Detection of cell viability by MTT assay

Paeonol was purchased from Aladdin Industrial Corporation (Shanghai, China) and diluted to different concentrations in DMSO (0, 0.05, 0.1, 0.2, 0.4, 0.6 and 0.8 mg/ml). Cells were seeded (5×10³ cells/well) in a 96-well plate and were treated for 24 and 48 h at 37°C by paeonol at different concentrations separately. The treated cells were then screened using the MTT assay. Into each well, 20 µl MTT (5 mg/ml) was added and incubated for 4 h. The medium was carefully aspirated, and 200 µl dimethyl sulfoxide was added into each well and incubated for 10 min at 37°C or oscillated for 10 min until the blue-violet crystals were completely dissolved. The absorbance value was determined at 570 nm using a microplate reader and a cell growth curve was then drawn.