Figure 2

Caged xanthones and doxorubicin combination toxicity. KKU-100, KKU-M139, KKU-M156 and Chang cells were treated with the appropriate concentrations of isomorellin and doxorubicin or forbesione and doxorubicin for 72 h. Combination index (CI) vs. fraction affected (fa) plots were obtained from the median-effect analysis program (CalcuSyn, Biosoft, Cambridge, UK). Dashed lines indicate a CI of 1. Each value represents the mean of three independent experiments.