Dear Mac,
Firstly, the best solvent to obtain plant extracts with antimicrobial activity will depend on determining the phytochemical(s) responsible for illiciting antimicrobial activity.
Ethanol is widely prefered for phytochemical extraction for a number of reasons: a wide range of phytochemicals are soluble in ethanol and it is considered safe due to low toxicity. The use of acetone on the other hand is impeded by toxicity and safety concern especially if you plan administering the extracts to in vivo animal models.
However, not all phytochemicals thrive in ethanol due to different range of polarity, hence some studies explore the use of other organic solvent either alone or by fractionating parent ethanol extracts with other polar and non polar solvents like ethyl acetate, diethyl ether, chloroform etc.
So, my suggestion would be first to consult the literatures, check for studies that have profiled antimicrobial phytochemicals, then check their polarity range and that will help you select the best solvent. It may be that the antimicrobial phytochemical prefers very polar, moderately polar or nonpolar conditions.
Notwithstanding, for general extraction of phytochemicals, absolute ethanol is recommended.
Best wishes,
Chigozie
Dear Mac,
Ethanol or any other organic solvent is used as a medium to extract the active ingredient/phytochemicals. Evaporating after extraction is an attempt to get rid of the solvent, leaving the active ingredients. Same as what freeze drying does using a non-organic solvent.
DMSO is often used to reconstitute the plant extract because of its ability to dissolve almost anything, although DMSO also have some safety concerns as well. Tween 20 and tween 80 is usually attempted before DMSO.
However, reconstituting in another solvent depends on the medium whatever protocol you are using requires. If water is what you need, then use water,. If its a HPLC analysis that requires a different solvent, then use that solvent. DMSO is used most times when there is a solubility problem.
I hope this is helpful.
Best wishes,
Chigozie
Hello Mac,
During maceration with ethanol (a polar solvent), ethanol-soluble phytochemicals are extracted from the plant material into the solvent medium.
Yes, your calculation is correct for 20% (v/v) DMSO. However, you may want to keep your DMSO concentration at the lowest possible concentration that can dissolve your plant extract for toxicity concerns. So my suggestion will be to take a range of 1%, 5%, 10% and 20% (v/v) DMSO and take some small quantity of your extract and try to dissolve it in these solvent. The lowest concentration that dissolves your sample should be your best bet.
Best of luck,
Chigozie
We have used both solvent to extract phytochemicals and acetone to be better since most it is removed by the rotavapor process leaving the extract
I've used both methanol and ethanol for extraction. Both may be okay but I observed that methanol extracts some other compounds such as as the flavonoids alongside fatty acids. So if the extract is destined to be used on food items such as storage of agric produce, methanol or ethanol is preferable because we take into consideration the toxicity of solvent used in extraction. However, I also discovered that a mixture of dichloromethane/methanol (1:1) is quite good as it extracts alkaloids, sterols, triterpenes and many lipophilic compounds. This also can be used only if the solvent mixture can be removed completely after extracting the compounds.
If it was for only to check antimicrobial activity Methanol and Ethanol will help you. In most of the literatures you can find that these solvents having high potential in extracting most of the phytochemicals mainly methanol which will give you better results in antimicrobial activity. For acetone, if you wish to go for particular compound isolation based on the compound you are looking for on that time you can opt for it.
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