Cheburator Software for Automatically Calculating Drug Inhibitory Concentrations from In Vitro Screening Assays
(A) Two types of IC50 which can be estimated by the software. Absolute IC50 is defined as the concentration of tested compound which results in 50% inhibition of cell growth as defined by assay controls (pink lines). Relative IC50 is defined as the concentration of tested compound which results in half of the maximum inhibition of cell growth attainable for that particular compound (orange lines). Imax is defined as upper plateau of the dose-response curve (solid orange line). (B) Example of a dose-response curve drawn on the basis of 4 values (black circles). The simple two-point method uses 2 data points bracketing 50% inhibition of proliferation (green lines) to estimate the IC50. In the second method, a linear model is built with the intercept and the slope, which are calculated by linear regression analysis using data points which are >0% and <100% (red lines). These parameters are later used to estimate IC50. In the third method, the software uses all data points to build nonlinear regression model and estimate IC50 (blue lines). Absolute IC50 values are shown on this plot, but software can also estimate relative IC50 in linear and nonlinear regression analysis.