Cytotoxic Effects of Curcumol and Ribavirin

The cells were treated with different concentration of curcumol (0.1, 0.05, 0.025, 0.0125, 0.00625, 0.003125, 0.0015625, 0.00078125 mg/mL) and ribavirin (4, 2, 1, 0.5, 0.25, 0.125, 0.0625, 0.03125 mg/mL) in the 96-well plates (0.1 mL/well). At the same time, untreated group (no drug) was applied and were incubated at 37 °C and 5% CO₂ for 72 h. The morphology of cells in the culture was observed every day and photographed. After 72 h of incubation, the supernatant was discarded, 0.02 mL of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H- tetrazolium bromide (MTT, Solarbio, China) was added to each well and incubated for 4 h. Subsequently, the supernatant was discarded and 0.15 mL of DMSO was added to each well, and incubated for 30 min. The optical density (OD value) was measured at 490 nm using the plate type multi-function analyzer (Tristar 2 SLB 942, Berthold Technologies, Berthold Technologies). The cytotoxic ratio (CR) was expressed as CR = (OD control—OD test)/OD control. CC₅₀ was calculated by nonlinear regression analysis using GraphPad Prism™ software 5.0 (GraphPad Software, Inc. California, USA) [37 (link)]. CC₅₀ is the constituent concentration at which 50% of cells have developed lesions while MNTC is a maximal concentration of a constituent that enables at least 80% of cells to survive [38 (link)].