Figure 1: Dose-response effect of extract A on micronuclei frequency. HaCaT cells were plated as described in materials and methods and treated with calendula extract A for 48h. They were then treated for 1h without H2O2 (No ROS challenge) or with 1h 300 μM H2O2 (ROS challenge). The frequency of micronuclei (MN) per 1000 binucleated cells was determined using the cytokinesis Block micronucleus assay (as described in section 2.8). Data shown as mean ± SEM; n=3; 1% (v/v) A=0.88mg dry weight equiv/ml.