Hi. I am making a research in my master degree in biotechnology. The assay is about finding new plants with antimicrobial activity. Plants without any kind of investigation in this area.
I prepared extracts of different plants (10 grams dry plant to 200 mL of solvent) in 99,5% ethanol and I am now about to test them with the Bauer method (disks).
But I also was suggested by my teacher to test if at least 1 kind of phytochemicals are present in my extracts. Since I used ethanol solid-liquid extraction, I was thinking of using the folin-ciocalteu method for the phenolics. I don't need to quantify them, since I don't even have the gallic acid needed to make the calibration curve, so my question is, what do I have to do to comprove that there are indeed phenolic compounds in my extracts, even if not measuring their concentration? IN a qualitative analysis.
Do I just choose a volume of the Folin-C. reagent and mix it with my extracts and see if they turn blue? Does this proves that there may be phenolics in the extracts? Everything I read about this is too complex and specific since they use this to quantify the phenolics. I just want to know if I have any, regardless of how much...
Also, are there any other qualitative methods to determine some of the antimicrobial compunds in plants, besides the FC for phenolics?
Thanks
Dear Tiago Santos,
There is always a certain standard required for scientific research, specifically you will publish something from you thesis in an international journal, so it is hard for the reviewers and editors to accept that forming a blue colour means presence of phenols. Gallic acid is not expensive and a stable materiel, also it will be nice figure when you do a calibration curve in you publication then you measure the content of total phenols in your extract through different concentration of the the standard.
Good luck
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Dear Tiago Santos,
You can also use the Fast Blue reagent that is more specific for phenols and less complicated. See here: http://pubs.acs.org/doi/abs/10.1021/jf103711c
You should always use a calibration curve to determine the amount of phenols in your sample. I agree that the gallic acid is not expensive and you could have a thesis with more accurate results.
Regards
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