How to compute IC50 value of a solution automatically
I performed experimentation, determining the percentage of bacteria growth in presence of different plant extracts and at different concentrations, with different solvents. I finally have more than 50 results that I have to determine their IC 50 value. I have started with Excel from a non linear regression, in each case, I plot the Percentage of growth inhibitory versus the concentration of the extract:
ei : for extract A concentration (percentage of inhibition) IC50
Extract A 0 (0.0000) 2(40.6202) 4(40,6202) 8(68.2698) 10 (100,0000) 5.3625 mg/mL
Except from Excel, is there other ways to find it? Thank you very much
Attached excel sheet with others results
One of the best software to for data fitting in the market today is Table Curve 2D - available for free (30 day trial) here: http://download.cnet.com/TableCurve-2D/3000-2053_4-10308067.html
The attached file show you the kind of results that you can get easily. Hope this helps.
The estimated IC50 depends which model will you used. If assuming the monotonic of the curve, you may use parameter logistic regression model. The 4 Parameter Logistic or 4PL nonlinear regression model is commonly used for curve-fitting analysis in bioassays or immunoassays such as ELISAs or dose-response curves.
The model has the following formula
F(x) = ((A-D)/(1+((x/C)^B))) + D
For your data, you can assume A=1, D=0,
You can select different B and D to fit your data
Then use
x = C*((1/(0.5-D))-1)^(1/B) to find IC50
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