In many papers for estimation of DPPH , I found IC50 and in other papers EC50.
Care with IC50, EC50, ED50. The term dose is used when we are referring to live animals and we determine the median effective dose (ED50) and/or the median lethal dose (LD50). For IC50 and EC50, we use concentration as we are dealing with an in vitro setup or minute organisms (e.g. bacteria, fungi, brine shrimps, etc....).
IC50 is used in case there is an assay in which there is a decline in activity; i.e. the higher the conc of the inhibitor, the higher is the inhibition (negative activity). EC50 is used for substances that complement a system, the higher the conc, the higher is the (positive) activity.
This confuses a lot of scientists
I think Wikipedia can explain this easily:
http://en.wikipedia.org/wiki/IC50
http://en.wikipedia.org/wiki/EC50
I think you should have a look at a previous discussion on this topic. Here is the link:
https://www.researchgate.net/post/What_is_the_different_between_IC50_GI50_and_ED5010
Regards
Dear Mohamed
EC50 is 50% efficacy but IC50 is 50% inhibition.
The efficacy dose is determined by measuring the effect of one drug or toxin in a living system, the inhibition dose is measured especially on isolated enzymes.
On other aspect of view, the concepts of IC50 and EC50 are fundamental to pharmacology. The EC50 is the concentration of a drug that gives half-maximal response. The IC50 is the concentration of an inhibitor where the response (or binding) is reduced by half.
Please use the following link
http://www.graphpad.com/support/faqid/1356/
Care with IC50, EC50, ED50. The term dose is used when we are referring to live animals and we determine the median effective dose (ED50) and/or the median lethal dose (LD50). For IC50 and EC50, we use concentration as we are dealing with an in vitro setup or minute organisms (e.g. bacteria, fungi, brine shrimps, etc....).
IC50 is used in case there is an assay in which there is a decline in activity; i.e. the higher the conc of the inhibitor, the higher is the inhibition (negative activity). EC50 is used for substances that complement a system, the higher the conc, the higher is the (positive) activity.
This confuses a lot of scientists
@ Everaldo Attard. Nice explanation. Agreed with your comments. This is what which confuses a lot of students and scientists and in that confusion sometimes they go wrong in their analysis too.
Masood and Everaldo have precisely explained the terms EC50 & IC50 generally used in biological assay and in-vitro studies. However these terms should be used carefully and logically.
Everaldo Attarad,
You explained it by the book, really great.
If it is an inhibitory reaction you may comfortably use IC50. However, at the same time you are also looking at the effectiveness of the extract/compound so EC50 is also adequate. All IC50 can be interpreted as EC50 but not all EC50 can be taken as IC50.
Can anyone explain about the minimum dose required to see any effect based on EC50 or IC50. I mean, if some drug has IC50 (24 pM) then what minimum concentration would be best in animal (in vivo) to see the inhibitory effects.
Thanks
Shahid
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