Cell viability test using MTT assay

Cell viability was examined by MTT assay following a previously described procedure [22]. Cells (5 × 10⁴ cells/well) were stimulated with different doses of chlorophyllides (50, 80, 100, 150, and 200 μg/mL). After treatment for 24 h, supernatants were removed from the wells and then 1% of 20 μL MTT solution was added to each well. The plates were incubated for 4 h at 37°C and the optical density was determined at 595 nm using a multi-well Multiskan spectrophotometer (Thermo Fisher Scientific, MA). All measurements made in the 96-well plates were performed using five technical replicates. Further statistical analysis was performed by one way ANOVA using SigmaPlot Version 14.0.