:
"Basic nitrogen compounds (mostly heterocyclic) occurring mostly in the plant kingdom (but not excluding those of animal origin). Amino acids, peptides, proteins, nucleotides, nucleic acids, amino sugars and antibiotics are not normally regarded as alkaloids. By extension, certain neutral compounds biogenetically related to basic alkaloids are included."[1]
Also, all other definitions I found with a quick Google search stress the basic properties. The part "biogenetically related to basic alkaloids" means that they fall under this definition if the basic parent compound has been isolated from natural sources (preferably the same source). This is for including all family members of alkaloids, even if they are quaternized or N-acetylated. I am not sure if that would include colchicine and it definitely excludes capsaicin. The mere inclusion of a certain compound in a 1940 book on alkaloids is not a convincing argument. Also, your opinion that they are "developed for defense, characterized by high physiological activity" might even be true in many cases but is clearly not a defining feature of alkaloids. Cacycle (talk) 14:53, 11 September 2008 (UTC)
Hi Cacycle, no need to jump ahead here—as I've clearly stated, I'm offering an opinion, and I am not hiding the fact that it's by the seat of the pants at this point. So no need to go for allegations of OR, because I'm guilty as charged, and this is merely the Discussion page. I'm working in the field of natural products, so I'm quite cognizant of different opinions on the matter of how to define or categorize such compounds. For example, you're referring to a definition given by IUPHAR, thus one that comes from a pharmacology point of view. That's all very well but also a bit of a tweak. For example, IUPHAR's definition (nearly) excludes peptides; yet as biochemists familiar with secondary metabolism will tell you, ergopeptines, such as ergotamine, are cyclic peptides (products of non-ribosomal peptide synthetases) and are widely regarded as alkaloids (the same may be true for the amatoxins and other cyclic peptides). And don't even get me started on antibiotics, which by definition are any small molecule that kills microbes, and there are certainly alkaloids out there that exactly do that (eg, see here). And there's the kiss of death to any serious definition in the ominous phrase "...are not normally regarded as alkaloids..." How do we define normal...? So if even IUPHAR chokes on that it goes to show defining alkaloids in way that makes pharmacologists and everybody else happy is a big toad indeed. Thus, I agree with you that the issue of definition is contentious and that this should probably have a place in this entry. Thanks! Malljaja (talk) 17:00, 11 September 2008 (UTC)
Ergot alkaloids are alkaloids because they have the lysergic acid alkaloid core structure. The non-basic cyclic amatoxin peptides are clearly not alkaloids. Also, please give page numbers, I am not going to read whole books just to argue with you. Cacycle (talk) 01:43, 12 September 2008 (UTC)

Please take also a look at the other ref I have given above, which is a modern teaching book, and what definition it uses. I am also not sure if the IUPHAR definition is strict and trustworthy, indeed what does "normally" mean. And are the pharmacologists competent for providing a definition, or is this a matter to be left to the researchers in the field? I will tag the current definition in the article with a fact tag. Colchicine should be in. You say:

The part "biogenetically related to basic alkaloids" means that they fall under this definition if the basic parent compound has been isolated from natural sources (preferably the same source).

This is OR.

This is for including all family members of alkaloids, even if they are quaternized or N-acetylated. I am not sure if that would include colchicine and it definitely excludes capsaicin.

This is OR too.

Furthermore: The xanthines are amides too, not very basic. The amides are basic too, only weakly. And: "mere teaching books" are good enough for inclusion as a ref. See reliable sources. (talk) 17:24, 11 September 2008 (UTC)

I think a historical perspective is also welcome in this century old topic; insofar a text book from the 40's would be fine. 90% of the materials is quite a bit dated, as the research of plant alkaloids has been a focus of pharmacology already 100 years ago. Think of the malaria research etc. and the research into modified opium alkaloids. I think we have to look at common and historical use to be useful in general, and not to be more catholic than the pope. (talk) 18:25, 11 September 2008 (UTC)

I also think a historical perspective is welcome. But as a historical perspective of what appears (based on present-day references) to have evolved into a slightly different (or at least more nuanced) meaning. It's fine to talk about how something was, but more important to talk about how it is now, since it's still a topic of modern research rather than of purely historical relevance. DMacks (talk) 01:23, 12 September 2008 (UTC)

For a recent teaching book see here, it still agrees with the old refs:,+Isolation,+Synthesis+and+Biology&sig=ACfU3U2ItEZqMh72a8Xc_AZGEijQ-i-A_Q

also see the two recent articles I included as a reference. See below. I hate to bring two old book refs, (1906 and 1947), one recent book ref (brand new) and two recent peer reviewed articles, and they are all "arbitrary" and don't understand the issue, "confuse" things etc. (talk) 01:36, 12 September 2008 (UTC)

Capsaicin is an alkaloid: YES, Sir[edit]

Acoording to this ref

capsaicin is an alkaloid, synthesized from vanillylamine by capsaicin synthase. There you are. No OR. (talk) 18:40, 11 September 2008 (UTC)

Vanillylamine is not a close analog of capsaicin, it is a precursor. An amine as a precursor does not make any biosynthetical product an alkaloid. Cacycle (talk) 00:50, 12 September 2008 (UTC)

Sorry, the REF SAYS THAT IT IS AN ALKALOID (literally). Thats not my funny idea. So they don't know what they are talking? (talk) 01:48, 12 September 2008 (UTC)

Piperine is an alkaloid: Yes, Sir[edit]

According to this review article

PMID: 17987447

But see also the book sources above. (They are not hippie books, how to grow your own etc. or popular science)

Cacycle: What you are doing here is WP:Synth from the IUPHARM/IUPAC definition, which is rather mushy. (*are NORMALLY not regarded..*)

Now don't tell me all these sources are wrong: 2 teaching books, one peer reviewed primary source, one peer reviewed review article. (talk) 19:14, 11 September 2008 (UTC)

Further historical context:

Pictet, "The vegetable alkaloids", 1906 (and 1896)

download pdf as a google book here:

says piperine is an alkaloid, weakly basic, does not form salts with weak acids, but does form salts with concentrated mineral acids. These salts are dissociated by water. The book gives in its introduction also a history of alkaloid research and the development of the definition, from initially only pyridine compounds to what we have as of 1906. It also lists, like above book references (Not: "How to grow your own" by M.R. Hippie, The Hippiepress) Colchicine as an alkaloid. This overrides Wp:Synth from the IUPAC definition. (talk) 20:09, 11 September 2008 (UTC)

You (or that outdated source) might have confused hydrolysis with salt formation. Piperine does not form salts (at least under normal conditions). Also, randomly citing books on alkaloids that merely mention certain compounds is not convincing. Find current and explicit definitions. Cacycle (talk) 00:58, 12 September 2008 (UTC)

Certainly Pictet has not confused salt formation with hydrolysis; neither would I. Read it. (talk) 01:07, 12 September 2008 (UTC)

What makes you disagree with this ref

and this ref

PMID: 17987447 (talk) 01:05, 12 September 2008 (UTC)

I think that numeric data may shed some light on this question. The pKa of piperine is reported to be 1.98 (see the ref. I added to the article). With that pKa, it should be possible to protonate it with a strong acid and form a salt. Piperine turned out to be more basic than caffeine! --Itub (talk) 12:33, 12 September 2008 (UTC)

Thats exactly what "Pictet, The vegetable alkaloids, 1906, 1896" says. Formation of salts with strong mineral acids. Also formation of salts ("double salts") with Platinum chloride and others like that. Same for "Henry, The plant alkaloids, 1947". So we may conclude piperine is rightfully an alkaloid, historically, from its basicity, its ability to form salts. (talk) 15:56, 12 September 2008 (UTC)

Cacycle: look at wp amides for the weak basic character of amides. and: The chemists of the early 20th century KNEW the difference between hydrolysis and salt formation. We are not dealing with k12 students here, and we wikipedia readers usually have a GED. (talk) 15:56, 12 September 2008 (UTC)

Comments on definition[edit]

I'm replying to a request for comments at Wikipedia talk:WikiProject Chemistry‎. All I can say is: Oh, my, this is about as productive as debating the definition of organic compound! (Something on which we have, sadly, spent too much time.) There is no unique definition and the distinction is blurry and arbitrary. You will always find some compounds that are called alkaloids by some authors and not by others. The article should reflect this reality.

One comment about the IUPAC Gold Book reference. I love the Gold Book and cite it a lot, but we should remember what it is: basically a collation of glossaries. IMHO, glossaries are meant to be useful for reference by providing a quick definition that is good enough, but should not be interpreted as "legislation". I've found some definitions in the Gold Book that I think are incomplete or deficient and, although I'm no alkaloid expert I suspect this definition may have its limitations too.

This book could be useful: Alkaloids:Nature's curse or blessing?, pages 1-5 (it's also readable on, where I could read pages 5 and 6, which I couldn't read on Google books). The good thing about these pages is that they quote several definitions from the 19th and 20th centuries and compare them. Some focused on the plant origin, some on the basicity, some on the heterocyclic rings, but there were always exceptions. The vague definition that the author ends up proposing is "nitrogen-containing organic substances of natural origin with a greater or lesser degree of basic character". --Itub (talk) 09:35, 12 September 2008 (UTC)

I would have to agree with sentiments expressed by Itub. It will just be wasted effort trying to agree on what exactly is an alkaloid and what isn't because there isn't any one concrete definition of alkaloid. The article can give examples that are always considered alkaloids and separately specify compounds that may be considered alkaloids. -- Ed (Edgar181) 12:16, 12 September 2008 (UTC)
Itub provided a very useful reference, which could certainly be incorporated into the article, and I agree with him (and Ed). As for the specific cases of piperine and capsaicin, let me quote directly from a recent book I found, after 70.137 asked my opinion back in August and I told him I'd never seen piperine capsaicin characterized as an alkaloid:
Returning to the question in the title of this section, capsaicin does not fall into any of the three classic types of nitrogen-bearing plant natural products, being neither a true alkaloid, a protoalkaloid, or a pseudoalkaloid. Capsaicin is of limited distribution in Nature and shows pharmacological activity, but it is non-basic, structurally unsophisticated, and not directly derived from an amino acidic precursor. On the other hand, the lack of attributes such as basicity, complexity, and an “amino acidic pedigree” can also be found in compounds commonly perceived as alkaloids. Thus, colchicine is neutral, ephedrine is structurally unsophisticated, and the nitrogen atom of the potato alkaloid solanine is not derived from an amino acid […]. For the sake of clarity and consistency, it seems therefore convenient to adopt the modern definition of alkaloids, and consider capsaicin, as well as alkylamides such as piperine and pellitorine, as such.
(Modern Alkaloids, emphasis mine).
Many more scholarly articles and books classify capsaicin as an alkaloid. Why not simply leave capsaicin and piperine in the article and actually expand on the definition of alkaloid, noting the IUPAC definition, drawing from the reference Itub provided, giving historical context, and noting that many compounds that do not fit into a certain definition have been considered alkaloids in the literature? That would take care of any WP:V/WP:NOR/WP:SYNTH issues and it would improve this very important and, currently, very brief article. Fvasconcellos (t·c) 22:31, 12 September 2008 (UTC)
That quote is very useful because the author is explicit about his rationale for including capsaicin, rather than just being an example of casual usage. The link you posted takes me to the cover page, but I see that the good stuff is on pages 73-77. This links takes me directly to page 73, I hope it works for everyone: [2] (I can't read page 77--the one containing the quote above--on Google, but again I can read it on --Itub (talk) 06:30, 13 September 2008 (UTC)
Sorry about that—I forgot to cite the page number! Fvasconcellos (t·c) 13:07, 13 September 2008 (UTC)

Cultural references[edit]

I have added some Literary references to alkaloids as seen in some famous novels. I thought this would broaden this interesting topic. I hope no one has a problem with it being included. Please add more to it. Proquence (talk) 18:31, 22 November 2008 (UTC)


just raised the importance rating from mid to top.personally I don't know how anybody see this topic as mid importance!!! alkaloids are a major class in both pharmaceutical and phytochemistry that include very important drugs like morphine,quinidine and many others in a very long and ever expanding list. I am know jammed with exams so as soon as they are over I'll work on improving it--7amada'sback:) (talk) 17:59, 5 January 2009 (UTC)

Morphine etc., isoquinoline alkaloids[edit]

Morphine etc. is sometimes grouped with the benzylisoquinoline alkaloids because of its natural synthesis pathway. Morphine, codeine, thebaine, oripavine are however so different in structure from the other opium alkaloids, that they are usually grouped together as phenanthrene alkaloids. They are also pharmacologically different from the others (narcotine, papaverine...) in that they are opioid agonists, while the others are not. Looking at the structure, they are more related to each other than to narcotine etc. See entry "phenanthrene alkaloids" in the list (talk) 05:02, 21 September 2009 (UTC)

I find this distinction somewhat problematic. Clearly, the naturally occurring opium alkaloids are closely related by biosynthetic origin being all derived from L-tyrosine via L-DOPA and tyramine. Since even very slight variation in structure, eg. between isomers, can have drastic effects on biological activity, employing a distinguishing nomenclature based on receptor-binding activity is imprecise. There are several articles that group morphine with the benzylisoquinolines (see eg. here), as does the Morphine entry. I think one way to address this could be to tally up usage of benzylisoquinoline alkaloids vs phenanthrene alkaloids in the context of morphine and related compounds, and state the caveat that chemists, pharmacologists, and biochemists may use different nomenclatures. Otherwise I'd feel inclined to place morphine back (supported by the above reference). Many thanks! Malljaja (talk) 18:12, 21 September 2009 (UTC)

You will find that in pharmacological literature this distinction generally has been made, based on the high structural similarity and receptor action of morphine, codeine,thebaine, oripavine. They really make up a distinct group of substances. Your recent addition of classification and the reference supports a view where biosynthetic pathway, structural similarity and pharmacological action may be criteria in this highly complex question. Separation into the phenanthrene group would be supported by structural and pharmacological relation. (talk) 20:07, 22 September 2009 (UTC)

There needs to be a good and current reference for this. I'm not a chemist or pharmacologist, so I'm not privy to their preferred grouping. Ergo I have to take your word for it at this point. However, the distinction based on biological activity, while convenient, is somewhat questionable. By analogy, there are, e.g., isoflavones that interact with the estrogen receptor, but they are not steroidal compounds like estrogen, so no one with a biochemical/chemical background would lump the estrogenic isoflavones together with steroidal estrogens. So my feeling is that the phenanthrene grouping for morphine and structurally similar quinolines is outdated, since the common biosynthetic origin of all of the benzylisoquinolines is now well established. It is also seems slightly inaccurate in that phenanthrene is a tricyclic aromatic compound, whereas morphine is a tetracyclic one with only one aromatic ring. It would be advantageous to find a recent reference that discusses this, but it'll probably take some digging. Malljaja (talk) 20:35, 22 September 2009 (UTC)

Here a recent book source stating that e.g. morphine, codeine etc. contain a hydrophenanthrene nucleus, and that "these phenanthrene alkaloids" are derived from benzylisoquinoline intermediates in the biosynthesis.

page 252. Take a look. I am not making it up. (talk) 21:22, 22 September 2009 (UTC)

The isoflavones with estrogenic action are a false analogy. In the phenanthrene alkaloids we have a group of opium alkaloids, which are extremely closely related in structure, synthesis pathway AND pharmacological action, but quite distinct from the other opium alkaloids in structure, synthesis pathway AND pharmacological action. The isoflavones, in contrast, have no such close structural relation to the estrogens and no common biosynthetic pathway with the estrogens. There are also synthetic opioids, which have no close relation to the phenanthrene alkaloids, sometimes also called morphinans, and there are many synthetic opioids built around the morphinan skeleton. The structure-activity relationships of morphine like alkaloids and their synthetic derivatives are very well investigated for 100 years. Alone the importance of the morphinan backbone for semisynthetic and synthetic analgetic substances justifies grouping them from the other benzylisoquinoline alkaloids.See Morphinan (talk) 21:40, 22 September 2009 (UTC) (talk) 21:40, 22 September 2009 (UTC)

I by no means suggest that you have invented the classification of morphine as phenanthrene alkaloids. You misunderstood me—I am aware of this classification in some parts of the literature. What I am advocating is that the prevailing classification in the literature is stated with a proper reference (citation from a book or peer-reviewed publication). The reference you gave is a start, albeit the wording in it is rather woolly. The authors refer to the opium alkaloids as phenanthrene alkaloids. Though they also appear to state that the opium alkaloids are grouped in the benzylisoquinolines because of their biogenic origin, but this is unclear (they say "opium alkaloids are included in this group", and from the preceding sentence it appears that by "group" they mean the benzylisoquinolines). So this is not very useful, as it does not establish a clear hierarchy in nomenclature. Again, phenanthrene alkaloids strikes me as an outdated classification, based on structure and biological activity only, but having said that, I am well aware that this would also need a proper ref. Hence my earlier suggestion to scan the literature for the most common classification of the opium-type and other benzylisoquinoline alkaloids. Malljaja (talk) 22:06, 23 September 2009 (UTC)

To find the prevailing classification is probably beyond the scope of WP editing, as it would require a review of contemporary literature. Using an existing review would include the task, to find if this existing review came to the prevailing conclusion etc. At least the given reference is recent and it states the morphine and alike alkaloids as phenanthrene alkaloids and as derived from benzylisoquinoline by biosynthetic pathway. They are actually benzylisoquinoline alkaloids by biosynthesis, phenanthrene and morphinan alkaloids as a subgroup. The situation may be similar to the carboline alkaloids, which are also indole alkaloids. If this recent ref treats them as phenanthrene alkaloids, then I don't care if this is maybe a bit outdated. We don't need to know this better than they do. (talk) 22:38, 23 September 2009 (UTC)


Since when bufotenine is a poison? Tryptamines (talk) 09:34, 29 March 2012 (UTC)

It's found in the secretion of toads as well as a constituent in some plants, most likely as a defensive compound, ergo one that negatively affects those that try to eat its producer. It's LC50 is several 100 mg/kg in mice, which is relatively high, but it goes to show that it can kill mice with a greater potency than, say, sugar. So it stands to reason that it can be described as a poison. Malljaja (talk) 20:57, 29 March 2012 (UTC)
Well, sola dosis facit venenum. What about closely related psilocin - would you call it a poison, or rather a psychedelic drug? Though of course it can kill, if one takes enough. I'll change from 'poison' to 'alkaloid' - eventually this is what this article is on. ;) Tryptamines (talk) 05:04, 18 April 2012 (UTC)

Gross-out Pictures in Wiki Articles?[edit]

Is it necessary to have the picture of cyclopia in a sheep in this article? I'm sure I'm not the only person who doesn't like to see unexpected body horror in academic articles! Obviously, the story about the lambs receiving birth defects as a result of their mother eating the alkaloid is important - but does the picture need to be on this page? Is there some way in wiki markup to hide it, on the basis that it might be upsetting to some viewers, so you have to consciously click to see it? Baratron (talk) 00:43, 24 June 2014 (UTC)

There were general discussions elsewhere on how to hide potentially shocking images - I don't know the outcome. In general, wikipedia is not censored, meaning images that are needed to illustrate the concept should be included even if they might disturb someone. In this particular case, I think just saying "cyclopia" won't tell people how bad it is, and this is not sensationalism - up to 25% of lambs born by sheep that had grazed on corn lily had serious facial deformations. Materialscientist (talk) 00:55, 24 June 2014 (UTC)
WP:NOTCENSORED is a policy. It essentially forbids using "offensive" as the criterion for removal of encyclopediac images. DMacks (talk) 16:35, 28 July 2014 (UTC)
Agree completely. And what concept about alkaloids is "illustrated" by such a picture? None, really, except that they can have profound biological effects. This article isn't a forum to raise consciousness about the plight of sheep eating corn lilies. (talk) 16:15, 28 July 2014 (UTC)
The article is exactly to discuss various aspects of alkaloids, including their natural occurrence and diverse biological effects. DMacks (talk) 16:28, 28 July 2014 (UTC)

External links modified[edit]

Hello fellow Wikipedians,

I have just added archive links to one external link on Alkaloid. Please take a moment to review my edit. If necessary, add {{cbignore}} after the link to keep me from modifying it. Alternatively, you can add {{nobots|deny=InternetArchiveBot}} to keep me off the page altogether. I made the following changes:

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I changed the solubility description. was originally:

Caffeine,[156] cocaine,[157] codeine[158] and nicotine[159] are water-soluble (with a solubility of ≥1g/L), whereas others, including morphine[160] and yohimbine[161] are highly water-soluble (0.1–1 g/L).

Changed it to slightly and very slightly soluble in water (for the alkaloids, not the salts), corresponding to the Remington's table (, or

Descriptive term Volume (ml) of Solvent Needed to Dissolve 1g of Solute
Very soluble < 1
Freely soluble 1-10
Soluble 10-30
Sparingly soluble 30-100
Slightly soluble 100-1000
Very slightly soluble 1000-10,000
Practically insoluble or insoluble > 10,000

In a medical context these substances might be considered highly soluble by some ( for example: "Solubility is based on the highest-dose strength of an immediate release product. A drug is considered highly soluble when the highest dose strength is soluble in 250 mL or less of aqueous media over the pH range of 1 to 7.5."), but I doubt this definition is widely used (and is only useful for oral medication, you don't inject someone with 250 ml... ). Prevalence (talk) 15:17, 22 December 2015 (UTC)

Actions of Ergot Alkaloids?[edit]

The Actions of Ergot Alkaloids in the table under the Applications heading is completely false. Whether this is by accident or ignorance, it is very misleading and may undermine the credibility of Wikipedia.

Specifically, ergot alkaloids are seldom if ever "sympathomimetic". There are no ergot alkaloids listed within the article Sympathomimetics. Second, ergot alkaloids are predominantly vasoconstricting, not vasodialating. For example, Ergotism is a disease marked by acute and chronic vasoconstriction leading to dry gangrene and vascular dementia after consumption of the alkaloids of the ergot fungus. Third, ergot alkaloids, causing vasoconstriction, are not antihypertensive. The vasoconstriction they cause increases blood pressure directly.

I'll fix it myself in a few weeks if no-one can argue why I shouldn't. (talk) 18:58, 16 November 2017 (UTC)

Corrected content with information found on the topic's article Ergoline#Uses (talk) 15:19, 18 November 2017 (UTC)