MTT cell viability assay

A total of 5×10³ cells/well were cultured at 37°C and 5% CO₂ for 24 h in 96-well plates. Following incubation with SSD (0, 2, 4, 6, 10, 12 or 15 µM) for 24 h, 20 µl 5% MTT solution was added to each well and incubated at 37°C and 5% CO₂ for 4 h. Subsequently, the medium was discarded and the purple formazan was dissolved in 150 µl DMSO/well. The absorbance was detected using a microplate reader (iMark™, Bio-Rad Laboratories, Inc.) at 495 nm. The half maximal inhibitory concentration (IC₅₀) was calculated using SPSS 17.0 software (SPSS, Inc.).