I do the cytotoxicity test on plant extracts and I get the % of Cell growth as function of concentration. I know to calculate the IC50 from the % of inhibition according to the concentration. But I don't know to calculate this IC50 from the % of Cell growth
Hi Marsi,
You can try CompuSyn software. It's much easier to determine IC50 by entering the data quickly and effectively. CompuSyn software can be free downloaded.
You can follow this way:
1. Click New Experiment;
2. Click New Single Drug;
3. Inputs Full name of the drug, Abbrev of the drug, and Units (e.g., nM);
4. Enter the first set of Dose+Effect values. For example, Dose=20, Effect=0.30 (which means 30% of cells killed);
5. PressENTER on your keyboard, then you can see the data are input and saved;
6. Type next set of Dose/Effect data, then press ENTER;
7. Repeat this process until all dose-response values are input and saved;
8. Press Finished;
9. Press Calculate Parameters, and the IC50 value is calculated and shown in the bottom. The software by default regards it as IC50, you can also calculate IC75 by entering 0.75 into the upper blank.
Hope it would help you.
Depending on the percentage inhibition points obtained from the absortion values, you can decide wether to use the linear, exponential or the logarithmic fit model/graph.
More number of points can be fit in logarithmic plot when I did .
So, after logarithmic plotting using excel between Concentration (x-axis) vs %inhibition (y-axis).
now, you will obtained
Y= a ln(x) +/- c (+ve or -ve depending on the data).
where Y= 50% of the Max. % inhibition
and x = the concentration at which 50% inhibition of the Oxidation can be achieved.
The "a and c" values are generated by the excel operation.
If the points are better plotted while using exponential plot you can use it and in that case
Y= a * x + or - c (+ve or -ve depending on the data).
where Y= 50% of the Max. % inhibition
and x = the concentration at which 50% inhibition of the Oxidation can be achieved.
Hope this helps.
if needed more elaboration, feel free.
Best of Luck.
If you have the % of cell growth, you can calculate the % of inhibition. If you have % of cell growth= 70 % then % of inhibition = 100-70= 30 % . Now use your calculation for IC50 as you know.
Good luck
Fist calculate % inhibition then plot Conc Vs % inhibition. From the plot you will get values For the equation Y=mx+c , now find the value of X from the values of above equation i.e x=y-c/m this results in your Ic50 value.
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