cerberus1983
Harmless
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Registered: 20-5-2007
Location: South Africa
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How would one remove the dangerous alkaloids from comfrey?
Id like to know which of the following methods would be the most effective in removing the bad alkaloids from comfrey in order to minimise the dangers
involved in its use.
1) soaking in warm 100% methanol
2) soaking in a methanol/aqueous mixture (50/50)
3) soaking in warm acidified methanol (using citric acid to acidify)
4) soaking in warm acidified methanol/aqueous mixture (50/50)
5) soaking in warm 100% ethanol
6) soaking in acidified 100% ethanol (using citric acid to acidify)
...or would there have to be more too it?
thanks guys
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not_important
International Hazard
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Registered: 21-7-2006
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The best way to minimise the dangers of comfrey is not to use it.
To answer your question you would have to specify what is present in comfrey that you wish to use, so as to be able to determine a possible
separation. Aqueous solvent mixes are likely to extract some of the main supposedly beneficial components of comfrey - allantoin, tannins, and
complex carbohydrates.
Use of technical grade solvents would seem to have the possibility of introducing unwanted substances. Failure to remove all of the methanol from the
extracted materials would also appear to be a potential problem.
It is doubtful a simple extraction would accomplish what you want. especially given the relatively small amounts of some of the pyrrolizidine
alkaloids that can cause harm. I suspect that treating a full extract with an acidic ion exchange resin would remove much of the alkaloids of all
types present, but perhaps not enough - testing would have to be done. It also could affect some of the other substances present in the extract,
especially on prolonged contact.
The most likely way to get the results you want is to find alternative sources of the substances you're after, ones that are safe for internal use,
and use them instead.
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Sauron
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Location: Barad-Dur, Mordor
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The alkaloids you refer to are pyrrolizidines and are hepatotixins, i.e., liver poisons. But there are also non-hepatotoxic alkaloids present in
comfrey, and unless you are sure they have no role in comfrey's benefits this might complicate any removal of the toxic principles.
It is not necessary to remove anything from comfrey to use it externally. Internal use is ill advised to day the least.
I would think a complex and expensive HPLC seperation would be required. Do you have any quantified toxicity data, that could be used to establish the
extent to which the toxic principles need to be removed? 90% removal, 99% removal, 99.99% removal? These impact on cost.
Ethanol would be a much more pharmacologically acceptable solvent than would methanol. USP or BP grade not technical, not denatured and not anhydrous
(which contains traces of benzene.)
Sic gorgeamus a los subjectatus nunc.
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not_important
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Proposed limits on pyrrolizidine alkaloids are fairly tight, as low as 1 ppm, some are know to exhibit toxic effects at a few milligrams/day intake
with the more toxic ones causing damage when 10 micrograms or even less are consumed daily on a long term basis. Comfrey has them present in the ppt
range ( 0,1 to 0,5 % is often given), getting the alkaloid level down to what appears to be acceptable would be seem to be difficult by any simple
method.
a short write-ip on pyrrolizidine alkaloids
http://www.itmonline.org/arts/pas.htm
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Sauron
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I agree with n_i. just do not use comfrey.
Sic gorgeamus a los subjectatus nunc.
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