Hi, I want to test the antioxidant power of my plant extracts using H2O2 as oxidant agent. Literature mentioned two different concentrations of H2O2: 40 mM and 4mM and I am really confused. So, please, could you tell me what is the adequate concentration of H2O2 in this test?
Also, could you please explain me what mixture I have to use as control: mixture without H2O2 or mixture without extract?
Thank you very much.
Dear Souad,
Thank you so much for an important question, which many people close their eye on it.
In this paper you can see 0.5 mM hydrogen peroxide concentration for SOD activity determination:
http://www.jbc.org/content/266/22/14151.full.pdf
In these papers you can see 5 mM hydrogen peroxide concentration (10 fold greater than before ref.) for SOD activity determination:
http://vri.cz/docs/vetmed/47-3-38.pdf
http://jmm.sgmjournals.org/content/45/5/383.full.pdf
And in this reference you can see hydrogen peroxide concentrations from 4.9 mM up to 39 mM for SOD activity determination.
http://www.jbc.org/content/273/46/30104.full.pdf
But the substrate half life time (t1/2) in the reactions, vary and depends on H2O2 concentration.
Finally for SOD activity determination using H2O2, you can use a wide range of H2O2 Concentration but kinetics of the reaction (reaction time and obtained OD) will be differ.
best
Mehdi
Dear Prof. Hedayati,
Thank you very much for your response.
I have used 40mM for H2O2 with ascorbic acid as standard. Surprisingly when the concentration of ascorbic acid increases the radical scavenging activity decreases, may be the concentration of H2O2 is too high, I will try again with 4mM.
Have you done this test with ascorbic acid or plant extract?
Best regards
Souad
Yes, I have experience with ascorbic acid, as you guessed, the hydrogen peroxide concentration was high and you can repeat the reaction with lower amount of H2O2.
best
mehdi
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