MTT viability assay

The cells were seeded at a density of 2×10³ per well in a 96-well plate and incubated for 24 h. CQ was added to each well in a concentration series of 50, 100, 150 and 200 µmol/l and incubated for a further 12, 24 and 36 h. A total of 20 µl MTT (5 mg/ml; Sigma-Aldrich) was added to each well and incubated at 37°C for 4 h, then 100 µl DMSO was added to each well to dissolve crystals and the plate was agitated for 10 min. Absorbance values at 490 nm were detected by a multi-mode detection platform (Molecular Devices Austria GmbH, Wals, Austria). Inhibition rate was calculated as [(A_control - A_blank) - (A_treated - A_blank)]/(A_control - A_blank)x100. Each experiment was assayed in triplicate.