A question about alkaloids

[Anonymous]

This may be a simple question, or it may be impossible to answer accurately; I've heard conflicting things.

In general, do alkaloids exist as organic acid salts when they are in the bearing plants, or do they exist in freebase form? Does it vary from plant to plant?

For the most part I've seen it claimed that they exist as acid salts (and I believe this to be true), but on the other hand I've seen some claim that freebase forms are common in nature.

Knowledgeable guidance appreciated!

[Guest electro]

it varies from plant to plant, and even within plants themselves ...

it is why people add generally acid first before defatting (if acid first otherwise reverse) in a/b extractions.

it is to ensure that all the alkaloid is in its salt form rather than its freebase or a mixture of both.

[Torsten]

sorry electro, but it doesn't vary all that much. There are very few plants that have alkaloids in their freebase form. In fact none of the common ones we talk about.

The reason why we use acids to extract is to make them more soluble. Citrates, acetates and hydrochlorides are generally more soluble than the salts of weaker acids such as malates, oxalates, ascorbates etc which often predominate in the plant. Also, salts are usually more soluble in acidic water than in neutral water.

[Guest electro]

wow, i stand corrected ....

i was sure i remembered an old post (like 2yrs plus) here with someone referring to an "active ingredient" occuring naturally as a freebase aswell as a weak salt, cant find the thread tho.

edit - lol found the post and sure enough torsten has stated there that generally alkaloids are present as salts..

------------------------------------------

sorry for giving out mis information ....

[ 21. July 2004, 21:39: Message edited by: electro ]

[Torsten]

I stand corrected - by myself .

In that oldpost I overestimated the effect of plant alkalinity. I think we can safely assume that in most plants all alkaloids are present as salts. There *may* be some very alkaline plants where alkaloids are present as freebases and I would presume these use latex to transport the bases. I think if this is in fact the case, then it would apply to VERY few plants and is a mute point for the species generally discussed here.

Let's just assume in general discussion that the alkaloids are present as salts.

[Rev]

As salts of weak acids maybe they exist also in some forms as freebases in some circumstances

Salts when stored in the vacuoles

but maybe freebases or conjugated in some way to a non-polar carrier when moving through cell walls or other functions

For example how does an alkaloid as a salt move from one part of the plant via aqueous solution to another.

Wouldnt the concentration gradient case dispersion throughout the whole watery network?

It seems like itd be better to load it into carriers and transport it that way - then change it back to a salt in the target tissues when trapped again within the lipid layer of the cell

[Anonymous]

Thanks everyone!

I read in another forum that while alkaloids are often freebase, that any processing of the plant material will result in them forming conjugates with the organic acids present.

Torsten, you say that none of the common plants have their alkaloids in freebase form, but I've heard tell several times that the common fungi do. Any idea of this is true? The context was the extraction of alkaloids via ethanoloic means, forming a mixture of precipitates including "freebase alkaloids."

Edit: for poor typing skills

[ 24. July 2004, 00:59: Message edited by: Anonymous ]

[Torsten]

Hofmann's original shroom extraction recipe seems to work on the basis that the alkaloids in shrooms are present as bases.

However, I have always wondered how much truth is in the psilocybin vs psilocin ratio analyses. Maybe shrooms transport all their psilocin as the much more polar phosphoryl ester psilocybin and the psilocin is an artefact of the extraction method. In effect then shrooms have overcome the polarity issue by making esters rather than salts, which is kinda the same thing. Anyone aware of any studies dealing with this issue?

Not sure what the pH is of shrooms, but I know that most don't tolerate acid conditions, so I presume they are somewhat alkaline themselves.

[John_Barleycorn]

Bear in mind that not all alkaloid bases are completely insoluble in water. We've had this discussion a couple of times before, but morphine, caffeine and mescaline spring to mind as examples. Plants clearly comprise a number of non-polar substances like lipids, terpenes, etc, and those substances are clearly mobile, so a precedent exists there. The transport could involve chemical transformations into more polar substances, it could involve use of natural emulsifiers, and a variety of other strategies.

Some substances most definitely are liable to give chromotography artefacts, and thus need to be analysed carefully. Hydrolysis of esters, amides, glycosides, etc, is one obvious potential confounding factor; oxidation is another.

[Auxin]

There are indeed plants with freebase alkaloids present in notable quantity- not because of plant tissue alkalinity but because of the alkaloids in most of those cases being very weak bases. In a cup of coffee for example, there are free acids but most of the caffeine is freebased at any given moment because of its mildly basic properties. If you dissolve caffeine cirtate, benzoate, or acetate in water you'll get a solution of the freebase alkaloid and the free acid.

But still generally people use vast quantities of acids needlessly- like those funny poppy folks, for example, who add 10 grams citric acid to a decoction of 10 poppy pods lol (morphine is in the pods as the water soluable meconate and citrate salts).

[Torsten]

thanks for clearing that up auxin!!