Dear Mariia Shanaida , the DPPH, ABTS, and FRAP have different action mechanisms. The DPPH method has the ability of the various antioxidants to donate an electron or hydrogen radical to the stable DPPH free radical. and FRAP method is based on the ability to reduce ferric (Fe3+) to ferrous (Fe2+) ion through the donation of an electron, with the resulting ferrous ion (Fe2+). a compound can be very active on an assay and less active on another, all depends on the structure and radicals. that's why it's better to do more than one assay. for myself I used to do the three of them; now I do only DPPH to calculate the IC50 and Frap to calculate the EC50. check the papers below for more details.
best regards.
hi
each method has its principle and different action mechanisms
FRAP) method: This method measures the ability of antioxidant to reduce ferric iron
The DPPH method measure the ability of bioactive compounds to donate an electron or hydrogen radical to the free radical dpph
Different methods work on different principles. And diffrent mechanism
Mariia Shanaida ,
If you plan conducting antioxidant screening just to have an idea for many plant extracts, then I will recommend DPPH radical scavenging assay. If you select and narrow the number of the plant extracts, I will also recommend you perform at least 5 different antioxidant assays on them in order to know the bests among them because the various assays differ by their mechanisms as suggested by Dr. Hicham Mechqoq . Also, remember to use a standard and in each case, determine their respective IC50 for comparison.
Best wishes,
Egbuna
Combine different methods, try to use methods with different mechanisms and different types of radicals (synthetics and natural), for example: DPPH, ORAC, FRAP
Of course it will vary with your plan, specific objective and desired precision level.
But mostly in various literature I found DPPH, ORAC and FRAP.
Antioxidant assay methods are usually governed by hydrogen atom transfer and single electron transfer.
DPPH, ABTS, FRAP, super oxide and beta carotene bleaching assays are most commonly used.
Selection of antioxidant assay method depends upon your aim as well as your sample constitutions.
Mostly plants extract have potential to reduce chemical species.
If you want to study in depth about the antioxidant methods please concern the following book
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