2.4. MTT cytotoxicity assay (CC50)

To evaluate the half maximal cytotoxic concentration (CC50), a stock solution of the tested sample of “Art/Zn” was prepared in 10% DMSO that was diluted with dd.H₂O and then addition to the working solutions with DMEM. The cytotoxicity of Art/Zn sample was tested by using the 3-(4,5-dimethylthiazol -2-yl)-2, 5-diphenyltetrazolium bromide (MTT) in (VERO-E6) cells. The (VERO-E6) cells were seeded in 96 well plates via concentration of (100 μl/well) and incubated at 37 °C, for 24 h in CO₂. After 24 h. Seeded cells were treated with different serial concentrations of novel Art/Zn complex in triplicates. After 24 h, the supernatants were discarded immediately, and the cell monolayer was washed with sterile saline phosphate buffer (PBS)1× for 3 times, MTT solution was added immediately to the target well and then incubation for 4 h at 37 °C. The collected formazan crystals formed were highly dissolved with ∼ 200 μl of isopropanol mixed with 0.04 M HCL. The absorbance was measured at wavelengths (540–620 nm) using a well plate reader. The % of cytotoxicity compared to the untreated (VERO-E6) cells was determined with the following equation [26].