Hi , i was doing a research related to antioxidant compound in P.Edulis. i get stuck with DPPH calculation. Is it compulsory to do the IC50 calculation ? or i can just proceed with percentage of inhibition for future discussion ? and if i need to do the IC50 calculation, all i need is the percentage and the concentration of sample, am i right ?
Then i need to plot a graph. Once i get the equation, i can calculate the IC50 by substitute 50 as y-intercept. Is it correct ?
To calculate the IC50 value: The inhibitor concentration against the percent activity is plotted ([I]-Activity % graph). Using the linear (y=mx+n) equation on this graph for y=50 value x point becomes IC50 value.
Dear Wanni,
Since the comparison of IC50 of your extarct with IC50 of reference antioxidant (i.e. gallic acid or vit C for example) gives an idea on how powerfull is your extract, It is preferable to calculate IC50.
In other words, higher IC50 value corresponds to lesser antioxydant potential exerted.
Bests
Antioxidant activity is based on the decrease in the absorbance when the diphenyl-picrylhydrazyl radical (DPPH•) is reduced at 517 nm. This assay depends on the fact that the purple color of the DPPH• radicals is bleached to a yellow color in presence of any molecule that can donate an electron or proton. Equal volumes of extract were mixed with 0.2 mM methanol solution of DPPH• and incubation in the dark for at 37 °C for 30 min [13]. After incubation, the absorbances of the mixtures were measurement against a blank at 517 nm using a Tecan® Safire II Reader. DPPH• with methanol was employ as control, while ascorbic acid was employ as reference in comparing to the extract. The efficacy of antioxidant in the samples were expressed in percentage of DPPH• reduction and was calculated using the formula below:
Inhibition (%) = 100 × [A517 (control) − A517 (sample)/A517 (control)]
Inhibition (%) = 100 × [A517 (control) − A517 (sample)/A517 (control)]
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