MTT cell viability assay

Cell viability was measured indirectly using the MTT colorimetric assay. Briefly, A549 or H1299 cells were seeded in 96-well plates and incubated at 37° C overnight to allow attachment. Following cellular attachment, the cell culture media was discarded and replaced with fresh cell culture media containing different concentrations of drugs/agents. These cells were incubated with the drugs for designated periods and then incubated with cell culture media containing 0.5 mg/mL MTT reagent solution. After 3 hours, the MTT containing media was discarded and the purple formazan crystals in each well were solubilized using 200 μL of DMSO. The absorbance of the resulting solution was determined spectrophotometrically by measuring the optical density (OD) at 570 nm. The OD values of the solution in the wells containing untreated cells were considered as 100% cell growth and used as a reference to calculate the percent growth of other wells. The arithmetic mean of 3 technical replicates was calculated at each concentration of PAC and WFA alone and in combination to obtain the percent cell viability. Data were expressed as mean±SD of more than 3 separate experiments.