I had used different solvent (water, methanol and ethanol) to do the extraction. The extracts are further analyzed with TPC test and DPPH assay. However, the results did not correlate with each other where the phenolic content of water > methanol > ethanol extracts in TPC and %inhibition of methanol > ethanol > water extracts in DPPH test. From the results shown, is it mean the water extract had affect the DPPH solution as I found that many researches stated that water is insoluble in DPPH.
hi mun,
Plant is rich in myriads of compound. When extraction is carried out, it is mostly based on polarity of solvent. If you did not performed sequential extraction, this might alter the solubility of yield. The solvent you're using were polar & medium polar. At the level of TPC & Dpph, i dont think there will be significance difference between EtOh & MeOH. Of course, solubility is one of the factor. But as long as your extract is dissolved,
% inhibition of MeOH or EtOH will be expected much higher compared with Aqeous, because many compound dissolved in medium polar solvent, might have better activity than polar one.
Thank you for the information. But why the total phenolic content of aqueous extract is more than methanol and ethanol when test with Folin Ciolcalteau?
Polyphenols compound are highly affinity with H2O molecule, So, it will dissolved in polar solvent like water. Aqeous extract will have much higher than other such as MeOH or EtOh which are medium polarity in nature.
Are the results of TPC should be similar with DPPH test as TPC test is correlated with DPPH?
Thank you for sharing. So although the trend of TPC and DPPH test are different, there still have reasonable explanation for the result that I had obtained right?
Dear Mun,
Obviously TPC is one of the factor which affect the free radical scavenging activity like ABTS, DPPH, FRAp etc... But all these scavenging activity of polyphenolic compound is also depend on the its structure like the number of hydroxyl group, position of hydroxyl group and other side groups associated with the polyphenolic structure.
By the help of FTIR, NMR and some wet lab exp you are able to quantify the hydroxyl, methoxy and methyl group, than you can better explain that why your 3 extract i.e. aqueous, MeOH and EtOH shows different activity towards DPPH assay.
Hope attach paper will help you to in this matter.
The Folin ciocalteu assay reacts with many more antioxidants in addition to the radical scavengers that contribute to the DPPH assay results. Therefore, FC assay actually is a measure of the total antioxidants in the mixture than the total phenolic content as conventionally known. Therefore, depending on the solvents used for the extraction, different types of antioxidants can be extracted and therefore, sometimes a direct correlation of the FC assay and the DPPH assay is not observed.
For the TPC test, can I test the TPC in different concentration of sample? Meaning that I had done a series of dilution to produce different concentration of sample, then I test the TPC in different concentration using Folin method. After that, I also test the dpph by using similar series of concentration. Then I will compare and correlate between TPC and dpph. Is the procedure of analysis correct?
For DPPH assay, is it possible the result of highest %inhibition of solvent extracts different with the IC50? Thank you.
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