Cell Viability Assay

Cell viability of cells (Huh7, HepG2, and SK-Hep-1) with TB treatment was determined by MTT assay. Cells were seeded on 96-well plates with a density of 8×10³ cells/well in 200 μL medium overnight and then treated with TB at various concentrations (0, 50, 100, 200, 300, 500, 600 μg/mL) for 24 h and 48 h (only for Huh7 cells). Twenty microliter MTT solution (5.0 mg/mL) was added to each well and the plate was incubated at 37ºC for 4 h. After the solution was pipetted off, 100 μL DMSO was added to each well to dissolve the formazan crystals. Then the optical density (OD) value was measured at 490 nm with a microplate reader (Biorad Laboratories, Inc., CA, USA). Inhibitory rate (%) = [1−(TB-treated OD/untreated OD)] × 100%. The low, medium, high doses of TB were determined as 100 μg/mL, 200 μg/mL, and 300 μg/mL for further use.