In order to evaluate the effect of triptolide on the growth of HepaRG cells, cell proliferation was assessed using a MTT assay. HepaRG cells (5.0 × 103 cells/well) were plated into 96-well plates overnight. The cells were treated with different concentrations of triptolide (0, 100, 200, and 400 nM) for 24, 48, and 72 h, while the control received 0.1% DMSO in place of triptolide. The cells were incubated with new culture medium containing MTT working solution (0.5 mg/mL) for 4 h at 37°C. Thereafter, the culture supernatant was removed from all the wells, and the water-insoluble formazan crystals were dissolved in 150 μL DMSO. The absorbance of the formazan solution was measured at 570 nm in a microplate reader (Thermo, Multiskan, GO, United States).
In the assay of lactate dehydrogenase (LDH), the cells (5.0 × 103 cells/well) were seeded into 96-well plates overnight and then treated with serial concentrations of triptolide for 24 h. The supernatant was used for the assay of LDH activity with a commercial LDH kit according to the manufacturer’s instructions. Absorbance was measured at 490 nm in a microplate reader (Thermo, Multiskan, GO, United States). Dual-wavelength measurements were performed with 600 nm as the reference wavelength. All the experiments were performed in triplicate.
In the assay of lactate dehydrogenase (LDH), the cells (5.0 × 103 cells/well) were seeded into 96-well plates overnight and then treated with serial concentrations of triptolide for 24 h. The supernatant was used for the assay of LDH activity with a commercial LDH kit according to the manufacturer’s instructions. Absorbance was measured at 490 nm in a microplate reader (Thermo, Multiskan, GO, United States). Dual-wavelength measurements were performed with 600 nm as the reference wavelength. All the experiments were performed in triplicate.