Greetings! I'm trying to develop a quick routine method (quality control) to determine polyphenols in hydroalcoholic extracts of Moringa oleifera seeds. However, the test results reflects considerably high values (1,71 gr/L eq. of Gallic Acid).
The extract was made in a 1:10 solute-solvent ratio, using 70% Ethanol. It was filtered, diluted in water and centrifuged at 10.000 rpm. The proteins were apparently extracted and the levels of sugars and vitamin C in Moringa seeds are very low.
It's possible that there is still some interference? Maybe the oleic acid? I appreciate your help.
Best Regards! Arturo Torres
Hi Arturo,
You need firstly to convert results into GAE/100 g dry extract or dry weight of seed (fresh weighmay be used too).
As you said, the interferences of Folin-Ciocalteu method are generally vitamin c and reducing sugars. So, I propose you to double check the calculations you performed.
Check https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/folins-reagent
Thank you for your answers, @Chinaza Godswill and @Duried Alwazeer... I will keep your suggestions in mind.
MANY substances other than polyphenols react in the Folin-Ciocalteu, starting with ascorbic acid. check DOI: 10.1021/jf048396b
Hi Arturo
Usually because of its high ratio of phenolic groups and low molar mass the gallic acid is considered as a low answer standard in folin, and an hydroalcoholic extract can concentrate other antioxidants like ascorbic or phenolic amino acids as already mentionned. It will depend on the dry matter extracted and antioxidant relative concentration of a selective solvant extraction ? And finally for folin the colorimetric answer itself can be modified by the presence of ethanol so you may need to remove it to avoid haze formation.
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