4.2. Preparation of Curcumin and Cisplatin

The preparation of curcumin and cisplatin used in this study was previously reported by our group [15]. The various concentrations of curcumin (10, 20, 30, and 40 μM) and cisplatin (5, 10, 15, 20, and 25 μM) were tested on both NSCLC cells for 48 h, and the same concentrations were used in the current study. In brief, both curcumin and cisplatin were purchased from (Sigma-Aldrich, St. Louis, MO, USA, Cat. No. C1386). Curcumin was dissolved in 1 mL Dimethyl sulfoxide (DMSO) to make a stock solution of 10 mM, while cisplatin (Sigma-Aldrich, Cat. No. C2210000) was prepared as a 10 mM stock in 0.9% sodium chloride (NaCl). Both curcumin and cisplatin were then diluted in complete RPMI-1640 medium to provide a substock and final working concentration and were filtered through a 0.22-μm membrane, aliquoted, and stored at −20 °C until further use. The viability of the cell was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2H-tetrazolium, inner salt (MTS) assay by Promega (Madison, WI USA). Cell viability was calculated according to the following formula: Cell viability (%) = cells (sample)/cells (control) × 100 and IC₅₀ was calculated using log formula.