Sciencemadness Discussion Board

Extraction of Resveratrol from Japanese Knot-weed

smaerd - 28-2-2010 at 16:31

So as a hobbyist chemist, and broke student, extractions seem like fun! Don't have to pay for the source if it can be identified accurately.

I am either fortunate or completely unfortunate because my front yard has a massive abundance of Japanese Knotweed. Which contains the "phytoalexin", resveratrol.

Whether resveratrol is as magic as it's advertised or not is irrelevant too me. I simply want to extract it! Like I said before I am a noob, but I do know a little about extractions in general, and general extraction techniques.

I do have a few questions however about phytoalexins. Can they be salted, and freebased like alkaloids? Meaning could I use acetic acid to create the salt resveratrol acetate(making it more polar to do pulls with a non-polar solvent to remove fats, etc)?

I have found only anecdotal documentation that it is found in the roots of Japanese Knot-weed? I'm struggling to find information beyond ambiguous marketing articles, on weather it is inside of the shoots and/or leaves.

the LogP is 3.1, so a suitable solvent won't be hard to find to pull it. I'd imagine ethanol or xylene would do just fine.

Luckily I have a chromatography column, so if I can get it to a relatively pure mixture I can separate it the rest of the way.

So far for the procedure out-line this is all I have:
- Harvest plant including the roots. Clean the roots with water.
- Freeze roots, then thaw to lyse the material.
- Macerate into as fine of a powder or finely chopped material possible.

I don't want to assume anything just yet without more information. So any idea's, articles, inputs, advice, or experience would be much appreciated!

If these questions were asked improperly, I apologize in advance, due to my noob nature.


[Edited on 1-3-2010 by smaerd]

smaerd - 28-2-2010 at 16:37

Well I just found this and this helps a bit:
Quote:
In the typical extraction process, Japanese knotweed roots are sliced before being heated up in large metal chambers known as extractors. The plants are first tested to prevent contamination with heavy metals or chemicals. Ethanol or methanol is used as a solvent to separate the resveratrol from the plant tissue, resulting in a crude liquid extract. The separated resveratrol extract is processed further by being run over a column of silica under high pressure, or by various other methods. It is then vacuum-dried to remove the solvent and produce resveratrol powder, which in turn is combined with fillers such as rice flour or hydroxypropylcellulose to manufacture pills and capsules.
- http://ezinearticles.com/?How-to-Extract-Resveratrol&id=...

So it seems like I had a decent idea of how to do it already. A soxhelet would probably come in handy, but with my budget that is out of the question so I'll have to figure out an alternative way to get good efficiency with my solvent.

edit - I just need to find out a good binary solvent system for the separation of resveratrol and what ever else is in there.

[Edited on 1-3-2010 by smaerd]

Sandmeyer - 28-2-2010 at 17:12

Quote: Originally posted by smaerd  

I do have a few questions however about phytoalexins. Can they be salted, and freebased like alkaloids? Meaning could I use acetic acid to create the salt resveratrol acetate(making it more polar to do pulls with a non-polar solvent to remove fats, etc)?


Well, there is no nitrogen there (as there is with alkaloids), you can not add a conventional acid to make a salt, but in case of resveratrol, you can use weak base to turn it into a salt since it is a phenol, anyway there is no need to make salts. There is at least one paper describing the resveratrol extraction: http://dx.doi.org/ then put: doi:10.1016/j.jfoodeng.2005.06.076 I have not read the paper but there should be some useful references within it. In the abstract it is mentioned "conventional solvent extraction with ethanol/water (80:20%, v/v) maintained at 60 °C for 30 min".

smaerd - 28-2-2010 at 17:21

Thank you very much. When spring rolls around I'll be sure to document it and post back! I am just gathering as much information as I can before the time comes around. That way I'm not clueless and make no hasty decision.

Learning new things every day, and every post :).

Eclectic - 28-2-2010 at 21:22

you may wish to try 70% isopropanol as initial extraction solvent in blender....then add salt to separate water from alcohol layer.

watson.fawkes - 1-3-2010 at 05:14

Quote: Originally posted by smaerd  
So it seems like I had a decent idea of how to do it already. A soxhelet would probably come in handy, but with my budget that is out of the question so I'll have to figure out an alternative way to get good efficiency with my solvent.
I don't see any particular reason you couldn't use a home-built metal Soxhelet apparatus brazed up out of mild steel parts and copper tubing. These materials seems to be used all the time for steam distillation of botanicals. Now I don't know your fabrication skill, but this is on the lower end of cost of materials and tools. You can do it with a propane-air torch, in particular.

starman - 1-3-2010 at 14:41

As a resorcinol derivative I would bet it has excellent solubility in acetone or ethyl acetate.As Sandmyer indicated these compounds can be isolated with dilute (3-5%) aqueous NaOH.Washed with Na bicarbonate and Na carbonate to remove non phenolics and then usually vacuum distilled or chromatographed or both.
Working with natural products usually yeilds all kinds of surprises and headaches and certainly is a learning experience.Good luck with your project.

Sandmeyer - 1-3-2010 at 15:47

Quote: Originally posted by starman  
As a resorcinol derivative I would bet it has excellent solubility in acetone or ethyl acetate.As Sandmyer indicated these compounds can be isolated with dilute (3-5%) aqueous NaOH.Washed with Na bicarbonate and Na carbonate to remove non phenolics and then usually vacuum distilled or chromatographed or both.
Working with natural products usually yeilds all kinds of surprises and headaches and certainly is a learning experience.Good luck with your project.


You can not first extract a phenol with dil. NaOH into aq. phase and then wash the aq. phase with aq. carbonate solution, you must first read for instance Moody http://www.organic-chemistry.org/books/reviews/0632048190.sh... or Vogel or on the Internet the principles of acid base extraction. There is a visual flow chart that you might find useful to understand how it works (link: http://www2.thu.edu.tw/~orglab/Txt-1/lab04.files/image003.gi...):
:)


[Edited on 2-3-2010 by Sandmeyer]

smaerd - 1-3-2010 at 18:35

Wow thanks! NaOH is something I keep on stock at all times. It's good for cleaning beakers/test-tubes when lightly heated. HCL is of course a given.

I'll probably use ethyl acetate to pull from the root first, then worry about seperations of other constituents of the roots. Hopefully there isn't too much going on in there, but either way it'll be good practice, certainly.

UnintentionalChaos - 1-3-2010 at 18:37

I know this topic is intended to be about extraction of resveratrol, but you can eat the knotweed too, while it's still small and unbranched. A bit of googling will turn up recipes. It makes an excellent substitute for rhubarb, but is a bit strong for a 1:1 substitution.

Relevant to extraction:
I wonder at what point in the year resveratrol concentrations reach a maximum. I suspect there is literature out there somewhere on this, and it's probably worth looking into.

starman - 1-3-2010 at 22:51

Naturally the phase is acidified and substrate taken up in an immiscible solvent prior to the wash.Perhaps my level of assumed knowledge of the originator was to high.Geez.