2.5. Cell viabilityThe MTT assay was performed to determine the number of viable cells present. The A549 cell line was cultured in a 96-well plate, and then MTT was added to each well and incubated for 4 h. After removal of the supernatant, the dark blue formazan crystals were dissolved in DMSO. The absorbance of the suspension was determined at 570 nm, and the measured values were reported as a percentage of the control (Alessandria et al., 2014; Hsiao et al., 2000; Mosmann, 1983).The toxicity and viability were calculated using Eqs. (1) and (2):