Aren't polyphenols fluorescent themselves? what is the cell treatment protocol you are interested in? the application will help in deciding a chemistry for you.

The reaction  between polyphenols and FITC is quite difficult, as both tend to be electrophilic. It would be better to choose a fluorescent dye that contains an amino group that would be able to react with polyphenols.

Thank you Sir, on checking, I have found that rhodamine B contains an amino group, so will that do?

I have not tried that, but I think that it can react with the phenolics when choosing slight oxidative conditions (for many polpyhenols alkaline pH values are enough)....

Dr. Rohn,

Does fluorescamine, a primary-amine specific fluorogenic dye, work?

Thanks!

Do you mean fluorescamine (4'-phenylspiro[2-benzofuran-3,2'-furan]-1,3'-dione) ? This does not contain an amino group. I have not tried that either...

Yes, fluorescamine, a primary-amine specific fluorogenic dye, does not possess an amino group, and  is not fluorescent by itself. Thank you. 

Dr.Rohn (Sir), could you put some more light on to what slight oxidative conditions and alkaline pH for polyphenols that you have indicated in your previous answers. This could help me out in setting up a protocol. Thank you

Slight oxidative conditions such as the use of a Fe-II solution or pH-values between 7 and 9 will oxidize most of the phenolic compounds (those with a o- or p-dihydroxybenzene structure) to their corresponding quinones. These are then susceptible to react with primary amino compounds and can be labelled. We do this on thinlayerchromatography plates or as post- or pre-column derivatization techniques in HPLC.

Thank you Dr Rohn, this information will be really helpful in thinking further

Dr Rohn coiuld you share some relevant papers in this regard related to use of Fe-II...oxidation...phenolic compounds that you have talked of? Thank you

I have not a specific paper in mind, because it depends on your phenolic compounds. Just try a Fe-II solution in different mM-concnetrations and see if it is appropriate. Science has lot to do with "trial-and-error" approaches...

Yes indeed, I will definitely try and come back . Thank you :)