2.6. Cell viability test

Cell viability was estimated by the MTT reduction assay, which is based on the conversion of MTT to formazan crystals by mitochondrial dehydrogenases. Following incubation for 24 h at 37 °C and 5% CO₂, the supernatant was removed and each well was treated with 100 μL DMSO to dissolve the formazan crystals. Absorbance was measured using ELISA reader at a wavelength of 570 nm. Cell viability was normalized to relative percentages as compared with untreated controls.