Inhibition effects of compounds plate 4 on HCT116 cells proliferation and in-vitro inhibition effects of selected compounds on CK2 kinase activity. A. After incubation with HCT116 cells for 48 hours, compounds 4A3 (hematein), 4A6 and 4A9 showed inhibitory effects on cell proliferation compared to the control sample (*4A1, DMSO). The longitudinal values revealed the absorbance at 490 nm recorded using an ELISA plate reader after addition of Cell Titer 96 AQueous One Solution Reagent to each well for 2 hours. Data represents the average of duplicate wells and bars indicate SD. Compound concentration: 4A3: 16.6 μM; 4A6: 23.1 μM; 4A9: 14.2 μM. B. Equal amounts (100 μM) of compounds were incubated with purified CK2, and CK2 activity was measured by Cyclex CK2 Assay/Inhibitor Screening Kit using 100 μM ATP. Ck2 kinase activity is represented as relative CK2 activity to controls (DMSO). Data represents the average of duplicate wells and bars indicate SD.4A3: hematein. Other negative results are not shown.