Cell viability assay

The effects of vernodalol on viability of human APL cells were analyzed by MTT assay (Sigma-Aldrich; Merck KGaA). Briefly, 5×10³ cells per well were plated on 96-well plates and treated with vernodalol at various concentrations (20, 40, 60, 80 and 100 µM) for the indicated times (24, 48 or 72 h). The RPMI-1640 with the compounds or 0.5% dimethyl sulfoxide (DMSO; as the control treatment) was then replaced with 180 µl of fresh media with 20 µl of MTT solution (MTT dissolved in PBS at 5 mg/ml) per well and incubated at 37°C for 4 h. The MTT-containing medium was discarded, and DMSO (150 µl/well) was added to dissolve the newly formed formazan crystals. The absorbance of each well was determined by a microplate reader (Synergy H4; BioTek China, Beijing, China) at a wavelength of 590 nm.