Fig. 1

Antiproliferative properties of FWGE and DMBQ. The effects of FWGE (mean IC₅₀: 10 mg/ml) and DMBQ (24 μmol/l; equal to the DMBQ concentration in FWGE) on cancer cell viability (a). Intracellular DCF fluorescence signals indicating intracellular ROS formation after 12 h (BxPC-3 cells) and 24 h (23132/87 and HRT-18 cells) of culture (b). The dashed line indicates the relative initial cell count at the start of treatment. For this, the seeded cells were stained with crystal violet directly after their adherence and the absorbance was normalized to 100 %. By definition, a cytotoxic effect was a reduction in initial viable cell count >15 %, a cytostatic effect a change in initial cell count of ±15 %, and a delayed growth effect an increase in the initial cell count >15 %. Ascorbic acid (2.4 mmol/l) was used to activate DMBQ [16]. Ascorbic acid had no influence on cancer cell viability or FWGE (not shown). Results are shown as mean ± standard deviation and representative for at least three independent experiments performed in triplicate. **P < 0.01, ***P < 0.001 in comparison to untreated control cells. RFU, relative fluorescence units