Nitrovolt - 29-12-2012 at 12:15
From Wikipedia:
Ginkgolides are biologically active terpenic lactones present in Ginkgo biloba. They are diterpenoids with 20-carbon skeletons, which are
biosynthesized from geranylgeranyl pyrophosphate
There are 5 types of different ginkgolides: A, B, C, J and ginkgolide M. According to medical investigations Gingkolide B may be effective as
preventive treatment in reducing migraine attack frequency
Does anyone know the isolation of ginkgolides from Ginkgo Biloba leaves?
[Edited on 29-12-2012 by Nitrovolt]
chemrox - 29-12-2012 at 12:54
I think I've scrolled past some papers on the subject in the J Nat Products and J Med Chem. I would do an all journals search at ACS. If you find
some papers there are folks here who can help you get copies. I would start thinking from, "terpenic lactones" and "diterpenoids ..."If you take away
acid extractables and base extractables you will have the neutral extracts left which is where I think you will find your terpenes, terpenoids,
lactones, etc.
kavu - 29-12-2012 at 13:17
I did some reading on the subject a few weeks back. I ran into this remarkably simple isolation in J. Nat. Prod., 2002, 65 (10), pp 1501–1504:
"The leaves were collected from a female G. biloba tree in Morningside Park, New York, NY. The yellow fallen leaves were collected from the ground in
November 2000, while green leaves were collected from the tree in June 2001. They were frozen in liquid nitrogen, crushed, and lyophilized until
constant weight.
Lyophilized leaves (250 g) were boiled for 1 h in 2 L of 5% aqueous H2O2 (or other oxidation reagents in water). After passing boiling solution
through a Buchner funnel without filter paper, the remaining solution was extracted up to three times with EtOAc (250/125/75 mL). The organic layer
was washed with a saturated aqueous salt solution (NaHCO3/Na2S2O3, NaHCO3/Na2SO3, or Na2SO3) followed by water and 80% aqueous NaCl (saturated aqueous
solution diluted to 80%). After drying over Na2SO4, solvent was removed to yield an amorphous yellow powder with 50−60% terpene trilactone
content.
For further purification these extracts were dissolved in EtOAc and passed through an activated charcoal column. Concentration gave an off-white
amorphous powder with 60−70% content of terpene trilactones. A more rigorous procedure involved dissolving the extracts in MeOH, adding
activated charcoal, and filtering over Celite 545."
Further purification was done with prep HPLC (might not be found in an average home lab), but a TLC method for purification was also referred. Sodium
acetate impregnated silica gel plates with ethyl acetate: hexane (9:1) proved to give good separation. This should also provide some insight with your
solvent system if you want to run a column.
[Edited on 29-12-2012 by kavu]
chemrox - 29-12-2012 at 15:18
Thanks Kavu, just the kind of thing I had in mind and here it is.
Attachment: np0201974.efficient extraction of Ginkolides.pdf (193kB)
This file has been downloaded 1189 times
BlackDragon2712 - 18-3-2013 at 17:07
Extract it first with ethanol, dimethyl sulfoxide will work even better, to ensure a maximum extraction wash 4 or 5 times the leaves with your solvent
then evaporate the solvent in order to be left with very impure ginkgolides. To purify this you will need to wash them a few times with a non-polar
solvent as hexanes, toluene, benzene, chloroform, etc. (I would recommend use chloroform) then recrystallize the ginkgolides in ethanol to even
further purity. Note: I don’t know if there is a possibility that ginkgolides would hydrolyze in these solvents, I don’t think so but to be sure I
wouldn’t exceed the 50 degrees Celsius, how to evaporate the solvents then? Well you’ll need to do it the slow way by bubbling O2 through it. Well
good luck with that and pls tell us how it goes! 