Fig. 5

Screening of the radioprotective effects of hydroxytyrosol using the sulforhodamine B microtiter plate assay (a, b). Human keratinocytes were treated with the indicated concentrations of hydroxytyrosol for 24 h and irradiated with 12 Gy (a). In separate experiments, cells were treated with 20 mM hydroxytyrosol for 24 h followed by irradiation with the indicated doses, and a DMF of 1.35 at D₃₇ was calculated (b). For both experiments, cells were washed and incubated for a further seven days prior to fixing and staining. Means ± standard deviations of optical densities at 550 nm from a representative of at least five independent experiments are shown. Evaluation of the radioprotective properties of hydroxytyrosol by clonogenic survival (c, d). Human keratinocytes cells were treated with the indicated concentrations of hydroxytyrosol for 24 h prior to irradiation with either 4 (c) or 12 (d) Gy. Means ± standard deviations of survival from a representative of at least three independent experiments are shown