The colour of alkaloids

[Torsten]

There is a discussion on EA about the colour of harmala alkaloids.

http://www.ethnobotany-australia.net/forum...7d18681cf291bdc

Extensive theories have been provided that alkaloids of the harmala group must be colourless for various physical reasons. However there was no need to reinvent the wheel as the Merck Index has some interesting details on this topic:

Harmaline base solutions fluoresce blue.

Harmaline HCl dihydrate is yellow needles.

Harmalol base trihydrate - red needles, or in aqueous solution yellow with green fluorescence.

Harmalol lactate monohydrate - bright yellow.

Harman base bright blue fluorescence in UV.

Harmine HCl dihydrate - blue fluorescence in aqueous solution

I am not saying that the actual dye effect is caused by the alkaloids (although it might be), but anyone who has seen these or similar alkaloids in solution would have marvelled at their beauty. When I first extracted some yohimbine about 8 years ago, I was startled by the intense yellow fluorescence it provided in solution. This was a tiny amount equivalent to merely a few doses (total of 300mg), but it coloured a solution of almost a liter. And under a normal office neon tube it looked like a rave-toy under blacklight.

[eccles]

Excellent information.

nice to see that someone has had some sleep and could be bothered doing the actual research instead of making wild speculations

thanks Torsten.

[eccles]

RE the Harmaline base Torsten, does that only flouresce under UV light? (like the harman base)?

So the salt is coloured then... different salts could well be different coloured.

And depending on the waters of crystallisation you get different coloured crystals. now that didn't even occur to me.

Is harmalol an alkaloid?

And what is the deal with the glycoside you mentioned? (ie hamalol lactate).

Which ones of these are active Torsten?

and which would be present in an alkaloid extract?

I imagine only Harmine and perhaps Harman salts, yes?

so any crystalline product (assuming you are isolating the salt in the extraction and not the base) will be yellow?

That seems to be confirmed by what people have said... but it doesn't answer the question of where the deep red colour might come from, unless it is the crystalline harmalol base... and yet it is not red in solution.

Hehehe again I wish I had the stamina to actually try researching this... maybe some other time.

[Auxin]

"Is harmalol an alkaloid?

And what is the deal with the glycoside you mentioned? (ie hamalol lactate)."

Harmalol is an alkaloid.

Harmalol lactate is not a glycoside, its a simple salt of harmalol and lactic acid

"Which ones of these are active Torsten?

and which would be present in an alkaloid extract?"

All of those are active to varying degrees and all of them are in any extract that isolates all alkaloids. Harmalol and (presumably) all other phenolic harmala alkaloids are bad for you.

[Torsten]

Originally posted by eccles:

RE the Harmaline base Torsten, does that only flouresce under UV light? (like the harman base)?

I never actually worked with harmaline base (details from merck), but have seen the crystals as a freebase. They are very bright yellow - the sort of bright colour that suggests fluorescence (like rave shirts still look extraordinarily bright even if there is no blacklight around ). The HCl crystals are a duller yellow. I saw them next to each other and the difference was striking.

So the salt is coloured then... different salts could well be different coloured.

Yes, I would think this is definitely possible.

Is harmalol an alkaloid?

And what is the deal with the glycoside you mentioned? (ie hamalol lactate).

I would not have put them there if they weren't alkaloids

Which ones of these are active Torsten?

and which would be present in an alkaloid extract?

I imagine only Harmine and perhaps Harman salts, yes?

The salting technique apparently is specific for harmaline and harmine, so it may leave the others in solution. Maybe they were simply ignored in the study. Harmine and harmaline are by far the most potent MAOIs I believe.

so any crystalline product (assuming you are isolating the salt in the extraction and not the base) will be yellow?

Apparently that is how you can tell the quality of your workup.

That seems to be confirmed by what people have said... but it doesn't answer the question of where the deep red colour might come from, unless it is the crystalline harmalol base... and yet it is not red in solution.

Actually, been thinking about this too, and the deep colour would not be due to these alkaloids above. however, I have seen that the extracted solution is no longer the vibrant red, but rather a dull brown/red. I feel that the alkaloids are at least partly responsible for lending the crude seed solution the vibrant red colour. Probably a combination of the brown/red and fluoro yellow.

[Torsten]

I don't have the ref, but McLean & Ivimey-Cook W R (1956) Textbook of theorical botany, Ed.Longmans, Green and co.,Vol.2, pp 1824 apparently discusses the name "Turkey red".

[planthelper]

in this field i am a beginner but, how about a guess than...

and i guess those colors are produced the same way as the opals get there color.

the molekules(that make the crystals)are layered in different bandwiths,

i dont know now if red is wide and blue narrow or reverse but do you understand me?

[eccles]

um... in things like opals and other gems, you DO get it like that... but that is due to the presence of transition elements and co-ordination bonding... (I think!).

In organic molecules it is due to the degree of freedom of electrons, and the way that increases and decreases is with the level of conjugation and aromaticity.

[eccles]

thanks for all that info Torsten

I really do have a long way to go wrt chemistry knowledge... but that's ok I guess we all have to start somewhere

(and thanks for pointing out my innacuracies Auxin).

[Auxin]

I tried to post this at EA but now I cant post there at all, so I'll put it here. Wira just gave a list of P. harmala seed constituents including quercetin, kaempferol and peganetin (flavonoids), so I tried to say:

 

quote:

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"quinones are known to be pigments."- wira

 

As are flavonoids. Thanks for listing the flavonoids, I was gonna propose them earlier but wasnt sure which ones were there and if there was even enough to be worth mentioning. The flavonoids themselves are most often used as yellow dyes, but they can easily be converted to flavylinium compounds like anthocyanin- thats the stuff that makes flowers and hot/sweet peppers pink, red, blue, or purple depending on concentration and pH. So the dye could be flavylinium based and then maby the fabric is mordanted (probably with a metal salt) to form a insoluble flavylinium lake when the dye is added.

 

Does anybody here have some of this dye?

 

If its anthocyanin or a close relative thereof it should turn from red to blue when the pH goes from acidic to basic.

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There, now I didnt type all that for nothing.

and eccles, you gotta fix that invalid session thing. I cant post, log out, edit my profile, nothing!

[woof woof woof]

pretty colors! :D