Cell Viability Assays

The MTT method was employed to determine the cell viability. In brief, cells were plated into 96-well plates at a density of 4×10³ cells/well. After incubation overnight, cells were exposed to BA alone, or in combination with other chemicals at the indicated concentrations for 24 and 48 h. After treatment, each well was added with 20 μL MTT (5 mg/ml) solution, followed by addition with 150 μL DMSO. The absorbance at 490 nm of the plate was measured by a Multiskan Ascent Revelation Plate Reader (Thermo, United States). The synergistic effect of combined treatments was evaluated by CompuSyn software package (Biosoft, Cambridge, UK). The combination index (CI) values of 0.9–1.1 indicate additive effect, and CI values of 0.1–0.9 indicate synergism (Adhireksan et al., 2017).