3.11. Cell Viability MTT Assay

Cytotoxicity was assayed through the colorimetric microculture MTT assay. Cell suspensions were plated in 96-well plates in triplicate at an initial density of 7 × 10⁴ cells mL⁻¹ and incubated at 37 °C for 24 h. After the incubation, the cells were treated with various concentrations of the evaluated compounds (7a,b, 8a,b, 9a,b, or 10a,b) and incubated for 24 and 48 h. After the treatment, the medium was removed, and an MTT solution (0.4 mg mL⁻¹) was added to each well and further incubated for 2 h at 37 °C. Then, DMSO (100 µL) was added for the solubilization of the formazan crystals, and the absorbance intensities were measured in a microplate reader (SpectraMax M2e, Molecular Devices, Sunnyvale, CA, USA) at 570 nm. The percentage of viable cells was calculated in relation to the control to determine the cytotoxic concentration that reduces 50% of the cell viability (IC₅₀).