Fig. 6.

The caspase-3 activation of NB4 cells treated by 0, 5, 10, 20 μg/mL of citral for 24 h. The results showed that citral induced caspase-3 activation, one hallmark of apoptosis, in a dose-dependent manner. Due to the insolubility of citral in RPMI-1640, ethanol was used as cosolvent in this experiment, we also incubated NB4 cells in the presence of ethanol (the final concentration in medium was 5 %V/V, equivalent to concentrations in other citral groups) to investigate its apoptotic effect to cells. No significant effect of ethanol was observed (a indicates the results from flow cytometry and b indicates the statistical results) (* compared with group 0 μg/mL, p < 0.05)