Figure 4.

The quantification of reactive oxygen species, expressed as relative luminescence units (mean ± SD), in human fibroblasts and keratinocytes. Cells were incubated for 24 h with culture medium (C) as the control in the presence of a commercial phycocyanin (PC) and a phycocyanin fractionated from Arthrospira platensis: (a) not treated with the prooxidant menadione, (b) treated with menadione. Statistical analysis was conducted with Student’s t-test by comparing each treatment with control cells; the level of significance set at (***) p < 0.005, (**) p < 0.01 and (*) p < 0.1.