Fig. 1

The cytotoxic effects of EP root extract on human lung cancer cells. A549 cells were exposed to different concentrations of EP extract (50–900 ng/mL) for 24 (a), 36 (b) and 48 (c) h. The percentages of viable cells were determined using MTT assay. Treatment with increasing concentrations of EP extract induced a time and dose dependent pattern of cell death in A549 cells. Pre-treatment with 10, 25 and 50 ng/mL of the CB2 antagonist (AM630) attenuated cell death significantly (d). Data represent mean ± SD of three separate experiments. The statistical differences between treated and untreated groups were analyzed by ANOVA and are indicated by asterisks (* = P < 0.05, ** = P < 0.01, *** = P < 0.001, **** = P < 0.0001)