elvisd - 1-3-2009 at 05:56
My kids and I have been working with extracts from willow bark to propagate a number of plants: rosemary, blueberry, button bush, etc. Willow
contains salicylic acid, which is thought to help heal a plant cutting, as well as the auxin IAA. Some sources say that Indole butyric acid (IBA) is
found naturally in the bark, others say not. Does anyone know for sure?
We took cheap vodka and soaked the bark overnight for our extract. I since have read that an alcohol of at least 70% is needed, but so far in
numerous trials, there is better rooting in cuttings that have been dipped for a few seconds, then put in pots with soil or for several weeks in
water. The results are pretty consistant after hundreds of cuttings. I've seen a few references that say that there may be symbiotic effects between
the IAA and salicylic acid (and/or IBA, if it is in the bark).
What we're wanting to do is to find out if these compounds are definitely in the extract to begin with, and if so, what are the concentrations we're
getting. I'm no chemist (although I'm in night classes now to learn), so I've asked some people. I've had photospectometry suggested, but that seems
to be pretty expensive, from what I've gathered in a couple of calls to labs. Is there a way we can isolate these compounds from the alcohol, I guess
in a manner that would render them solids? The kids have had such great results so far, we'd love to be able to document some accuracy as we move
along further (other high schoolers will continue the work).
sparkgap - 1-3-2009 at 06:34
Well, salicylic acid per se isn't in willow bark; rather it's the glycoside salicin. I suppose something during the extraction and
introduction to the plant hydrolyzes the salicin to salicyl alcohol (which is subsequently oxidized to salicylic acid).
sparky (~_~)
P.S. Thanks n_i for refreshing me as well.
[Edited on 2-3-2009 by sparkgap]
not_important - 1-3-2009 at 08:58
Most of the plant hormons are present in the parts per million range, say 100 ppm (1 in 10 thousand) on down to a fractional ppm. These would be
difficult to isolate at most home labs, and/or take a lot of raw material.
Salicin is present in a bit higher concentrations, as high as a percent or so; there are also several related compounds and a trace of salicylic acid
itself. Salicin is a glycoside of o-hydroxybenzyl alcohol, which is metabolised to o-hydroxybenzoic acid.
Oil of wintergreen is methyl salicilate, if the wintergreen plant grows in your area that might be a better route. Steam distillation can be used to
isolate the ester, the hydrolisys with a base would give the salt of salicylic acid.
http://en.wikipedia.org/wiki/Salicin
http://www.bluestem.ca/willow-article1.htm
natural hormones
elvisd - 1-3-2009 at 19:11
Thanks for the replies. I know wintergreen pretty well. I'll look into that. I have a friend who might be able to help me with your distillation
suggestion.
If anyone has info on IBA or IAA. I'd seen the link
http://www.bluestem.ca/willow-article1.htm before, and it makes it seem that IBA does occur in the willow. Some other sources, which I can't
call up right now, say not. Would a steam distillation metjhod of some sort work on the IBA or IAA? We've got more willow than we know what to do
with! LOL
kclo4 - 1-3-2009 at 19:35
You could hydrolyze aspirin to get salicylic acid. I think other chemicals in the willow is helping more so then the salicylic acid. either way I am
interested to hear more about this!
not_important - 2-3-2009 at 06:16
IBA and IAA have high boiing points, steam distillation might remove them from the base plant matter but a lot of other stuff is going to come over
too.
You are dealing with compounds present in less than 1 part per thousand on down to a few parts per million. I think that chromatographic be the other
method to isolate them, and even then only in fractions of a gram from many kg of plant material.
'preciate it
elvisd - 2-3-2009 at 10:28
Thanks for the help, all of you. I'll see what I can do with this info. We're having a lot of fun with this! (And making money-we've had a
successful fundraiser selling what we've propagated. Whether we can really establish that our hypothesis is correct, we've had great success with
these extracts, and plan to keep going and refining our work. )
I'll post any new developments that might interest.
Ebao-lu - 6-3-2009 at 13:38
Thanks for the info you provided that willow extract can help with cuttings enrooting. Most chemicals sold for this purpose are practically useless.
IAA and IBA do work only with limited range of plants, that even can sprout roots without any help, just more time is needed. As for shrubs and trees,
i generally got poor results with them and IAA/IBA. There is a proverb in my country, that is translated like: A cured running nose is thrown off
after a week, and uncured - after 7 days.
I'm sure willow extract if it works like you have described, can not be replaced with any chemicals, solids etc. Why not to store 70% alcoholic
extract just like that?
As for analysis of IAA/IBA and salicylic acid, you dont need the quantitative analysis right?
Then for salycilic acid you can do the coloring with CuSO4 (green color), and Fe3+(violet, that becomes brown if sodium acetate is added). But Fe3+ is
not selective to salycilic acid, other phenols would give same reaction. So use all 3 tests (with CuSO4, Fe3+, Fe3+ and CH3COONa) to be more sure it
is SA. The only thing is you need your solution to be colourless. Evaporate ethanol extract and add water(bit basified) to dissolve SA. If it would
be brown, add some activated charcoal to clear it.
For IAA/IBA you can use Erlich's reagent that will give purple/violet colour with indoles(all indoles).
But if you use TLC(thin layer chromatography) you can separate the indoles and analyse IAA and IBA separately (as well as salycilic acid separately
from other phenols). TLC analysis is possible to do at home also, you need only chromatography plates and some solvents. Or ask your chemists to
analyse the extract with HPLC or some other method. (HPLC probably will show all the compounds of your extract without any special treatment before
analysis)
[Edited on 6-3-2009 by Ebao-lu]
[Edited on 6-3-2009 by Ebao-lu]