Sonication, temperature and flavonoid stability - AED and degradation (Apr/30/2009 )

I am trying to dissolve or create a homogenous suspension out of a flavonoid supplement on powder form into DMEM as a solvent. I have tried simply shaking this and it doesnt seem to dissolve or break up the particles sufficiently. I then tried sonicating this lumpy suspension for 1 hour at 37 C. Then the suspension was deffienetly more homogenous and smoother, this was the desired effect. However I also noticed a change in colour, the lumpy suspension went from a very dark and deep purple before sonication to more of a dark red suspension.

My question is related to flavonoid stabilty under the conditions mentioned above: 1 hour sonication at 37 degrees celcius. I thought as 37 degrees was just body temperature that sureley that would not degrade the flavonoids significantly and weather acoustic energy could lead to degradation?

Thank you very much, I hope you can help me with this!

Green

My first thought would be that you are oxidising the flavonoids but you may just be seeing the effect of the DMEM buffering ie change pH = colour change.

Is this a commercial supplement? Many of these contain inactive ingredients which are very insoluble and it may be easier to extract the flavonoids in solvent, dry and then resuspend.

The other trick that may be useful is to increase the amount of serum in the media. The binding proteins of serum are particularly good at holding insoluble compounds in suspension.