2.3. Cell Viability Assay

Cytotoxic effects of Rg3 on MPBPAs and MPBAs were evaluated by MTT assay. Cells were cultured for 24 h in 24-well plates (Corning Inc.) in DMEM containing 1% FBS and the indicated doses of Rg3. After removal of the culture medium, cells were incubated with 300 μL of MTT (0.5 mg/mL) for 2 h at 37°C in a 5% CO₂ incubator. Formazan crystals in viable cells were dissolved in 200 μL of DMSO, and the absorbance in each well was measured at 570 nm using a SpectraMax ELISA reader (Molecular Devices, San Jose, CA, USA).