Hello everyone ! I'll be conducting different antioxidant assays for my sample ( Mangosteen leaves soaked in three different solvents for extraction ) and I want to know what's the difference between percentage of scavenging inhibition capacity of ABTS or DPPH and IC50 ? How are they related , what do they tell and whether I shall use % inhibition or IC50 to present my results .
Thank you xx
% inhibition is the ability of the sample to inhibit free radicals that were used (ABTS or DPPH) which is given in percentage while using different concentrations of the sample. IC50 is the particular inhibitory concentration of the sample when it inhibits 50 % of the free radicals that were used (ABTS or DPPH).
Siriluck Ponyam To calculate the percentage of inhibition (% inhibition), you can use a single concentration of the analyte against DPPH. However, determining the IC50 requires testing multiple concentrations of the analyte to identify the specific concentration that inhibits 50% of the free radicals. The choice between these methods depends on the type of data you need. If the literature relevant to your research emphasizes IC50 values, it may be worthwhile to calculate it, even though it requires more experimental effort. However, this process can become challenging if you are handling a large number of samples.
To begin with, it's essential to know the initial concentrations of your extracts. From these starting concentrations, prepare a series of dilutions, with each subsequent dilution being half the concentration of the previous one. This approach allows you to calculate how the percentage of radical neutralization (DPPH and ABTS) changes with the concentration of the sample, which is necessary for determining the IC50 value later on.
As explained in previous responses, the IC50 value indicates the concentration required to achieve 50% radical neutralization. If the percentage of radical neutralization for your samples is close to 50%, you can use these values to calculate the IC50. However, if the neutralization percentages are much lower, it means that at the concentrations you’ve chosen for testing, your extracts do not exhibit strong antioxidant activity. In that case, you may need to increase the starting concentrations of your extracts.
Of course, for publishing scientific papers, it is necessary to perform the experiments in triplicate to calculate the standard deviation, and the results are most commonly expressed using IC50 values.
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