EC50 is an uphill dose response that plots an increased response. This is the concentration of an antioxidant  drug that gives half maximal response or the 50% maximum concentration for anymeasured biological effect of interest (FRAP). IC50 is a downhill dose response that plots inhibitory response, the drug concentration causing 50% inhibition of the desired activity (DPPH).

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there are not any efferent between them? 

hi 

thanks for your replies. it's very useful for me. thanks a lot.

regards...

Read the attached publication.

Esam Mansour 

Article In vitro antioxidant activity and total phenolic content of ...

IC50: Extract concentration providing 50% inhibition. The EC50 value whose absorbance was 0.5, which means it was an effective concentration, was calculated using a concentration absorbance graphic. When the EC50 value gets smaller, the antioxidant activity increases.

hello

thanks for all.

best wishes...

The differences are just nomenclature, and not conceptual.

"EC" means effective concentration, and is used for dose-response curves that go up hill. Sometimes it is also used for a curve that goes downhill.

"IC" means inhibitory concentration, so is used for dose-response curves that go downhill, because the drug inhibits a response.

hi mohammad

you said sometimes EC50 used for a downhill curve, i have seen at some papers too. dosent matter from scientific point ?

There is a difference in which abbreviation is used, but no fundamental difference. I rather to use IC50 for downhill curve

Dear Mahya, The thought of IC50 and EC50 are elementary to pharmacology.

The EC50 is the concentration of a drug/extract that gives half-maximal response.

The IC50 is the concentration of an drug/extract where the response (or binding) is reduced by half.

Correct answer from Abhay Mishra and Mohamad Hamdi. For downhill curve  uses IC50 and for upward curve EC50.Using two indicators depends on the method of analysis.

Although, IC50 and EC50 are to different terms in drug pharmacology,  since in the case of antioxidant activity the expected response is inhibition of a reaction, there is no difference to use IC50 or EC50.

EC50 is 50% efficacy, and IC50 is 50% inhibition. The efficacy dose is determined by measuring the effect in a living system meaning in vivo, while the inhibition dose is measured on isolated enzymes.

In enzyme studies IC50 is the concentration of inhibitor where enzyme activity is reduced by 50%. EC50 is the concentration of inhibitor at which we see a 50% decline in the cellular activity resulting from enzyme activity. So if I am understanding this, inhibiting enzyme activity by 50% does not necessarily mean that the cellular activity will also be reduced by 50%? So in this case EC50 and IC50 are not the same.

The IC50 represents the concentration of a extract that is required for 50% inhibition of viral replication in vitro (can be corrected for protein binding etc).

The EC50 represents for obtaining 50% of the maximum effect in vivo

hi

yes i understand it. your replies was very perfect and useful. thanks alot for your attantion.

best wishes..

mahya beygi