MTT assay

Cell viability was detected by MTT assay. H9c2 cells plated in 96-well plates at 3×10⁴ cells/well were pre-treated with cyanidin for 3 h and co-treated with cisplatin for 24 h, and then cells were incubated with different treatments and different times. After incubation, the medium was removed and 10 µl MTT (5 mg/ml) (Sigma-Aldrich, Saint Louis, Missouri, USA) was added for 4 h. After the incubation, 150 µl DMSO was added to dissolve formazan crystals, and the absorbance was measured at 570 nm with a microplate reader Elx800 (Bio-Tek, Winooski, Vermont, USA).