Effect of the application of methanol extracts of four strains belonging to the Nannochloris (SBL1 and SBL4), Picochlorum (SBL2) and Desmochloris (SBL3) genera, applied at a concentration of 125 µg/mL for 72 h, on the viability of human hepatocarcinoma (HepG2), cervical carcinoma (HeLa) and non-tumoral murine stromal (S17) cell lines, in comparison to a control without extract (DMSO, 0.5%, v/v). Bars and lines correspond, respectively, to cell viability and selectivity. * Significant differences (p < 0.001) compared with the control (n = 6). Half maximal inhibitory concentrations for etoposide used as a positive control were 1.9, 4.2 and 10 µg/mL for HepG2, HeLa and S17 cells, respectively.