Note: I considered putting this in the extractions section, but as this plant is not DMT containing nor even psychoactive. I figured I would put it in our main "garden" related section, though I suppose it may not even belong here, as it is a healing herb and not entheogenic. If it is ethnobotanical, it is probably Euro-Celtic.

Anyway, my new garden area is a wondrous place that had been overgrown for at least 15 years, but had been a healing garden for an oldschool curehouse for perhaps 90 years or more before that. As such, many of the wild plants it contains are actually quite useful. After beating back the giant blackberry vines and clearing some of the stinging nettles (I love nettles, so I won't be eradicating them)... The place literally exploded with giant and fast growing COMFREY.

Now, for those who don't know, Comfrey is a longstanding wonder herb of epic proportions. For skin, wound healing, bone fractures, tendon repair etc. etc. it can be unmatched in effectiveness. This is primarily due to the ingredient Alantoin. This chemical causes rapid cell repair and proliferation, and from my experience, can be magical in its ability to knit flesh and heal injuries.

Sadly, in recent years it has become clear that Comfrey also contains a number of hepatoxic alkaloids. Thus, its use internally has become ill-advised and even banned in many countries. The buggers responsible are pyrrolizidine alkaloids (PA's) and while we can handle them in small amounts, there is no good reason to ingest them if not absolutely necessary.

So... I guess you can see where this is going?

I need to find the best way to extract the good stuff (alantoin etc.) and remove the PA's. At the moment, I make simple salves, ointments, and lineaments from infusions, alcohol & vinegar based tinctures etc. Occasionally I will also eat the flowers as they appear to be rather low in PA's.

Anyone with knowledge about PA's and or Alantoin would be a godsend, but I imagine a number of you chem cats can come up with a simple extraction for me.

Thanks in advance.




PS I have heard anecdotal stories of comfrey concentrates being boiled with meat that had been cut into pieces and the pieces actually growing back together. While this seems extreme to me, I can say that it is rather good at knitting wounds and the plant is known as knitbone in healer circles. The extreme cell regeneration and proliferation ability of the plant has led some to caution that it could cause cancer or non-cancerous growths... though, it seems that the consensus among the research shows that it is pretty much only the PA's that pose health risks here.

Good to see you still around

Do you hace the name of the specific PAs that are found in it? I would search for these specific substances and "solubility" in google and google scholar, or find references that mention analysis of this plant, because often the analysis will say how the substances were extracted before analysing and give you hints (or direct info) how to separate them.

Maybe some chemist knows it off the top of his head, though, but im not one. If I were you, thats what I would do ^

Good luck!

Thx endlessness

Yeah, I figured something like that might work. Though, I have yet to find a complete list of the PA's in comfrey.

There are references to symphytine, and retronecine has been mentioned. I have a feeling that the solubility of the unsaturated PA's will be fairly similar as they all share the pyrrolizidine structure. It seems only the unsaturated PA's have been found toxic to the liver.

This is not just a problem limited to Comfrey. A number of otherwise amazing healing herbs have high levels of PA's including coltsfoot, borage, and a number of Chinese & Ayurvedic herbs. It is clear that most of these plants can be used without developing pyrrolizidine alkaloidosis... still, it would be nice to eliminate these PA's from our herbs.

According to wikipedia:

More than 660 PAs and PA N-oxides have been identified in over 6,000 plants, and about half of them exhibit hepatotoxicity. It has been estimated that 3% of the world’s flowering plants contain pyrrolizidine alkaloids. Honey can contain pyrrolizidine alkaloids, as can grains, milk, offal and eggs. To date, there is no international regulation of PAs in food, unlike those for herbs and medicines.

Maybe methanol works for Pyrrolizidine Alkaloids?

http://www.ncbi.nlm.nih.gov/pubmed/19836573

allantoin is freely soluble in basic aquous solutions.

http://new.orglist.net/archive/msg04252.html

Don't know if this helps....?

Thanks WingChun, I considered this, and will probably give it some more thought when I am not so ridiculously busy.

Obviously if methanol or another solvent can take on either the PA or the Alantoin without the other coming with, then this is a done deal. Concentrating the PAs, though, is absolutely what shouldn't happen.

Anyway, if anyone out there knows for sure if methanol will take up the Pyrrolizidine Alks while leaving the Alantoin in the aqueous solution let me know.

I second that

I thought we were going to have to send a search party into hyperspace to try and find you

Ha! No search team would ever find me...

Though I might enjoy being found by friendly schnapps keg carrying dogs next time I am out on one of those passes where the world stands still and the frozen ages of yore tumble down silent valleys sending cascades of fluffy potency all along their wake.

I'm interested in this. Does anyone know how or have a suggestion to separate unwanted PAs from beneficial Allantoin?

I got a nice big comfrey plant, but now I don't want to do a simple water decoction or alcohol tincture due to PA concerns. Want to use the plant for bone health. Thanks!

Its not advised to consume this plant or its alkaloids internally. However its fine to use it topically. I made a skin cream out of comfrey before to help with a swollen ankle. I used beexwax, soy lecithin, glycerin, borax and water to make the skin cream. Its tricky to get the ingredients right to avoid phase separation but doable. You don't need to extract or concentrate the alkaloids to do this. Just the whole plant. The alkaloids will extract out into the ingredients used. Of course you can make a crude extract to make infusion easier but seems like more hassle then its worth.

High burnt, cool to get an answer from you here. I've read a lot of your posts.

You are right about comfrey, but isn't the reason it is not advised to consume due to the PAs? If we can remove those and leave the the allantonin (and other plant stuff, the moar the better) then, in theory, we can get internal benefits. Before the PA issue caused concerns there was a history of internal use as I understand things.

Topical preparations are great and safe like you mention. In my case I want to get to an old broken clavicle that is making creaky noises sometimes. I'm wondering if I would get better results if I could get the comfrey internally, sans the PAs (unless I'm wrong and there are other concerns).

Hi Loveall,

My apologies if I misunderstood but yes your right the issue with comfrey is the PA's and their effect on I believe the liver when taken internally. I always thought the main inflammatory effects of comfrey were due to the PA's.

Allantoin is also found in comfrey. It also happens to be found in various species of animals urine. So there might lie another source (just kidding but its true).
Its used in a lot of cosmetic and dental products.

If you want to consume allantoin though I think you can just buy it in bulk online? Separating PA's from this component if not done properly could cause you to accidentally ingest PA's unless you had some way to really verify they aren't present.

As I understand it:

Some comfrey is low in PA's - regions where internal use of comfrey was more commonplace probably had this variety, but now that higher PA Russian comfrey is much more widespread the pyrrolizidine alkaloids have become more of a problem.

Russian comfrey hybridises freely with the low-alkaloid variety to produce specimens of intermediate alkaloidal content which are very hard to discriminate from the original, low-alkaloid comfrey.

And it's the pyrrolizidine alkaloids of the retronecine type that present the main toxicity hazard. If one were to find an easy way of testing for this, that would surely be helpful.

Thanks for the info and ideas guys.

Burnt, good suggestion on simply looking for the commercial isolate. As you may already know, turns out there is a comfrey substitute for sale:



Seems safe and straightforward, worth a try

The whole plant minus PAs by a targetted extraction, or minimun PAs by using the right cultivar as downwardsfromzero mentioned, seem out of reach at this time. I'll just have to be happy by limiting miself to only looking at the comfrey plant growing in my garden.

This is good advice. Looking at this, PAs seem very water soluble when in salt form at low pH (charge +1 from a proton on the tertiary amine). Unfortunately allantoins are slightly soluble in water (~0.5% seems low but maybe too much for effective separation) and soluble in NaOH (as wingchun mentioned already).

The paper that wingchun mentioned for PAs used methanol and water in the abstract, so it is not clear what pure methanol would do for PAs, but it is reported in pubchem that allantoin is insoluble in methanol.

Attached is the chemaxon predictions for logS vs pH. The molecules not labeled allantoin are both representative PAs.

The partition coefficients are also attached. Even though there is a delta, unfortunately, both compounds seem to want to stay in the water in the basic chemaxon calculation since log D <0. This is of course, for octanol, if allantoin is soluble in a different non-polar in-miscible solvent we may be in business.

There does seem to be a temperature dependence for Allantoin solubility in water (factor of 8x higher at 75C vs 25C). Maybe rinsing the comfrey with cold acidic water would remove most of the PAs and leave Allantoin? Then, extract with basic water. Can dry that and rinse again with cold acidic water (or pure methanol?), etc.

Please no one assume the above is right or a final proposed way to do this. It could very well fail. Would need to run some tests followed by analytical test, etc.

The PA scare was way overblown/hyped in the late '80's/early 90's, I remember well...I was running a small medical herb consulting business and managing a huge health food store in Fairbanks, AK at the time (which, BTW, was voted "most psychedelic city" in High Times magazine at the time back then, lol)...

I also became dear friends around the same time with Ed Smith, owner & co-founder of Herb Pharm, one of the first and best medicinal herbal tincture companies here in the States.

What I learned from him at the time was:

1) The PA scare was overblown. People had been using Symphytum officinale for centuries, if not millennia, before some lab rats were stuffed with enough comfrey to kill a cow and all of a sudden comfrey was the new "devil herb" to hate for a while. There always is a "devil herb" to hate for the gullible public, since the pharmaceutical corps don't like anyone finding out anything about traditional medicines that really do remarkable things.

2) The pyrrolizidine alkaloids in Symphytum officinale are found in the highest concentration in the root portion of the plant, much lesser in the leaves (and flowers) and the leaves alone can be fairly potent medicine on their own.

3) The higher the level of nitrogen present in the growth medium in which a given comfrey plant grows, the higher the corresponding levels of PA in the plant.

4) Around that same time Ed Smith at Herb Pharm figured out a way to remove the pyrrolizidine alkaloids from their comfrey tincture and they still sell it today if I am not mistaken (I don't buy or sell that one any more since I grow all my own comfrey nowadays and create my own extracts and salves with it; and no, I do not worry about PA levels because I am not consuming it in large quantities over long periods of time; it is not an herb that is meant to be taken that way anyway). He would not share the exact method of just how his company removed the PA's from their comfrey tincture, but all their products are simple alcohol/water tinctures and extracts, so it can't be that difficult to achieve.

5) Making a giant comfrey tea in a five gallon bucket for your garden is one of the best gardening secrets ever!!!

I hope this helps a little....

Thanks doc. That helps. So a simple leaf tea would suffice, right? What dose would you use? About 3g of dry leaves? Boiling water or just hot water?

From the earlier posts I think a cold pre-rinse in lemon water may remove a lot of PAs. While this may not be needed it should reduce them. Then when making the tea some baking soda may help eliminate the effect of any residual lemon when brewing the tea and help the good stuff come out.

I'm trying to build a Raman spectrometer. If I ever get that to work (a big if) I'll check if the cold acidic pre-rinse is effective.

Yes, absolutely.




3-9 grams, standard infusion method.



For those unfamiliar with the standard infusion method, it's the same as when you make a cup of tea with a tea bag, i.e. boil water, pour over herb, let steep for several minutes and cool a bit. Boom, you're set to go (some folks prefer one final step of straining the infusion if they're using loose-leaf tea/herbs as to not get plant matter stuck in their teeth ).

+1.

The smell it makes won't be very secret!

So true!!!

That's why I use a bucket with a lid and put it on pretty tightly...

The first time I ever did this it was without a lid on the bucket and my wife was like, "what the hell is that smell!!??" After I explained what it was, she came up with the lid idea.

What I have discovered over the years of doing this though is that after many months of steeping, the smell finally goes away and you can use it without the nasty odor.

So now I will generally make a bucket or two of comfrey tea for the gardens about 6 months before hand, keep it covered with a lid and, lo & behold, after that long of time I can use it all over the property without anyone smelling anything unpleasant.