Antioxidant activities

[Dolphin]

Dear people,

I am trying to dissolve my plant extracts which are extracted from 6 different polarity solvents (water, ethanol, methanol, acetone, ethyl acetate and hexane) with methanol in order to proceed with antioxidant activities assays. However, plant extracts of water, acetone, ethyl acetate and hexane could not dissolve with methanol. I had tried to sonicate them but unsuccessful to dissolve.

I was told two ways of solution. First, dissolve with its initial solvents. Eg. Hexane extract dissolve with hexane solvent instead of methanol. Second, dissolve with additional of DMSO.

Is there any ways to make it possible to dissolve in methanol? How to compare if the extract are dissolve in different solvents? If use DMSO, what is the recommended amount to add in?

Thanks and appreciate!

[tom jupille]

The use of a co-solvent is not unusual. The real question is the effect of a co-solvent on your activity assay. Methanol is not fully miscible with hexane ( I'm not sure about its miscibility with ethyl acetate) so you will have a problem there.

The first thing to do is to find out how much of the other solvents mixed with methanol your assay will tolerate. Then dissolve each fraction in a minimal volume of its appropriate solvent and add methanol to the desired volume. For the hexane fraction, you may have to use a "cocktail" (maybe ethyl acetate+ethanol?) To get around the miscibility issues.

If you go the DMSO route, the same approach applies: how much can your assay tolerate, dissolve in minimal volume and dilute out.

[Dolphin]

Thanks for the speedy reply.

I think I will go for DMSO route. I had came across a journal that mentioned using DMSO and dilute with distilled water but not in details. If dilute with distilled water, it won't be able to mix with certain solvents such as hexane right? Any recommended sources on the usage of DMSO in plant extracts and to determine the antioxidant activities? Thanks!