Figure 5.

Photoprotective effect of genistein and daidzein in combination evaluated with the Comet assay. (a) BJ-5ta cells were treated for 2 h with different combination of genistein and daidzein before UVB irradiation (60 mJ/cm²) and harvested 24 h after UVB. The Comet assay procedure (see Section 2) was performed according to the manufacturer's instructions. The results were quantified using the NIH Image Software. The data are reported as Tail Moment (TM) and represent the mean ± SD of three independent experiments. *P < 0.05, **P < 0.001, ***P < 0.0001, °°°P < 0.0001 (Ctrl: untreated and unirradiated control cells; without substance: untreated and irradiated (60 mJ/cm²) cells). (b) Cell viability was measured by Trypan blue in BJ-5ta cells incubated with genistein and daidzein in combination for 24 h (genistein 6 μM + daidzein 24 μM, genistein 4 μM + daidzein 16 μM, genistein 2 μM + daidzein 8 μM). The results are reported as percentage of cell viability and the values represent the mean values ± SD of three independent experiments (Ctrl: untreated control cells). (c) Image of alkaline single-cell gel electrophoresis performed on BJ-5ta treated with genistein or daidzein alone or in their most effective combination (Ctrl: untreated and unirradiated control cells; without substance: untreated cells with severe DNA damage after irradiation with 60 mJ/cm² UVB).