Figure 1.

The chemical structures of compounds in M4, the cytotoxicity and synergistic effect of M4 on H460 and H460/TaxR cells. (a) The chemical structures of compounds in M4. (b) An overlay of structures of the four compounds in M4. (c) Effect of M4 treatment on cell growth in cancer cells and normal cells. The four compounds 27, 107, 167 and 254 were mixed with equal molar ratio. The cells were treated with different concentrations (μM ) of M4 for 72 h. The cell growth inhibition was measured by SRB assay. Each experiment was repeated three times independently. Data are shown as means±S.D. (d, e) Combination index (CI) for treatment in H460 and H460/TaxR cells, respectively. The CI was determined using the Compusyn software to evaluate the interaction of the four compounds in M4. A solid horizontal line marks CI=1. The CI offers definition for addictive (CI=1), synergism (CI<1), and antagonism (CI>1) in drug combination. The data are the mean values from three independent experiments