I have a crude methanolic extract, and I want to further process it. There is a method described using hot methanol or acetone, in order to separate triterpenes from the rest. Can you suggest other alternatives?
Triterpenes such as lupeol, stigmasterol, b-sistosterol, etc. can be obtained by partition of the methanol extract with dichloromethane or chloroform, however, other compounds of similar polarity could be extracted too.
Gloria's method would work.
An alternative is "wide polarity range chromatography" on silica based C18. the sample is run on a C18 flash column, and the sample dry-loaded on celite or C18 media. The column is run normally with water/methanol. After reaching 100% methanol, a gradient is run with a methanol/dichloromethane gradient to 100% dichloromethane (DCM). The use of DCM precludes polymeric reverse phase which would swell.
Here is an example: http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN77_Wide_Polarity_Range_Chromatography.pdf
I call it "wide polarity range chromatography" because I start, in this case, with polar solvents and finish with very non-polar solvents. The DCM allows very non-polar materials, such as terpenes, to elute. without the DCM gradient, these would be retained on the C18 column. The dry loading on celite or C18 will improve the chromatography.
By Steam distillation followed by extraction with ether.Use TLC later.
Start column chromatography with nonpolar solvents and then slightly increase polarity
Firstly you should evaporate methanol if you used 70% or 80% methanol: dist. Water you evaporate methanol with rota vapor apparatus then add acetone to viscous aqueous extract (5:1) & leave it till precipitation the mix of triterpenes
after that use silica for backing column & use mobile phase with low polar solvent at the beginning like (chloroform: methanol) then gradually increase polarity till reach 100% methanol
You can use ethyl acetate for separation of triterpines from the plant extract.
Dear Madhukar, can you please be a little more descriptive about your proposed method, it appears simple enough. Please describe how it can be done exactly.
............and Gloria, are you talking about simply partitioning the methanolic extract into dichloromethan or chloroform fraction and methanol fraction. and then accepting that my dichloromethane or chloroform fraction actually contains terpenoids.
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