2.7.4. Calculation of the IC50 Values

The half-maximal inhibitory concentration (IC50 value) of each treatment group was determined from the obtained in vitro cytotoxicity data. The following equation calculated the %viable cells [39,41]:

The absorbance for the MTT-assay (560–630 nm) and NR-assay (540–690 nm) was measured at different wavelengths, and Δ represents the difference between these values. The %viable cells at each concentration were subtracted from the initial %viable cells (100%) to calculate the %inhibited cells. Regression analysis calculated the IC50 value (x-value), where the y-value was set to 50% (inhibition), m was the slope, and c was the y-intercept [42,43].