What is the mechanism involved in phosphomolybdenum antioxidant assay? How do we calculate total antioxidant activity from this parameter?
Hey Aastha,
The total antioxidant assay based on reduction of Phosphate-Molybdenum (VI) to Phosphate-Molybdenum (V). The incubation of extracts with the Molybdenum (VI) will tell you the presence of antioxidant components in the extract, which can be assessed by recording the absorbance at 695 nm (to detect the reduced green molybdenum complex). So, this assay is very useful to predict the antioxidant activity of crude extracts on the total basis.
The reducing capacity of extract was calculated by using the formula:
Final absorbance= Absorbance of sample - Absorbance of Blank - Absorbance of Extract.
(or )
%inhibition= (1- Absorbance of sample/absorbance of control) * 100
Good Luck..!!!
Dear Upendar Rao Golla what is control and blank in this case.
the results of this assay can also be represented as Gallic acid or ascorbic acid equivalent/g of dry weight of the sample. the procedure is same as described Upendar Rao Golla.
Why do we need to incubate the samples at 95 degree celcius? Anyone knows the mechanism behind?
Dear Aastha
Please find related paper with your query.
http://helvia.uco.es/xmlui/bitstream/handle/10396/10963/Spectrophotometric%20Quantitation%20(1).pdf?sequence=1
Dear DR / Upendar Rao Golla
what is the control and blank in this case.?
Hi Abdulelah,
In the formula, %inhibition= (1- Absorbance of sample/absorbance of control) * 100
One can use a typical blank solution that contains 1ml of reagent solution and the appropriate volume of the same solvent (say solvent control or the blank) used for the sample (extract), and it was incubated under the same conditions as the rest of the samples.
If one wants to represent the antioxidant activity in terms of / relative to any standard, the positive control includes the standard reducing agents (gallic acid/ascorbic acid/tocopherol).
To get the final absorbance (actual that represents the antioxidant activity), one can get it by using this formula: Final absorbance= Absorbance of sample - Absorbance of Blank - Absorbance of Extract.
Absorbance of sample: It includes entire reaction mixture containing Molybdenum (VI) and the extract/sample. (i.e.Molybdenum with extract )
Absorbance of Blank: It includes entire reaction mixture containing Molybdenum (VI) and the equivalent amount of solvent that was used in extract/sample (i.e. Molybdenum with only solvent).
Absorbance of Extract: It includes entire reaction mixture without Molybdenum (VI) , but it includes the extract/sample (i.e. only extract without Molybdenum)
All the best.
Upendar
Hi Upendar
Is there any difference between the mechanism of DPPH method and phosphomolybdenum antioxidant assay?
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