Photoautotrophically grown Chlorella vulgaris show genotoxic potential but no apoptotic effect in epithelial cells

This study investigated the effect of Chlorella vulgaris (C. vulgaris) on genotoxicity, cytotoxicity and apoptosis in Caco-2 and HT-29 cells. C. vulgaris significantly induced DNA damage in both cell lines at a concentration of 200 µg dry matter/mL (comet tail intensity CTI: 24.6 ± 4.7 % for Caco-2, 16.6 ± 0.9 % for HT-29). The application of processing (sonication, ball-milling) did not affect the genotoxicity negatively and lowered the lipid peroxidation in C. vulgaris preparations. C. vulgaris induced intracellular formation of reactive oxygen species in human cell lines and might be responsible for the genotoxic effect. A solid fraction mainly triggered the observed DNA damage (CTI: 41.5 ± 1.9 %), whereas a hydrophilic (CTI: 7.9 ± 1.7 %) and lipophilic (CTI: 10.2 ± 2.1 %) fraction revealed a significantly lower tail intensity. Even though C. vulgaris significantly induced DNA damage in both cell lines possibly through intracellular formation of reactive oxygen species, however, it is repaired after a 2 h-recovery time or avoided at lower concentrations. In addition, none of the preparations indicated an adverse effect on cell proliferation or revealed apoptotic activity.