I have used Mo(VI) reduction assay for total antioxidant capacity of plant extracts. i got the absorbance values, now how to calculate total antioxidant capacity of plant extract by using these values? is the calculation for total antioxidant capacity same as in case of DPPH scavenging method?
Dear Ajay
Its very simple. You need to construct a standard curve using any of the known antioxidant molecule. Usually people prefer ascorbic acid. Just do as we calculate protein concentration in unknown samples using BSA as standard. And express the obtained value in microgram equivalent to ascorbic acid.
You will need to prepare a standard curve with known anioxidante as Trolox and ascorbic acid, in the case of the Trolox from 0 to 2.0 millimoles per liter. And comparing their absorbance with the curve of Trolox.
Antioxidant and antiradical activities are distinct to each other. Antioxidant is based on inhibition of redox reaction while antiradical is based on quenching of free radicals generated by DPPH. Antioxidant is calculated on basis of direct absorbance and like dose dependent response while antiradical is calculated on basis of percent inhibition and inverse proportional to absorbance. Hence phosphomolybdenum assay is calculated on directly concentration against absorbance and gives straight line in graph while DPPH is higher potency with lower absorbance.
How can we prepare of ascorbic acid standards solution for phosphomolybdenum method ?
Dear Abdulelah Ahmed Thabet
make a standard solution of ascorbic acid (0.5 mg/ mL) by dissolving it in methanol/ethanol and then make minimum of five dilution accordingly.
Thank you Dear Ajay Sharma
Ascorbic acid dissolve in methanol only or we have to add the mixture of reagent solution (0.6M sulfuric acid, 28mM sodium phosphate and 4 mM
ammonium molybdate) too?
Dear Abdulelah Ahmed Thabet
First dissolve ascorbic acid in methanol only and after that follow same procedure as followed in case of various extracts under investigation.
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