Cell viability assay

The viability of HaCaT keratinocytes was analyzed by conducting a colorimetric MTT assay. HaCaT cells (1x10⁴ cells/well) were cultured in 96-well plates and incubated for 24 h at 37˚C prior to treatment with different concentrations (1, 5 and 10 µM) of CMDA that were introduced in serum-free fresh medium. After incubation for 24 h at 37˚C, the supernatant was removed and 100 µl MTT [1 mg/ml (m/v)] in PBS was added to the cells. Following incubation for 4 h at 37˚C, 50 µl DMSO was added to each well to stop the reaction and solubilize the formazan crystals. The optical density of each well was measured at a wavelength of 540 nm using a GENios^® microplate reader (Tecan Group, Ltd.). Cell viability was plotted as a relative percentage against the untreated control group.