Which is the best method of extraction for Herbs? Is it differs according to the active principles?
Dear Vaidya Vasant Patil,
The best extraction method is Soxhlet Extraction. Please note that no single solvent is able to extract all compounds contained in a given herb. It is suggested that for extraction, you use the solvents in the order of increasing their polarity: hexane, chloroform, DCM, ethyl acetate, methanol, ethanol and water. It should be emphasized that utilizing this apparatus (Soxhlet Extraction) is only for the solvent boiling temperature less than 80 C.
Alternatively , the maceration method is advantageous when the compounds contained in the herb are heat labile. For the complete removal of compounds, you need to repeat the maceration steps with fresh solvent.
Therefore the best approach is to use the combination of Soxhlet Extraction and Maceration.
Hoping this will be helpful,
Rafik
The extraction method does differ based on the compounds involved.. For example, capsaicin compounds are extracted in low-polarity solvents and purified by column chromatography. However, capsaicin compounds are also soluble in methanol and could be extracted with that solvent as well. Alkaloids can be extracted in methanol, and can be purified by ion exchange, as can flavonoids.
In this link, capsaicin compounds weredetermined, by a column screening, be be purified on alumina and C18: http://www.isco.com/WebProductFiles/Applications/101/Poster_and_Paper_Reprints/New_Techniques_In_Extraction_Column_Screening.pdf
In this link, flavonoid compounds were purified by ion exchange followed by C18: http://www.isco.com/WebProductFiles/Applications/101/Poster_and_Paper_Reprints/New_Techniques_in_Extract_Column_Screening_II.pdf
Also, alkaloids were isolated with ion exchange columns
These links show that the purification really depends on the nature of the active compound- is it polar? Ionic? Non-polar?
If you would like to study the Herb for bio-activity aspect, you should extract the herb at room temperature by soaking the macerated herb in the different solvents as suggested previously with increasing polarity of solvents. You should collect the soluble matter 4-5 times using fresh solvent per each extraction.
If bio-activity is not of interest, you can go for extraction as suggested in previous comments
You may try this new method
https://www.researchgate.net/publication/308357814_Optimization_of_Ficus_deltoidea_Using_Ultrasound-Assisted_Extraction_by_Box-Behnken_Statistical_Design
Article Optimization of Ficus deltoidea Using Ultrasound-Assisted Ex...
Dear Vaidya,
The best solvent set for herb extraction is:
Water
Ethanol (EtOH)
Ethyl Acetate (EtAc)
Hexane
Extract your material(s) with above listed solvents individually. Then the four sets of extractions need to be concentrated to dryness with lyophilize (frozen drying).
Finally, to the concentrated or dried extractions, if you desire to dissolve it in water and further use it in medium culture for biological/cell-based screening and animal study, it is a good selection to apply very small amount of Ethylene glycol mono-tert-butyl ether, one of most efficient solubilizers for organic compounds, as a cosolvent, for making your extraction mixable with water, as well as for your target to easily act in experiment medium.
If you want to try ionic surfactants, to prevent the chemicals from the affect to your experiment, the amount of ionic surfactants is a key. Same as ionic surfactants, many of non-ionic surfactants are cell killers.
Enjoy Holiday Season and Have A Wonderful New Year!
Best Wishes,
Ying Li
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