Figure 5

24-hour cytotoxicity of α-bisabolol in Ph⁺ cells as compared to imatinib mesylate. (A) Scaled α-bisabolol alone (solid line) or in combination with 3 μM imatinib mesylate (dashed line) in 2 representative cases out of 10 (Ph⁺B-ALL #04 and #05 in Table 1, Figure 3B and Figure 4, where α-bisabolol concentrations are represented up to 160 μM). The imatinib mesylate-dependent cytotoxicity is indicated at point 0,0. Cells resistant to imatinib mesylate were sensitive to α-bisabolol. In cells sensitive to imatinib mesylate, α-bisabolol potentiated the effect of the other drug. (B) Analysis of synergism between imatinib and α-bisabolol in the imatinib-sensitive BCR/ABL⁺ human cell line CML-T1. Left side. Effects of 40 μM α-bisabolol and 0.1 μM imatinib, alone and combined, on proliferation of the cell line. Means ± SD of 5 experiments. Right side. Plot showing the corrisponding combination index (CI) vs. the fraction affected (Fa). CI values are <1, indicating that the two drugs are synergistic. Bars represent the variability of effects according to the sequential deletion analysis [16].